Tremoverb loop as a second master / solo?

[hal9000]

I soldered the pin to ground within a right angle jack, it could have been intermittent I suppose (i'm at work now so can't check). Does that give a clue to the problem? I'm guessing it's at least a fried resistor or cap or relay? Anyway, nothing I think I would tackle myself.

I did remove the jacks immediately and tried all the effects loop switching options, including always-bypass, and replacing all the preamp tubes, still had the problem.

If you could detail each step exactly like you performed the mod that would help. For instance, did you use a single cable or two jacks? Did you put the plugs in the correct jack? Did you verify conduction between the soldered points? Like I said before, I can't imagine anything in this mod that would cause the symptoms you're seeing. If you look at the schematic I posted, you'll see what I mean. You're bascially duplicating the FX SEND pot further down the line.

 

[canon]

I soldered the inside pin of a right angled jack to the sleeve/case, then screwed it back together. The shorted jack I put in 'return', the standard open jack I put in 'send', had send and mix cranked, I noticed the volume went up as I turned mix down vs. what I would normally expect (volume goes up as mix goes up). The effects loop in/out switching was silent and the change in volume was smooth and good, ahhh, so close! Overall volume was higher, I assume due to the 'send' volume.

I didn't verify conduction, so that's probably where the issue lays, but a mod where a short in a cable or other can damage the circuit .. I just don't trust cables/jacks to not short ever over time? If/when I can get it fixed, I think I'll be gun shy for a while, too many gigs coming up.

 

[hal9000]

I soldered the inside pin of a right angled jack to the sleeve/case, then screwed it back together. The shorted jack I put in 'return', the standard open jack I put in 'send', had send and mix cranked, I noticed the volume went up as I turned mix down vs. what I would normally expect (volume goes up as mix goes up). The effects loop in/out switching was silent and the change in volume was smooth and good, ahhh, so close! Overall volume was higher, I assume due to the 'send' volume.

I didn't verify conduction, so that's probably where the issue lays, but a mod where a short in a cable or other can damage the circuit .. I just don't trust cables/jacks to not short ever over time? If/when I can get it fixed, I think I'll be gun shy for a while, too many gigs coming up.

Well, from your description, it seems you did everything correctly. The fact that it worked at all pretty much means that you did it right. Since I don't have a T-verb around to play with, I can't say for sure, but I think you might just have had a stinking case of coincidence or an unfortunate inadvertent problem somewhere else in the amp. IMO, if there was a problem with the mod, it should have caused a failure immediately, not after enough time to really tell that it worked. Finally, new tubes can be bad right out of the box. Did you verify that the rest of the signal chain is still good, like the guitar, cable, speaker, footswitch, etc.?

 

[hal9000]

Canon, can you describe the exact problems that you're experiencing with your amp? Perhaps the clean channel drives the FX recovery tube (V4a) so hard with the FX send pot cranked that it goes into cutoff.

 

[canon]

I tried replacing all the preamp tubes right away after the problem showed up, so I think it's something on the board?

channel1 makes good sound for 2-3 seconds, goes silent for 5-8 seconds, then makes sound again for 2-3 seconds, goes silent again, and so on

channel2 is fine

 

[hal9000]

I tried replacing all the preamp tubes right away after the problem showed up, so I think it's something on the board?

channel1 makes good sound for 2-3 seconds, goes silent for 5-8 seconds, then makes sound again for 2-3 seconds, goes silent again, and so on

channel2 is fine

Both channels are equally affected by this mod, so IMO, what you did last night had nothing to do with this problem. Does the second channel switch cleanly from FX loop BYPASS to ON such that the volume change is evident from the Mix pot?

 

[canon]

hmm, I didn't want to risk it after what happened with the first channel. I'll post about what the tech says.

 

[canon]

Meh, they're closed today, so I'll post back later.

