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Re: Bootstrapped circuit


 :
12/12/1997 1:34 PM
David Axt
Re: Bootstrapped circuit
Did somebody say "home brew bass amp"?  
 
I would like to findout the details 'cause I'm fix'n to build me one of them suckers.  
 
I am in the minority here being a bass player and interested in tube amps.  
 
Thank you
 
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12/12/1997 1:39 PM
Steve M.

David,  
 
I have Kevin O'Connor's "Tonnes of Tone" which has a chapter on building Fender and Ampeg style preamps. The power amp in the book is more representative of guitar amps, FWIW.  
 
Regards,  
 
Steve
 
12/15/1997 7:10 AM
Dave Harris

Sorry the home-brew bass amp is solid state not tube. I will probably get incinerated for heresy on AMPAGE for saying this but I think solid state is best for bass. To compete with a drummer and two guitarists using 50W tube amps you need lots of clean power at low frequencies. A solid state power amp with no output transformer is best for this.  
 
Opinions anyone ?
 
12/15/1997 8:25 AM
David Axt

Dave,  
 
Don't worry. You said "solid state" and "bass" in the same sentence. Nobody here cares about solid state bass amps.....except me. Please tell me more. I am interested!  
 
Had you mentioned "solid state" AND "guitar" in the same sentence two very large disagreeable men would show up at your house at 3 AM and "convince" you that tube amps are better for guitar. ; )  
 
David Axt
 
12/15/1997 9:29 AM
Dave Harris

The bass amp is rather primitive and the pre-amp never got finished so there is little in the way of tone controls but I have used it for 2 years with no problems. The output is 250W - 300W into 4 ohm using 4 x MJ15003 (20A 140V 250W) transistors. There is a fixed compressor using an NE571 and a pre amp using a TL072 dual op amp. The pre-amp will have a 3 band Baxendall tone circuit one day but Iím too busy using it to mod it. It is powered by a toroidal transformer and fits in a 2U high box. Not quite the power of an SVT but you can lift this one with your little finger ! Email If you want to know more. We could get booted off the board for talking solid state.  
 
Dave H.
 
12/15/1997 9:50 AM
David Axt

>>The bass amp is rather primitive...<<  
But bass players are primitive. We are not as evolved as guitar players, but we are more evolved than drummers.  
 
>>The output is 250W - 300W<<  
Whoa!  
 
>>There is a fixed compressor using an NE571<<  
So you're the guy that sent me info on the compressor chip. I never built it though.  
 
>>It is powered by a toroidal transformer<<  
I have no idea what this is, but it sounds exciting.  
 
>>Email If you want to know more.<<  
Yes, please please.  
 
>>We could get booted off the board for talking solid state.<<  
Let them try! I'll have Johny Cochran and F. Lee Bailey all over them. And yes I will play the race card...the human race card.  
 
David Axt
 
12/16/1997 4:02 AM
Dave H.
Transformers in guitar amps are usually wound on a core made up of E and I shaped laminations. A toroidal transformer is wound on a donut shaped core. The toroid is wider and flatter than an E I transformer which makes it a good choice for low profile heads or rack style amps.  
 
Dave Harris
 

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