DIYstompboxes.com

DIY Stompboxes => Building your own stompbox => Topic started by: nelson on October 28, 2005, 04:10:21 PM

Title: Got some Tube transformers, what amp to build?
Post by: nelson on October 28, 2005, 04:10:21 PM
I managed to get my hands on a 40W output transformer for 2X6L6 and a mains transformer with 350VAC + 6.3VAC.


Now, what amp should I build?

I am Thinking about a Vibrolux Reverb.

I understand this is a DIY stompbox forum, however I hate the board style over at the amp forums...needs a serious overhaul....and less spam.....

Also, I am having trouble finding a suitable aluminium chassis, I mean the Vibrolux has ( tubes and 4 transformers/choke) Chassis needs to be large...Every place sells them predrilled for $100 plus....not quite what I had in mind paying for sheet aluminum....


all ideas suggestions welcome....
Title: Re: Got some Tube transformers, what amp to build?
Post by: jrc4558 on October 28, 2005, 11:46:12 PM
Hey Nelson!
I suggest you build something like this:
This peramp and phase inverter http://www.blueguitar.org/new/schem/trainwreck/wrek_pr.pdf
with a generic 5881 or 6L6 class AB1 output stage.
I tried it with a quartet of EL84s in class AB1 and its a killer.
I mean you will obviously have to tweak the voltages and reduce some gain here and there, but should be ok.
Title: Re: Got some Tube transformers, what amp to build?
Post by: Paul Marossy on October 29, 2005, 10:01:31 PM
Build an Octal Madness (http://www.diyguitarist.com/Schematics/OctalMadness-Full.jpg)! I'm really considering building this one myself in the near future.
Title: Re: Got some Tube transformers, what amp to build?
Post by: Peter Snow on October 30, 2005, 11:00:42 AM
Hey Paul (& others),

I was just looking at the schem for the Octal Madness and I noticed that the speaker jack connected to the output transformer was a "shorting" type.  That is, with no plug (connected to the speaker) inserted, the output windings of the trasnsformer are shorted to ground.  Would this not destroy the transformer in pretty short order?  :icon_cry:   I guess the best solution is to have a load of the correct impedance connected, but for those times when you forget... I always thought that an open circuit was better than a short circuit in this situation.  Is there some other reason for the shorting jack?  ???

Cheers,

Peter
Title: Re: Got some Tube transformers, what amp to build?
Post by: Paul Marossy on October 30, 2005, 03:08:13 PM
QuoteI was just looking at the schem for the Octal Madness and I noticed that the speaker jack connected to the output transformer was a "shorting" type.  That is, with no plug (connected to the speaker) inserted, the output windings of the trasnsformer are shorted to ground.

I wonder about that myself. The designer of the circuit, David Jones, must have done it for a reason.