Author Topic: Concert PA for bass and keyboards  (Read 205 times)

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Offline Isaac

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Concert PA for bass and keyboards
« on: November 30, 2016, 08:21:15 am »
I know that a lot of people over the years have used the old tube PA heads for guitar. Has anyone used one for bass?

That may seem an odd question. Why use, say, a Concert PA head when you can use a 200S? But I find myself incorporating more instruments. Two keyboards in one band, bass foot pedals in another, and I could use a few more inputs. Of course, I could use a mixer, but then I lose the advantage of a tube front end. I'll be experimenting, but I'd appreciate any input from anyone who's done a similar thing or knows of anyone who has in the past.
Isaac

Offline EdBass

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Re: Concert PA for bass and keyboards
« Reply #1 on: November 30, 2016, 11:17:23 am »
Haven't done it myself, but sounds like an excellent idea. A little extra gain never hurts!

Offline Isaac

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Re: Concert PA for bass and keyboards
« Reply #2 on: November 30, 2016, 12:05:07 pm »
My concern is that it may roll off the lows. We'll see.
Isaac

Offline Isaac

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Re: Concert PA for bass and keyboards
« Reply #3 on: December 02, 2016, 06:41:06 pm »
I pulled it out of the Pile o' Crap™. First thing I noticed is that I've been wrong for years. It's not a Concert PA, it's a Studio PA. I scrounged around for tubes. Took it to rehearsal and gingerly turned it on. After all, as far as I know, it still has all of the original caps. I still have the original RCA 6550 power tubes, but I used JJ KT88s this time. No sparks, no smoke, no bad smells. So far, so good.

It's noisy. Keeping the master volume down helps quite a bit. Pots are scratchy. No surprise there, either. Didn't sound too bad.

Used it at a show that night. All of the same issues. Noisy, scratchy pots. Didn't seem to have the low end of either the 200S or even the Sentura II. So it could definitely use some new caps and new tubes, but even then, I don't think it will work well for bass, if one wants deep bass. For those who want a less deep, more punchy sound, it should work well. Or, with the master volume, one could crank the preamp volume and get some distortion at low levels. And it does have four independent inputs!
Isaac

Offline Isaac

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Re: Concert PA for bass and keyboards
« Reply #4 on: December 06, 2016, 12:50:52 pm »
More information, for anyone interested.

And apparently noise is a common issue with this amp: http://sunnforum.ampage.org/index.php?topic=6746.0

Schematic: attached in linked thread
Isaac