Has anybody built a 6V6 version of the 18Watt?

[PhatTele]

I have a Tweed Deluxe PT and OT as well as a blank chassis all ready to go for my next project. I was going to build another 5E3. However, because of a shift in some other project plans, I'm left with a chance to build any preamp circuit I want. So, I'm curious how a 6V6 version of an 18Watt Lite might sound. Has anybody experimented with this?

Thanx

[GlennG]

I have built a 6v6 18 watt and I call it the 22 watt It sounds great.

Glenn Gertis

[zaphod_phil]

Are you saying you get more power out of the 6V6s than EL84s? I would have thought you would get slightly less. Also, did you use a lower value tail resistor in the PI to get more drive onto the 6V6 grids? Could you describe the sound in a little more detail? Sorry to beat you up with so many questions! The concept sounds a little like the Marshall Studio 15 which also used 6V6 tubes...

[markh]

I built a 6V6 version of the November, and found the 6V6 responds well to the "normal plexi" PI values, i.e., the 10K tail resistor and the Prescence NFB connection. http://mhuss.com/Plexi6V6/

--mark

[Plexi]

I also have one sitting here.. Amp is the one i use for experimenting..
its been a little of everything. but as it is now,it has the TMB plexi sorta channel.. And a somewhat 18 normal channel..
These do sound very good. This one is AC-DC Kinda Bad Company tone to it..

Richie

[Attilio]

I built a 6V6 version of the November, and found the 6V6 responds well to the "normal plexi" PI values, i.e., the 10K tail resistor and the Prescence NFB connection. http://mhuss.com/Plexi6V6/

--mark

Hi Mark!
I am very interested to your 6V6 Plexi, and I have some question for you:
I already own a 300-0-300/150mA PT (actually it pushes more than 300V, I measured over 315V) and a Hammond 125E OT: are these trannies good for your Plexi?
How loud is this amp? Is it louder than a 18Watt?
Thank you very much!
Bye!
Attilio

[markh]

I already own a 300-0-300/150mA PT (actually it pushes more than 300V, I measured over 315V) and a Hammond 125E OT: are these trannies good for your Plexi?
How loud is this amp? Is it louder than a 18Watt?

hi Attilio,

This amp might be a bit louder, but not enough to make a difference in a band situation. I'd suggest a 4xEL84 ir 4x6V6 output stage if you want to take it to the next level.

The PT & OT you have would work, but I think the B+ would b a bit too high (as it is in my amp.) I'd rather have a B+ of 350 or so.

--mark

[Attilio]

Thank you very much!
Another question: if I use a bigger OT can I use 6V6s and EL34 simply swapping them? I think no, because of bias and impedance problems, but I'm not sure. Does a way to make it exist?
One more ( ): I found at my local store very cheap 280-0-280 and 250-0-250/200mA PTs. Are they better suitable for this project, isn't it? I think a 280V PT ss rectified should work fine, am I right?
Thanks in advance!
Bye!

[zaphod_phil]

It's pretty easy to switch your impedances on a multi-tap output transformer. And the impedances aren't that critical, more it's what it sounds like. You can also switch cathode bias resistor values quite easily as well. So yes, what you suggest is perfectly possible to do. I remember seeing a recent posting from Paul Ruby somewhere on this very subject,, where he talked of using two cathode resistors of equal value in parallel, with one you could switch out to change the bias.

The 280V transformer will give you close to 400V if SS rectified, which is fine for those tubes. Just beware that SS rectifiers can introduce some HF noise into your amp. So you might like to try Paul Ruby's trick of placing a .01uF cap in parallel with each one and a resistor of around 10 to 100 ohms (IIRC) in series.

Paul got two mentions in this posting, so that's a new record - whoops, that just made it three!

[LeeM]

If you use a power tranny that will give the max B+ you'd ever want with a s.s. rectifier, then you have the option (provided you wire in an octal socket) off dropping the voltage varying degrees with different tube rectifiers.

[markh]

Thank you very much!
Another question: if I use a bigger OT can I use 6V6s and EL34 simply swapping them? I think no, because of bias and impedance problems, but I'm not sure. Does a way to make it exist?

Anything is possible You'd need to have a bias switch as many newer amps do that allow both 6L6 and EL34.

One more ( ): I found at my local store very cheap 280-0-280 and 250-0-250/200mA PTs. Are they better suitable for this project, isn't it? I think a 280V PT ss rectified should work fine, am I right?

Opinions vary on this, but IMO the 250 would be good for SS rectification and the 280 would be good for a tube recto.

--mark

[zaphod_phil]

I have built a 6v6 18 watt and I call it the 22 watt It sounds great.

As JIG has raised this subject again on another thread, can you tell us about how you did it? What plate voltage on your 6V6s, what cathode resistor, any changes to the PI resistir values?