Bryston BP-25 Preamp, 10B-Sub Electronic Crossover, and 3B-ST Amplifier - Measurements and Review

[MAB]

I agree the caps very often do not need replacing unless there is a problem. I do it on 30+ year old gear where I do not know it's history. Maybe it has been powered for 20 years continuously ??
I do it for peace of mind, mostly.... and for future-proofing. It gives an excellent placebo effect improvement.

Continuous use is not a problem, unless the caps are garbage, or the gear isn't well designed thermally, or just not well-designed. In fact, constant use better than intermittent or periodically stored. It's a capacitor physics thing. There is a field of study regarding capacitor aging, this is covered extensively, and in many manufacturer's spec sheets.

Capacitor-swapping does give a placebo effect, unless you damage the gear while swapping parts. I've posted many examples of capacitor swaps gone bad in gear brought to me to work on. I prefer to only swap the parts that are in need, typically relays in old gear since those have audible degradation mechanisms. Too bad it is often impractical to swap controls since nearly every piece of vintage gear I work on has some channel imbalance and/or pot noise due to the contacts aging.

 

[EJ3]

Hmm , it's a tad harsh to claim that the spent boards from modern electronics all goes to the landfill , they get recycled for valuable materials that's inside the components . So modern electronics are rarely repaired but recycled .

Where i live no one puts electronics or batteries in the normal garbage bin ?

I do tend tend to agree that stuff should be repairable , it would be better if also modern designs where repairable then it would be even better as their small size and low mass did not consume so much resources .

There would be no point in replacing fully functional 90's electronics .

If you have the skills repairing 90's electronics is a really good solution . the amplifier already exists, nothing but a hand full of components needs to be produced .

Refurbishing already existing stuff is usually almost always better for the environment than producing new stuff .

Energy consumption is a factor for things that runs 24/7/365 but for a power amp you can always turn it off when not used .

Don't use Class A space heaters if you can avoid it !

Here: we have found a lot of corruption in the recycling chain: only about 30% of what we actually believed was being recycled (based on what we knew was being picked up for recycling [which we knew and expected to be along the lines of 80%} due to who knows what). So the chance of you throwing it into it's proper bin and it actually getting recycled (here, this city, it will naturally vary) is about 30%. Someone (or many someone's) has figured out a way to get rid of things without recycling them (and, of course, the motive is to get paid for recycling them and (somehow???) make extra money to make it worthwhile to take a chance of being caught doing illegal transactions.
Eventually, I expect, what is occurring, will be found out.
Until then, if you want to be sure, you will have to figure out how to get it to the actual recyclers yourself.
There are companies that offer this service on their own products (and there are some that offer it on other than their own products). BUT: can you trust them to do what they say they will do. Or is it the same trick the government, the unions and the NGO's are playing?

 

[EJ3]

Continuous use is not a problem, unless the caps are garbage, or the gear isn't well designed thermally, or just not well-designed. In fact, constant use better than intermittent or periodically stored. It's a capacitor physics thing. There is a field of study regarding capacitor aging, this is covered extensively, and in many manufacturer's spec sheets.

Or was simply stored in an attic (which around here, can easily be 140+Farenheight) for 40 years.
This is where testing comes in.
It does not have to be heat from continuously being in operation.

 

[Vhond]

In the first post of this thread an original and unmodified BP-25 preamp is tested. It shows stellar performance, no evidence of deteriorating capacitors. Also no aged relays, which quite frankly are often more responsible for deterioration than capacitors, unless the capacitors were under stress or flat out poor quality.

Back to your BP-25, what is wrong with it? And if nothing is wrong, why would you speculate that it needs new components (capacitors or otherwise)? Unless something bad happened in the past few decades that you haven't mentioned.

When I play music (and leave my set on for days) the sound becomes less detailed (smeared). I know it's the pre amp (Bryston BP25).

After switching it off and then switching it on (after waiting for about 15-12 minutes) the sound is more open and detailed.
I suspect the electrolytics although I can’t see anomalies. As a matter of fact I already measured the "blue ones" but they seemed ok (but I didn't remove them from the circuit , though that's better for accurate measurement) But it also may have to do with stability of the circuit (voltage stabilization and overheating)?

 

[MAB]

When I play music (and leave my set on for days) the sound becomes less detailed (smeared). I know it's the pre amp (Bryston BP25).

After switching it off and then switching it on (after waiting for about 15-12 minutes) the sound is more open and detailed.
I suspect the electrolytics although I can’t see anomalies. As a matter of fact I already measured the "blue ones" but they seemed ok (but I didn't remove them from the circuit , though that's better for accurate measurement) But it also may have to do with stability of the circuit (voltage stabilization and overheating)?

The blue ones... Sounds like you have a choice.

Randomly swap capacitors. Or have a working preamp.

I hope service technicians don't start diagnosing electronics with audio review shtick. "Smeared sound", "lacking PRaT", "not resolving", "lost microdetails" etc. are not diagnostic. More likely perception of issues since our hearing is so unreliable.

 

[Vhond]

How predictable. I don't understand much of your answer. I'm asking clearly what it could be. Not asking for an randomly swapping caps.

When I hear it several times it's more than a coincidence or questionable perception. I agree it must be measurable (but where to look)??

 

[MAB]

How predictable. I don't understand much of your answer. I'm asking clearly what it could be. Not asking for an randomly swapping caps.

Not likely the preamp's capacitors.
More likely a contact with dirt in it, like the input selector or volume control.
Also likely is normal human 'why does my system sound bad today?' syndrome.

I hope you appreciate, nobody can diagnose 'smeared sound' online.
And fixing gear involves measuring the problem so that the tech doesn't randomly swap parts. There are certainly many techs in many fields who randomly swap parts, those are the ones we should avoid.

I hope this helps.

 

[Vhond]

Not likely the preamp's capacitors.
More likely a contact with dirt in it, like the input selector or volume control.
Also likely is normal human 'why does my system sound bad today?' syndrome.

I hope you appreciate, nobody can diagnose 'smeared sound' online.
And fixing gear involves measuring the problem so that the tech doesn't randomly swap parts. There are certainly many techs in many fields who randomly swap parts, those are the ones we should avoid.

I hope this helps.

Sincere question: why would you think it's a dirty input selector or volume control? You would expect loss of sound or a cracking sound when adjusting the volume (that's not the point). My experience has to do with loss of detail. Overheated and aging components which result in improper functioning would be more likely (= less stable voltage in the circuitry)

 

[MAB]

As equipment warms up, contacts change conductive properties. It's common for relays, volume controls, switches to become intermittent after power on. All contacts degrade with time and use condition. Contacts of all kinds are by far the most common issue in old gear, unless the gear has poor thermal design, improper application of components, etc. Bryston seems to avoid these types of systematic design and application errors in their products.

For sure you might have a bad sample, or it was used or stored in a really hot environment, or some other manufacturing issue. If so, I'm not sure loss of detail is what you would expect to hear, although I admit I am not sure what that means. I tend to hear mains leakage, periodic sounds like put-put, frequency response changes, to name just a few. Even these are often unrelated to capacitors. Capacitor degradation is pretty easy to measure though, but you need a bench with quite a variety of gear. So are many other issues. You perceive an intermittent issue, which I appreciate makes it difficult. It's easier when one channel is consistently 6dB down from the other for example.

 

[Vhond]

@MAB : thanks for your long answer. Yeah, it's hard to tell what I hear after a couple of days. It has nothing to do with dropouts or things alike and indeed easier when one channel is less audible. As I wrote it has to do with sound which becomes less detailed (less separate instruments/sounds).

The righthand side becomes really hot, maybe I have to look for a solder which is not as good as it was or components which become overheated. What I read on another forum is the blue electrolytics are not especially good in the long run

I did measure them soldered (and didn't find bad values), but better measure them off print.
These especially are getting very hot:

 

[Midiot]

My experience has to do with loss of detail. Overheated and aging components which result in improper functioning would be more likely (= less stable voltage in the circuitry)

I would encourage you to continue to consider that this "loss of detail" is indeed your ears getting used to the "detail and separation" when you first turn on your system. Our brains are sensitive to subtleties initially, then they homogenize toward normality over time.
For example, I can tell when my lower neighbor cooks food. I will smell it when I first enter my unit. But in about 2- 3 minutes, I do not notice the smell anymore ....until I walk outside then come back inside - the smell is still there.
This is likely not the answer you "want" to hear. (did I made a pun ?) But if you are still convinced you hear a noticeable loss of detail caused by the electronics, then you could verify this by taking a snapshots of your system using soundcard-based spectrum software.... at cold startup vs warmed-up. Like people say on this forum, "If differences can be heard, they can be measured". (don't ask me "how" to do this, I am just now beginning to learn how to measure my room, acoustically).
Another option is to replace the older electrolytic caps that you suspect might be the culprit. This would satisfy/eliminate a portion of your worries. If this mechanically fixes the problem, great ! If it psychologically fixes the problem, great as well !

 

[Haflermichi]

@MAB : thanks for your long answer. Yeah, it's hard to tell what I hear after a couple of days. It has nothing to do with dropouts or things alike and indeed easier when one channel is less audible. As I wrote it has to do with sound which becomes less detailed (less separate instruments/sounds).

The righthand side becomes really hot, maybe I have to look for a solder which is not as good as it was or components which become overheated. What I read on another forum is the blue electrolytics are not especially good in the long run
View attachment 516119

I did measure them soldered (and didn't find bad values), but better measure them off print.
These especially are getting very hot:
View attachment 516120View attachment 516121

How did you measure them? Multi-meter, ESR meter? Caps do not have to be unsoldered to be measured with an ESR meter.
Also, the anodizing on heatsinks, particularly small, non-cosmetic (internal) ones as shown can turn purple quite easily and this is not a reliable indication of overheating.
The solder joints and traces on the board leading to those devices would discolor as well. How are you determining "very hot"?
Infrared laser thermometers are inexpensive and would let you quickly measure and compare surface temperature amongst several components.

 

[Vhond]

Using Multimeter (not ESR meter) and about the heatsink: it's impossible to hold them.