Hoffman AC30 voltage

[labb]

Been looking for a schematic of the Hoffman AC30 build that has power supply, plate and screen voltages on it. Have not been able to find one. Anyone know where I might find this.

[stratele52]

And what about 1996 Vox AC 30 ?

EL84 plate is 324 VDC with very very hot bias . Screen pin 9 ; 332 VDC

[stratele52]

Here ?

www.el34world.com/charts/valve/ValveDataIndex.php

[stratele52]

Did a search on Hammond's site and found a replacement P/T (EDB290NX) was 290-0-290, so stratele52's numbers sound reasonable. 

Which version of the AC30 are you working on? 

+1 if he look to buy one ; look on PDF sheet here

www.hammondmfg.com/guitarLinePWR.htm

[labb]

Thanks...The valve data chart helps a lot..I have a hard time searching on the site. I am looking at the AC-30 normal and top boost no tremolo channel. Actually I have a Marshall 18 watt IIB clone that I want to convert to the Vox. Make it initially a 15 watt keeping the Marshall xformers that I can up grade to the 30 watt Vox at a later date. I will have to add the third pre amp tube. I will go ahead and add the two additional EL84's and wire the sockets.

[stratele52]

You'll need another Power transformer and Output transformer . You must rewired Phase Inverter , and change many value on capacitor and resitor . 

Better to build a new one and keep Marshall original.

[labb]

Meant to say add the two additional EL84 sockets and wire them up. That keeps me at the 18/15 watts with the two El84's which should let me use the existing transformers untill I decide ($) to upgrade to the 30 watts. The PT should be able to handle the extra Pre amp tube.

[stratele52]

Meant to say add the two additional EL84 sockets and wire them up. That keeps me at the 18/15 watts with the two El84's which should let me use the existing transformers untill I decide ($) to upgrade to the 30 watts. The PT should be able to handle the extra Pre amp tube.

A 18 watts amp's Power Transformer can't drive a  30 watts output amp with 4  X EL84

 
When all finish , you scrap the 15 watts output transformer AND the Power Transformer . What about news capacitor and resistors ?

You'll loose all tha money ?  Better to sell you amp and built a new real AC30 .

[Willabe]

Why not?

Chassis space for 1.

2. Layout design noise/oscillation problems. Could be a lot of head scratching tracking down any and all new problems.


             Brad     

[Willabe]

Look at the VOX et -1

Where?????   

I looked in the schemo and layout section here and I don't see it in there.

It would be nice if you posted a link to what you want us to look at. Or at least tell us where to look.


            Brad     

[stratele52]

Look at the VOX et -1

Where?????   

I looked in the schemo and layout section here and I don't see it in there.

It would be nice if you posted a link to what you want us to look at. Or at least tell us where to look.


            Brad     

+100000

[sluckey]

Look at the VOX et -1

I'll bet you mean Ampeg ET-1? Totally unrelated to the info lab seeks.

[Willabe]

I'll bet you mean Ampeg ET-1? Totally unrelated to the info lab seeks.

Ohh, well that's a horse of a different color then.     

[tubenit]

Here you go. AC-15 complete with voltages.  It was in the schematic library that is NOT ExpressSCH

http://www.el34world.com/Forum/index.php?topic=5048.0

And here is a Hoffman style layout to go by:

http://www.el34world.com/Forum/index.php?topic=4811.0

With respect, Tubenit

FYI ................. we have 3 schematic libraries.  1) original manufactured amp schematics, 2) ExpressSCH editable and 3) non-editable schematics that posters have posted.

[labb]

Thanks tubenit. That is what I was looking for. There is so much info on this site that it is unbelievable.  Just hope that one day I will learn how to find all of it.

[labb]

For Stratele52-thanks for your input. I understand what you are saying about just keep the Marshall and build the AC 30 and normally you would be correct. My situation is a little different. I build amps as a hobby and give them to my Son. I don't even play guitar. We currently have three of the Marshall 18 watt amps.(TMB, Lite IIB and Zaphode Phill's  Superlite TMB)So giving up one of them is no big deal. I can strip the Lite IIB and build the VOX for about $75 worth of resistors, caps and pots. I don't have to buy $230 worth of xformers, a chassis, speaker and Cab. I will build it with the intent of upgrading to the 30 watt at a later date if we like the sound. Thanks to  all for your help.