#1
This is one of my weaker knowledge areas.... I own a Tremoverb that has two speakers. Lately I have been considering the acquisition of a head with 6l6 tubes. My Tremoverb has EL-34s fitted, so a head fitted with 6l6s would be cool to have. Perhaps a Mark IV head or the new Mark IIC+ JP head comes to mind (yeah, like I can afford it). Or I could simply buy a used Tremoverb head and keep the 6l6s in that one. Lots of options here.

Anyway, I am curious regarding the feasibility of adding an A/B type switch to my rig so that I could switch between the head and the combo amplifier on the fly, but have them both set up to use the combo speakers. That way I could rest the head on top the Tremoverb, and use the Tremoverb speakers for either the head or the Tremoverb amp. Anybody ever try this?
#2
Nope. You can use a specialized box like the Radial headbone for this, but a regular A/B will not transfer load correctly and you'll fry it, hopefully before ruining both of your amps.

If the cab has two or more speakers you can wire it in stereo, if the speakers can handle each amp separately.
#3
Just unplugging the speakers from the compo and plugging them into the other amp is really the simplest solution.
I don't give a shit if you listen to me or not
#4
Quote by Kevin Saale
Just unplugging the speakers from the compo and plugging them into the other amp is really the simplest solution.


Yes, but that's not going to let swap between the two on the fly with a footswitch.
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#5
Roc is right you will need something like the Radial head-bone for tube amps (there are several different types.
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#6
Quote by the_bi99man
Yes, but that's not going to let swap between the two on the fly with a footswitch.


Yeah, but you'd have to turn off one amp and turn on the other amp to do that anyways. It simply isn't something you'll be able to do on the fly anyways without something like the Radial Headbone, which is not cheap.
I don't give a shit if you listen to me or not
#8
Wow, I am glad I posted. Thought this would be an easy solution but have learned otherwise. Interesting, I looked at the reviews for the headbone and one of the reviewers states that you cannot use the effects loop on your amp if you are using the headbone. I'm not a huge effects user but I might miss the delay pedal.
#9
Something else you could do, maybe, is use one amp to slave the other (preamp of amp: A>effects loop of amp: B). You wouldn't be able to switch completely on the fly, but you could change between channels, ie: keep amp A in clean to "switch it off", and use amp B in overdrive, or vice-versa).

Also, as someone else said, you could use the speakers a a stereo configuration if they can handle it.
#10
Quote by Leather Sleeves
Something else you could do, maybe, is use one amp to slave the other (preamp of amp: A>effects loop of amp: B). You wouldn't be able to switch completely on the fly, but you could change between channels, ie: keep amp A in clean to "switch it off", and use amp B in overdrive, or vice-versa).

Also, as someone else said, you could use the speakers a a stereo configuration if they can handle it.

yes, but if you slave the amps, the second amp will be using the pre of the 1st amp, so it really doesn't help TS. he wants the sound of both amps
2002 PRS CE22
2013 G&L ASAT Deluxe
2009 Epiphone G-400 (SH-4)
Marshall JCM2000 DSL100
Krank 1980 Jr 20watt
Krank Rev 4x12 (eminence V12)
GFS Greenie/Digitech Bad Monkey
Morley Bad Horsie 2
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#11
Quote by Seriden
Wow, I am glad I posted. Thought this would be an easy solution but have learned otherwise. Interesting, I looked at the reviews for the headbone and one of the reviewers states that you cannot use the effects loop on your amp if you are using the headbone. I'm not a huge effects user but I might miss the delay pedal.

That's strange. I don't see any reason why you wouldn't be able to use the effects loop. That makes no sense to me. I'd look into that further before believing it. I wonder if that person meant that the headbone doesn't magically allow you to use the same effects through both loops, which, duh. That's rather different than not being able to use the effects loop, though.
#12
Quote by Roc8995
That's strange. I don't see any reason why you wouldn't be able to use the effects loop. That makes no sense to me. I'd look into that further before believing it. I wonder if that person meant that the headbone doesn't magically allow you to use the same effects through both loops, which, duh. That's rather different than not being able to use the effects loop, though.


