GREAT Article about Celestions!!!!


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Jun 4, 2012
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Written by Filippo F. Olivieri, AKA Fil at found here:

Celestion Loudspeakers: From Blues to Greenies and beyond

I had to remove the pics, but go to the link above to see them.

Celestion Loudspeakers: From Blues to Greenies and beyond

Speakers are extremely important when we are talking about tone. They give the amp its “voice” and so, in order to get the right sound, you will need to use the right speaker. So, what should I get to achieve the tone I want? Well, now that’s a tricky question.
This article will be a (maybe not so) small post about the history of Celestion, as well as a brief description of each model they produced over the years. Of course, this won’t cover every one of them. I’ll simply feature the ones that I think are the most popular and most widely used models.
Let’s start, shall we?
Early years and the G12 AlNiCo
Celestion started as a manufacturer of speakers for general use (radio, TV, etc.) back in the 1920s. In 1947, it was bought by British Rola and, one year later, production moved to Thames Ditton.

AlNiCo Blue 15w (as used by VOX) It wasn’t until the 1950s that Celestion developed their first guitar dedicated speaker: the G1
AlNiCo T530 (a.k.a. “Blue”), basically a modified version of the CT4507 radio speaker. These first speakers went through quite a few changes (also appearing in different colours like silver, chrome and red – also with different codes) during the early years, but they remained with a low (in today’s standards) 15w (20w in latter versions) power handling and with both 8ohms and 15ohms options. It was used in Vox and early Marshall amps. With the 100db sensitivity, it was a very “loud” speaker. It was also bright, lively and had a more restrained bottom end. It’s probably more suited for Blues with clean or lightly crunchy tones.
About Greenbacks
Let’s start with a simple little thing. Most of you probably already know, but it’s worth to clarify this to the “newbies”, alright? (just joking! ;P)

G12M Greenback​
The old Celestions from the late 60s and early 70s had a green plastic back cover and this is why they were nicknamed “Greenbacks” (no sh*t, Sherlock!), but “Greenback” does not refer to any specific model. It’s simply a “generic” name that was given to the speakers of this period, similar to how “Plexi” is a name to all the pre-1969 Marshalls. In other words, both the G12M and G12H can be called “Greenbacks”. Not only that, but also their many variations, such as the 55hz “bass” cones and etc. But I will explain everything in details shortly. The bottom line is: be careful when using the name “Greenback”.
Early 20w G12M 25w 75hz​
Celestion first introduced the G12M (medium 35oz ceramic magnet) around 1965 with a power handling of 20w, with options of 8ohms or 15ohms and a resonance frequency of 55hz (bass cone) or 75hz (lead cone). Around 1968, the G12M became a 25w speaker and the label of the 15ohm version also changed to 16ohm at some point.
G12M Blackback 25w 55hz​
The sound of the G12M tends to be very pronounced on the midrange, with a sweet, woody, warm and smooth sound. It also tends to compress a lot when pushed too hard, because of the lower power handling and so, it can sound a bit muddy if you are not careful with the amp EQ. It’s not a very loud speaker, since it has an efficiency of 96db (or 97db or even 98db in a few versions).
So, I’ll emphasis again the fact that it’s not the power handling (watts) that will determine if a speaker is “louder”, but the efficiency (db). The power handling will only tell how much wattage it can take safely without blowing.
Also, an important note is: 15ohm to 16ohm does NOT really make a difference, since it’s too small on its own. I’d say it was more of a label mistake. You can run any 16ohm amp safely through them with no worries. Because of this, I will always call them 16ohm speakers in this post from now on, even if the label says otherwise, in order to avoid confusion.
The G12M speakers were mostly found in the old Marshall 1960A and 1960B cabs.
1969 Marshall 1960A cab with G12M 25w 75hz​
The 55hz version was used in the 1935A and 1935B cabs (same measures as a 1960 cab – they usually came with a “Bass” logo on the upper corner until the early 70s).​
1970 Marshall 1935A cab with G12M 25w 55hz and the “Bass” logo​


An early G12H 25w
Note how bigger the magnet is when compared to the G12M​
The G12H (heavy 50oz ceramic magnet) was introduced as a heavy-duty speaker to handle more powerful amps (in a similar way to the G12M, the G12H’s first versions handled only 25w and then they were powered up to 30w in 1968 – Yeah. It can be a bit confusing – the labels are even more unreliable in this transitional period, so you have to be careful). It also was available in 8ohm and 16ohm, as well as the 55hz or 75hz versions.
G12H 30w 75hz​
The G12H is generally regarded as a more “balanced” speaker, with no emphasis on any frequency in particular. Because of this, it’s also considered a bit cold and stiff by a few players. On the other hand, due to the higher power handling, it won’t compress as much as the G12M when pushed and will sound more “open”. This is also why the G12H has a certain “bright” character, since the mid frequencies won’t mud it out. It also has a lot of low end available. The big magnet provides a very strong attack and aggressive sound. I’d say even “percussive”, depending on the situation. The 100db efficiency makes this speaker even louder, with a huge impact, especially in a 4×12 cab.

