Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: kagliostro on March 16, 2015, 02:35:06 pm
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I got this Roland DAC-80D - SS 80W - 12" Roland Speaker
with the intention of a tube coversion
(http://www.piazzostrumenti.it/wp-content/uploads/2015/02/ROLAND-DAC-80-D-1.jpg)
(http://image5.sahibinden.com/photos/45/96/18/2004596180g0.jpg)
I'm not a fan of the UpDown chassis because the heat will go directly to the chassis instead of be dissipated in the air
the chassis has a dimension of near 45cm x 20cm x 5.5cm
do you think I can fit there a 30W or is better to go lower ?
Thanks
Franco
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I think 30W will be fine. Just keep the circuit simple. Remove the back panel and consider redesigning it to allow more air flow to the chassis.
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Just keep the circuit simple
I was thinking to use the layout you sent me with two tubes more :icon_biggrin:
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I was thinking to remove the wood panel and use a metal grid
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How large is an AB763 ?
Franco
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Should be no problem, that's how a million Fenders are built, with tubes upside down. Single channel AB763 = 4 little tubes, 2 power tubes (I assume 2 rather than 4) and rectifier or SS rectifier. What are you thinking, a Princeton (6V6) or Pro/Super (6L6) ? Either should work fine, I have a SF Princeton Reverb running 6L6's. I have a Peavey Valveking that runs 6L6. No problems.
You will most likely have to change reverb cans if you intend to build in reverb. If you *don't* care to build in reverb you can lose two little tubes.
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@ Eleventeen
I was thinking to build Sluckey's Vox AC15 in a 30W version (and with reverb :icon_biggrin:)
May be too much ?
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@ Drgonzonm
I tried to find the spec, but wasn't able to find any info about, I know only the amp was an 80W and the speaker is 12"
Franco
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I am sure you could make it fit. That cabinet appears to be almost as wide as a Deluxe Reverb. It's all a matter of planning, planning, planning, making sure the tubes do not hit the speaker magnet, that kind of thing. Take the chassis out and tape together some graph paper so you can carefully lay it out. My only comment is (and I have never built one) that the AC15/AC30 seems to have almost twice as many parts (R's and C's) as a Fender single channel AB763. The heat/upside down tube thing is no big deal, millions of amps have been built that way.
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I think that with Sluckey's AC15 I'm on the limit with space
Steve, I would like to know the measures of the chassis you used
I estimated your chassis to be longer than mine (that is ~45cm) of about 2"
Franco
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My chassis is 20" x 6.5" x 2.5". I don't think you have enough room inside that cab to build the version of the AC-15 that I just sent to you. However, there is a short board version that puts the filter caps on a small board mounted on top of the chassis like a Fender doghouse. The short version is the same circuit but it will fit a 17" x 6.5" chassis if you plan well. Lego4040 built his AC-15 using the short boards but in a 20" chassis.
But, if you are serious about adding reverb and two more EL84s you better get a BIG chassis and forget about stuffing it in that little box.
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I'm only thinking around - this is all thinking talk
your chassis is 20" x 6.5" x 2.5" = 50.8cm x 16.5cm x 6.34cm
my chassis is (near) 45cm x 20cm x 5cm = (near) 17-1/2" x 8" x 2"
so your is 5cm longer (as I was thinking) and 3.5cm less deep
may be the solution is the method you used on your Stuffed Vox (you're my Mentor)
http://home.comcast.net/~seluckey/amps/vox/vox.htm (http://home.comcast.net/~seluckey/amps/vox/vox.htm)
with the PS + PI + Power Tubes on a separated chassis in the bottom and the preamp on the top
this way there will be enough space for the reverb tubes but I don't know if there there will be enough space for the tank
between the added chassis for the power section (making it long and not very deep) and the speaker
Franco