Hi ostripper,
-Chris
They were a Motorola shop all the way. I don't know about now.
I have an original SymAsym, it's the same way. Cool and very stable. If you match the outputs, it will run with very low bias. I used the excellent (and NLA NJW0281A and MJW0302A) pairs. They came from the factory matched better than most hand matching efforts. I think the bias was set at 10 or 15 mA, lowest THD on mine occurred around 5 mA as I recall. Not the highest rated outputs, but really excellent transistors.
-Chris
Hi SY,
-Chris
Do you remember the model number of the amps you had? The 3B and 2B were both far better amplifiers than the 4B.
That, I can believe. I was authorized warranty for Adcom. Those are amplifiers that were engineered well. Still no speaker protection to speak of. Was yours a 555 or 555 MKII? For sure it wasn't the poor amps that suffered from bad capacitors. I have one here that is stubbornly holding onto the electrolyte from those caps.
That's what happens when engineers are allowed to work with relative freedom. It's pretty funny, your amplifier choices. You went from a well engineered product that had on bad habits (Adcom) to a pretty crappy design if you had the original *B series of Bryston amps.
-Chris
This is absolutely true. I have been offered by H-Kong importer to sell tonnes of amps into China if it was only made in USA. Its a trust issue...... even if it was just assembled in Asia from all USA made parts, it would have a hard time selling it. They made and sold junk for so long but got rich doing so... but they wont buy their own made stuff...... China made especially.
As for the car analogy.... each car company makes high-end models --- pick your favorite one. Whether Hi-Perf sports car or Limo.
Still, where are the truly equivalent audio products?
THx-RNMarsh
That's funny! I was just talking about that Bob & Ray record, shown in the picture on the left, in another place. What are the odds?
That is what I also discovered , some designs exhibit their lowest THD
at what would be considered a non-optimal class AB bias.
In fact , the current CFA "fetish" is quite easily explained. A >200V/uS
slew seems to error correct the AB X-over glitch down to nearly
class B (no bias). THD will stay PPM right down to 10ma on one of
my "kypton ND" input stages.
Symasym and other current (VFA) input stages have a lot longer group delay -
they are not fast enough to do this , and need a stronger 60-
75ma bias to "bottom out" (THD wise).
Output devices with their individual Cob , combined the basestopper and
"suckout cap" also determine how much THD the OPS contributes.
That contribution is mainly odd order , this is why AB offends some
golden ears if not implemented correctly.
The Sanken outputs also will require less bias for optimal AB , I suspect
this is why they market these devices "for audio" - they outperform
at lower heat/bias.
OS
0.5 preamp, 2B and 4B NRB power amps. I also had a smaller power amp of theirs, but I don't remember the model number. Worked fine but the power transformer made too much mechanical noise, so I gave it away.
Original 555.
He he. Exactly the story of the company I was working for in ~1970. Scientelec. Began with kits made from a RCA App Note. The amps were burning faster than the "Road runner" or "Speedy Gonzales". And sounded awful.
I remember those bins, in the SAV, full of those slow 2N3055 !
Please, note that they made their commercial succes with this sh*t.
Then they hired ingeneers to build a R&D department (I was one of them).
We produced quite decent stuff after one year. (I mean very good for the time;-)
Probably the reason why this company went bankrupt few years later ?
Newer model? Probably had the chat around 1982. He was mentioning that they had custom made European capacitors as all the others failed. Also that he was the only one using a compound NPN PNP exploiting the transistors for the full cycle...
So I read that as a sign of instability causing heating. Of course it could have been undersized and ripple failure, but I presume that power amplifiers have oversized capacitor banks and consumer amps rarely see the kind of use as do the ones I use.
Ever wonder what my actual cost of a warrant failure could be? Worst case a round trip Pittsburgh to Seattle (twice) and shipping the amplifier to a service center (often the manufacturer.) I once explained to a group of vice presidents that a 5% failure rate was ridiculous and their claimed .2% was still inadequate.
Then there was the manufacturer who would only pay for warranty repairs what it cost them to do one inhouse excluding pick up and shipping. (15$ maximum as they insisted on replacing parts not paying for them.)
For some reason we have a design rule of only using products that have been on the market for at least one year.
So what's the big deal about Bentely? An old British company, long gone in original form, still pit tgether in the UK, but using moe or less all German made parts? Same goes for the Mini, still put together in the UK, using German designed and made parts. So whose product actully are they? Typical modern bastard produtc caused by globalization and the drive to dibersify portfolios by buying out those who stmbled cheapely.
I don't know what the failure rate is for consumer electronics these days, but I can remember when it was shockingly high, although they tend to count NTF (no trouble found) returns along with genuinely defective goods.
When Harman still had OEM computer customers, Dell said our cheap speakers were running about 300ppm. You would think that would count for something, but they were programmed to say things like Quality is a foregone conclusion and keep chiseling. Then they discussed "studies" that showed that their brand on suppliers' products was helping the suppliers, so branding was not a value (supposedly). It is perhaps little surprise that Harman exited the OEM business. Lots of potential liability, no margin. Next!
Airfare 2 trips $1,600.00 Hotel $300.00 Car $200 48 hours billing $2976 per diem $600.00 repair shipping $90 210 amplifiers (One day out, one on site and one back.)
5766 * 210 * 300 / 1,000,000 = $363.26
or as the amplifier division was doing
5766 * 210 * 5 / 100 = $60,543.00 But it would actually been lower as multiple amplifiers could be done per trip
or as claimed
5766 * 210 * 2 / 1000 = $2,421.72
Now the folks I used for the system in Seattle did have one possible infant failure. Found during installation. Shipped UPS to the manufacturer and destroyed in shipping. So UPS paid for it. As that manufacturer did advance replacement no time lost to replace the unit.
5766 * 210 * 300 / 1,000,000 = $363.26
or as the amplifier division was doing
5766 * 210 * 5 / 100 = $60,543.00 But it would actually been lower as multiple amplifiers could be done per trip
or as claimed
5766 * 210 * 2 / 1000 = $2,421.72
Now the folks I used for the system in Seattle did have one possible infant failure. Found during installation. Shipped UPS to the manufacturer and destroyed in shipping. So UPS paid for it. As that manufacturer did advance replacement no time lost to replace the unit.
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Hi ostripper,
-Chris
The Symasym was the amplifier I was talking about. When others used similar matching and good output transistors their results were very similar to mine. That silly little amplifier sounds really good. I was looking for a utility amplifier around 50 wpc when I decided to build that one, it exceeded expectations on all counts. I can hardly wait to try one of yours (building up funds).
-Chris
Hi SY,
-Chris
The NRB version was improved from the original bag of stool. The 2B wasn't bad, because the voltages were low enough for it not to burn up and it was a standard amplifier design. The 2B was the smallest power amp they made unless you had the newer little fella. I would expect the 2B to be reliable compared to the other amps. I haven't really examined the 4B NRB, but I'll bet they fixed the bias network so it could run cooler.
-Chris
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