1969 Marshall 1982B cab with 30w G12H 55hz and the (lovely) “100″ logo​
The 55hz version was used by Marshall in the 1982A and 1982B cabs. During the late 60s, they had a “100” logo on the upper corner, indicating that the cab was loaded with the heavy-duty 25w speakers (remember that early G12M had only 20w and the G12H speakers had 25w instead – thus making the 1982 the first 100w cab). Just before the 70s, the “100” logo was dropped (the cab was now rated at 120w, since the G12H was powered up to 30w sometime around April 1968 – you can still find the “100″ logo on cabs made up to 1969) and so, since they also had the same measures as the 1960 model cabs, it’s almost impossible to tell them apart without further inspection (just like the 1935 cabs).
I’m not really sure if the 75hz version was used by them at all.
1971 Marshall 1982A cab with G12H 30w 55hz​
55hz vs. 75hz: What is this all about?
I bet a few of you were wondering this.
To say it quickly, 55hz cones were designed for bass. 75hz cones were designed for guitar.
So, this means we can’t use 55hz speakers with a guitar? No, you CAN (remember that the JTM-45 was a copy of the Fender Bassman – a BASS amp). And this is the point: bass speakers will give you a different tone.
How different? Now, this will be harder to put into words.
Being a bass speaker, it doesn’t necessarily mean the speaker is “dark”. It just means it will deal with lower frequencies better. In other words, bass speakers will give you a “rounder” low end, although many still say they are really… darker sounding (I know… I contradicted myself, but it’s really what some people say), but I would describe them as “deeper” instead.
Guitar speakers tend to deal better with mid-frequencies, so they will have a little more “sizzle” in that area. This may please you or not, since what some hear as “hot”, may sound like “harsh” to a few others. I like to think of these speakers as slightly “drier”.
It’s a really subtle difference, but I can tell you it’s really there. It’s more about all the “overtones” produced. It’s quite complex.
And I know… It doesn’t make much sense to say a speaker that was designed for guitar may sound bad for a guitar player, but people like to experiment, don’t they? Plus, we all have different ears.
Jimmy Page in 1969 playing through G12H 55hz loaded Marshall 1982 cabs​
If you want to have an idea of what I’m talking about: Paul Kossoff favoured bass speakers (a bit unclear if they were G12Ms or G12Hs, but they were 55hz), Jimmy Page used 55hz G12Hs, as did Hendrix during his latter years.
The Young brothers used mostly 75hz speakers through the years, as well as Van Halen and many others. My memory is a bit short right now, but you are very familiar with the 75hz speakers. Most of the G12Ms we see and hear are 75hz, so you probably know how they sound like.
Angus and Malcolm playing through G12M 75hz loaded Marshall 1960 cabs (or… I think so)​
“Pre-Rola” Greenbacks: Why are they so desirable?
A common thing is to refer to these old late-60 speakers as “Pre-Rolas”.
Pre-Rola “Celestion LTD” label G12M​
The “Rola Celestion LTD” labels didn’t appear until the early 70s, but, as you read a while back, Rola already owned Celestion since 1947. So, all of them are actually “Rola” Celestions, one way or another and yet, this naming has become a standard.
They are the “Holy Grail” of the Celestions. The sweetest and perhaps most desired speaker ever among the gear-heads. So, why is it so special? Is there anything special at all? Or it’s all just hype?
The truth is in the… cone!​
Aside from all the MOJO and “mysterious” factors, there’s one thing in particular that pretty much defines the “Pre-Rola” tone: back in the day, Celestion didn’t actually manufacture the speakers from scratch, but actually used cones made by another companies, such as Kurt Mueller and Pulsonic, the latter one being mostly used in the late 60s – early 70s.​
So, basically, when we talk about “Pre-Rola” Celestions, we are talking about Pulsonic cones.

