Do Pre-Amp Tubes Really Alter Basic Tone?

freefrog

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FWIW...

In V1, typically, I'd swap a 12AX7 for a 12AY7 rather than a 12AT7: IME, the 12AT7 has a bit more gain but tends to enhance the fundamental and to ignore the harmonics... Hence a duller tone.
A 12AT7 in the PI slot is another story.
At least it's the case in my experience.

Anyway, the 12AY7 is another tube to consider if you want less gain without loosing your beloved harmonic richness. :)
 

JohnnyN

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Yes! It can alter EQ range/focus, pickresponse, gainrange.
The speaker will do more for overall tone, but in the end it is the combination of every thing between (and including) your brain and the air in front of the speaker.
Play with preamp tubes if you have the time and money, but do a bit of research first. It can be very rewarding - and is a must if you have tone OCD :D
 

dmoss74

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in v1 (especially) you bet they do. not just in changing the gain structure, through other values (ax,vs at, etc), but also brands. especially when you start finding some nos tubes, or lightly used older tubes. they most certainly can--and do--make a difference.

how much is dependent on your amp, and it's overall circuit, but there are definite tonal characteristics that certain brand tubes bring to the table.

my vox ac15c1 had (from a prior owner) "jj" tubes put in it. that particular brand seems to be the go-to choice for a lot of folks in regards to that amp. to me, they sounded like ****. i dropped a couple nos tubes in v1, and v2, and the sound is much nicer now...to me.

i still have the jj power tubes, but will eventually swap them out, too. i'm just deciding which ones to try.
 

ScottMarlowe

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i dropped a couple nos tubes in v1, and v2, and the sound is much nicer now...to me.
The nice thing is how cheap you can get lots of used, tested, old tubes. You can find 10 or 20 on ebay for $5 to $10 a tube.
 

jbrew1977

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Not gonna makes claims for a specific brand or argue for or against the virtues of NOS tubes, but I will say this. Tubes/valves depending on which side of the pond we're on have so many variances in the internal structure even within the same brand and type. Might be simple as the alignment of things or it might drastically differing plate structure and materials used. Now I don't normally jump on the tone-wagon BUT I have witnessed the differences in action building circuits in electronics classes for school. They ALL amplify the signal a bit differently and some do so to quite some degree even if the end result is within spec. Meaning tube A and B both produce about the same amount of gain but accentuate wildly differing portions of the input frequencies. This is typically less severe given same brand and type but it still varies. As some other guys have said factor in the various types of 12a-- preamp tubes which have different gain ratings, current, and transconductance, you can see where this will most certainly have an impact on tone. Yet another factor is that ALL preamp tubes are slightly microphonic, especially in a combo amp. Maybe not microphonic like the nasty squealing you are thinking but prone to produce some degree of coloration or noise if you will. So what does this all mean? The people in the crowd will very likely be completely oblivious to any tonal differences unless of course you have a badly microphonic tube. YOU and possibly your band mates very likely WILL notice subtle differences in most cases and in some quite drastic changes. The overall character of the amp will remain intact but you can very likely fine tune it to better suit your tastes with a good tube roll. If you find one you like however rock that baby until it dies, because unless it's a very consistent and heavily weeded out brand/type of tube it'll probably not sound EXACTLY the same the next time around. As an example if you order BRAND X 12ax7 high gain with matched and balanced triodes you will be best served to continue to order that same EXACT tube from a reputable source like Doug Preston from Doug's Tubes rather than a cheaper version from GC, SA, or MF. If you roll some tubes and don't find one that's magic, none of this matters anyway! As for what that magic may be if you do find it I will make no claims because we all have different tastes and perceptions!
 

jbrew1977

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How was that for an overly exhaustive explanation??? Lol I would like to add that the guy that said JJ preamp tubes sound like $hit, I have to totally agree, at least in my V3M! Their EL-84s however are quite nice and cheaper than just about anything out there. Not quite as durable as Sovtek but a sound difference that is terribly obvious and they aren't nearly as prone to tube rattle as Sovtek or any of the other 10 million (humor) New Sensor brands. I can also vouch that the JJ 6V6 is one of the most capable of handling the abuse they will see in say a Deluxe Reverb or any other 400+ plate voltage amp, BUT they will add a massive amount of low end. A lot of reviews say they sound like a 6L6 for that reason and I have to agree completely. As an example Bass on 5 in my Fender became more bass than 10 before the swap and bass on 1 became the previous tube's (Groove Tubes) bass on 5-6.
 

Leroy

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12AX7's are a manufactured device built to be within certain criteria. Like all manufactured parts their tolerances will vary by an allowable amount set by the manufacture. You can buy two valves built by the same company on the same day and they could vary by 10%.
Also the construction methods used to create the valves can be quite different between manufacturers, or runs by the same manufactures. Long or short plate. Welded or crimped plate. Getter types etc....

How much difference it makes in your situation will depend the preamp topology your amp has. It will always make some difference, whether that difference is perceivable or not is a different matter.
My personal experience is that it does make a difference, albeit a subtle one.

My advise is don't get sucked in to the whole NOS thing. Sometimes they sound better sometimes they don't. Try and forget what's on the label. I've got a whole range of valves from the 60's and onwards. My main gigging amp uses all new Tung Sol preamp valves.

Bigger changes in tone will come from your speaker/cab choice. There's a reason a JTM45 and Bassman sound different despite the circuit being nearly identical and it's not the preamp valves.

