I decided to separate my ramblings from Con's main Brother of Quasi (NBIP) thread since it's more about my custom retro-fit project than his circuit, and I don't want to pollute his main thread anymore than I already have.
So, to recap, I'm retrofitting a Bryston 4B chassis with the Quasi NBIP (N-channel bipolar) Quasi Complimentary amp circuit. But Cons' original PCB layout won't fit into the chassis so I am altering his board to fit. The chassis also uses 4 heatsinks per side that hold 2 TO-3 transistors each. The 4th heatsink is 'around the corner' on the chassis so to speak.
So this PCB layout is my mod to make it fit into the chassis and work with the existing TO-3 heatsinks. NB: The PDF file uses layers so if you have a recent version of the Adobe reader, you can turn them on-off to view the traces, the parts or the output transistors behind -- if you can figure out how.
Hint: nav. panel.
The output transistors connect with wires that feed through holes in the PCB that are located as near as I could get to the transistors, except the 4th pair which doesn't require a hole.
Any concerns/mistakes here? Assume I got the circuit correct (I don't expect anyone to trace it for accuracy) and I'll take responsibility for making that so. I'm thinking more about heatsinking, thermal coupling, instability due to layout problems. That sort of thing.
The drivers now mount on their own small heatsink similar to the pre-drivers. Is it big enough?
Thanks.
..Todd
So, to recap, I'm retrofitting a Bryston 4B chassis with the Quasi NBIP (N-channel bipolar) Quasi Complimentary amp circuit. But Cons' original PCB layout won't fit into the chassis so I am altering his board to fit. The chassis also uses 4 heatsinks per side that hold 2 TO-3 transistors each. The 4th heatsink is 'around the corner' on the chassis so to speak.
So this PCB layout is my mod to make it fit into the chassis and work with the existing TO-3 heatsinks. NB: The PDF file uses layers so if you have a recent version of the Adobe reader, you can turn them on-off to view the traces, the parts or the output transistors behind -- if you can figure out how.
Hint: nav. panel.The output transistors connect with wires that feed through holes in the PCB that are located as near as I could get to the transistors, except the 4th pair which doesn't require a hole.
Any concerns/mistakes here? Assume I got the circuit correct (I don't expect anyone to trace it for accuracy) and I'll take responsibility for making that so. I'm thinking more about heatsinking, thermal coupling, instability due to layout problems. That sort of thing.
The drivers now mount on their own small heatsink similar to the pre-drivers. Is it big enough?
Thanks.
..Todd
Hey Todd,
Why did you pick an amp with such an ugly face and terrible reputation for sound do upgrade??? Mind you, it will be a massive upgrade.
Ahhhh, just figured it out. You're building a "sleeper", except it's not a car.
I don't know about the board, but it's a marvelous idea. Keep us informed please.
-Chris
Why did you pick an amp with such an ugly face and terrible reputation for sound do upgrade??? Mind you, it will be a massive upgrade.
Ahhhh, just figured it out. You're building a "sleeper", except it's not a car.
I don't know about the board, but it's a marvelous idea. Keep us informed please.
-Chris
anatech said:
Hi Chris.
There's nothing about the faceplate that a wire-wheel and a can of spray paint can't fix.
And for the sound? Well why do think it's getting the Quasi circuit?
The hardware is great. Far too valuable to use to keep my car from rolling back down the driveway. (which is plan B)
..Todd
anatech said:Hi Todd,
I hope Quasi doesn't feel insulted by the association with Bryston.
Once you have the buggies worked out, see if there is interest in a GB. I don't think it will be that popular but it doesn't cost anything to find out.
-Chris
Well, as long as we're replacing Bryston circuitry with Quasi circuitry, Con should feel rightly proud. However, I would NEVER have a faceplate that insinuated the Quasi amp had any relationship to the Bryston products. Just wouldn't be kosher.
(And FWIW, of all the amps I have, the Bryston 4B's are NOT the worst sounding!) but there's plenty of room for improvement.
I guarantee there won't be interest in group buy to retrofit 4B's. The beauty of Quasi is that it's a single-sided PCB, same voltage range, same output device format, so as a DIY Bryston retrofit project, it's almost a no-brainer. So, if it works out, I'll keep the information on the web for anyone else willing to tackle it.
..Todd
Okay, back to serious [topical at least] matters...
The original 4B has a main amplifier PCB and 2 "sidecar" boards for the far left and right output sections. All the boards solder directly to the output transistor sockets. Would it be worth the extra work to try to mimic this? If *I* did it, I'd run the risk of modifying the existing PCB layout so much that it would probably have all sorts of weird problems.
Or does my existing layout work fine using the holes and fly leads? Opinions?
..Todd
The original 4B has a main amplifier PCB and 2 "sidecar" boards for the far left and right output sections. All the boards solder directly to the output transistor sockets. Would it be worth the extra work to try to mimic this? If *I* did it, I'd run the risk of modifying the existing PCB layout so much that it would probably have all sorts of weird problems.
Or does my existing layout work fine using the holes and fly leads? Opinions?
..Todd
Hi Todd,
If your board is okay (I didn't check it), use it as is. You will have the one flying board for the part "around the corner".
If you used two flying boards you could simply not install them when working on a 3B. Your existing board may fit without the outer transistors installed on the 3B as is. I don't know.
You have an excellent idea. Check your work and proceed. I wish you success!
