I have 2 old Bryston 4B amplifiers that I would like to retrofit with new amp circuits. (see drawing attached). Any ideas which existing DIY amp circuit projects might suit these chassis without too much hassle? The hardware is too useful to be sitting in my junk pile.
The chassis are 19" rackmount by 5.25" high. There are 4 heatsinks per channel each one currently holding 2 TO-3 output devices and a TO-220 device. (8 output devices per channel, 16 total in the chassis)
The existing circuit boards (shown in green) are about 4.5" wide mounted vertically and they use 2 daughter output boards. The blue one is an I/O and power board. The existing power supply provides approx. +/-72V rails.
I was thinking maybe a Leach amp, with additional output devices, but I don't know enough about electronics to modify that circuit without serious help from this forum. But any other ideas are welcome.
Thanks!
-- Todd
The chassis are 19" rackmount by 5.25" high. There are 4 heatsinks per channel each one currently holding 2 TO-3 output devices and a TO-220 device. (8 output devices per channel, 16 total in the chassis)
The existing circuit boards (shown in green) are about 4.5" wide mounted vertically and they use 2 daughter output boards. The blue one is an I/O and power board. The existing power supply provides approx. +/-72V rails.
I was thinking maybe a Leach amp, with additional output devices, but I don't know enough about electronics to modify that circuit without serious help from this forum. But any other ideas are welcome.
An externally hosted image should be here but it was not working when we last tested it.
Thanks!
-- Todd
Zero Cool said:
If these amps were in any acceptable shape, I would completely agree with you. However, they are 25 years old, used at many thousands of concerts. They are completely beat up in every sense almost beyond recognition, and the circuit boards and output sections have been repaired so many times the traces are half replaced with jumpers. That's why my old company gave them to me free.
The only real remaining value is in their hardware to a DIY'er like myself.
So, enough with all the objections, lets hear some ideas.
..Todd
Send 'em here.
If you proceed I'll buy your old PCB's from the Bryston's and then you'll have some extra cash for new stuff. Buying two new chassis like these in Canada would be in excess of $600 so your logic is not so far off after all. I don't think I'd do it just the same.
Show us some pics of the inside of your amps? They can't be that bad?
Cheers,
Shawn.
taj said:
If you proceed I'll buy your old PCB's from the Bryston's and then you'll have some extra cash for new stuff. Buying two new chassis like these in Canada would be in excess of $600 so your logic is not so far off after all. I don't think I'd do it just the same.
Show us some pics of the inside of your amps? They can't be that bad?
Cheers,
Shawn.
Ribbons?
What's in there? How many Motorola TO3's mount on the heat sinks? Do you want to use TO3 devices on the new design? Are you going to buy new PCB's? Are you going to etch your own PCB's? The Bryston chassis is optimized for a certain set up. If you are confident to carry through with it then strip one block down and give us the run down. Anything could fit in there but not anything really.
Heck who needs a chassis if you use a UCD module?
As john65b suggests? Don't those things suffice from a piece of aluminum foil 2x3cm?
Do you really want to tear down such coveted amplifiers? What is wrong with them? It's almost hard to take you serious. I'm not saying they are the best but what is soooo wrong with them that leads you to rip them to ribbons?
Cheers,
Shawn.
taj said:
What's in there? How many Motorola TO3's mount on the heat sinks? Do you want to use TO3 devices on the new design? Are you going to buy new PCB's? Are you going to etch your own PCB's? The Bryston chassis is optimized for a certain set up. If you are confident to carry through with it then strip one block down and give us the run down. Anything could fit in there but not anything really.
Heck who needs a chassis if you use a UCD module?
As john65b suggests? Don't those things suffice from a piece of aluminum foil 2x3cm? Do you really want to tear down such coveted amplifiers? What is wrong with them? It's almost hard to take you serious. I'm not saying they are the best but what is soooo wrong with them that leads you to rip them to ribbons?
Cheers,
Shawn.
Cut 'em up??
" ... I was thinking maybe a Leach amp, with additional output devices ..."