Pulsonic lead cone​
And so, if this is the secret for the “magic” tone, then why didn’t they continue using these Pulsonic cones? Well… Call it fate, irony, Murphy’s Law or anything you like, but the Pulsonic Factory was destroyed by a fire in 1973 or 1974 and the cone formula was probably lost forever.
It’s a bit unclear if this fact itself made the Pulsonic cones more desirable, but it’s true that they do sound different.
One last note is that very early Celestions had a paper voice coil that gave them a slightly different voicing. They are also very desired for their unique tone, but can sometimes lack in power handling. The PVC was dropped during 1968 in order to make the speakers more rugged and the result was the increase of power.
“Rola” Greenbacks: Don’t put them down!
In 1970, Celestion moved their production to Ipswich, Suffolk and so, the new label didn’t only feature the new location, but also the “Rola Celestion LTD” name.
1971 Rola label G12M 55hz​
They were still using Pulsonic cones, so what exactly is different in these early “Rola” Greenbacks? Nothing. They are the same, but with a different label. That’s all. This is exactly the reason I don’t like the “Pre-Rola” naming. To me, “Pulsonic Celestion” is a better way of describing this breed of speakers.​
Pulsonic lead cone with shortened code, as used from 1971-1973​
Crembacks: Pulsonic to RIC cones
Four Creamback G12H 55hz speakers inside a 1973 Marshall 1982B cab​
By 1972-1973, they started to use cream or grey-ish colored plastic back covers instead of the famous green ones. A bit off-putting, maybe (unless you prefer cream or don’t care about the colour – like me), but it didn’t change the sound at all; at least not in these early Creambacks.
RIC xxx cone of a post-1973 Celestion Creamback​
The problem is: since the Pulsonic cones supply was cut short by late 1973, RIC label (Celestion made) cones were used from 1973 to 1975. These are said not to be as “sweet-sounding” as the Pulsonics, but that’s subjective. We will talk more about this in a while.
Blackbacks: Kurt Mueller cones
Blackback G12M​
From late 1975 onwards, Celestion speakers would have Kurt-Mueller cones. Also around this timeframe, the black back plastic covers replaced the cream ones. These speakers had their own character. They are said to be more aggressive, more efficient, maybe a bit shriller and colder, as well as having a sharper high end. This was the last incarnation of the old original “(Black)Greenback” G12M and G12H as we know them today, before they were replaced by the G12-65 and the G12-80 in 1978-1979.​
Kurt Mueller 1777 lead cone​
Pulsonic vs. RIC vs. Kurt Mueller: wich is the best?
So, here is the topic I wanted to talk about. What kind of speaker will give you the “best” tone? Truth is: there’s no answer.
The Pulsonic cones have the reputation of being the sweetest of them. Now, why were the Pulsonic cones in particular chosen as the “Holy Grail”? Only the sound? Perhaps, yes. I’m in no position to judge that, since I’ve never played one of them, but I believe there are more reasons.
Eric Clapton and his “little” toys (Denmark, 1967)
Yeah, the bottom cabs are taller: they were like this before 1968. The speakers in those cabs are probably G12H 25w (“100″ logos = 1982 cabs).​
If we think about the Classic Rock history, we can notice that the time when it truly exploded was exactly during the late 60s and early 70s, with bands like Cream, Led Zeppelin, the Jimi Hendrix Experience, Free, Deep Purple and others: the exact same period when the Pulsonic Celestions were being made and, coincidentally or not, it was also the time of the “Plexi” Marshalls.​
Paul Kossoff in 1970 or early 1971
Really, who don’t want to sound like those guys?​
So, I think it’s not wrong to believe that the sound these guys created with this gear in particular is the real reason why everyone is crazy about them. It’s simply the sound we all grew up loving, so of course we will identify these sounds as “the best”.
But these artists didn’t use this gear because it was the “Holy Grail” of tone. They simply used it because it was what was available to them. And it sounded good.
So, is it right to say that, just because most people love the “Pulsonic cone” sound, the RIC and Kurt Mueller cones are not as good?
AC/DC in 1977 using Blackbacks: Pulso… what? F*ck that crap!​
And I guess AC/DC fans are the living proof of this fact. The Young brothers came rocking out in the mid 70s, so evidences indicate that (and it’s well documented) they used mostly RIC and Kurt Mueller era Celestions. And still, the tone they got with them is out of this world. They didn’t need Pulsonic cones to sound good. They made their Celestions sound good by themselves.
