Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: sumac on March 06, 2014, 08:33:11 am
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Hi all,
for my next project I would like to build a small one-channel amp capable of putting out about 8W or so.. I would like to mount the tubes and transformers inside chassis like in the old european amps http://www.nahravaciestudio.sk/admin/imgbox/MAX_233_1352127701.jpg (http://www.nahravaciestudio.sk/admin/imgbox/MAX_233_1352127701.jpg) with horisontaly mounted tubes to make it slim and super-portable. It seems that it will be necessary to keep the tube count to three which means I am looking at SS rectifier and possibly pentode/triode output tubes with triodes used for PI. Checking various projects here I found mini bassman "Little wing" that looks like a good candidate (tube cathode follower would have to be replaced by the mosfet one). However the more I go through the different threads here the more projects/variatins I find! :huh: (like HOSO56, 56T, TOS, TBM, etc etc :) )
So I was wondering if any of you guys who know these amps could help me here and recommend which of these projects would work the best for me.. Sound-wise I'm looking for clean-ish amp with big warm sound that will go into nice (lets say bassman or plexi like) crunch when cranked. It will be used mostly for chording with humbucker equipped tele in a duo band - singer and a guitarist so not much lead guitar work will be involved.. If necessary I could probably squeeze in one more preamp tube.
thanks!
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i was thinking about using ECL80's in a PP amp. they are really cheap but i haven't seen them in guitar amp schematics yet. maybe you can have a look on what is possible. should be good for a small amp of around 4W i think.
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If you want to be real creative, build yourself a little P-P power amp with something like a couple 6AQ5's. That should make for a relatively low powered P-P amp. A 12AX7 on the front end will give you a couple gain stages, or one gain stage and a cathode follower to precede a tone stack. The latter of the two should be more of a clean amp at any volume.
Jack
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Here's another option. It's very small and uses 3 tubes (if you use SS rectifier).
http://home.comcast.net/~seluckey/amps/PeeWee/peewee.htm (http://home.comcast.net/~seluckey/amps/PeeWee/peewee.htm)
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Sound-wise I'm looking for clean-ish amp with big warm sound that will go into nice (lets say bassman or plexi like) crunch when cranked. It will be used mostly for chording with humbucker equipped tele in a duo band - singer and a guitarist so not much lead guitar work will be involved.. If necessary I could probably squeeze in one more preamp tube.
do you mean clean volume at 6, dirty from 7-10? or clean volume at 10, that gets dirty when you dig in on your pick attack?
You can go the SE route, most SE designs are 5W , either EL84 or 6V6. you can juice 'em for 8W.
another way to go would be a 12W-15W amp, that you can turn down. If you need crunch/dirt at lower volume, put a pedal out front.
this is worth considering, especially if you are going to play live.
I'd look at a single channel Deluxe AB763. When you remove the vibrato and second channel, the footprint gets small enough to fit in the type of enclosure you describe. Especially if you go with a SS rectifier.
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I built an amp to fit into a small space and had to be creative with the chassis.
(http://i406.photobucket.com/albums/pp142/printer2_photo/guitar%20amp/TabletopBack.jpg)
(http://i406.photobucket.com/albums/pp142/printer2_photo/guitar%20amp/TabletopBackinside.jpg)
It is a 12AQ5 P-P amp with a 70V OT. I was running them Class A with around 230V and getting about 5-6W but at a higher voltage and Class AB 8W should be doable.
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For ideas... I built an amp with this PI and power section about 10 years ago.
http://web.archive.org/web/20061127164835/http://www.schematicheaven.com/bargainbin/wem_westminster_mkIX_10w.pdf (http://web.archive.org/web/20061127164835/http://www.schematicheaven.com/bargainbin/wem_westminster_mkIX_10w.pdf)
I used an EF86 primary tube and a Hammond 125C P-P OT. Great sound with a 12" speaker and plenty of "living room" headroom. Not sure about describing the breakup flavor. For 10 watts, its loud. Instead of the pricey EF86, a pentode-triode tube similar to a 6AN8A would also sound great. I would leave some room for modding. Tastes vary.
Robert
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wow, thank you all guys, I will check all your suggestions
will keep you posted