According to the old reviews, the amps were >> US$2000 when new. Are you sure you want to gut them, they had a "20-year warranty"? Example: http://www.soundstage.com/revequip/bryston_4b_st.htm
The existing 4B power supply could handle as many as four good modern mono block amplifier boards of >> 100 watts each ... just reconnect the 120/240 VAC transformer (or lock the Euro 240 volt switch, perminently) so that the rails are +/- 36 VDC (instead of +/- 72 VDC). ... Then I might suggest several aussieamplifiers.com modules like two of these : http://aussieamplifiers.com/NX400+.htm ... or four of these : http://aussieamplifiers.com/nx150.htm ... ( here is what I did : http://3dotaudio.com/ampics.html = simple as making a pie )
I might also suggest that you keep all the I/O connections and hardware or you will spend a lot of time shagging new parts.
Before you cut them up, you consider making some trades ... maybe Tom (Shawn) in Canada (above) has something you could use. (You are both in Canada, so shipping should be reasonable ... add an extra US$50 or so, each, to ship south to the states.) Heck, I'd take the worst one and offer something in trade ...
" ... I was thinking maybe a Leach amp, with additional output devices ..."
According to the old reviews, the amps were >> US$2000 when new. Are you sure you want to gut them, they had a "20-year warranty"? Example: http://www.soundstage.com/revequip/bryston_4b_st.htm
The existing 4B power supply could handle as many as four good modern mono block amplifier boards of >> 100 watts each ... just reconnect the 120/240 VAC transformer (or lock the Euro 240 volt switch, perminently) so that the rails are +/- 36 VDC (instead of +/- 72 VDC). ... Then I might suggest several aussieamplifiers.com modules like two of these : http://aussieamplifiers.com/NX400+.htm ... or four of these : http://aussieamplifiers.com/nx150.htm ... ( here is what I did : http://3dotaudio.com/ampics.html = simple as making a pie )
I might also suggest that you keep all the I/O connections and hardware or you will spend a lot of time shagging new parts.
Before you cut them up, you consider making some trades ... maybe Tom (Shawn) in Canada (above) has something you could use. (You are both in Canada, so shipping should be reasonable ... add an extra US$50 or so, each, to ship south to the states.) Heck, I'd take the worst one and offer something in trade ...
Re: Ribbons?
Two TO3's per HS plus they have a TO220 device mounted on each as well. (See diagram above.) Yes, I'd like to stick with TO-3's since they are a natural fit for these heatsinks.
I would make my own PCBs if the design was single-sided (doubtful). I'd buy them if something suitable exists. I might even organize a group buy for manufactured boards if there was enough interest.
As for the run down, I've ripped open plenty of 4B's and have one apart on my bench now. What do you want to know? (that I haven't already described above.)
UCD: The money/DIY ratio isn't right for me. Too much money, not enough DIY. The path should be as rewarding as the destination young Grasshopper. I'm not short of cash, but mounting a module and connecting a power supply isn't exactly my idea of DIY.
Trust me, these ones have used up all their coveted esteem. They work, but the bias trimmer is now used mainly to tune for minimal smoke output
and the chassis are now held together by chunks of angle-iron bolted through the faceplate. 
I'd like to build something newer, cooler, designed by DIYers like you. I'm learning this craft now and this is a perfect learning opportunity.
..Todd
Two TO3's per HS plus they have a TO220 device mounted on each as well. (See diagram above.) Yes, I'd like to stick with TO-3's since they are a natural fit for these heatsinks.
Originally posted by TomWaits
Do you want to use TO3 devices on the new design? Are you going to buy new PCB's? Are you going to etch your own PCB's? The Bryston chassis is optimized for a certain set up. If you are confident to carry through with it then strip one block down and give us the run down. Anything could fit in there but not anything really.
I would make my own PCBs if the design was single-sided (doubtful). I'd buy them if something suitable exists. I might even organize a group buy for manufactured boards if there was enough interest.
As for the run down, I've ripped open plenty of 4B's and have one apart on my bench now. What do you want to know? (that I haven't already described above.)
UCD: The money/DIY ratio isn't right for me. Too much money, not enough DIY. The path should be as rewarding as the destination young Grasshopper. I'm not short of cash, but mounting a module and connecting a power supply isn't exactly my idea of DIY.
Trust me, these ones have used up all their coveted esteem. They work, but the bias trimmer is now used mainly to tune for minimal smoke output
and the chassis are now held together by chunks of angle-iron bolted through the faceplate. I'd like to build something newer, cooler, designed by DIYers like you. I'm learning this craft now and this is a perfect learning opportunity.