And so, AC/DC fans will love the RIC and Blackbacks just the same.
Then, why can’t we all love these cones too?
If all these guys had come around during the RIC years, I bet that they would have been the most desired ones instead.
And here is a nice post comparing a 1972 Pulsonic to a 1974 RIC to prove my point.
(Clips with a Gibson at the bottom of the page, by the way)
Listen to these clips carefully and open-mindedly. And tell me: do any of these two speakers sound actually “bad” to you?
Well… I was actually browsing around while listening to them and I thought: “damn… this sounds good!” I went to check and what was my surprise to see that the file I was listening to said “74 Creamback” (RIC).
Blasting the 80s: G12-65
G12-65: A G12M on steroids!​
Around 1978, Celestion decided to “upgrade” their medium magnet speaker from 25w to 65w. The result was the G12-65. The speaker was very similar to the old G12M (still with a 35oz magnet) and with the efficiency of 97db, but because of the larger dust cap that was used, it had a deeper bottom end, slightly scooped, but still very strong mids and more restrained highs. This is also partially caused by the higher power handling itself. Since it can take a lot more power, it won’t compress like the 25 watter, but this also means it won’t break-up as easily.
Front of a G12-65: note the bigger dust cap​
1979 Marshall label G12-65 85hz speakers​
It was offered in both 8ohms and 16ohms, as well as lead cone (85hz - yes, a bit higher than the old ones) and bass cone versions, but I’ll tell you right now that the bass cone has the reputation of being worthless for guitar use. Probably it’s still usable, but it seems to be a bit too dark and lacking on the treble side.
1979 Marshall 1960A cab with 85hz G12-65​
The 85hz lead version was found in all the Marshall 1960A and 1960B cabs after 1978 until around 1983.
The bass version was used in the 1935A and 1935B cabs of the same period. Be careful: they look exactly the same as the 1960 cabs!
From 1981 onwards (JCM800 Series), the cabs had a golden badge in the lower part that says either “JCM800 Lead Series” or “JCM800 Bass Series”.
Badge of a JCM800 1935A with ’444′ bass cone G12-65​
According to a few sources, the G12-65 is said to have over 40 variations in its short lifespan (Yes, I’m shocked as well).
So let’s make a pause and consider this for a minute. Maybe this information is not exact, but what can we interpret from it? It basically means that the speaker changed a lot during the time it was produced. Even so, I doubt that these differences were that huge and I bet they were so subtle it would be impossible to hear by most of us
Break for a little tone talk
And this also raises a question: When we think of the “perfect tone”, what speaker are we talking about? If you say: “Pulsonic G12M 75hz” or even “early G12-65 75hz”, how can we be exactly sure “what” tone we are looking for? Is it the sound we hear on records? Perhaps. Or is it what we “think” they should sound like? It’s impossible to tell. And it’s also impossible to tell how a speaker sounded over 40 years ago when we are listening to them today, with years and years of aging. Add to that the fact that production back then was pretty much inconsistent. A speaker could turn out to be magical or pure crap being produced in the same day.
This is why making comparisons is a wild goose chase. It can be too much to expect that a reproduction made today will sound exactly like the speakers of those distant years when even back then they varied from one to another.
So, I’ll just give my humble opinion: as far as I know, a good speaker will be always a good speaker, be it what brand it is, be it what model it is, be it made when it was. Some will work for you and some won’t. There’s no reason to keep saying: “this doesn’t sound like A”, “B sounds way off because it doesn’t have the midrange of C. Don’t buy it” and so on.
I’m not saying it’s wrong to make these comparisons. Heck, I even do them myself very often. But what I’m trying to say is: don’t take all of this too seriously; after all, it’s just for fun, isn’t it? There’s no “right” when we are talking about tone. The thought that “There’s always something that will sound better than the gear we already have and it’s impossible for us to get it” is way too depressive. At least I think so. And so, if we find something that sounds good, why bother to lust for something else that is “intangible”, comparing minimal nuances that are almost impossible to hear? Yes, experimenting different stuff is great and this is why tone-hunting can be so fun. But there’s no reason to keep looking for something “perfect”. Just look for what sounds good to you.
And it’s not just about the gear. It’s how you use it.

