mismatched ohms and lower volume?

cherrysunburst00

TUBE AMP JUNKIE FOR LIFE BAD ASS
Silver Supporting Member
Joined
Mar 14, 2015
Messages
19,164
Reaction score
39,631
I read through the Wiring Cabs, Speaker OHMS all in one thread and only 1 post seemed remotely related to what I would like to know (I believe it was 144?)

I have a Laney Lionheart Studio head and it says in the manual that it can drive an 8 or 16 ohm cabinet (from the same output jack). I'm pretty sure that this means it is 8 ohm output (correct).

I also have the Lionheart L5T combo which came with an 8 ohm stock speaker (Celestion G12H 30 watts).

The cabinet I'm using for the head has a 16 ohm speaker (Warehouse Guitar Speaker ET 65 which is 65 watts) and I have noticed a definite reduction in volume.

So, does this mean in general that driving a 16 ohm speaker with an 8 ohm output from the amp acts as a form of attenuation?

What about the difference in wattage ratings and brands?

Thank You in advance
 

jchrisf

Senior Member
Joined
Oct 30, 2015
Messages
125
Reaction score
39
I ask a very similar question on TGP:

I have the same user name there if you want to search for it.. didn't want to post a link because I wasn't sure if it was prohibited here.

BTW.. I just got an IRT Studio too! :) You'll see me mention it in the thread.. I hadn't gotten it when I started the thread. Posted the same video Stealth did.. the TGP crowd didn't like the guy on the videos answer.
 

cherrysunburst00

TUBE AMP JUNKIE FOR LIFE BAD ASS
Silver Supporting Member
Joined
Mar 14, 2015
Messages
19,164
Reaction score
39,631
Well this is great. Seems like an automatic and safe way to shave a few db's off without sacrificing tone

Philip McKnight on OHMS I love this guys channel too.

Thanks Steath. Exactly what I wanted to know, and in everyday speak :applause:

I ask a very similar question on TGP:

I have the same user name there if you want to search for it.. didn't want to post a link because I wasn't sure if it was prohibited here.

BTW.. I just got an IRT Studio too! :) You'll see me mention it in the thread.. I hadn't gotten it when I started the thread. Posted the same video Stealth did.. the TGP crowd didn't like the guy on the videos answer.

jchrisf: I'll check your tgp. Congrats on your Laney as well :thumb: Definitely the unsung British brand of amps, aye? Marshall, Vox, Orange, well seems Marshall & Orange in particular get lots of love 'round these parts, but Laney???
 

jchrisf

Senior Member
Joined
Oct 30, 2015
Messages
125
Reaction score
39
jchrisf: I'll check your tgp. Congrats on your Laney as well :thumb: Definitely the unsung British brand of amps, aye? Marshall, Vox, Orange, well seems Marshall & Orange in particular get lots of love 'round these parts, but Laney???

It seems to be that way. Wow.. what a versatile amp the IRT is! And it comes with one of the best foot pedals I've seen on a tube amp. A lot of control right there. I like 80's metal music and this amp nails it but was surprised at the nice clean tones and everything else it can do. Direct record too.

How is yours on the bottom end? I'm running mine through a Marshall 1960B 4x12 and there is not enough bottom end at bedroom levels at least. I haven't cranked it yet. I ordered an EQ pedal to try to boost the bottom end but I am also getting a Fryette PS when they come back out and that can boost the low end too. I can't get my volume over 1 for the bedroom :) so hopefully the Fryette will allow me to crank it at bedroom levels too:cool:

My cab has a switch which allows me to change the ohms from 4, 8 and 16. I put the amp on 8 ohms and the cab on 16 ohms. It sounded better when I put the amp on 16 and the cab on 16.
 

jchrisf

Senior Member
Joined
Oct 30, 2015
Messages
125
Reaction score
39
Here was an interesting article posted on my other thread but keep in mind this was done by H&K on their equipment only:

Ohm cooking 101: understanding amps, speakers and impedance - Hughes & Kettner BLOG

SpekerImpedanceChart.jpg
 

cherrysunburst00

TUBE AMP JUNKIE FOR LIFE BAD ASS
Silver Supporting Member
Joined
Mar 14, 2015
Messages
19,164
Reaction score
39,631
It seems to be that way. Wow.. what a versatile amp the IRT is! And it comes with one of the best foot pedals I've seen on a tube amp. A lot of control right there. I like 80's metal music and this amp nails it but was surprised at the nice clean tones and everything else it can do. Direct record too.