 

[jbird]

I beleieve what we're missing here is that the mod for the F-series is to attain a master volume for the amp through use of the F/X Loop! But, has someone overlooked the fact that when the F/X Loop on the two channel Tremoverbs and Solos is engaged, theres a Loop Active Master control on the front that becomes an overall Master for both channels! The F-Series does not have a Loop Active Master, hence the mod! I don't believe canon's desire (anyways) was to have an overall master volume control mod! I believe he's trying to attain a way to have the F/X Loop switchable, at a louder volume (or quieter), for a solo boost! Now, if I'm right up to this point, lets start over! I always thought the only source to switch the F/X Loop on/off via the external switching jack, was some sort of midi device/processor? If indeed, you can use an ordinary 1/4" instrument cable from the F/X Loop external switch, to an ordinary latch device (footswitch), set the F/X Loop rotary dial to external switching, connect a short 1/4" instrument cable from the Send jack to Return jack, set the Loop volume(s) louder (or quieter) than the Channel Masters, then you may have a footswitchable Solo Boost, by use of the F/X Loop! I've never heard of it done, would it work? :idea:

 

[hal9000]

I beleieve what we're missing here is that the mod for the F-series is to attain a master volume for the amp through use of the F/X Loop! But, has someone overlooked the fact that when the F/X Loop on the two channel Tremoverbs and Solos is engaged, theres a Loop Active Master control on the front that becomes an overall Master for both channels! The F-Series does not have a Loop Active Master, hence the mod! I don't believe canon's desire (anyways) was to have an overall master volume control mod! I believe he's trying to attain a way to have the F/X Loop switchable, at a louder volume (or quieter), for a solo boost! Now, if I'm right up to this point, lets start over! I always thought the only source to switch the F/X Loop on/off via the external switching jack, was some sort of midi device/processor? If indeed, you can use an ordinary 1/4" instrument cable from the F/X Loop external switch, to an ordinary latch device (footswitch), set the F/X Loop rotary dial to external switching, connect a short 1/4" instrument cable from the Send jack to Return jack, set the Loop volume(s) louder (or quieter) than the Channel Masters, then you may have a footswitchable Solo Boost, by use of the F/X Loop! I've never heard of it done, would it work? :idea:

LOL! I can understand how all the “Master Volumes,” “FX,” “Switching,” and “MIDI” can get confusing. Take heart though, it’s rather simple to understand when each piece is taken by itself.

1) You are correct that the F-series has no overall master for both channels, hence the mod which works great at getting low volumes out of a loud amp.
2) The Tremoverb’s FX loop is switchable via a latching switch. The switch itself merely connects the sleeve and tip of the jack together, which brings in an alternate path that bypasses the FX Loop in its entirety.

3) Yup, there is Loop Active Master that is switched in with the FX loop. For an experiment, balance both channels so they are at a good playing level without the FX loop engaged (this is your maximum volume). Then, switch the FX loop on. The Loop Active Master should now be the overall volume for the amp. If you set the Loop Active Master about 3 dB below the solo volume, you’ve now got your rhythm volume. So, Loop bypassed is solo volume, and loop engaged is rhythm volume. Mmm… Footswitchable solo boost. I don’t think you’ll need the cable to connect the FX send to FX return. If the Tremoverb is like every other Mesa amp, it has a shorting FX send jack that connects to the FX return if nothing is plugged-in.

 

[jbird]

Excellent then hal9000! I wonder why no-one has considered this, or why Mesa never mentioned it! I've heard so many people complain of no solo boost function on the two channel Rectifiers! Maybe now we have one! My question to you now: By not considering the Loop Active Master on canon's Tremoverb, and shorting the loop's send/return jacks, in order to attain a master volume, could have harm been done?

 

[hal9000]

Excellent then hal9000! I wonder why no-one has considered this, or why Mesa never mentioned it! I've heard so many people complain of no solo boost function on the two channel Rectifiers! Maybe now we have one! My question to you now: By not considering the Loop Active Master on canon's Tremoverb, and shorting the loop's send/return jacks, in order to attain a master volume, could have harm been done?