After all, nothing remains the same forever, so why should tone be like that?
I’m saying this because you guys who love the G12-65 might want to collect all the 40 versions of it. So don’t get too excited! But if anyone wants to, I will not stop you! (kidding!)
Let’s get back to the Celestions. You will have more of this a bit later when I start talking about Reissues and Boutique replicas.
Blasting the 80s part 2: G12-80, Vintage 30, G12T-75 and a few others
Now, here is when things start to get tricky for me. I didn’t intend to make the G12-65 as a separated topic, but it ended up like that (and rightly so), but now I reached a point where I have dozens of speakers to cover and I guess most of you don’t care about many of them. So let’s try to be brief.
G12-80: the G12-65′s big brother​
The G12-80 was the reworked version of the G12H 30w (just like the G12-65 was the reworked version of the G12M). It had the same 50oz magnet, handled 80w, had 8ohms and 16ohms options and, again, lead cone and bass cone versions (a few reports of success using the bass cone with guitar, but I’m not very sure). It’s said to have a similar tone to the old 30watters, but with more bottom end and less treble, retaining the strong punch and a lot of volume (efficiency of 100db).
The bass version was found on the Marshall 1982A and 1982B cabs from around 1978 onwards. Not very sure about the lead version though. Information about these old Marshall cabs is rather scarce. I’ve heard of folks who found the lead version instead of the bass version inside de 1982 cabs.
JCM800 1982A cab with bass G12-80 speakers​
The G12-80 had a short life too, being replaced by the G12H-100. The G12-65 was replaced by the G12M-70 in 1983
Not much info about these speakers, but they don’t have that good of a reputation. Probably they work better with 80-ish high gain tones.
Names here start to get messy too. I wonder why the magnet sizes were omitted in the G12-65 and G12-80 (their names should be G12M-65 and G12H-80, at least in theory).
Anyway, it seems that the G12-80 also evolved into the Classic Lead 80 (still in production to this day)and the G12M-70 became the Modern Lead 70 (discontinued, it seems).
There’s a speaker called G12K-100 in Celestion’s website. I’m not sure if it’s the same as the G12H-100, but seems to be so.
Yeah. The G12T-75 looked like this back in the mid-80s​
The G12T-75 first appeared in 1985, as the new version of the G12M-70. Curiously enough, this speaker is in production until today and is found almost everywhere, also being used in the current Marshall 1960A and 1960B cabs. It’s offered in both 8ohms and 16ohms.
Handling 75w, this speaker is heavily mid-scooped, with a very strong low end and shrill highs. Like most of the medium magnet Celestions, it has an efficiency of 97db.
It’s funny that Celestion’s site markets them as “a Greenback on steroids”, quoting that many see them as “the ultimate incarnation of the original G12M”. In the sense that it is an evolution of our beloved 25 watter, it’s a true statement; but to me, that sounds very laughable. The G12T-75 is the complete opposite of a G12M. It’s still a good speaker for more modern sounds, though.
Present day G12T-75s inside a Marshall 1960B cab: scooped mids of doom!​
One thing that is worth mentioning is that the G12T-75 also changed a lot over the years – early versions had a vent on the magnet, as did the G12-80 (one of the things that the CL80 is missing as well) – and so, there are reports that these first versions had a better tone (smoother high end) than the ones made today.
So… what are you, anyway?​
The G12 Vintage 30 was introduced 1986, trying to recreate the feel of the old AlNiCo speakers, that weren’t being made anymore (the Cold War made Cobalt – the “Co” of “AlNiCo” – too expensive). The result wasn’t exactly accurate, but it did sound more “vintage” than most of Celestion products at the time. Since it used the same heavy 50 oz magnet as the extinct G12H 30w, it was marketed with such a strange name, even though it was not even rated at 30w. The demand for a more classic sounding speaker was quite big, so it’s easy to understand why they did this. Nevertheless, the V30 turned out to develop its own fan base and, to this date, it’s still very popular.
It is actually a 60w speaker, with efficiency of 100db and is offered in both 8ohms and 16ohms. It is an extremely aggressive speaker, with very strong mid range bark (nasal sounding), screaming high end and very shallow bass response.
Interestingly enough, it features Kurt Mueller’s “444″ bass cone. Even so, it’s still a 70hz speaker, according to the specs sheet. Do you find this confusing? Well… Me too.
Marshall 1960AV cab loaded with Vintage 30s​
The Vintage 30s are used in the Marshall 1960AV and 1960BV cabs.​
Identifying an old Celestion: Codes, serial numbers and all that crap
So, I think this is an important topic if you are into the vintage speaker market. Prices are rather high, so you have to know what you are buying.
I’ll start with serial numbers. I have no choice but to copy and paste this from somewhere, so I’ll just post the source here (if the poster – Jim – is reading this, I hope you don’t mind it, but it’s for a good cause – and thanks for all the valuable information you provided for everyone!).
1963 – 1967
On speakers made up to 1967, you will find the serial number on the front of the cork gasket.
T code and (unreadable) serial number of a pre-1967 G12M 75hz​
1965 G12H 25w 75hz (21MK = Dec. 21st, 1965)​
And, just for show, look at this funky label!​
1963 = H
1964 = J
1965 = K
1966 = L
1967 = M
January = A
February = B
March = C
April = D
May = E
June = F
July = G
August = H
September = J
October = K
November = L
December = M
The date codes from this era are written in the form: Day (number), Month (letter), Year (letter). For example: 19MK = 19th December 1965
1968 – 1991
T code and serial number of a G12H 75hz
Serial number dates it to around August 1971​
You will find the serial number of Celestions made from 1968 onwards on the frame of the speaker.
1968 = A
1969 = B
1970 = C
1971 = D
1972 = E
1973 = F
1974 = G
1975 = H
1976 = J
1977 = K
1978 = L
1979 = M
1980 = N
1981 = P
1982 = Q
1983 = R
1984 = S
1985 = T
1986 = U
1987 = V
1988 = W
1989 = X
1990 = Y
1991 = Z/A
January = A
February = B
March = C
April = D
May = E
June = F
July = G
August = H
September = J
October = K
November = L
December = M
The date codes from this period are written in the form: Month (letter), Year (letter), Day (number).
For example: KH7= 7th October 1975
Speaker “T” codes
T1281 without the label. Check the list below to find out what speakers this is.​
So, now it’s time to go into the model codes.
Celestion was really messy with labels in the late 60s. It’s a common thing to see bass speakers labeled as lead cones and other errors like that; and also speakers with no label at all, since it was simply glued to the plastic cover and it could fall over time. So, it’s more reliable to use the codes found on the speakers themselves and the ones on the cones.
Label says G12M 75hz, but the frame says T1511; so this one actually is a G12M 55hz​
Another example: mislabelled G12H 55hz (T1534, according to the poster of the pic)​
You will usually find these codes right next to the serial numbers. They will tell you exactly of what kind a certain speaker is. Finding all the codes and the corresponding speaker model is an impossible task, since the list is endless. I’ll give you a few examples (the most common ones – at least the ones I was able to track down):
T1221 = G12M 75hz 16ohms
= G12M 75hz 8ohms
= G12M 55hz 16ohms
= G12M 55hz 8ohns
= G12H 75hz 16ohms
or T1234 = G12H 75hz 8ohms
or T1534 = G12H 55hz 16ohms
or T3054 or T3120 (Marshall label) = G12-65 85hz 16ohms

