circuit suggestion

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ernie jr
Junior tube assistant
Posts: 75
(3/16/04 8:03 pm)
 circuit suggestion
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 i have a power tranny 400-400v 200ma, 5v 4a, 6.3v 5a
and an output tranny 9000 ohm ct, 8 and 16 ohm 50 watt.
any ideas as to a bass guitar circuit i could build? maybe something with 6550's using the o/p taps as 8 and 4 ohm to
bring the primary to about 4500 ohm. the o/p tranny is a stancor "hi fi" tranny with a broad freq range.
thanks for the help
ernie
 
6G6
Junior tube assistant
Posts: 129
(3/16/04 10:16 pm)
 Re: circuit suggestion
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 I'd vote for a simple, single channel Fenderish amp.
Perhaps the "normal" channel of an AB 165 with values on the tone stack somewhere between the bass & normal channel.
If the OT has UL taps, you might want to use them for a bass amp.
400-0-400 with full wave SS rectifier will give you about 560V.
In real life that would be less, maybe 540-550 at the plates.
6550 would be fine.
Other choices would be :
KT 88
KT 66
El 34
I'd use 6550 or KT 88.
Don't bias them too hot, there's not a lot of current to work with there.
Another option would be the Sunn S200.
 
wayneosdias
Senior tube assistant
Posts: 268
(3/16/04 10:18 pm)
 Re: circuit suggestion
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 have you looked at the svt's w/6550's

wayne
 
6G6
Junior tube assistant
Posts: 131
(3/16/04 10:47 pm)
 Re: circuit suggestion
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 Ampeg makes great bass amps, but I was looking at keeping it simple and keeping the current draw down some by only needing one preamp tube and a PI before the output tubes.

Another thought I just had is that there's nothing to prevent you from from adding a midrange pot or even hi-mid and lo-mid.

The Duncan amp tone stack calculator would let you tailor it to suit.
I have a G-K that uses four pots and it's very versital.
I think (off the top of my head) they are at something like
50Hz, 200Hz, 1200Hz and 4000Hz.
If you like that idea, I can find out for sure just where they are. I can say for sure that they work!
If you want another knob there is always the Presence from a Brownface bassman.
I'd bet that is enough to get almost any sound you need with only one channel.

 
ernie jr
Junior tube assistant
Posts: 76
(3/17/04 6:57 am)
 circuit help
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 i have bulit a sunn 200s, but it uses ultralinear o/p trans,
the one i have is not. what changes would need to be made to convert the circuit to a non-linear o/p trans.
thanks
ernie
 
6G6
Junior tube assistant
Posts: 132
(3/17/04 9:30 am)
 Re: circuit help
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 The ultra linear taps provide the voltage for your screens.
If you look at most Fender schematics, you will see that they use the second filter stage for that.
It's fun to look at a couple of transformers sitting on your bench and try to decide what they want to become part of.

 
ernie jr
Junior tube assistant
Posts: 77
(3/17/04 10:58 am)
 circuit help
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 i was thinking maybe a sunn 200s in triode mode, or a hoffman plexi 50 with 6550's
any thoughts
ernie
 
6G6
Junior tube assistant
Posts: 135
(3/17/04 1:32 pm)
 Re: circuit help
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 Personally, I've never really liked Marshall type amps much for bass.
If you already have a Sunn S200, you could change it to cathode bias to see if that's what you want, way easier than building another amp.
I'm kinda surprised that no one has suggested some circuit I never thought of. I know there's more options than I've ****d.
 
wayneosdias
Senior tube assistant
Posts: 270
(3/17/04 5:07 pm)
 Re: circuit help
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 if your going simple what about a bassman 135 or 200w?

wayne
 
 
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