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Reducing output by removing tubes
- Thread starter awilkie84
- Start date
That's only 1.8 db difference at most - you do know how to calculate this stuff, right? A 1 db step is about the minimum a human ear can detect...
so the problem is that we can't easily go from "too quiet" on the master volume without jumping to "too loud"?
that sounds like the master volume pot needs to be changed out from linear taper to audio taper, so it comes up from "off" much more slowly.
where do you tend to run the preamp volume and the master volume?
(the volume control in the loop thing can work too, i suppose; as a line-level loop, you'll want a "low impedance" control, like 25kΩ.)
reducing output power just means it loses low end authority, no good for bass. it also means mucking about with the operation of a high-powered tube output section, something best avoided if you don't want to damage the amp.
finally, if the idea is to push the amp into some kind of overdrive, +1 to the idea of a smaller cabinet, that can make as much or even more difference to the loudness as the amp's wattage. can't say i like that idea for bass though, i'd want as much headroom as i could get for a tube amp so i kept my low end, and instead get my overdrive upstream.
that sounds like the master volume pot needs to be changed out from linear taper to audio taper, so it comes up from "off" much more slowly.
where do you tend to run the preamp volume and the master volume?
(the volume control in the loop thing can work too, i suppose; as a line-level loop, you'll want a "low impedance" control, like 25kΩ.)
reducing output power just means it loses low end authority, no good for bass. it also means mucking about with the operation of a high-powered tube output section, something best avoided if you don't want to damage the amp.
finally, if the idea is to push the amp into some kind of overdrive, +1 to the idea of a smaller cabinet, that can make as much or even more difference to the loudness as the amp's wattage. can't say i like that idea for bass though, i'd want as much headroom as i could get for a tube amp so i kept my low end, and instead get my overdrive upstream.
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I don't want to switch to an audio taper, cuz then it's weighted heavily on the other end. The linear pot is fine, the head's just pushing too much power for my day-to-day needs. I like my gain to be pushing the tubes into overdrive but that's when the volume becomes unmanageable. I've already starting pulling parts out to build the volume control for the effects loop. Just have to locate a 25k pot. May need to buy that, as most of my stuff is from passives.
I don't like overdrive pedals much. They're not the same as a true tube drive.
the power tubes? for bass?
i'm not sure you do, unless you're going for '60s jack bruce fuzz bass. if so then just sell the thing and get a 100w marshall guitar amp or something.
i like a grindy, fat SVT-type tone myself, but i'm convinced that comes from a power section that's staying mostly clean (for headroom and bottom end) and a little grit from the preamp.
So do I. I 1st noticed how 'little' clean headroom my SVTII had one night years ago when I had it running into just one (gutsy) 4 ohm 115 cab.
I usually used it into a 215 and had never run outta headroom. But this night I found myself thinking thati needed WAY more wattage. When really I needed more speakers. Do these days, if I ever feel the need for an overdriven all tube tone, I just take my Bassman Neo 115 cab and the Super Bassman 300w all tube amp will quite easily power tube overdrive with it. Sure the volume is getting up there and the cab is probably quite close to its limits too, but it works. Usually I like good CLEAN all tube tone, so I usually use my 412 or 810 to get me there.
Maybe a stupid idea, but could you sub 6v6 tubes for the 6l6s? I know Eurotubes makes a big deal out of doing this on the Fender Hot Rod amps, but the specs on your Traynor may not support it. Would be good for dropping output power by half, but that'll only save you around 3db (?)
I don't see how this can be. What overdrives any stage of amplification is the strength of the signal you are feeding it. Sure, you can overdrive a preamp if you have separate gain control of the power amp and turn it down, but you have to feed the preamp plenty of signal to do it. I don't see how turning down the bass and turning up the amp overdrives anything.
Honestly, I don't know. I know it can take EL34s but I'm not sure about the 6V6. That's the first I've even heard of that tube type, honestly.
My thoughts exactly.