T2633: another code for the G12M 55hz 16ohms. It comes with a little surprise though.​
Well… As you can see, sometimes many codes can refer to the same speaker. These are just a few examples, so you will certainly find many more different ones (T2633, for instance, that is a G12M 55hz 16ohms; or a T1976, that is a G12H 75hz 16ohms – and so on). In these cases, you will have to search a little, but you are certainly going to find out what you are looking for.
T1976 G12H 75hz. This one also comes with a little easter egg.​
Cone codes
Let’s talk about the cones.
It’s easy to tell of what kind it is by inspecting it carefully. Somewhere you will be able to find a small code printed in white. They will be one of the following:
Pulsonic cone codes
Example of a Pulsonic bass cone​
Please note that they will vary depending on the date of the speaker:
You will find these codes on the G12M and G12H up to mid-1973.
Speakers with these codes are the most desired ones.
Lead cone (75hz): 102 003 or 102 3 or simply 3
Bass cone (55hz): 102 014 or 102 14 or simply 4

Many examples of Pulsonic cones​
Celestion cone codes

Celestion made RICxxx cone of a July 1975 G12M 75hz​
The cones made by Celestion during the 1973-1975 period (usually Creamback G12M and G12H speakers) had the RIC xxx code (Look at the picture above). RIC probably stands for Rola Celestion (in that case, the “I” would actually be a “/”, but let’s call them RIC for convenience)
I’m not sure if there’s a way of telling lead cones and bass cones apart based on it, but at this timeframe, labeling has become more reliable.
RICxxx cones of two 1974 G12H 75hz 8ohms speakers (T1234)​
Kurt Mueller cone codes
You will find these codes on probably all the speakers made from 1975 onwards until the present day, ranging from the Blackback G12M and G12H to the G12-65, Vintage 30s and etc.​
Kurt Mueller bass cone of a 1977 Blackback G12H 55hz​
Lead cone: 1777
Bass cone: 444
Kurt Mueller lead cone​
Important note: speakers up to 1967 had either H1777 (lead) or SP444(bass) cones, but they aren’t Kurt Muellers because the company didn’t even exist back then. Nobody knows who made these cones. Some believe they are simply Pulsonics with different codes (since they are said to sound exactly the same), while others say they are Celestion made.
Mid-60s H1777 and SP444 cones: unknown origin – but they do sound fantastic!​
Be careful: oddballs, UFOs and freaky stuff
Well… Not much to say here, but I thought I should mention this.
A few speakers came with a very strange aluminum dust cap, including G12Ms, G12Hs and I think I’ve seen a few G12-65s with them, but I can’t find them again.
Do you remember the T2633 G12M 55hz I showed you a while back? Well… Take a look at this:
Is it just me or does this look like an UFO or something like that?​
And the T1976 G12H 75hz. Just as weird:​
We are under attack! Oh… Wait…​
Even so, these do not seem to be considered really “bad”. They will just sound a little “brighter”.​
Now, you will have to be careful with this one instead:​
70s G12H with the “whizzer” cone
Is that some kind of parasite? Looks gross to me.​
This so called “whizzer” cone is something like a “cone inside the cone”. These things accent the high frequencies to a point where many consider them unusable as a guitar speaker. With this bad fame, the “whizzer” things are usually removed. It’s a somewhat risky procedure, but it can be done. With the right treatment, they can sound just like any other Celestion.​
But I would try to avoid them.​
For your enjoyment, here are other examples:​
These are G12H-100 speakers with whizzers. So it’s a double “YUCK!!” from me.​
The T1837 G12H 55hz and the T3O62 G12-65 have these things. There are probably others, but I just won’t bother to find them (because… well… How would you not notice these things on a speaker?)​
And speaking of the T1837… Here is one of them successfully converted into a “normal” T1281 G12H 55hz:​
Doctor, the conjoined twin was removed with success!​
I’m not sure if there are other “strange” kind of Celestions, but this is just to show that a little bit of knowledge is necessary when buying old gear.
Celestion Reissues: Back in Green
For most of us who don’t want to risk buying 40 year old speakers that might be worn out and tired (even totally crap sounding) or simply prefer to have the reliability of a brand new Celestion, there are both the Classic Series and Heritage Series to choose from.
“Classic Series” G12M (older “Made in the UK”)​
The G12M 25w 75hz was (re)introduced in 1989 and, just like the original ones, it was nicknamed Greenback (and was marketed as so). It uses the 1777 Kurt Mueller cone (or 6402 during some period – it’s basically the same. Just a different number), so it’s probably fair to say that it is (perhaps) closer to a mid-late ‘70s Blackback than to an actual Greenback. It has an efficiency of 98db (that also is closer to the “more efficient” Blackback specs)and is offered in 8ohms and 16ohms versions.
6402 cone of a ’90s G12M Greenback (actually, just a KM 1777, don’t get fooled)​
Kurt Mueller 1777 cone used in the current G12M Greenback​
This is exactly where the confusion about the true meaning of “Greenback” started. Now, to many people, “Greenback” is simply a G12M 25w 75hz, when it actually represents a broader range of models.
1960BX loaded with 25w G12M Greenbacks​
1960TV: an oversized 1960A cab with four G12Ms​
This is the speaker used in the current Marshall 1960AX, 1960BX and 1960TV cabs.

Current G12H 30w 70th Anniversary​
In 1997, the G12H 30w 75hz was re-released as the 70th Anniversary Special Edition. It has a golden back, with no actual plastic cover, so it wasn’t marketed as a “Greenback” for obvious reasons. It is, though, basically the same as the old G12H speakers with the 1777 Kurt Mueller cone. It has an efficiency of 100db and is offered in 8ohms and 16ohms.
2061cx cab with two G12H Anniversary speakers​
You can find these speakers in the Marshall 2061CX cab (2×12).​

The G12C was introduced not too long ago as a special speaker to be used with the Marshall “Jimi Hendrix” stack and, later, it was used in the 425A and 425B Vintage Modern cabs. This one in particular was built after a “great sounding” mid-60s G12M, but was called G12C to avoid confusion with the normal G12M (“C” stands for ceramic). It uses the 1777 Kurt Mueller cone, handles 25w, has an efficiency of 98db. It sounds similar to the regular G12M, but with a slightly different voicing. It is exclusive for Marshall and can only be bought through them.
Marshall Vintage Modern 425A cab loaded with G12C speakers​
The 15w AlNiCo “Blue” is also reissued under the Classic Series.