..Todd
Re: Cut 'em up??
These were built long before Bryston offered the 20 year warranty, and even if that warranty covered them, it would have expired AT LEAST 5-10 years ago.
Now there's a cool idea. Wish I'd thought of that. Not sure it has the 110/240 option (dual primaries) though. I'll check.
See my comments regarding UCD.
Hmm... "shagging" must mean something different in your area.
What I'd like in trade would be an amp chassis, much like a Bryston 4B chassis, especially with heatsink and power supply intact!
..Todd
FastEddy said:
These were built long before Bryston offered the 20 year warranty, and even if that warranty covered them, it would have expired AT LEAST 5-10 years ago.
Now there's a cool idea. Wish I'd thought of that. Not sure it has the 110/240 option (dual primaries) though. I'll check.
See my comments regarding UCD.
Hmm... "shagging" must mean something different in your area.
What I'd like in trade would be an amp chassis, much like a Bryston 4B chassis, especially with heatsink and power supply intact!
..Todd
Angle Iron Bolted Through...
I'd like to see some pictures of the inside of these Angle Iron bolted together hunks of junk.
If that is all that is mounted to those delicious heat sinks, then by all means exploit the chasis for something greater. And if you have serviced these before, then you know you want and the old school Bryston ain't it.
Still I want pics.
Shawn.
taj said:Trust me, these ones have used up all their coveted esteem. They work, but the bias trimmer is now used mainly to tune for minimal smoke output
I'd like to build something newer, cooler, designed by DIYers like you. I'm learning this craft now and this is a perfect learning opportunity.
..Todd
I'd like to see some pictures of the inside of these Angle Iron bolted together hunks of junk.
If that is all that is mounted to those delicious heat sinks, then by all means exploit the chasis for something greater. And if you have serviced these before, then you know you want and the old school Bryston ain't it.
Still I want pics.
Shawn.
" ... Hmm... "shagging" must mean something different in your area. ..."
Not really. Shagging is searching for the "Mcguffin", the object of your desire, the holy grail ... If you spend excessive time fetching exotic parts, you are "shagging" them ... if spending too much time searching for whatever, you are "shagging" sheep, chasing the wool or the golden fleece ... Modern reference: "The Spy Who Shagged Me" = a goofy movie.
Not really. Shagging is searching for the "Mcguffin", the object of your desire, the holy grail ... If you spend excessive time fetching exotic parts, you are "shagging" them ... if spending too much time searching for whatever, you are "shagging" sheep, chasing the wool or the golden fleece ... Modern reference: "The Spy Who Shagged Me" = a goofy movie.
Have you tried the NS LM4702C Chip? +/- 75v although I suspect it could go higher “A” and “B” are +/- 100v
I have upgraded 3x medium power stereo amplifiers in recent weeks with this chip and the improvement in sound quality is spectacular.
I made a tiny PCB for the Chip and the 15 other small parts (see the NS applications note)
As long as your output transistors and driver transistors are still OK you could do this mod for less than $10.00 as NS are sampling for free.
The only problem is this is a stereo chip and some amplifier layouts may not be upgrade friendly.
I have upgraded 3x medium power stereo amplifiers in recent weeks with this chip and the improvement in sound quality is spectacular.
I made a tiny PCB for the Chip and the 15 other small parts (see the NS applications note)
As long as your output transistors and driver transistors are still OK you could do this mod for less than $10.00 as NS are sampling for free.
The only problem is this is a stereo chip and some amplifier layouts may not be upgrade friendly.
Okay, here's some pics...
That amp in your photo is a MUCH newer model. Maybe an ST or SST, mine is a plain old 4B.
The pics show the heatsink assembly. 4 smaller heatsinks per side mounted onto a stamped steel wall.
The front panel shows the holes that used to host the notorious angle-iron bracket bolts.
That amp in your photo is a MUCH newer model. Maybe an ST or SST, mine is a plain old 4B.
The pics show the heatsink assembly. 4 smaller heatsinks per side mounted onto a stamped steel wall.
The front panel shows the holes that used to host the notorious angle-iron bracket bolts.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
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