They're used in lower powered old Fenders, like the Deluxe and Princeton. Most amps that take 6l6 tubes can swap out 6v6, but they may need a rebias, and most 6v6 aren't up to handling the voltages a 6L6 design is spec'd for, but the JJs were specifically developed for this application. A pair produces ~20ish watts, vs 6l6s which can produce in the mid 50s, depending on circuit. So you'd have ~120 watts output, vs 300.
Here's a link to the tubes
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It is in no way a cheap option
Hmmm...they're even JJ's...I like that.They're used in lower powered old Fenders, like the Deluxe and Princeton. Most amps that take 6l6 tubes can swap out 6v6, but they may need a rebias, and most 6v6 aren't up to handling the voltages a 6L6 design is spec'd for, but the JJs were specifically developed for this application. A pair produces ~20ish watts, vs 6l6s which can produce in the mid 50s, depending on circuit. So you'd have ~120 watts output, vs 300.
Here's a link to the tubes
[Invalid or Expired Link Removed]
It is in no way a cheap option
I love JJ 12A's for my pre-amp section. Luckily, the YBA-300 has bias controls on the back to make it stupid simple. 
That said, retubing my amp would be incredibly expensive and I could just buy a class D 1x15 combo for what I'd spend on 12 tubes. They're $26.75/ea in my area so 26.75*12*1.12 (tax) = $359.52 CAD Yeah...that's pretty cost-prohibitive for an experiment.
I like the thought of an additional volume pot put either in front of your input, or in the effects loop. A power soak used carefully could be cool too, but the more you keep your adjustment low power, the cheaper it's going to be. If you add that new volume pot, Im very curious about the difference in sound if you put it between your bass and amp input, or in the effects loop. My guess it in the effects loop would give the best tone from the preamp.
Another not-cheap option would be to replace all the 6L6's with Yellow Jackets.They're used in lower powered old Fenders, like the Deluxe and Princeton. Most amps that take 6l6 tubes can swap out 6v6, but they may need a rebias, and most 6v6 aren't up to handling the voltages a 6L6 design is spec'd for, but the JJs were specifically developed for this application. A pair produces ~20ish watts, vs 6l6s which can produce in the mid 50s, depending on circuit. So you'd have ~120 watts output, vs 300.
Here's a link to the tubes
[Invalid or Expired Link Removed]
It is in no way a cheap option
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I said it wasn't cheap, didn't I?
I have a pair of them in my (formerly) 50W Marshall and they work great.
When you build you box it should be in a metal box. Hammond makes the 1590 series which are available black. I'd use an audio taper pot. If you are concerned about the taper you could put in a DPDT toggle switch to change over the wiring fro the top and bottom lugs of the pot. In the normal position it will be a clockwise to increase log pot. In the other it will be anti-log, anticlockwise to increase. You can select the taper that suits you best. With a tube amp i'd be using a 500K or 1M pot.
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Can you elaborate as to why?
Also, I seem to recall you telling me that running my 4Ohm tube head into an 8Ohm cab would cause issues (despite the manufacturer and several other tube amp techs telling me otherwise) and I've had no issues with it. So, forgive me if I take what you say with a grain of salt.
Plate voltage.
Also any tech will tell you that an amp with good (see: overbuilt) transformers will be able to handle a step up or two down in impedance mismatch. But it puts strain on the tubes and if your transformers aren't so good you have a chance of blowing them. I've run my Ampeg V-4 at 4 ohms into a 16 ohm load, no problems, I've run my Science Hellhawk at 16 ohms in 64 ohms, also no problems this was all accidental though. It's the fact that the Ampegs' are the size of my head and the Hellhawk's Classic Tones are probably the best vintage spec transformers you can buy today.
Also any tech will tell you that an amp with good (see: overbuilt) transformers will be able to handle a step up or two down in impedance mismatch. But it puts strain on the tubes and if your transformers aren't so good you have a chance of blowing them. I've run my Ampeg V-4 at 4 ohms into a 16 ohm load, no problems, I've run my Science Hellhawk at 16 ohms in 64 ohms, also no problems this was all accidental though. It's the fact that the Ampegs' are the size of my head and the Hellhawk's Classic Tones are probably the best vintage spec transformers you can buy today.