Current AlNiCo Blue​
How do these sound when compared to vintage ones? Hard to say, but they do sound very good to me. They are as fine as the old ones, in my opinion.
Around 2002, Celestion started to move the production of many models to China. This also included the G12M and G12H models. There’s a lot of hype concerning the quality of the speakers made in the Far East, but it has to be noted that all the machines that were used in England to make them were moved to China and they also still use the very same Kurt Mueller cones. It’s hard to tell what is true or not, but the Chinese speakers are not, by any means, bad or low-quality.
The Heritage Series: I wanna “(Pre-)Rola” lotta tone!
The Heritage Series was introduced in 2005 as “UK-made” and “hand-built” speakers, a more accurate reproduction of the late ‘60s “Pre-Rola” era. Unfortunately, these adjectives also make them cost almost two times more. The first models introduced were the G12M 20w and the G12H 30w 55hz.
Heritage G12M​
There’s a bit of a debate about the Heritage G12M, since many believe that it is not really 20w, but actually 25w instead (maybe they also wanted to reproduce the “inconsistent” label and info of that time). Either way, it’s fair to say this speaker is basically a 1968 G12M 75hz Reissue. It has an efficiency of 96db, so it’s a bit quieter than the “Classic” version. It’s offered in 8ohms and 16ohms. The code stamped on the cone (with a few varying added characters) is 11914. I have no idea from where it comes from, though (perhaps it’s a Celestion made Pulsonic cone reproduction?).

Cone code of the Heritage G12M​
It was well received by the tone-freaks in general and sounds warmer, smoother and perhaps a little fuller than the “Classic” G12M.

Heritage G12H 55hz​
The Heritage G12H 55hz (a reproduction of the 1968-1973 G12H 55hz) is a 30w speaker with an efficiency of 100db and is offered in 8ohms and 16ohms. Interestingly, this speaker actually has 102 014 stamped on the cone, like an old Pulsonic (please note that this is NOT a Pulsonic cone just because the code is the same. It’s probably just a reproduction as well). I wonder why the G12M didn’t have the 102 003 stamp on it then.
Cone of the Heritage G12H 55hz​
This one has received very mixed reviews, with many people complaining that it’s “too harsh” and “too bright”, while many others say “it’s the best speaker they’ve played with. Not harsh at all”. Now, I find this very strange. The G12H tends to sound bright anyway, though.
I have these speakers right now and I must say they sound very much balanced. They are somewhat bright as they describe, but I find it “pleasantly” bright and with a very strong and round bottom end (like the bass cone should be – there are a few guys saying it is a 100hz cone, but that sounds ridiculous to me). It also matches the sound I hear on my favourite old Led Zeppelin recordings quite well.
Maybe these guys who didn’t like them are more used to the “warmer” G12M tone.

