I lack the knowledge unfortunately.
The first one is a John Shearne Phase 2 integrated, one of which I owned some 25 years ago and am contemplating to perhaps buy again if a good example turns up.
It looks like the firsst one may already had something changed but I can't be sure. Many thanks
The first one is a John Shearne Phase 2 integrated, one of which I owned some 25 years ago and am contemplating to perhaps buy again if a good example turns up.
It looks like the firsst one may already had something changed but I can't be sure. Many thanks
The large toroidal transformer and the bank of six large power supply capacitors bode well for a stiff power supply and well sustained power into the speakers.
The substantial heatsink for the four output transistors is also a good sign, as is the fact that the control pots/switches are placed at the back, operated via extension shafts, well away from the magnetic field of the transformer.
Apart from that that, I would seek out reviews which contain some degree of information on circuit topology.
For example: https://www.soundstagenetwork.com/revequip/shearne_phase2.htm
EDITED for numerous typos!
The substantial heatsink for the four output transistors is also a good sign, as is the fact that the control pots/switches are placed at the back, operated via extension shafts, well away from the magnetic field of the transformer.
Apart from that that, I would seek out reviews which contain some degree of information on circuit topology.
For example: https://www.soundstagenetwork.com/revequip/shearne_phase2.htm
EDITED for numerous typos!
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Yup, many eighties/nineties design features that look technically sound.
Very good: switches and volume control where they need to be and non ferro (brass) extensions rods... good things. No bushings in the front cover though (for the extensions rods). Film input caps. Styroflex caps in general.
Negative: small heatsink or beter said no heatsink. Just an L bracket. Mains wiring too close to audio circuits. The concession they did was to use a too small casing as the transformer is close to sensitive circuitry. As a result AC secondary wiring is very long. They could have placed the rectifiers and caps at the same side as the transformer and move all audio circuitry to the right.
Very negative: NO speaker protection. Likely power on/off plops. DC resistant 🙂 loudspeakers advisable.
Points of care because of age: switches, electrolytic caps, spare set of semis.
Very good: switches and volume control where they need to be and non ferro (brass) extensions rods... good things. No bushings in the front cover though (for the extensions rods). Film input caps. Styroflex caps in general.
Negative: small heatsink or beter said no heatsink. Just an L bracket. Mains wiring too close to audio circuits. The concession they did was to use a too small casing as the transformer is close to sensitive circuitry. As a result AC secondary wiring is very long. They could have placed the rectifiers and caps at the same side as the transformer and move all audio circuitry to the right.
Very negative: NO speaker protection. Likely power on/off plops. DC resistant 🙂 loudspeakers advisable.
Points of care because of age: switches, electrolytic caps, spare set of semis.
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The only inherent weakness I can immediately see is the fact that the outputs are darlingtons. I just happen to recognize the MJ1101x series. It’s not necessarily “bad”, but does put a couple of limitations on the design that are hard to overcome. Both “driver” and “output“ device are stuck with a 3MHz fT. It would be better if the driver were faster. You’re stuck with the internal base-emitter resistors. The drivers run just as hot as the outputs, which is harder (but not impossible) to compensate. They are not bad transistors per se, those tend to be among the more rugged types among epi-base darlingtons. The 2N605x types have a nasty habit of blowing up in the same circuits.
One might be able to change them out with D2560/B1647, assuming one still had some. PNPs are already on MOQ. The 10A variety likely won’t cut the mustard, and the 25A are gone baby gone.
The heatsinking is adequate only for very low power. The amplifier should not be used with difficult speakers.
Ed
Ed
Oh yeah , the Sanken's ! Many 80's Sony AV receivers used those. More "YUK".
At least Sanken still exists and makes my favorite C3519/A1386 pair , 34 years later...
"active" part status - I like Sanken's datasheet "for making high quality audio sound"
OS
It worked 25 years, if you enjoy what it sounds like, then why do you want to change it! I think you just want to bragg with your amp and you have the right too do so 👍 👍 👍 👍 👍. If something does not itch, don't scratch it.
The first one is a John Shearne Phase 2 integrated, one of which I owned some 25 years ago and am contemplating to perhaps buy again if a good example turns up.
Okay, now what? I can't see why everyone is eager to change anything, he is contemplating to perhaps buy again. Is it good or bad. I don't know. It looks nice and I am sure if the designer thought that mains interference was an issue, he would have done something about it. He seemed to think copper rods was a good idea, no?
Okay, now what? I can't see why everyone is eager to change anything, he is contemplating to perhaps buy again. Is it good or bad. I don't know. It looks nice and I am sure if the designer thought that mains interference was an issue, he would have done something about it. He seemed to think copper rods was a good idea, no?
Is this a question of the merits of the design generally? Or is it a question about the differences that we see in these two specific examples?
How “good” is an EF2 design with 3MHz drivers? How “good” is an amplifier whose idle current in the drivers cannot be optimum regardless of how it was designed or adjusted? How ”good” is an amplifier with about the same amount of heat sink as a NAD3020? How “good” is amplifier that will probably run away if it’s DC supply is above +/-40V?
“Good” enough for you? If so fine. If not look elsewhere.
Those look like minor revisions. Basic architecture isn’t changing.
“Good” enough for you? If so fine. If not look elsewhere.
Those look like minor revisions. Basic architecture isn’t changing.
You are absolutely right, I actually forgot all about the pop when switching on/off. It didn't bother me too much though I guess it may not be great for the speakers which were Ruark Sabre IB's. CD player was a Trichord Genesis 🙂. Brings back memories.
That's the question Adam.
drummerman111 wants to know if one can tell an amp is based on good circuitry just by looking at its innards.
English translation is a little wonky. Even OnSemi data sheets have that feature now.
My faves were traditionally the Toshibas, but they maybe past their peak now. On is as good or better now, and easier to reliably obtain than Sanken. Their supply chain still hasn’t come back from the latest interruptions.
Ive been building smaller stuff around the Sanken darlingtons recently (that don’t suck) but since they are disappearing from general distribution channels that practice will stop when I run out of them.
With that angle bracket bolted to the chassis, it’s about as effective as that NAD3020. For 30 volt rails it’s good enough. For 35-40 it’s a little light. For 45 it’s TOO light. Just depends on what it actually IS.