How is yours on the bottom end? I'm running mine through a Marshall 1960B 4x12 and there is not enough bottom end at bedroom levels at least. I haven't cranked it yet. I ordered an EQ pedal to try to boost the bottom end but I am also getting a Fryette PS when they come back out and that can boost the low end too. I can't get my volume over 1 for the bedroom :) so hopefully the Fryette will allow me to crank it at bedroom levels too:cool:

My cab has a switch which allows me to change the ohms from 4, 8 and 16. I put the amp on 8 ohms and the cab on 16 ohms. It sounded better when I put the amp on 16 and the cab on 16.

I'm just running it through a 1x12. To my taste, it is probably not as much low end as you would like, but my eq is set at 1:00 (or #7 on the faceplate). I like the old '70s hard/heavy rock tone, and this thing is pretty dead on. Strictly bedroom player (try to stay at 87 or so db, but sometimes I live dangerously and go up to 91 or 92 db, but not for too long).

The really nice thing about the low watt Lionheart series is that Laney wanted to get players the ability to get power tube distortion at lower levels. I'd say they succeeded, especially with this new Studio which has the full 5 watt output jack as well as a .5 watt jack

At 50 I'm very conscious about retaining my hearing. I think in the backstage area someone posted about AC/DC cancelling shows and Brian Johnson being pretty well deaf :(
 

cherrysunburst00

TUBE AMP JUNKIE FOR LIFE BAD ASS
Silver Supporting Member
Joined
Mar 14, 2015
Messages
19,164
Reaction score
39,631

SWeAT hOg

SWeAT hOg
Joined
Feb 22, 2009
Messages
37,704
Reaction score
67,943
Yes, I have seen that article but honestly I forgot all about it.

But I'm confused: case 2 shows 16 going into 4. Although, as you indicated, it is H&K gear

That is indeed questionable and I've never heard that this is ok. I find it hard to believe that's from H&K. Fine if you want to overwork your amp, shorten tube life, blow a transformer. I always believed what my old man told me. Amp output is the 'fire' and the speaker ohm rating is the 'chimney'. As long as the 'chimney' is big enough to vent the 'fire', you're fine. :thumb:
 

jchrisf

Senior Member
Joined
Oct 30, 2015
Messages
125
Reaction score
39
I'm just running it through a 1x12. To my taste, it is probably not as much low end as you would like, but my eq is set at 1:00 (or #7 on the faceplate). I like the old '70s hard/heavy rock tone, and this thing is pretty dead on. Strictly bedroom player (try to stay at 87 or so db, but sometimes I live dangerously and go up to 91 or 92 db, but not for too long).

The really nice thing about the low watt Lionheart series is that Laney wanted to get players the ability to get power tube distortion at lower levels. I'd say they succeeded, especially with this new Studio which has the full 5 watt output jack as well as a .5 watt jack

At 50 I'm very conscious about retaining my hearing. I think in the backstage area someone posted about AC/DC cancelling shows and Brian Johnson being pretty well deaf :(

I didn't realize the Lionheart also has a studio version. I assumed you had the Ironheart. I have the Ironheart Studio that is 15 and 1 watt. Awesome amp as I am sure the Lionheart is.
 

cherrysunburst00

TUBE AMP JUNKIE FOR LIFE BAD ASS
Silver Supporting Member
Joined
Mar 14, 2015
Messages
19,164
Reaction score
39,631
That is indeed questionable and I've never heard that this is ok. I find it hard to believe that's from H&K. Fine if you want to overwork your amp, shorten tube life, blow a transformer. I always believed what my old man told me. Amp output is the 'fire' and the speaker ohm rating is the 'chimney'. As long as the 'chimney' is big enough to vent the 'fire', you're fine. :thumb:

Your wise Dad raised a wise son :thumb:

I didn't realize the Lionheart also has a studio version. I assumed you had the Ironheart. I have the Ironheart Studio that is 15 and 1 watt. Awesome amp as I am sure the Lionheart is.

