Hoffman AC-30 Top Boost/ no vibrato

[tubenit]

Tried to follow Doug's AC-30 schematic/layout.

Check for errors.

Tubenit


Bruno drew up an AC-30 with 6V6's, so I am including that one also.

[tubenit]

I have not built this.

Check for errors.  

If I were building an AC30 with reverb, I would use this D'Lite type version. It has been successful to me on numerous builds.


(Also look at Hoffman's "add reverb to a western circuit" in the Library of Information for another option)

EDIT:  I added another version that allows a hybrid DaGeezer HoSo56 or 5879 preamp

Tubenit

[tore_t]

Hi Guys !!

I looked into the project, and here is my proposal:

http://www.triple-t.no/tore/gmf/ac_30_tore_t_reverb.sch

Tubenit's last proposal with "my" mixing cirquit before the PI will also work, at the cost of a little signal loss (and gain) before the PI. I opted for this cirquit in my bassman / plexi reverb, as I didn't wanna mess with the presence control at the other input of the PI.

In this case, where the other PI input is free (No presence or negative feedback or other channel hooked up to the "other side" of the PI), I'd rather use this input for the reverb, and keep the gain / signal level of the dry signal unaltered.

By playing with the values of the 2 220k resistors at the reverb input to the PI, or alternatively adding a trimpot, you can alter the amount of reverb available... and the "sensitivity" of the reverb mix pot.

Good luck !!

EDIT:  THANKS Tore T!    

This design came about as the result of Ground Hog Ken suggesting an improved version of
the reverb being added.  As Ken pointed out, this preserves the normal channel for those individuals who like the AC30 for the Brian May  "Queen" type sound.

[tubenit]

Use the two spring 4AB3C1B tank. 

Larger caps allow more lower frequencies.  But two .1 caps in series ought to be around .05 (.047)?
You can always post on the Tweaks to ask that question and reference the schematic I drew. I simply don't know what changes in the "series" cap question when they are on opposite ends of the 100k?

If you need to see a layout for the reverb circuit look at the SCH files for the:

Carolina Blues Rocket,  Texas Raptor, Blues Amp, or Little Wing (w/reverb).

With respect, Tubenit

[vintagescream]

Hi everybody!
I just want to say I have built this circuit, with the addition of the EF86 preamp channel. Reverb circuit is D'Lite type.
The sound is great! Allthough I tried it only with the stock speaker of Marshall VS100R, it still sounds great!
Many thanks to tubenit for the help he provided.
Layout I used is not carefully planed, so I suppose I was pretty lucky since there are no oscillations or excess hum. I used shielded cable for the signal path all the way to the PI.
Would it be a good idea to post some pictures?

[bnwitt]

Would it be a good idea to post some pictures?

Sure we'd love to see it.

AGREED!  I'd like to see pics also!  With respect, Tubenit

[vintagescream]

I dont have the pics yet, haven't had time...
Just one info: dissipation is 14W per tube. I'm affraid it's pushing them too much (factory rating is 12W max.), so I will experiment with bigger value of cathode resistors (maybe 55,60 ohms?). Man, those tubes are hot! I'm guessing it will run cooler with smaller dissipation.

[vintagescream]

Pics:









Clips:

[tubenit]

I found Old House Scott's schematic and layout for an AC-30 & Top Boost that he built.

Check schematic with layout.

With respect, Tubenit