Building Bryston amps from the service manuals

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Unique

Member
Joined 2007
Hello gentlemen. I own an original Bryston 3B ( bought in 1978 ) and i have fried some of it's output devices ( specificaly, one 2N6609 and one 2N3373 ). I also found out that an FT417B driver had some damage and needs replacement too. So, as i am a noob in this kind of DIY and you seem to know this amp so good, I would like to have a suggestion on which devices should i buy. At first i want just to make the amp work again ( so quality doesn't matter that much ) and after a while i am interested in replacing all of it's output devices as an upgrade ( so i would also like to have a suggestion on some better quality drivers that can also be found in stock ). At this point, let me tell you that i have replaced it's power capacitors with Phillips LL series at 10000uF each. So, could you give some help please? :)

Thanks in advance,

Nicholas
 
D

Dukanita

Member
Joined 2006
Hi
Does anyone tried to make pcb for 2B or 3B. As I suppose waching schematic from both 2B, 3B or integrated amplifier BR26 schematic is same instead number of output transistor and voltage.
If anyone have high resolution pics of 2BLP both side pcb it can help.
Thanks
Duka
 
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drydenjw002

Member
Joined 2008
Tazzy/lawbadman
Can one of you send me
Briston: 3bsst and 4b sst manuals.
Thanks.
John
jwdryden@roadrunner.com

For lawbadman:
I see you are from Jamaica. I am from Jamdown too.
Hope all is well in JA. I am from St. Mary. Have you built yours yet?

:rolleyes: FOR ALL THE REST:
There is NO violation under US law (copyright/patent) if you build it for yourself. However,
this as far as I know does not fall under copyright but under patent law.
Since no patent exist (as far as I know-Will check that out) no law is broken, however, it still can not be be manufactured and sold as a BRYSTON amplifier as the tradename is protected.
So my fellow DIYers build away.
Remember you can't copyright/patent a circuit that has been done before.

Only in Canada eh!
 
R

rouleau

Member
Joined 2009
Bias on a Bryston 4B

Hello i have change all the transistor on one side of my bryston 4B. I have check alle the component on the borad and everything is ok. I'm ready to start it slowly with variac and amp meter. I want know what is the method to adjuste the bias for the Bryston 4B.

thank's
 
Stee

Stee

Member
Joined 2005
esafono.it
foundamental is the output stage

need just true complementary devices (hFE matched) :eek:
 

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wkbdgeorge

Member
Joined 2010
Id be willing to create the pcb design. I've gotten pretty good with altium designer. I would need a really good scan or something of the board. Or best yet, If someone could send me an unstuffed board, that would be best. Having the unstuffed board would make it easier because I could use my 64th ruler. Any takers?
:deer:
 
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spookydd

Member
Joined 2012
wkbdgeorge said:
I'd be willing to create the pcb file. I've gotten good with altium, and I'd be up to the task. The thing I would need to make it perfect would be an unstuffed board of theirs. That way, I can make sure its perfect. Any takers? -g
Click to expand...

I know a lot of time has passed since this last posting.

But just in case, has anything come out of it? Did you finally put this in altium and make gerbers and pcbs?

I wouldn't mind some pcbs, depending on which model it is.
 
Bigun

Bigun

Member
Joined 2009
diyaudio.com/community/threads/tgm8-an-amplifier-based-on-rod-elliot-p3a.245619/
Paid Member
I have the BP60 and can attest to the good sound. It can sound bright - something I now believe is related to some long heavy speaker cables. Overall I find it to be very neutral with strong bass - clean from top to bottom.

I've tried to build a better amp for years, my TM8 amplifier (my 8th attempt) is the first one that sounded better than the BP60 power stage (I used the pre-amp from the BP60 for listening tests with my TGM8). The Bryston is a hard act to beat if you are after a clean powerful amplifier.
 
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spookydd

Member
Joined 2012
Bigun said:
The Bryston is a hard act to beat if you are after a clean powerful amplifier.
Click to expand...

Quite true. They really look for ways to get the best sound.

I just wanted to see how their output stage topo would perform, so I just made a simulation, using ordinary ltp with ccs, 2 transistor vas with ccs, and then slapped on that output stage. I can say that it is very prone to oscillations and not so easy to stabilize. But once compensated and stabilized, I was able to make an amp with 23ppm thd at 20khz on 8ohms, with rails at 40V and 25Vrms output signal.

I'm sure it can probably be even better with a few tricks and using other compensation scheme than plain miller.

That same sim gave me about 1.7ppm at 1khz, under the same other conditions, and down at 10hz, it was down below 0.08ppm (0.000008% thd). Not bad.

The key is to avoid oscillations, and as long as they don't start, then the signal is crystal clear.
 
TonyTecson

TonyTecson

Member
Joined 2003
PB2 said:
Hi AndrewT,

I would agree with you about reservations. Do we know who designed this amp? It looks so much like the SWTPC designs that I wonder if it was the same designer or did they "borrow" it and add their patented output stage to claim innovation. It seems to add unnecessary complexity. The output stage looks like they couldn't make up their mind, I kind of laugh when I look at it.

Concerning those who commented about the patent, as I understand it, experimentation with patented designs is encouraged to promote further innovation. And people here do seem to be innovating.

I have many concerns about this design, there are 4 common emitter stages, but the first VAS has so much degeneration that it probably operates almost as common collector. The first VAS has 2.2K emitter degen wonder if it has much voltage gain at all? Then it has a speed up cap across it.

I could go on, but this design does not give me a warm fuzzy feeling.
Click to expand...

hi,

i built over a dozen of D Mayer's Tigersaurus amps, what i remember was the punchy bass, mids and highs, so-so....

when i built the Leach Super amps, i never looked back on the Tigersaurus...

i have never heard a Byston but i suspect that they will not be far from the Tigersaurus,
these amps will appeal to many folks, but for hifi, i would take the Leach anytime...
 
S

spookydd

Member
Joined 2012
Ok, I'm once again resurrecting this thread, hoping to find some details about how the bryston bias sensing transistors are actually used and mounted on the heatsinks.

They use 2 transistors in pretty much all of their bias spreaders. I think probably all of the amps with their composite output stages are done that way.

But what I'm wondering is which, if not both, bias spreader transistor(s) are actually mounted on heatsinks. How? Anything different from standard practice?

They use one TO126 and a small signal TO92 type of bias spreader transistors, so I'm thinking due to the difficulty to mount a small TO92 to a heatsink, that it wouldn't be the one actually sensing the sink. Is that right?

Can the thermal sensing be done using only the TO126 and leave the other TO92 alone?

They also use a few diodes in the bias spreader, so are those also used to sense heat?
 
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