The Lionheart Studio just came out in late(?) 2015. The names (Ironheart & Lionheart) are so close it can get confusing. But Marshall takes the cake: they have the JMP 1 preamp and the JMP 1 50th Anniversary :laugh2:

Sounds like your Ironheart is a lot like the smaller Iommi Signature combo (15 & 1 watt).

I REALLY like Laney
 

cybermgk

“Happiness is the most insidious prison of all"
Gold Supporting Member
V.I.P. Member
Joined
Jul 7, 2011
Messages
16,470
Reaction score
25,199
How is yours on the bottom end? I'm running mine through a Marshall 1960B 4x12 and there is not enough bottom end at bedroom levels at least. I haven't cranked it yet. I ordered an EQ pedal to try to boost the bottom end but I am also getting a Fryette PS when they come back out and that can boost the low end too. I can't get my volume over 1 for the bedroom :) so hopefully the Fryette will allow me to crank it at bedroom levels too:cool:

I had an Irt IRONHEART Studio for awhile. very, very versatile amp. Lot of great recording features like simple reamping etc. Great tone, particularly when I rolled Amperex EL84s into it.

But, the reason I no longer have it, and I have a 6505 Mini, is because of that lack of bottom end. Did a great classic rock, punk and metal. But, I wanted it for the high gain stuff, as I have other amps I like better for the classic rock and Marshall and similar tones. As such wanted that low-end thump. Could never dial it in, even on a 4x12, not at lower volumes. Recorded and louder, a bit better. My Orange and the 6505 MH, however, have that low end (and both EL84 amps fwiw) at lower volumes. Orange does that classic Brit crunch and distortion ( and I liked it a little better than the Laney Ironheart). And the 6505 does the high gain thing.

Still a great sounding amp that can cover a lot of ground.
 

Marshall & Moonshine

Senior Member
Joined
Jul 21, 2010
Messages
30,563
Reaction score
74,349
Mismatching impedances does lower the volume a little, but not nearly enough to save your hearing or keep the neighbors from complaining. It is noticeable, though. I used the impedance selector on my JCM 800 to do this experiment with my WGS Vet 30, and while 8 into 16 lowered the volume, it also seemed to lose some clarity, which wasn't worth the trade-off. You may also have been hearing a difference in speaker efficiency.
If it was a big enough deal to lower the volume to save hearing or not bother the neighbors, you're far better off with an attenuator.
 

cherrysunburst00

TUBE AMP JUNKIE FOR LIFE BAD ASS
Silver Supporting Member
Joined
Mar 14, 2015
Messages
19,164
Reaction score
39,631
I had an Irt IRONHEART Studio for awhile. very, very versatile amp. Lot of great recording features like simple reamping etc. Great tone, particularly when I rolled Amperex EL84s into it.

But, the reason I no longer have it, and I have a 6505 Mini, is because of that lack of bottom end. Did a great classic rock, punk and metal. But, I wanted it for the high gain stuff, as I have other amps I like better for the classic rock and Marshall and similar tones. As such wanted that low-end thump. Could never dial it in, even on a 4x12, not at lower volumes. Recorded and louder, a bit better. My Orange and the 6505 MH, however, have that low end (and both EL84 amps fwiw) at lower volumes. Orange does that classic Brit crunch and distortion ( and I liked it a little better than the Laney Ironheart). And the 6505 does the high gain thing.

Still a great sounding amp that can cover a lot of ground.

You know, those EL84s really do sound nice. My only non EL84 amps are the Marshall 50th Annis and My Phaez Sibly (EL 34) which I' contemplating selling since this new Lionheart Studio does "the British thing" so nicely

Mismatching impedances does lower the volume a little, but not nearly enough to save your hearing or keep the neighbors from complaining. It is noticeable, though. I used the impedance selector on my JCM 800 to do this experiment with my WGS Vet 30, and while 8 into 16 lowered the volume, it also seemed to lose some clarity, which wasn't worth the trade-off. You may also have been hearing a difference in speaker efficiency.
If it was a big enough deal to lower the volume to save hearing or not bother the neighbors, you're far better off with an attenuator.

