| taj |
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 |
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| anatech |
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 |
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| taj |
| quote: | Originally posted by anatech
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 |
Hi Chris.
There's nothing about the faceplate that a wire-wheel and a can of spray paint can't fix. :cool:
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 |
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| anatech |
Hi Todd,
As a joke, you should leave the faceplate be. Use a "MKII" sticker or something. "by Quasi" would be nice on a lower corner.
| quote: | | The hardware is great. Far too valuable to use to keep my car from rolling back down the driveway. (which is plan B) |
I did see a 4B used for that a few years ago. I thought it was both understandable and hilarious at the same time.
I'm thinking of a 4B retrofit kit.
-Chris |
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| taj |
| quote: | Originally posted by anatech
Hi Todd,
As a joke, you should leave the faceplate be. Use a "MKII" sticker or something. "by Quasi" would be nice on a lower corner.
-Chris |
How about this: |
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| taj |
| quote: | Originally posted by anatech
I'm thinking of a 4B retrofit kit.
-Chris |
Are you serious about that? Help me turn the Quasi NBIP amp into a 4B retrofit kit, if you're game. I'll do all the drawing, I just need the technical direction. It'll help me with my learning too.
..Todd |
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| taj |
| Heck, why not go all the way.... |
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| anatech |
Hi Todd,
I hope Quasi doesn't feel insulted by the association with Bryston. :D
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 |
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| taj |
| quote: | Originally posted by anatech
Hi Todd,
I hope Quasi doesn't feel insulted by the association with Bryston. :D
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 |
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| anatech |
Hi Todd,
You may be surprised by the number of takers on this. There are a ton of "dead soldiers" around.
-Chris |
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| taj |
By the way, Chris, I like your signature. :devilr:
..Todd |
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| taj |
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 |
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| anatech |
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 |
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| taj |
| quote: | Originally posted by anatech
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".
-Chris |
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 |
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| anatech |
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 |
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| quasi |
| quote: | Originally posted by anatech
Hi Todd,
I hope Quasi doesn't feel insulted by the association with Bryston. :D
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 |
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| Bonsai |
Wow, is the Bryston that bad?
Quasi's amp is great, but why frig with (I assume) a functioning amp with a 20 year warranty?
A lot of studios use these amps and swear by them.
:) |
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| anatech |
Hi Bonsai,| quote: | | Wow, is the Bryston that bad? |
Oh yes, they certainly were. The early amps were terrible.| quote: | | Quasi's amp is great, but why frig with (I assume) a functioning amp with a 20 year warranty? |
Mostly because that old amp is a liability and sounds terrible. The parts they used were the worst and there is zero speaker protection.| quote: | | A lot of studios use these amps and swear by them. |
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 |
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| taj |
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 |
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| anatech |
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 |
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| taj |
:angel: I'm not a very passionate apologist for Bryston since I haven't compared them face-to-face with anything, and I don't really care that much about any commercial amps. Those 4B's are just great DIY chassis & heatsinks to me now, pleading to be retrofitted for my own personal amusement and gratification.
I am excited about the the amplifiers that culminate from the designers that frequent this forum though, and I wish I knew enough to build them all. But I'm just learning this transistor stuff, and it's a steep learning curve for a 47 y/o that hated math. But some of it's sinking in slowly.
Awful-tones. :D We called them Aura-Phones. And I'm with you regarding the NS10M's (I don't recall ever seeing or using a non-M).
I'd like to hook up some auratones to a 4B and see if I can get them to blow smoke rings. :devilr:
And one studio I worked at a lot had big honkin JBLs, and they were indeed woofy-honky things. I really liked the Meyer and Genelec monitors, though and a pair of MTM's we had but I don't recall who made them. They were a bit crispy so we used them to mix vocals that we wanted warm sounding. It saved us from the constant urge to boost the treble on vocal tracks.
..Todd |
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| anatech |
Hi Todd,
Just different areas we worked in.
An easy way to recognize an NS-10. It's the one with tissue taped over the tweeter. The NS-10M is a modified NS-10 for near field monitoring with no wall behind the speaker. ;)
| quote: | | But I'm just learning this transistor stuff, and it's a steep learning curve for a 47 y/o that hated math. But some of it's sinking in slowly. |
We're both youngsters! I'm only 48. This is a great place to learn for sure.
The only other thing to watch for on the 4B chassis is the front panel. The chassis would rip along the front side. Check yours and do some work there if you see this. Some angle aluminum sold in hardware stores will fix that problem.
-Chris |
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| taj |
| quote: | Originally posted by anatech
The only other thing to watch for on the 4B chassis is the front panel. The chassis would rip along the front side. Check yours and do some work there if you see this.
-Chris |
Yup, These are road warriors. Already fixed. Aluminum? Nah, inch and a half angle-iron brackets!
What brand tissue did you use? We were a Scotties Little Softies shop. :headshot:
..Todd |
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| quasi |
| quote: | Originally posted by anatech
........We're both youngsters! I'm only 48.......
-Chris |
So am I!
1959.. a jolly good year. |
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| taj |
| quote: | Originally posted by quasi
1959.. a jolly good year. |
1960 for me. But with the time zone difference between our hemispheres, and exchange rate in effect at the time, we're probably the same age. :scratch1:
..Todd |
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| anatech |
Hi Todd,
LOL!
That won't work for me dude! You are between my brother and I in age.
'59 was an excellent year Con, look - no rust!
-Chris |
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| taj |
Okay, I need some advice. I'm not quite sure how best to handle this part...