I thought so too, but according to the manual:

Effects such as echo or loop-playing devices, MUST BE
CONNECTED BEFORE the Headbone so that their residual
or sustaining sound can be disconnected from the input of
the amplifiers. This means that you cannot use any type of
echo device that prolongs a signal on the amplifier’s effects
loop or after the Headbone in your signal chain. Failure to
do so could cause the echo to continue to play through the
standby amp which, in turn, would continue to amplify the
signal without a load. This could cause the amp or the Headbone
to malfunction. The Headbone’s internal resistor load
is only designed to support the standby amplifiers residual
output. The Headbone is NOT a load box

also:

Q: I have heard that using an echo with a head switcher can cause
a problem with the amps. Is this true?
A: It depends on where the delay is positioned in the signal chain. If the
delay is placed before the Headbone, there is no problem. If the delay
device is placed after the Headbone, or in an amplifier’s effects loop,
you can have a problem because the echo may continue to generate
a signal and send it through the “stand-by” amp with no speaker load
connected. It is generally not good to run an amp this way as the output
transformer can heat up and ultimately short out. Thus, always put
delay and looping devices before the Headbone in the signal chain.

Straight from this manual: http://www.tonebone.com/pdfs/manual-headbone.pdf

Still doesn't make sense to me, but obviously something is going on there.
I don't give a shit if you listen to me or not
#13
I have a better solution for you.

Your cabinet should be wired to 8 Ohms via 2x 16 Ohm speakers in parallel.

I'd rewire the cabinet of the combo to have a left and right jack with the left speaker only connected to the left jack and the right speaker only connected to the right jack.

This gives you 2x 16 Ohm speaker connections. Install a jack plate on the back of the speaker cab section of the combo.

Your Tremoverb has a 16 Ohm speaker option. Plug one speaker into the amp in the combo chassis and the other speaker into the second external head.

Run an A/B/Y switch up front before your guitar going into either amp to select which amp(s) is/are being fed your guitar signal.

If you want to run either of the amps with both speakers just plug the 2x 16 Ohm speakers into the 2x 8 Ohm connections and you'll be fine (at least according to my Roadster cabinet mismatch guide).
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Amps:
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Laney IronHeart IRT-Studio
Peavey Vypyr 30
Peavey ReValver Amp Sims
TOOOO many T.C. Electronic Pedals. . .
#14
Precisely. As long as each speaker is big enough just run them as stereo; one amp into L the other into R.
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#15
Quote by Kevin Saale
I thought so too, but according to the manual:

Huh! So it's not the effects loop itself, it's that you can't have anything that would send signal after the head was switched. That makes sense. Thanks for looking that up.
#16
I guess that is a 100W amp. If using only one speaker don't turn a single amp up past 1/2 to play it safe
Guitars:
Jackson Kelly KE3 - MIJ (Distortion/Jazz)
Jackson DKMGT Dinky (EMG 81/85)
ESP E-II Eclipse Custom (JB/'59)
ESP LTD EC-1001FR (EMG 81/60)
Fender MIM Strat

Amps:
Mesa/Boogie Dual Rectifier Roadster 212
Laney IronHeart IRT-Studio
Peavey Vypyr 30
Peavey ReValver Amp Sims
TOOOO many T.C. Electronic Pedals. . .
#17
And what speakers are in it?
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#18
Quote by Kevin Saale
Yeah, but you'd have to turn off one amp and turn on the other amp to do that anyways. It simply isn't something you'll be able to do on the fly anyways without something like the Radial Headbone, which is not cheap.


Yeah, but that's what the guy wants to do. Telling him to do something else entirely isn't really offering a solution.
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#19
Quote by metalmingee
I guess that is a 100W amp. If using only one speaker don't turn a single amp up past 1/2 to play it safe

That's not playing it safe! 1/2 volume on a 100 watt amp is NOT 50 watts. Depending on the amp it may actually be over 100 watts already at half volume.

