Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Papa Jim on June 08, 2016, 09:03:57 pm

Title: Advice needed. 1 Tube Reverb for my 4-4-0 (trainwreck) type amp.
Post by: Papa Jim on June 08, 2016, 09:03:57 pm

Is the location and resistor where I am trying to add tubenit's 1 Tube reverb look correct.

Title: Re: Advice needed. 1 Tube Reverb for my 4-4-0 (trainwreck) type amp.
Post by: TIMBO on June 09, 2016, 12:42:31 am

That will work, usually insert it just before the PI. :icon_biggrin:

Title: Re: Advice needed. 1 Tube Reverb for my 4-4-0 (trainwreck) type amp.
Post by: Papa Jim on June 09, 2016, 04:45:20 am

Thanks. Going to order the parts. I'll report back the results in the near future.

Title: Re: Advice needed. 1 Tube Reverb for my 4-4-0 (trainwreck) type amp.
Post by: tubenit on June 09, 2016, 05:16:03 am

I would also insert it prior to the LTPI.

With respect, Tubenit

Title: Re: Advice needed. 1 Tube Reverb for my 4-4-0 (trainwreck) type amp.
Post by: Papa Jim on June 09, 2016, 06:16:42 am

Like this, right before the coupling cap to the phase inverter?

Title: Re: Advice needed. 1 Tube Reverb for my 4-4-0 (trainwreck) type amp.
Post by: Willabe on June 09, 2016, 10:18:03 am

Quote from: rolloman on June 09, 2016, 06:16:42 am

Like this, right before the coupling cap to the phase inverter?

Yes.

But you need to add a small value cap to cut the low end bass (mud) going into the reverb tank driver tube.

Title: Re: Advice needed. 1 Tube Reverb for my 4-4-0 (trainwreck) type amp.
Post by: Papa Jim on June 09, 2016, 10:57:52 am

Thanks for catching that. Somehow when I copied and pasted the 1 Tube Reverb I lost that cap. Lol
Revised my drawing.

Title: Re: Advice needed. 1 Tube Reverb for my 4-4-0 (trainwreck) type amp.
Post by: Papa Jim on June 11, 2016, 11:01:42 am

Does Hoffman stock a xfmr that will be suitable for this reverb circuit.

Title: Re: Advice needed. 1 Tube Reverb for my 4-4-0 (trainwreck) type amp.
Post by: tubenit on June 11, 2016, 01:54:02 pm

Yes, I've always used Hoffman's fender reverb pt replacement and the standard fender reverb tank that he carries also.

with respect, Tubenit

Title: Re: Advice needed. 1 Tube Reverb for my 4-4-0 (trainwreck) type amp.
Post by: Papa Jim on June 11, 2016, 03:02:01 pm

Since I last posted I found that I had a reverb tank stored away. Concerned though about if it is usable without some mods to the circuit since it has 600 ohm input and 2275 output. It is an accutronics 4eb2c1b.

Title: Re: Advice needed. 1 Tube Reverb for my 4-4-0 (trainwreck) type amp.
Post by: Papa Jim on June 16, 2016, 11:38:59 am

I have this exact reverb tank so would like to use this circuit for my 4-4-0 reverb. Has anyone used this reverb ciruit? I found it in one of tubenit's posts about 1 tube reverbs. I noticed it does not use a transformer so should only cost me the price of the tube, caps, and resistors.

Title: Re: Advice needed. 1 Tube Reverb for my 4-4-0 (trainwreck) type amp.
Post by: sluckey on June 16, 2016, 12:03:02 pm

I haven't used that exact 6BM8 circuit but I've had two amps that used a similar cap driven tank. Ampeg Gemini II and Magnatone M10A. Reverb sounds great on both amps.

If I had that tank (which BTW will not work with a Fender transformer driven circuit) I'd build that nice 6BM8 circuit.

Title: Re: Advice needed. 1 Tube Reverb for my 4-4-0 (trainwreck) type amp.
Post by: pompeiisneaks on June 16, 2016, 12:28:06 pm

cool!  Is the 6BM8 one of those dual pentode/triode tubes?  I guess I can look it up :)

~Phil

Title: Re: Advice needed. 1 Tube Reverb for my 4-4-0 (trainwreck) type amp.
Post by: Papa Jim on June 16, 2016, 12:52:02 pm

It's labled as a Triode-Beam Power Tube.

Anyways thanks sluckey, glad to hear of some experience with this species of reverbs. It will save me a lot of the cost to go this route.

Title: Re: Advice needed. 1 Tube Reverb for my 4-4-0 (trainwreck) type amp.
Post by: sluckey on June 16, 2016, 01:04:02 pm

I've been interested in that 6BM8 one tube reverb circuit ever since I first saw it.  I'd love to hear your opinion when you get it done. Give us a report.

Title: Re: Advice needed. 1 Tube Reverb for my 4-4-0 (trainwreck) type amp.
Post by: Papa Jim on June 16, 2016, 01:10:33 pm

 :thumbsup: Will do.

Title: Re: Advice needed. 1 Tube Reverb for my 4-4-0 (trainwreck) type amp.
Post by: tubenit on June 16, 2016, 01:17:18 pm

Quote

I've been interested in that 6BM8 one tube reverb circuit ever since I first saw it.  I'd love to hear your opinion when you get it done. Give us a report.

+1

Would love to hear a sound clip when you're finished.

With respect, Tubenit

Title: Re: Advice needed. 1 Tube Reverb for my 4-4-0 (trainwreck) type amp.
Post by: Papa Jim on June 16, 2016, 01:40:40 pm

I will do that also. No promises on my playing talent though.   :l2: :l2: :l2: