Bryston 4B ST Clone Started

rsbonini · 29th January 2010, 09:52 PM

Bryston amps are legendary, and many people here have toyed with the idea of building one. Well, I've started a 4B ST clone. So far the PCB's have been designed, manufactured and I have most of the components for the main amp boards installed. I've been pondering how exactly to set the bias on the amplifier though. I've not had any luck finding a service manual or other document with this information. Any ideas?

(will post pics soon)

mak müh · 4th February 2010, 09:39 AM

I am looking for waiting your project.

h_a · 4th February 2010, 09:49 AM

Quote:

how exactly to set the bias on the amplifier

The Brystons are optimum biased ClassB amps, no? So you would need a distortion analyzer to set the bias to minimum distortion.

Soundcard with decent software will do also.

Have fun, Hannes

rsbonini · 5th February 2010, 01:32 PM

Here are the amp boards, I have all the passives installed minus some jumpers and output inductors. The output transistors in the one image are just to show spacing and that these will go through the heatsink and solder directly into the pcb. The boards will also mount directly onto the heatsink. Signal paths are short and compact. Metal film 1% 3/4W resistors for the most part, audio critical caps are poly film, boards are double sided gold plated. Schematics can be found on the Bryston website. Next is to clean these up, mount them on heatsinks and get a power supply running to start testing. Wish me luck!

Zero Cool · 5th February 2010, 01:55 PM

I will be very curious to see how these come out. The 4B for some reason really has good bass control. I couldn't believe the difference, it was like adding another entire octave to the bottom end of my speakers simply by swapping in an old 4B, but the top end was too harsh for my liking. But that was an old 4B I was playing with too. not the ST version.

Zc

Bigun · 5th February 2010, 03:20 PM

I have a Bryston integrated, essentially the 2B. It's no 4B but I would echo that comment on the bass and the high end of the frequency range, although I wouldn't describe the trebles as harsh I would say I find listener fatigue after a few hours.

taj · 5th February 2010, 05:16 PM

So, is this just "show and tell", or are you going to divulge your PCB layouts and plans for the project? Will others be able to build this based on the work you're doing? What's your plan?

What chassis are you designing this for? The cutouts in the PCB have an obvious purpose, but I can't guess what that might be.

..Todd

rsbonini · 5th February 2010, 05:30 PM

Not entirely sure yet. Just wanted to get some feedback on how to set the bias on this properly. Depends on how much interest there is and how well it works out. I'll document as I go and put together a build-through pdf,

I'll be building the chassis from scratch (that's the current plan plan anyway)

Stormrider · 5th February 2010, 08:21 PM

How about posting the schematic you're working from?

AVWERK · 5th February 2010, 10:10 PM

What was the reason you designed the TO3 closer to center rather than at the edge where it would be easier to sandwich a heat sink assembly together?

Regards
David

29th January 2010, 09:52 PM	#1
rsbonini diyAudio Member Join Date: Jan 2010	Bryston 4B ST Clone Started Bryston amps are legendary, and many people here have toyed with the idea of building one. Well, I've started a 4B ST clone. So far the PCB's have been designed, manufactured and I have most of the components for the main amp boards installed. I've been pondering how exactly to set the bias on the amplifier though. I've not had any luck finding a service manual or other document with this information. Any ideas? (will post pics soon)

5th February 2010, 03:20 PM	#6
Bigun diyAudio Member Join Date: Jan 2009 Location: K-W Ontario Blog Entries: 2	I have a Bryston integrated, essentially the 2B. It's no 4B but I would echo that comment on the bass and the high end of the frequency range, although I wouldn't describe the trebles as harsh I would say I find listener fatigue after a few hours. __________________ "The test of the machine is the satisfaction it gives you. There isn't any other test. If the machine produces tranquility it's right. If it disturbs you it's wrong until either the machine or your mind is changed." Robert M Pirsig.

5th February 2010, 08:21 PM	#9
Stormrider diyAudio Member Join Date: Apr 2006 Location: Connecticut	How about posting the schematic you're working from? __________________ AJ

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4th February 2010, 09:39 AM	#2
mak müh diyAudio Member Join Date: Oct 2009 Location: es-es	I am looking for waiting your project.

5th February 2010, 01:55 PM	#5
Zero Cool Audio Junkie diyAudio Member Join Date: Sep 2004 Location: MN	I will be very curious to see how these come out. The 4B for some reason really has good bass control. I couldn't believe the difference, it was like adding another entire octave to the bottom end of my speakers simply by swapping in an old 4B, but the top end was too harsh for my liking. But that was an old 4B I was playing with too. not the ST version. Zc

5th February 2010, 05:16 PM	#7
taj diyAudio Member Join Date: Feb 2005	So, is this just "show and tell", or are you going to divulge your PCB layouts and plans for the project? Will others be able to build this based on the work you're doing? What's your plan? What chassis are you designing this for? The cutouts in the PCB have an obvious purpose, but I can't guess what that might be. ..Todd

5th February 2010, 05:30 PM	#8
rsbonini diyAudio Member Join Date: Jan 2010	Not entirely sure yet. Just wanted to get some feedback on how to set the bias on this properly. Depends on how much interest there is and how well it works out. I'll document as I go and put together a build-through pdf, I'll be building the chassis from scratch (that's the current plan plan anyway)

5th February 2010, 10:10 PM	#10
AVWERK diyAudio Member Join Date: Jan 2004 Location: OC,Calif.	What was the reason you designed the TO3 closer to center rather than at the edge where it would be easier to sandwich a heat sink assembly together? Regards David

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