If I owned a Tremoverb, you can bet I would've been doing this already!

From looking at the schematic, you can see that the FX send pot is 25k to ground. The FX Mix pot duplicates that function with the FX return tip grounded. So, as long as the FX send pot doesn't cause a problem, neither will the FX mix pot. The FX send plug is just to disconnect the internal normalling to FX return. Also, in looking at the preamp stages before the loop, there is no physical connection to the rest of the amp when the FX loop is disengaged: http://www.tubefreak.com/tremvrb2.gif So, if the FX loop is bypassed, there can be no affect on the rest of the amp.

BTW, in Canon's case, he actually had three master volume controls in parallel with each other. Normally, you'd only have the FX send and Loop Active Master. So, if any of them are too low, you'll get very little output.

 

[jbird]

True dat! Now, can you tell me: What/where are some "latching" pedals one might look for to trigger the external jacks? In looking at Boss products, they have a FS-5L! Would that work as a "latch" switch, connected to a standard 1/4" instrument cable? What about the pedals in Mesa's accessories dept? I see some single button footswitches, labeled: F/X Loop, Tremolo, Reverb, etc, etc. Are they "latching" (?) type pedals? Thanks hal9000!

 

[hal9000]

True dat! Now, can you tell me: What/where are some "latching" pedals one might look for to trigger the external jacks? In looking at Boss products, they have a FS-5L! Would that work as a "latch" switch, connected to a standard 1/4" instrument cable? What about the pedals in Mesa's accessories dept? I see some single button footswitches, labeled: F/X Loop, Tremolo, Reverb, etc, etc. Are they "latching" (?) type pedals? Thanks hal9000!

Yes, the FS-5L will do the trick. I have one and it works great. It even has an LED powered by an internal 1.5V battery. When I first got my F-100, I built a remotely switching Master volume for the FX loop. It defaulted to attenuation, and if I pressed the FS-5L's button it switched to true bypass. That was my solo boost for a while.

 

[jbird]

Nice! And what about those Mesa footswitches? Would they work for the external switches? This has been an enlightening conversation BTW! Thanks!

 

[hal9000]

Nice! And what about those Mesa footswitches? Would they work for the external switches? This has been an enlightening conversation BTW! Thanks!

Yes, Mesa's switches will work too, they're just more expensive. You could build a Mesa-type switch for about $10 using top quality parts.

 

[canon]

Well, it will be 2 or 3 weeks before I know what happened in detail, but the tech agreed that it doesn' make sense that only one channel was affected.

Hey, if someone else wants to try it, I'm all eyes. For now I need to scrape up a suitable backup.

 

[jbird]

What do you mean: "Hey, if someone else wants to try it?" We just explained how to accomplish a solo boost function from your Tremoverb! And for that fact, the two channel Solo heads! True, it did'nt require the "shorting" of the loop's send & return jacks, but again, if you read the post, you'll see the answer to your original question!

 

[canon]

Which post? Sorry if I'm coming off a little dense, but I tried the cable directly from send to return when I first got the amp, and that had no effect for reasons I don't understand, regardless of my send or mix knobs.

Hal9000's mod seems to me bleeds some signal to ground when the loop is engaged and does require either a shorted jack or a crossed cable, worked great for a while, but then my amp stopped working, maybe coincidentally. So I'm saying if someone wants to try Hal9000's mod, I'd be curious to see if they didn't have the intermittent channel problem afterwards.

 

[jbird]

I guess your not getting it? Hal9000's mod was for a F-Series amp, to attain an overall master volume, through use of the the F/X Loop! On your Tremoverb (or the two channel Solos), when you employ the F/X Loop, the Loop Active Master (on the front) becomes the amps overall master volume! So why would anyone without a F-Series want to try it? Again, try reading through this thread!