The Quasi NBIP PCB's I'm laying out will fit a Bryston 4B chassis, as a drop-in replacement for the Bryston PCB's (along with appropriate output device replacements of course). But here's the problem. I'm making single-sided boards. Brystons were double-sided and the TO-3 sockets mounted on the inside of heatsink soldered directly to the PCB. On my boards, that would end up being the component-side of the board, so no solder pads there.
Should I ... :scratch:
a) put pads on the solder-side for attaching the TO-3 sockets, and learn to solder around corners;
b) put pads on the edge of the PCB to feed leads behind for soldering directly to the sockets;
c) Get rid of the sockets and solder leads to the output device pins;
d) some other idea you tell me about;
Thanks!
..Todd |
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| quasi |
Hi Taj,
You could try using PCB solder sleeves; http://www.tarapath.com.au/products.cfm?CID=2333. I've never used them but I believe you crimp them in a PCB hole then you can solder both sides. Not sure how much these cost.
Or
you could find some small
copper / brass eyelets (like they use in shoes for the laces) and do the same thing.
Or
You could pass some stiff wire through the holes first and bend it 90 degrees on both sides of the PCB, cut and solder one end to the trackside pads. Then pass all transistor legs through the same holes and solder the other side. Because the wire is bent at 90 degrees it should stay put.
Cheers
Q |
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| taj |
Thanks Con! Very good ideas.
After having thought about it more, I think I will just put pads near one edge and run short leads behind to the sockets, which are fairly close. The main reason is simply to avoid the track routing restrictions imposed by those TO-3 transistor pad locations -- which are VERY inconvenient for a single-sided board. Trying to layout tracks around them caused me much gnashing of hair and pulling of teeth. With those pads out of the way, I'm free to use the space more effectively.
Here's another question... How did you mount T8 onto the output heatsink? It's a TO-92 package isn't it? Would longer leads affect its operation?
..Todd |
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| bigpanda |
Hi Taj,
I think I missed you thread before and when I try to look at your pcb today, it isn't there anymore. Can you please post it again? |
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| taj |
I'm not happy with the first one I did. I'm still working on it and I'll post it when it's ready for public tweaking.
..Todd |
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| bigpanda |
| What's on your list for the output transistors? |
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| taj |
| MJ21194 (x16 for one stereo Bryston 4B chassis) |
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| taj |
Well, I finished the left half. :rolleyes:
The board will be 4 in. high by 8.25 in. wide.
See any problems so far?
..Todd |
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| taj |
Okay, here's the [current] fruit of my labour. What do you think Mr. Q? Does it get the Quasi seal of approval? Or did I commit some heinous PCB layout faux pas?
http://members.shaw.ca/toddj/Quasi/...-PCB-layout.pdf
By the way, I changed the footprint of many of the film caps to suit my taste for polypropylene, of which I seem to have amassed a considerable collection.
..Todd |
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| taj |
And here's a diagram of how it would ultimately fit into the 4B chassis. I think I read somewhere that a BD139 would work for T8, if that's the case, it will fit nicely into the location shown on the diagram, connected by leads to the back of the PCB, as all the output devices are.
http://members.shaw.ca/toddj/Quasi/...%20HEATSINK.pdf
..Todd |
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| quasi |
| quote: | Originally posted by taj
Okay, here's the [current] fruit of my labour. What do you think Mr. Q? Does it get the Quasi seal of approval? Or did I commit some heinous PCB layout faux pas?
http://members.shaw.ca/toddj/Quasi/...-PCB-layout.pdf
By the way, I changed the footprint of many of the film caps to suit my taste for polypropylene, of which I seem to have amassed a considerable collection.
..Todd |
Hi Todd,
I like the layout and I also like the placing inside the case. There are 3 maybe 4 errors though.
1. The two 470r resistors are shorted out. These should have seperate feeds to the emitters of T2 & T3.
2. Similarly the emitters of T2 & T3 are also shorted.
3. The collector of T8 should go to the collector of T6. At the moment it doesn't go anywhere.
Maybe 4. It looks as though you have a bolt inside the speaker output coil. This is a no-no particularly if it is a steel bolt. You should either remove it, shift the coil or use a brass one (make sure it's really brass).
Otherwise nice work and well thought out.
Cheers
Q |
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| taj |
Oh thank you! :worship:
1) Fixed
2) Fixed
3) Fixed
4) Deleted (rethinking that)
Drawings were updated and re-posted.
I'll pick up the tab for tasting charges at the first 20 or 30 wineries in Barossa. :drunk:
..Todd |
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| bigpanda |
Hi taj,
Not trying to be funny or picky, should you have "Quasi", "DANGER HIGH VOLTAGE" & "4BIP' in mirror mode? Doesn't matter to the circuit but does for the look. If that's something that give you only 99 / 100. |
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| taj |
| quote: | Originally posted by bigpanda
Hi taj,
Not trying to be funny or picky, should you have "Quasi", "DANGER HIGH VOLTAGE" & "4BIP' in mirror mode? Doesn't matter to the circuit but does for the look. If that's something that give you only 99 / 100. |
Yup, except that to build this as intended, you will need to burn two PCB's, one flipped, because the layout had to be created to fit an asymmetrical chassis layout. So unless I create two separate boards, just to fix the fonts, then it'll backwards for one channel anyway. So I didn't bother.
And I removed the "Danger High Voltage" wording 'cause it wouldn't help much unless it was on the component side. If the power was still applied while the board was removed, you'd be in trouble long before you could read the warning. :rolleyes:
..Todd |
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