I agree on the attenutation observation. That is 1 of my main hesitations in selling the Phaez: it has power scaling.
 

Big John

my cat, my bitch
V.I.P. Member
Joined
Mar 18, 2007
Messages
8,313
Reaction score
9,711
...I believe it was 144?...
Here's that post...

Old topic, I know. I've searched and read. I'm trying to straighten out what is safe for my gear, not necessarily what sounds best. Here's what I think is right.

A 4 Ohm amp can drive a 4, 8, or 16 ohm speaker.
(8 and 16 will not be optimal performance-will likely have less volume.)

A 8 Ohm amp can drive a 8 or16 ohm speaker.
(16 will not be optimal performance-will likely have less volume.)

A 16 Ohm amp can drive a 16 Ohm speaker.

==========

A 4 Ohm speaker can be driven by a 4 Ohm amp.

A 8 Ohm speaker can be driven by a 4 or 8 Ohm amp.

A 16 Ohm speaker can be driven by a 4, 8, or 16 Ohm amp.


Am I right?
This info above is how I've been running amps for 35 years and I haven't lost one yet.

There have been a number of times that I've sat in with others with borrowed gear and didn't know the cab's ohms during set-up. This is why I always have a cheap, little RatShack multimeter in my guitar case. In fact, I'd say about half of the borrowed the cabs I've played thru had their ohms mis-labelled for whatever reason. That meter has saved my bacon a number of times.
 

jchrisf

Senior Member
Joined
Oct 30, 2015
Messages
125
Reaction score
39
I had an Irt IRONHEART Studio for awhile. very, very versatile amp. Lot of great recording features like simple reamping etc. Great tone, particularly when I rolled Amperex EL84s into it.

But, the reason I no longer have it, and I have a 6505 Mini, is because of that lack of bottom end. Did a great classic rock, punk and metal. But, I wanted it for the high gain stuff, as I have other amps I like better for the classic rock and Marshall and similar tones. As such wanted that low-end thump. Could never dial it in, even on a 4x12, not at lower volumes. Recorded and louder, a bit better. My Orange and the 6505 MH, however, have that low end (and both EL84 amps fwiw) at lower volumes. Orange does that classic Brit crunch and distortion ( and I liked it a little better than the Laney Ironheart). And the 6505 does the high gain thing.

Still a great sounding amp that can cover a lot of ground.

I'm hoping the EQ pedal will help but if it doesn't it will probably go back.. I really like that thump and punch. Might have to trade it for the 60w because it has a wattage dial that will allow me to saturate the tubes more.
 

jchrisf

Senior Member
Joined
Oct 30, 2015
Messages
125
Reaction score
39
The Lionheart Studio just came out in late(?) 2015. The names (Ironheart & Lionheart) are so close it can get confusing. But Marshall takes the cake: they have the JMP 1 preamp and the JMP 1 50th Anniversary :laugh2:

Sounds like your Ironheart is a lot like the smaller Iommi Signature combo (15 & 1 watt).

I REALLY like Laney

Yeah.. that JMP-1 through me a bit at first too :)
 

cybermgk

“Happiness is the most insidious prison of all"
Gold Supporting Member
V.I.P. Member
Joined
Jul 7, 2011
Messages
16,470
Reaction score
25,199
K

Time for another analogy :)

If you check the other thread by our Friend Cherryburst, where the question was asked about running amps in standby with no speaker, I talked ad nausea about how the output transformer works.

It basically transforms high voltage, low current from O Tubes, to low voltage, high current needed by speakers.

What I didn't mention is that the aim is to match the two for optimum performance, and in very simple terms this is matching the impedance of amp and speaker.

But, it helps, for this discussion to understand voltage and current.

Going back to a water hose analogy. It works, because water flowing through the hose, is similar to electrical flow. If you take a hose, and plug it with your thumb, you can feel the water pushing against your thumb. That pressure, is similar to voltage.

Plug it completely, the pressure is still there. But, the current isn't flowing.

Now, move the thumb a little, and water flows. Your thumb is now restricting the flow of water to some degree. In other words, it is impeding its flow. In an electrical circuit, items that impede the flow of current are said to impede it, and have impedance.