The actual output of a tube amp has little relation to what you might expect based on its advertised output and the volume knob.
#20
Quote by Roc8995
Huh! So it's not the effects loop itself, it's that you can't have anything that would send signal after the head was switched. That makes sense. Thanks for looking that up.


No prob, I thought the same thing so I had to check. The way you just explained it there makes sense to me now too. Just goes to show how much is really going on with stuff like this.

Quote by the_bi99man
Yeah, but that's what the guy wants to do. Telling him to do something else entirely isn't really offering a solution.


Yes, but he obviously didn't understand the complexities of the situation, so offering alternatives is viable, not to mention the Headbone had already been brought up. No one is telling this guy what to do, these are all just suggestions. I usually like economical solutions, but other's may not. Like my sig says, I don't give a shit if you listen or not.
I don't give a shit if you listen to me or not
#21
Fair enough. The first amp is a Mesa Tremoverb with I'm assuming the stock Mesa V30's. They're rated 60-70W each. 100W amp into a 70W speaker at 1/2 volume should be good - at least I'd run it.
Guitars:
Jackson Kelly KE3 - MIJ (Distortion/Jazz)
Jackson DKMGT Dinky (EMG 81/85)
ESP E-II Eclipse Custom (JB/'59)
ESP LTD EC-1001FR (EMG 81/60)
Fender MIM Strat

Amps:
Mesa/Boogie Dual Rectifier Roadster 212
Laney IronHeart IRT-Studio
Peavey Vypyr 30
Peavey ReValver Amp Sims
TOOOO many T.C. Electronic Pedals. . .
#22
Quote by metalmingee
Fair enough. The first amp is a Mesa Tremoverb with I'm assuming the stock Mesa V30's. They're rated 60-70W each. 100W amp into a 70W speaker at 1/2 volume should be good - at least I'd run it.


Like roc said though, that's assuming you get half power at half volume, which is probably not the case. The fact that almost all amps use logarithmic volume pots would point to that almost certainly not being the case. Now, in this instance I'd probably agree with you, but the penalty for failure is so high I'd not risk it. Just my opinion.
I don't give a shit if you listen to me or not
Last edited by Kevin Saale at Feb 21, 2016,
#23
I suppose the more basic solution might be the safest way to go. Simply bite the bullet and get a cab for the other head and use an a/b switch from the guitar to the amps. The only reason I was trying to avoid that was the space savings. The Tremoverb is a large combo as it is.

I do already own a whirlwind a/b so I suppose that is the most straight forward route.
#24
Half volume is like 10 dB less. Half power is 3 dB less. If you are at half volume you are way under half power.
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#25
Quote by Kevin Saale
Like roc said though, that's assuming you get half power at half volume, which is probably not the case. The fact that almost all amps use logarithmic volume pots would point to that almost certainly not being the case. Now, in this instance I'd probably agree with you, but the penalty for failure is so high I'd not risk it. Just my opinion.


The problem there is that precisely because of the log nature of sound that half volume on a 100w amp is 10w, well under the threshold. (Double volume = 10x power)

Even if the amp could actually put out 300w at full volume, the relationship would still apply and the speakers would be fine.

I'm not sure what roc was suggesting?
“Ignorance more frequently begets confidence than does knowledge.”
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#26
Quote by Arby911
The problem there is that precisely because of the log nature of sound that half volume on a 100w amp is 10w, well under the threshold. (Double volume = 10x power)

Even if the amp could actually put out 300w at full volume, the relationship would still apply and the speakers would be fine.

I'm not sure what roc was suggesting?


I think the point is between log pots and incorrect ratings for amplifiers you can't really assume anything.
I don't give a shit if you listen to me or not
#27
No, but your ears will tell you close enough. We aren't talking about a JTM45 where it is pretty much at full volume on 5 and from there it just distorts more. This is a Tremoverb, find what is about half volume by your ears and stay around that and you'll be fine.
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#28
Quote by Kevin Saale
I think the point is between log pots and incorrect ratings for amplifiers you can't really assume anything.

