Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: hesamadman on January 08, 2016, 03:42:31 pm
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I have parts of my new breadboard complete. So far I have two boards made. I have a quad octal socket board for the power amp section of a el34 or 6v6 style amp. I am aware that I realistically should have included the PI tube socket on this board as well but my preamp board has five 9-pin sockets. As of right now I am assuming that 5 9-pin sockets will be enough for anything I will ever do. If for some reason it is not, I will just make a PI board. My 9-pin board is not complete (notice the wires hanging out the back). I will eventually make a quad 9-pin board for el84 output tubes.
My over all goal when setting up on a breadboard is to create as much as possible a similar layout for when its actually built and fit into a chassis. I like to build my amps with 1 board only (as much as i can). All filter caps, rectifiers(i plan to build another tube socket board for tube rectifier), power and pre components all on the same turret board. I know that is not always possible but I strive for that. So when im finished on my breadboard, I would like to be able to put the components on my turret board in a very similar fashion. I already wish I would have put another set of terminal strips on the back side of the tube socket boards so that the B+ could enter there, but I am going to leave it for now and (again) try to remain true to how the layout will be.
So I have all my parts just laying on my bench. Im going to fix them to a board that I have made but I wanted to get some opinions on my layout. All the way on the left you can see a set of terminal strips highlighted in green. I was going to use these for SS rectifier and bias voltage components. I will also build a board for cap cans next to my choke and PT. The cap cans will be use for filters for the choke and OT. I lilke to put my preamp fiilter caps on the preamp board close to the appropriate stage as I have read about this in Merlins book and my last couple of builds have been dead quiet so I have come to like this method. The red highlighted area is obviously the power amp. I have a ground bar I took out of a banged up circuit panel that I had in stock. Same with the preamp ground bar. I will send a lead from each of these bars back to the PT center tap. Im heading out to get some angle iron for the front and read of the board. The front will house the pots, jacks, and switches. The rear will house speaker jacks and other things necessary. The yellowish brown highlighted area is the preamp section. I will obviously organize these strips and straighten them out. I will consolidate things a little more appropriate as well.
My first board that I built was very similar to this. But not nearly as well constructed. I had tube sockets with wires coming of them. The wires were a mile long. So needless to say, when the amp worked....it was loud. Lots of hum. Grid wires were a mile long. This will keep lengths shorter. Much shorter. So if anyone could give me some input before I actually fix these components to the board I would appreciate it.
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pots are closer to user and B+ on the other end. ground rail between controls and circuits. B+ rails on top of tubes.
----- B+ rails -----
----- tubes -------
----- ckts -------
----- gnd rails ----
----- controls ----
--pete
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I can understand the B+ rails being before the tube. However, in an actual amp chassis (especially a combo type) theres no easy way to do that. In the case of a hoffman style AC30, the B+ rail is between the circuitry and the pots. When I layout a board, I put my b+ rail on the bottom of the board. This breadboard layout mimics how I like to layout my amps. I've had some very quiet amps with this layout.
I still have some laying out to do but im almost there.
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The power supply is another critical component.
I see you have the iron to build one, but something like this is easier and more versatile.
Big 6.3VAC supply, positive 0-450 VDC, negative 0-300 VDC with Volt and Amp meters.
If you can get one cheap like I did, that is the way to go IMO. :icon_biggrin:
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Yea that is awesome and something I would be interested in.
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Yea that is awesome and something I would be interested in.
Not the same, but maybe something to do some research on. Looks like it might have everything you need in a Bench PS. :dontknow:
http://www.ebay.com/itm/VINTAGE-U-S-ARMY-HIGH-VOLTAGE-POWER-SUPPLY-MADE-IN-THE-USA/131694598989?_trksid=p2047675.c100010.m2109&_trkparms=aid%3D555012%26algo%3DPW.MBE%26ao%3D2%26asc%3D35006%26meid%3Dcc023d70cea84ef3b9e9e751120ddd5c%26pid%3D100010%26rk%3D2%26rkt%3D24%26sd%3D141873420952 (http://www.ebay.com/itm/VINTAGE-U-S-ARMY-HIGH-VOLTAGE-POWER-SUPPLY-MADE-IN-THE-USA/131694598989?_trksid=p2047675.c100010.m2109&_trkparms=aid%3D555012%26algo%3DPW.MBE%26ao%3D2%26asc%3D35006%26meid%3Dcc023d70cea84ef3b9e9e751120ddd5c%26pid%3D100010%26rk%3D2%26rkt%3D24%26sd%3D141873420952)
:icon_biggrin: