Bryston 2B recap

templetec

Member
2011-12-02 6:16 am
I have just acquired an old 2B pro... Not the lp version. I'd like to recap it and am thinking either nichon kg or mundorf gold audio. Any advice or input on these caps... Which are better and which caps (in circuit) will make an audible difference. Also wondered if the resistors would have strayed from spec. And if they're worth changing. Exciting!:D
 

templetec

Member
2011-12-02 6:16 am
I talked to them and YES they are great. They will sell me a set of caps but to me they seem sort of pedestrian. I feel this circuit is special and want to elevate it. That said, I don't want to waste money either. If exotic caps aren't going to make a tick of difference then.... Also wondering if Bryston chose the replacement caps based on auditions or just reliability and availability... hate to ask them that! :eek:
 

templetec

Member
2011-12-02 6:16 am
pedestrian

Struth, I have nothing but respect for Bryston but all companies make compromises based on price points. I'm wondering if there may be an advantage to increasing the quality/price point of the caps... that's the main question I have here. Which caps would benefit form higher spec replacements? Which caps would you folks recommend in which position? If higher spec caps would make no discernible difference due to position in the circuit then I'll go 'pedestrian'. ;)
 

templetec

Member
2011-12-02 6:16 am
Struth....another point here. Mike at Bryston told me he'd have to charge me more for the caps than if I went to an outside source and bought them myself.They offer them as a convenience (service) to owners. I'm looking at partsconnexion and see Nichon KG and Mundorf M-lytic ag. Not 'voodoo caps'...just well respected good quality caps. I'm far too sensible (and poor) for voodoo!
 

llwhtt

Member
2008-06-12 3:43 am
SoCal
Doesn't Bryston have a 20 year warranty? Can't do that with mediocre parts. One thing I've noticed about commercial vs voodoo parts. All of the commercial parts have spec sheets. I have yet to see a spec sheet for voodoo parts. Nichicon is not voodoo, not sure about Mundorf caps.

Craig
 

templetec

Member
2011-12-02 6:16 am
Excellent question... I have no idea. I'm running purely on the feedback I get online with some people saying even when caps aren't directly in the signal path they can have an effect. That said, I understand there's a lot of subjectivity and the influence of expectation in there but.... I noticed you're involved in guitar amplifiers... do you read schematics? Would be great to have your input as to which caps are likely to have an influence if (1) you're into it and (2) I can find a schematic.
 
Doesn't Bryston have a 20 year warranty? Can't do that with mediocre parts. One thing I've noticed about commercial vs voodoo parts. All of the commercial parts have spec sheets. I have yet to see a spec sheet for voodoo parts. Nichicon is not voodoo, not sure about Mundorf caps.

Craig

I found spec sheets for both nichicon and Mundorf on partsconnexion. The Mundorf specs were more complete, listing size, deterioration over temperature and ripple current as well as ESL and ESR. My question is whether they will sound different/better and/or last longer. The Mundorfs are about $20 each vs $7 each for the Nichicon (X4). Yes Bryston does have a 20 year warranty which they honor with great generousity but caps are caps and many people have sent 10 year old amps in for recap...free of cost of course.
 
Found a schematic for the 2B but the caps here are 6000uf 40V and Bryston told me my amp (based on serial #) was 6800uf 50V. Apparently the circuit layout is nearly identical from the first 2B till current 2B (with the exception of the SST version).

Bryston2B.jpg
http://www.diyaudio.com//www.pinterest.com/pin/create/extension/
 

Eldam

Banned
2012-09-13 12:25 am
France
You just should find a good industrial cap which is solid : 105° C to 125C° LongLife performance à la Siemens Sicorel, etc. At this position you can't dream better.

Look at the datasheets to see the pitch between the legs and size caps as you did for the Mundorf. A good cap is a cap which fit in the pcb :D !

It's a Bryston... better to look at the current output capabilitie of the cap... don't bother with ESR spec here as it's also the smoothing cap (and not only the reservoir cap!)

6800 uF will be ok and all voltage above 40V. (avoid more capacitance to avoid to overload the power traffo if made for those cap capacitance)

For the 470/16V, just get a good Panasonic FC serie !

It should be ok both for a guitar speaker or hifi speaker one :)

All other questions could be for techs who believe to try be philosoph :D
 
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I've been working on a project to re-cap several 30+ year old Bryston 2Bs and 2BLPs. As has already been noted, there are a variety of original filter cap values, but I've been using 6800/50 Nichicons with a 105º C rating, and they seem to work fine, although the real test will be how they work in another 30 years.

These amps had been on 24/7 for almost 30 years, and the other thing I found was that the 2.7 KΩ resistor in series with the power/clip LED was well baked, and had damaged the PC board, as well as lifting the traces slightly. I replaced them with another 1/2W, but tried to get the component off the board instead of sitting right on it.

The schematic above seems to be from the original 2B, the one with a green power LED in the middle of the front panel, and two red clip LEDs on either side. A slightly later version, with the bi-colour LEDs is also on their web site. Interestingly, both drawings have a small error. There is no connection shown between the output transistors' collectors and the speaker output. There should be a connection dot just to the right of the 33K resistor and 47 pF cap in parallel, near the center of the drawings.

GTD
 

templetec

Member
2011-12-02 6:16 am
cbc6403, thanks for your input there. My resistor on the led is fried as well. I'll try the 1/2w replacement. I'm not terribly worried about a cap lasting 30 years @24/7 as I doubt this beauty will ever see that service again. I'd rather use a good reliable audio rated cap than a cap that's going to last 30 years. That said I don't read schematics and have no idea which of the caps in this circuit will impact performance. Your advise here would be much appreciated.
 
...I'd rather use a good reliable audio rated cap than a cap that's going to last 30 years. That said I don't read schematics and have no idea which of the caps in this circuit will impact performance. Your advise here would be much appreciated.

I'm not sure I can help you much there. I come from the same school of thought as Eldam: the right component is the one with the right value that will fit on the circuit board. That said, the Nichicons are well regarded components. For the original 2B (not 2B-LP) the 470 uF cap needs to have axial leads, which I could only find in an 85ºC rating. Same thing for the 220s. The 2B-LP needs a radial 470 uF, which is available in 105ºC.

The audio doesn't actually pass through any capacitors on its way from the input to output, although it's arguable that the capacitors in the circuit may influence the negative feedback in some way.

I actually did the older 2Bs first, and wound up using Vishay (also well regarded) capacitors. The Digi-Key part numbers are 4688PHBK-ND, 4004PHCT-ND and 4021PHCT-ND.

GTD
 

Eldam

Banned
2012-09-13 12:25 am
France
Templetec,

IMHO : which is important with the aluminium caps of your shematic :

-when involved in a filter : the value of a cap is important ! so the values maybe be checked with a capacitance tool (there are cheap ones !)

- when involved in power position, you should stay near the value of the caps if the values were calculated exactly to the traffo VA value. But here a much more important quality then audiograde is solidity and aging of performance as the smoothing/reservoir cap when a unique cap is the much solicited cap of the whole Hifi devices by far ! Here the qualities becomes : temperature rating (105° is fine). As I was advised in an other thread for the same question for my amp by two specialists : low ESR is fine as the lower ESR, the lower temperature rises. All the good brands have both low ESR/Long Life-high ripple "input" caps. Both Nippon Chemicon and United Chemi Con, if you are sensible to the origin of the cap, were advised !

For the game, you may try after swapping the main cap to listen to the new 6000/50V. Then add in // if space enough Panasonic FC 1000uF/50V (here a little more than 10% will not change the relation too much with the traffo imo), then listen. You may find the sound more thight, , more transcient, maybe more clearness... or not at all (and if not remove and stay to the original conf) ! Cheap to try !
 
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