In a nutshell, yes. More than the curve fit of the pot itself, the pot is not typically in a place in the circuit where it would really make sense to say that it scaled the volume (or power) nicely. It would be like saying that having the gas pedal halfway down and your car in third gear is exactly half as fast as it can go, or putting out half its horsepower. Too many other variables involved for that to be a neat linear (or logarithmic!) relationship. You could design it that way, but nobody does.
Quote by Arby911
The problem there is that precisely because of the log nature of sound that half volume on a 100w amp is 10w, well under the threshold. (Double volume = 10x power)

Even if the amp could actually put out 300w at full volume, the relationship would still apply and the speakers would be fine.

I'm not sure what roc was suggesting?

Halfway through the sweep of the volume knob is neither half the rated output nor half the volume of the amp. The relationship you suggest does not apply, at least not in common use in tube amps. These are not nice clean circuits, unfortunately. No amp maker that I'm aware of ever bothered to neatly map output or volume to scale neatly with the volume control.* So it has no reliable relation to 10% of the power or 50% of the volume, or anything, really, which is why I said it wasn't safe to make a blanket statement about speaker compatibility.

Most of the time a tube amp will hit its rated wattage fairly early on in the sweep, then after that it's diminishing returns on volume and after a certain point it's just distortion. There might be some amps out there that are quite neatly linear but the ones I bothered to test when I had a rig capable of such things were nowhere near it. A lot of Plexis for example hit their rated wattage around 50% on the volume control. I don't think any real thought ever went in to where 'half volume' was on these amps. There's just no point. You slap in a pot, and let the user figure the rest out. Anything more mathematically clean than that is just wasted profit.

As Cath says, though, with a modern MV amp like the Mesa and a V30, it's going to be fine. I just thought I'd address the misconception becaus it is not a safe assumption in every case. With a Plexi and Greenbacks, for example, you can get yourself in trouble in a hurry assuming that halfway is 50 watts. It's not! It's a lot easier to get in trouble with non-MV amps. I should have clarified all this in my initial post, but as you can see it's a bit of a writeup.
Quote by Cathbard
No, but your ears will tell you close enough. We aren't talking about a JTM45 where it is pretty much at full volume on 5 and from there it just distorts more. This is a Tremoverb, find what is about half volume by your ears and stay around that and you'll be fine.

The practical answer for the current issue. I just worry that the one time nobody posts a "careful!" caveat to one of those half-volume misconceptions, someone's going to fry a speaker or an amp. That would suck.

*And why would they? The Hi-Fi guys that do this end up with absurd stuff like a $300 volume pot with 24 discrete resistor steps:
http://www.diygene.com/store/index.php?route=product/product&product_id=452
Nobody's going to notice or care that your 50 cent pot doesn't line up with any meaningful volume or power curve on a guitar amp.
#29
Exactly. Which is why I said to do it by ear. Going for half volume by ear will give you a good 7dB of tolerance.
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#30
Yup. I think the earlier suggestion meant half volume as 5/10 on the knob.

I wonder if we could get some interesting information about volume perception now that phones have dB meter apps. I have a hard time perceiving "half as loud" myself.
#31
Well, it just needs to be 3dB lower. 3dB isn't much at all really. So as long as it's a really noticeable drop in volume, you'd be pretty safe with a V30. I wouldn't be at all surprised if a V30 could hang with it anyway. They're a tough speaker.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#32
With a Tremoverb you could also just pull two of the power tubes. It's not really a difficult problem to solve either way, is it?
#33
Absolutely. That's what I'd do 'twer it mine. Who needs four tubes?
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#34
Quote by Roc8995
Yup. I think the earlier suggestion meant half volume as 5/10 on the knob.

I wonder if we could get some interesting information about volume perception now that phones have dB meter apps. I have a hard time perceiving "half as loud" myself.


Yeah, I didn't think of it as "halfway on the knob" but that makes sense.
“Ignorance more frequently begets confidence than does knowledge.”
Charles Darwin