-Chris
If your board is okay (I didn't check it), use it as is. You will have the one flying board for the part "around the corner".
If you used two flying boards you could simply not install them when working on a 3B. Your existing board may fit without the outer transistors installed on the 3B as is. I don't know.
You have an excellent idea. Check your work and proceed. I wish you success!
-Chris
anatech said:
ahem... I don't have any flying boards currently. It's all in one (see file in post #1) -- the full monty. No 3B possibilities as it stands I'm afraid. But I'm thinking about laying out a closer mimic of the Bryston 4B PCBs, which might lend itself to 3B retrofits better than my current board layout.
I don't know much about the 3B, like rail volts, physical size, etc. so it would be difficult to design this retrofit with the 3B in mind too.
Thanks,
..Todd
Hi Todd,
You will need at least one flying PCB for the 4B. I think the 3B used the same chassis with two less heatsinks. You can always check on their site for the physical case dimensions. The schematic are also available for download, and that will let you know what the supplies are.
-Chris
You will need at least one flying PCB for the 4B. I think the 3B used the same chassis with two less heatsinks. You can always check on their site for the physical case dimensions. The schematic are also available for download, and that will let you know what the supplies are.
-Chris
anatech said:Hi Todd,
I hope Quasi doesn't feel insulted by the association with Bryston.
Once you have the buggies worked out, see if there is interest in a GB. I don't think it will be that popular but it doesn't cost anything to find out.
-Chris
I'm good. Looking forward to the piccies. I like Quasi dressed in font too.
Cheers
Q
Hi Bonsai,
Bryston made a name for themselves. That's what I mean, they didn't earn their name, they advertised that they were great.
I hear their products are much better these days.
-Chris
Oh yes, they certainly were. The early amps were terrible.
Mostly because that old amp is a liability and sounds terrible. The parts they used were the worst and there is zero speaker protection.
No, a lot of studios use the new ones. They swear at the old ones. More older studios use the Crown (Amcron) DC300 than the Bryston 4B types. That and there is very little money to replace a mistake, once purchased.
Bryston made a name for themselves. That's what I mean, they didn't earn their name, they advertised that they were great.
I hear their products are much better these days.
-Chris
Hi Chris,
With all due respect, Bonsai is quite correct. I was a recording engineer for 15 years. Bryston 4B's (plus 3B's for biamped systems) were (in my era at least, the 80's and early 90's) the defacto standard in studios. I didn't see very many DC300's, though we used one in one mastering suite.
In a conversation about studio amps, I was mentioning my three old 4B's to a very well respected recording engineer at a party recently, and he offered to buy them from me on the spot. They are still obviously very well respected in that business. I'm too out of touch to know what the current trend is now-a-days though.
I kept the Brystons however, with every intention of butchering them and turning them into something VERY well respected. The Quasi design fills that bill nicely.
---------
And to answer the question of why... Yes, I expect the Quasi amplifier to sound that much better based on its reputation here. The warrantee on my Brystons has long since expired. We (me and the Brystons) are no longer spring chickens.
..Todd
With all due respect, Bonsai is quite correct. I was a recording engineer for 15 years. Bryston 4B's (plus 3B's for biamped systems) were (in my era at least, the 80's and early 90's) the defacto standard in studios. I didn't see very many DC300's, though we used one in one mastering suite.
In a conversation about studio amps, I was mentioning my three old 4B's to a very well respected recording engineer at a party recently, and he offered to buy them from me on the spot. They are still obviously very well respected in that business. I'm too out of touch to know what the current trend is now-a-days though.
I kept the Brystons however, with every intention of butchering them and turning them into something VERY well respected. The Quasi design fills that bill nicely.
---------
And to answer the question of why... Yes, I expect the Quasi amplifier to sound that much better based on its reputation here. The warrantee on my Brystons has long since expired. We (me and the Brystons) are no longer spring chickens.
..Todd
Hi Todd,
Out here in Bryston land (Toronto was a Bryston heavy area) their amps were dumped by a few companies. One very large one in fact that had a large investment in them. They did sound reenforcement and video conferencing, so those amps were not driven hard. They did manage to fail in ways that had nothing to do with the outside world. One Recording studio (The Metalworks) has no Brystons in sight, although studio A is still running on the DC300A's they have always had.
One thing that you learn quickly in Studio work is that they are far from immune from advertising and whatever their equipment suppliers want to push. I worked during your time frame BTW. But then again, awfultones are a standard and so are NS-10 and NS-10M speakers. What does this really say? JBL studio main monitors, now there is a lesson in high fidelity.
Being a standard has exactly zero to do with being a good product.
-Chris
Out here in Bryston land (Toronto was a Bryston heavy area) their amps were dumped by a few companies. One very large one in fact that had a large investment in them. They did sound reenforcement and video conferencing, so those amps were not driven hard. They did manage to fail in ways that had nothing to do with the outside world. One Recording studio (The Metalworks) has no Brystons in sight, although studio A is still running on the DC300A's they have always had.
One thing that you learn quickly in Studio work is that they are far from immune from advertising and whatever their equipment suppliers want to push. I worked during your time frame BTW.
But then again, awfultones are a standard and so are NS-10 and NS-10M speakers. What does this really say? JBL studio main monitors, now there is a lesson in high fidelity.Being a standard has exactly zero to do with being a good product.
-Chris
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