Leroy
 

jbrew1977

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Great advice from Leroy about NOS tubes and speakers. They are typically VERY expensive and rare so you run the risk of not being able to get another one if you find THE ONE! That said I will endorse one... While not a pre amp tube I highly recommend the Cold War era Russian 6p14p-ev. You may also see it as 6n14n-eb or EL84M. Sovtek actually manufacturers this tube new and I promise it is the SAME EXACT TUBE (owned both new and old) but in a lot of cases the older ones made by Reflektor can be had for the same money or less and I find it kind of cool that a tube that was destined for a MIG jet fighter can be in my amp. For an EL84 style tube they are beastly with nearly twice the weight from thicker glass and much more beefy internals. EL84 amps are not usually very friendly on power tubes due to running them FAR in excess of their designed plate voltage. These things are designed to handle 450 volts and have an increased max dissipation of 14 watts versus 12. They are noticeably louder and have more headroom so some people claim they are sterile. They are not! Get them breathing and they sing! They are my backups for one reason... They are too loud in my amp! If you have a lower watt EL84 amp give them a try. Dr. Z and Hughes and Kettner actually use them in a couple of their amps for the reasons I just stated. BTW Leroy, don't forget the differences in the negative feedback loop causing tonal differences between the JTM45 and Bassman... Takes more than Greenbacks to make a Marshall out of a Fender! Sorry about the novels I'm writing but LOVE talking about tubes and amps even more than Les Pauls!!!
 

ScottMarlowe

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Another vote for EL-84M/6P14P tubes. I LOVE the way they work in Classic 50 2x12. Just amazing tubes and you can get them for peanuts from Russia etc.
 

jbrew1977

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Another vote for EL-84M/6P14P tubes. I LOVE the way they work in Classic 50 2x12. Just amazing tubes and you can get them for peanuts from Russia etc.
Man I gotta say I find it quite amazing that there is another person on this planet that not only knows a FANTASTIC EL84 but ALSO can appreciate the hidden gems that Xaviere guitars and GFS pickups are! Now if you tell me you like a Sovtek 12ax7 LPS for the phase inverter and a Ruby 7025 SS in the V2 gain stage I'll probably swear you're my brother from another mother!
 

ScottMarlowe

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Man I gotta say I find it quite amazing that there is another person on this planet that not only knows a FANTASTIC EL84 but ALSO can appreciate the hidden gems that Xaviere guitars and GFS pickups are! Now if you tell me you like a Sovtek 12ax7 LPS for the phase inverter and a Ruby 7025 SS in the V2 gain stage I'll probably swear you're my brother from another mother!
Yes, and not sure. I've never used the Ruby 7025 SS. I prefer GE JAN 12AX7WA for gain stages. If you've never tried them, find the tube swapping thread over on everything SG forum and get in line for the box o tubes. It should have one or two in it.

But yeah, I got a batch of Sovtek 12AX7LPS when I bought my second Classic 50 for $250 from GuitarDenter. It came with all GT tubes. The power tubes were two sovtek GTs and two JJ GTs, the preamp was three Sovtek 12AX7LPS GTs. So I'll not run out of those any time soon.

My other favorite preamp tube is GE 5751 for V1.
 

mdubya

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From what I've read, you want the best tube you can afford In v1, any noise induced here is only going to get worse in the later gain stages.

LOL @ gain stages. If you have gain stages, your tone will never be great. :naughty:
 

mdubya

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So any amp with more than 1 12AX7 is just screwed on tone? :shock:

No, any amp with gain stages. ;)

Might sound good, but not great.

And yes, I am stirring pots. :wave:

You can add in amps with channel switching and effects loops, too. :D

Each of these things is like ice and tap water added to 12 year old Scotch.
 

ScottMarlowe

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No, any amp with gain stages. ;)

Might sound good, but not great.

And yes, I am stirring pots. :wave:

You can add in amps with channel switching and effects loops, too. :D

Each of these things is like ice and tap water added to 12 year old Scotch.
You do realize that except for the PI and / if you have it reverb circuit, ALL 12AX7s, including V1, are gain stages. If they weren't you wouldn't hear anything on the output of the amp.
 

jbrew1977

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That Ruby 7025 SS is actually an 8th generation Shaguang 12ax7. All the gain of the 9th gen but it has a smoother delivery. Has a cool character to it. I'll answer your last question for him... Sniffing cork turns you into a retarded dick with more jaded opinion than knowledge or ability. So no of course he doesn't realize that.
 

mdubya

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That Ruby 7025 SS is actually an 8th generation Shaguang 12ax7. All the gain of the 9th gen but it has a smoother delivery. Has a cool character to it. I'll answer your last question for him... Sniffing cork turns you into a retarded dick with more jaded opinion than knowledge or ability. So no of course he doesn't realize that.

I am not a cork sniffer.

More of a cork soaker.

I have no need to argue. Point taken, even if it is not universally true. :hippie:
 

sonar

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9 pins in general have always varied a lot, both old and new, from manufacturer to particular runs within the same company.

Some people have made a fair amount of money by just simply grading tubes.

So, yes.

Enough to worry about?

"Eh..."

New 8 pin (power and current pre) are pretty dependable and sound decent to good.

9 pin still kind of sucks, but NOS/NIB supplies have been picked over for 30+ years and the chance of getting a good ax7/au7 becomes more and more of a crap shoot.

Of new the Tung Sol labeled 12AX7 is okay enough... I guess.
 

jbrew1977

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I am not a cork sniffer.

More of a cork soaker.

I have no need to argue. Point taken, even if it is not universally true. :hippie:
I actually have doubts any of my inflammatory comments were even remotely true. I can appreciate somebody stirring the pot as you said just for the sake of it! I'm not totally sure at this point but it seems after the quoted comment you were simply doing just that, trying to razz everybody a bit and again I can appreciate that... I don't necessarily regret antagonizing you for your comments but I was really doing the same thing, just trying to get under your skin. Clearly I failed! Me 0 You 1 Truce?
 

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