BGW250 uses 4 MJ15015/16 pairs to produce 126 w/ch at 4 ohms. That is 1.4 amps per pair. MJ15015/16 has a 60 v soa for 0.5 sec of 3 amps. That is pretty compliant current. Of course with all TO3 On packages costing >$10 now, no reason not to upgrade the entire set to MJ15003/4, MJ15024/25 or MJ21195/96.
I had 30 MJ15015 I bought from Newark for $1.60 ea that my local unemployed house painter hauled to the steel scrap yard for me 9/2020.
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That could be the active/passive switch.
Maybe someone here has the complete schematic.
I got my service manual from eserviceinfo.com https://www.eserviceinfo.com/downloadsm/184715/. Various_bgw 250d 250e.html
Very good amp.
extremely easy to disassemble (like a Bryston, disassembles in less than 10 minutes) and to maintain, very well documented, almost indestructible, passive cooling is a real plus for hi-fi.
If it has been revised, up to 400€/$, if to be revised, between 250 and 300.
For the sound, it has a large current capacity, is nice in the low and high medium but lacks a little detail in the high end, honestly, it's really a great amp, super nice for everyday use.
extremely easy to disassemble (like a Bryston, disassembles in less than 10 minutes) and to maintain, very well documented, almost indestructible, passive cooling is a real plus for hi-fi.
If it has been revised, up to 400€/$, if to be revised, between 250 and 300.
For the sound, it has a large current capacity, is nice in the low and high medium but lacks a little detail in the high end, honestly, it's really a great amp, super nice for everyday use.
One of the best systems I ever heard had an SP3A1 driving a D76. I couldn't tell you what else this system was comprised of, but the speakers sounded like horns, and the turntable looked like an old rim-drive model.
I have heard many ARC based systems since, but none had the same magic that system did.
I have heard many ARC based systems since, but none had the same magic that system did.
This reflection makes no sense.
First of all, these are two totally different amps, two completely different uses, two totally different prices, and the reviews are written by different people with different ears and different systems.
Buy, listen, judge, keep or resell.
As already said in the past, I have and have had a lot of audio equipment (really a lot), today I still have a few dozen amps including Bryston, H/H, C-audio, Inkel etc. etc, not one of them sounds the same, and the same amp with different speakers, preamp, sources does not sound the same, it's all a question of agreement and it is, so to speak, not predictable because even in the case of experience shared by a user who would have the same set as you, would not have the same tastes, feelings, pieces, mood...
Buy, try, keep or resell.
The early SP3A1s were good at first, and then went south. Bill said it was the tubes.
Perhaps. But deductive reasoning indicates that the Onkyo is the best option for my current system. But I do want to experience what the 250D has to offer.
Is this a matter of the tubes being defective, or a matter of not being able to continuously secure a good lot of them?
See post 9 & 26 for enthusiasts. Four output transistors are MJ15015/15016 which it does not use very hard, a defined SOA contrasted with 2n3055. MJ15003/4 and MJ15024/25 are more capable and about the same price these days. Input op amp is lm318 which is still available & cheap, but for 1000 ohm load 80 nv/sqhz a bit noisy IMHO. Substitute AD797 are $20 each today but 20-20khz voitage noise max 2.5 nv/sqhz. If your band plays level 11 all the time no signal noise may not matter to you (wg ski post 15 does not care). In my living room I would prefer the quieter op amp. AD604 is $2.90 and quieter than lm318 but no longer stocked in long leg dip package.
250E VU meter board has LM3915 bar display driver, now obsolete. Driving the LM3915 is LM324N quad op amp, still in stock at $.44 . But you said the candidate was a 250d with no VU board.
The 8 pin input routing plug has no part number and might be hard to find.
250E VU meter board has LM3915 bar display driver, now obsolete. Driving the LM3915 is LM324N quad op amp, still in stock at $.44 . But you said the candidate was a 250d with no VU board.
The 8 pin input routing plug has no part number and might be hard to find.
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Upgrading op amps doesn’t universally work. But if the AD797 is known to work in these amps it can certainly be used. I wouldn’t go do anything that’s not tried and tested unless you were prepared to work out all the bugs, including re-compensating.
Upgrading the output transistors usually does work. The 15105/6 have pitifully low gain, caused by taking an already marginal 2N3055 and extending its voltage capability. If it wasn’t an EF3 design already it would probably sound like ***. They’re not being run too hard and won’t just burn up unless the user is an idiot about 2 ohm loads at war volume, but if they ever do need replacement or you want to update/upgrade it’s very low hanging fruit.
At some point we will be making LM3915’s out of a bank of 324 op amps. It can actually be done, just not in an 18-DIP form factor. But a plug in module made out of SMDs is possible.
Upgrading the output transistors usually does work. The 15105/6 have pitifully low gain, caused by taking an already marginal 2N3055 and extending its voltage capability. If it wasn’t an EF3 design already it would probably sound like ***. They’re not being run too hard and won’t just burn up unless the user is an idiot about 2 ohm loads at war volume, but if they ever do need replacement or you want to update/upgrade it’s very low hanging fruit.
At some point we will be making LM3915’s out of a bank of 324 op amps. It can actually be done, just not in an 18-DIP form factor. But a plug in module made out of SMDs is possible.