More thumb covering, means more impedance, means less water flow, or current.

Higher Speaker impedance, means more thumb over the water.

Ohms law gives us current = voltage/impedance

So, assuming a constant output voltage from the amp, if voltage is 32 (just using it cause 4, 8 and 16 are multiples)

4 ohm speaker means current of 8
8 ohm spekaer, current of 4
16 ohm gets us 2

The effect is that the amp is effectively producing more output watts at lower impedance load.

This is why you see ratings on amps in their specs XX watts at Y ohms.

So, say we have a 50 watt amp, rated for 50 watts at 8 ohms. Use a 4 ohm speaker, it will increase the effective wattage of the amp.

But remember, doubling the wattage of an amp, generally only means around 6 db MAX difference in volume at full crank.

ALL of that holds true for SS amps. SS amps will also state a minimum impedance. It holds true because the output transistors are directly connected to the speaker

Even with SS amps, you should not go below the stated minimum.

Tube amps are a little different. We have that pesky Output transformer between the O tubes and the speaker (and sometimes some other gizmos).

If you go to that other thread, or remember, Output transformer on a tube amp has one function. That is, change high voltage, low current from output tubes to low voltage, high current to drive the speakers. It uses a lot of turns of wire on the core on the output tube side, and less turns on the side connected to the speaker.

Amps with just one output jack, that transformer is such that that secondary winding is done and setup for 1 impedance. The design is to produce X output when Y impedance is used. X is the max output, and fl;attest frequency response for the output.

In reality, it is not a good idea to ever mismatch impedance with a tube amp. This is because of the above. ANY mismatch of speaker load and output tap impedance will result in a reduction of output power AND a change in frequencies produced. Just how that transformer process works, electrical to magnetic to electrical.

Most modern tube amps can handle a 2:1 mismatch. CAVEAT, IT IS BEST TO ASK SAID MAKER ABOUT THIS. Lower impedance speaker to Output impedance runs the whole output section harder, like high revving a car. Higher impedance speaker on lower amp tap is moving towards the direction of no speaker hooked up (i.e. infinite impedance) and goes toward the 'flyback' voltages going the wrong way.

If either is happening it can fail the amp over time in different ways. Running too hard can cause a tube to hard fail, make the transformer run physically hotter than it is designed to dissipate heat, which can cause cumulative damage. And too much flyback can run from causing arcing damage which leads to failure, or real fast like no speaker attached.

But, as I said MOST modern tube amp designs can handle a 1/2 or 2x mismatch. I.E. amp O Tranny tap is 8 ohm, so 4 or 16 ohm speaker. AND, by far going down half is less risky than up. Flyback is a much worse potential issue than running too hot. I suspect, the Laney in the OP is designed for 16 ohm tap, thus an 8 ohm is ok.

AGAIN, CHECK WITH YOUR AMP MAKER FIRST. IF IN DOUBT, MATCH IMPEDANCES

SS amps, however, it is real bad to have too low an impedance speaker. That is why they give a min required. Drive those output transistors too hard, and they just go poof. But, there is no chance for flyback voltage if too high an impedance, or infinitae as in no speaker.

NOW, tube amps with multiple impedance selection (either multiple jacks or a switch) have multiple secondary taps on the O Tranny. Most of those will produce the same output, and mostly same tone and feel whether an 8 ohm speaker on the 8 ohm jack, or 16 ohm speaker on the 16 ohm jack, etc. Those taps are designed to get the same result, with their different designed loads.

Of course, on a multi impedance/tap amp, if you mismatch on a particular jack, see above.

________________________________________________________________

HOWEVER, if you goal is to just produce less volume on a tube amp, then really, the better way is not mismatching loads. Use a lower sensitivity speaker of the matched impedance.

Why? What is sensitivity you ask? In theory, it means driving 1 watt of output power into a speaker, and measuring at 1 meter away. A 100db speaker will produce 100db, a 96, 96dbm a 102 speaker 102db. Lower sensitivity speaker is not as loud as a higher sensitivity speaker at the same output volume.

NOTE: If folks are getting value from these dissertations, I'll keep doing them, when I think I have knowledge. Otherwise, I can stop if they are annoying.
 

Latest Threads



Top