1982… I mean… 1960AHW loaded with “aged” Heritage G12H 55hz speakers​
A special “aged” version of these speakers is used in the 1960AHW and 1960BHW cabs (with the “100” logo on the corner).
On a side note, they should have been called 1982AHW and 1982BHW instead or something like that (1982 was the cab with heavy magnet speakers of back in the day), but the 1982 cab number was used to designate the Jimi Hendrix stack cabs (1982AJH and 1982BJH), that have 1982 cosmetics, but actually are loaded with medium magnet 25w G12C speakers. So: “What the f*ck???”
Heritage G12-65​
The Heritage G12-65 is a reproduction (of one of the 40 versions) of the 85hz G12-65, the only speaker of the Heritage line (so far) that doesn’t fall into the “Pre-Rola” category. It has (obviously) 65w, an efficiency of 97db and is offered in 8ohms and 16ohms. The cone has Kurt-Mueller’s 1777 stamp. Specs aside, this speaker seems to get really close to the original ones (according to a Celestion employee, the very same persons who built them back in the day are building them now) and it has that strong low end, punchy mids and a very smooth high end that are characteristics of the G12-65.
This speaker in particular received a very good “thumbs up” from a professional player called Robben Ford, who wouldn’t use anything but his original G12-65s. Over the years they got harder and harder to find and re-cone kits were becoming rare as well. Long story short, he tried the Heritage G12-65 and was quite satisfied with it, saying “he finally got his sound back”. You can read the whole story here.
Heritage G12H 75hz​
The Heritage G12H 75hz (a reproduction of the 1968-1973 G12H 75hz) was introduced more recently and I wasn’t able to gather much info about it. I do believe that it has the same cone as the G12M Heritage, but I actually have to confirm this. I know for sure that it’s some kind of Pulsonic cone reproduction, like the others. It’s basically the lead version of the G12H, with 30w, 100db and both 8ohms and 16ohms. This one is said to have that mid-high “sizzle”, but still with a strong bottom end (sounds like they got it right to me).
Many ask what is the difference between this and the 70th anniversary version. At first inspection, the cone probably is different (the Anniversary uses the Kurt Mueller cone, while the Heritage – probably – uses a reproduction Pulsonic), but apart from this, they seem pretty much identical, besides the “hand-made in the UK” thing.
Are the Heritages really worth it?
And this is where most opinions diverge. But truth is, like I said before, there’s not really an answer. The Heritages will sound a bit different, but the question is: do you really want to pay the extra cash for this small (or not so small) difference? Some will say yes, some will say no, and rightly so.
Plus, I really think of the “Classic Series” versions more like a “continuation” of the G12M and G12H from where they were left rather than actual “reproductions” of something. The Heritages that would be the “reproductions”. So, it’s more like: “Modern versions” vs. “Reissues”.
If you want a G12M, you will be basically torn between a Kurt Mueller cone that is slightly more aggressive, with a more present high end and a “reproduction” Pulsonic cone, that is warmer, a bit more compressed, slightly mellower, etc; between other things I don’t know about. Slightly different voicings, but both really nice. If you want a more direct comparison, check this.
If you are after a G12H, things will get a little more complicated, since they also offer the 55hz version.
For you guys who love the sounds of Page, Kossoff, Blackmore and others; and really want that “round” bass cone sound, I’m sorry to say that there is no other option besides the Heritage version, since there’s no “regular” 55hz G12H (unless you go for the vintage ones or… boutique replicas, but we will talk about this really soon).
If you are more into the “drier” (that’s not a bad adjective, just DIFFERENT) and “hotter” 75hz version, you can choose between the 70th Anniversary, that is slightly more aggressive and with a stronger high end (like a Blackback – Kurt Mueller, anyone?) or the smoother “Pulsonic voiced” Heritage 75hz. Again, it’s you who are going to choose what you really want.
But remember the following: a true Pulsonic will be going for a hell lot more, so the Heritages are not that bad of a deal in comparison.
And finally… The G12-65. Well, it’s a no-brainer, since the Heritage is the only option available from Celestion. If you are not happy with this, you can always browse through Ebay. You might find some very nice oldies there by a very reasonable price. Or…
Or, we can go for the “boo-teak” route.
Boutique replicas: Scumback, Weber, WGS and others
And here we have a very different approach. While Celestion offers us very nice new reproductions of old speakers “as brand new”, these boutique replicas will offer you something quite different: brand new, reliable reproductions of old speakers, but, at the same time, with all the MOJO and feel of an old speaker. In other words, you will have a brand new speaker with the feel of a (mellowed-out, well broken in, etc.) 40 year old (or more) Celestion!
And this is exactly why many people have the impression that the boutique speakers generally sound better than the present-day Celestions. New speakers need to be broken-in and will sound “stiffer” and “colder” out of the box (this doesn’t necessarily mean that a crap speaker will “magically” sound good after a while – although you might get that impression sometimes – and neither that a speaker will sound like crap when new). After they are well broken in, they will get a lot sweeter and more responsive. And even so, years and years of aging makes the vintage Celestions something quite different. This is exactly what the boutique replicas want to achieve and where they get the most points: they are already somewhat treated to sound “old”, so even if they are not broken in, they will certainly already sound smoother right out of the box.
Keep in mind that, since these old speakers varied a lot, it is fair to say that neither the Celestion reissues or the boutique replicas are exactly a 1:1 copy of the originals (that would be, perhaps, impossible), but more like a “recreation” of the overall “feel” these speakers would give you.
Scumback (fondly nicknamed “Scumbag” by their customers – the pun is unavoidable, I guess – or maybe it was deliberate) is, perhaps, the most famous and most acclaimed brand when it comes to “Pre-Rola” voiced speakers. Jim (the owner – a great guy, it seems) is an expert on Celestions and collected dozens and dozens of them through the years, so he knows how they sound like. They have a great reputation and their speakers are truly fantastic. The Scumback line is very varied, ranging from AlNiCo speakers, going through 55hz G12M (something Celestion itself currently doesn’t offer in any format) and going as far as the Blackbacks and G12-65s (it’s called M75-LHDC by them). You can check their site for more information.
Weber also has a great reputation of making great sounding speakers. It seems that Jim worked with them for a while and Weber was actually manufacturing speakers for Scumback until recently. Nevertheless, these are now different brands with different products, different approaches (and different prices). Really worth checking them out.
Warehouse Guitar Speakers (or WGS) offers high quality speakers by very reasonable prices. The reviews in the internet are hugely positive too. They seem to sound great as well. Why not check them out?
Avatar Speakers offers re-branded versions of two Celestions under the Hellatone name: the Hellatone 30 (G12H 70th Anniversary) and the Hellatone 60 (Vintage 30). They are basically the same as the regular Celestions, except that they are already well broken-in and sound fantastic, but at a very friendly price. Hellatones don’t exactly fit into the “boutique” category, but I guess they also deserve some attention.
None of these brands is necessarily better than the other, neither they are better than current production Celestions. It all comes down to what you think that sounds better to you.
There are probably other small manufacturers out there that I’m not aware of. If you know of any, feel free to mention it on the comments.
So, in the end, all I have to say is that I hope this post was useful to you and helped to give you a better idea of what you are looking for and what options you have.
So… Good tone hunting!


Senior Member
Oct 1, 2010
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yes it is a great article i read it before.
extremely helpful and informative.


Senior Member
Jul 19, 2011
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Only had time to scan through it. But looks interesting. Didn't see anything on my favourite current Celestion the Gold though :-(


Senior Member
Dec 30, 2009
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Does that article tell why their speakers are $149 each even though they are made in Chinese sweatshops?


Senior Member
Nov 4, 2011
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Thanks for quoting this article because I was not in the mood to register at this website to read it.

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