Hmmm ... regretting my choice of PCB then as this layout is not conducive to heatsinks (devices too close together) ... I was under the impression they would run fine as-is.
Back to eBay for some cheap offshore extrusions!
You can use heatsinks that clamp onto the transistor. You don't have to have the heatsink mounted on the board. They cost about 50 cents each, they just are a U shape that has fins on one side for the cooling. And if you run 2 diodes, which is what Richard Marsh does, you really don't need them. but again, you can get heatsinks that sit right on the devices on the same boards.
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Listening to the amp now via the Chord Hugo fed by my DX90. Excellent huge stage. Transparent and dynamic and these aren't my best headphone.
One thing I have to say is that this amp is very, very sensitive to any changes so whatever you go to, different caps, resistors, you have to give them time to settle or burn-in. Got to have the electrons do their thing and the dielectric. I changed the resistors and good then lousy sound and then slowly it came back and was better than before then another power supply so that the amp has a supply for each channel, great then down hill, then slowly back and now more open, dynamic and transparent with great speed.
Now I have some new caps I want to try. I could put some Black Gate non polar on the board, or some Nichicon Muse KZ or some Gold, all bypassed by decreasing values of the same but I know I won't have great sound for a while. :^) I have some Silmic but not sure if I want to use them as they can muddy things. The thing I don't want to do is over cap. Some different resistors would be fun also. Too bad I don't have the value of NOS tantalums that I would use. They are the best resistors IMO, the Japanese version not the magnetic Audio Note UK through they now make them non magnetic but the price is too dear for me.
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Vishay MKP1837 are MAGIC in a bypass position!
Did you notice much of a difference with the BG's bypassed and not bypassed?
Vishay MKP1837 are MAGIC in a bypass position!
Will have to get some.
Did you notice much of a difference with the BG's bypassed and not bypassed?
I haven't installed the BG's yet in on the board as the main caps. I bypassed the stock caps with non polar BG's but always have run it that way so I had no way to know if there was a change with the bypass.
I added 4 Nichicon Muse KZ 470uF, one for + and - x2, off of my 2 power supplies and these are bypassed by KZ. Will see how it sounds after they form/burn-in. The stock caps, Silmic have mixed feelings by users. Some like them, many don't. A highly respected developer I no has a low opinion of them. I had bypassed mine with the BG's and they seem to sound good to me. Will see how this mix goes. Always fun to experiment.
I have had a run of requests for boards -- ran out several weeks ago. I was thinking to modify a bit by providing for adjustment of the 2N5087/8 and allowing folks to use SMT input JFETs, or K170/J74. As before, and in deference to Richard's IP, will offer the boards out at cost:
Attachments
I am really liking the the Nichicon KZ. Cleaner sound and more articulated sound.
On a more versatile board, I would think that would always be a plus. I have a friend who is a designer of amps and his boards always allow for variables, which he makes full use of and it allows for on the fly changes that don't require a new board being made each time.
On a more versatile board, I would think that would always be a plus. I have a friend who is a designer of amps and his boards always allow for variables, which he makes full use of and it allows for on the fly changes that don't require a new board being made each time.
Any chance of spreading the output transistors apart more to allow for heatsinks to be attached?
My personal preference is Nichicon K* in power supply and Silmic II in coupling IF a high value where a film is not available, too expensive or size prohibitive. I ALWAYS bypass electrolytic with Vishay MKP1837's. I am going to try this amp with the Black Gates unbiased at first just to see if it makes a difference.
BTW ... AudioNote bought the IP for Black Gate and is working with their capacitor manufacturer to bring them back under the AN name!
My personal preference is Nichicon K* in power supply and Silmic II in coupling IF a high value where a film is not available, too expensive or size prohibitive. I ALWAYS bypass electrolytic with Vishay MKP1837's. I am going to try this amp with the Black Gates unbiased at first just to see if it makes a difference.
BTW ... AudioNote bought the IP for Black Gate and is working with their capacitor manufacturer to bring them back under the AN name!
Yes, they said the lower voltage caps are supposed to be available this summer. They will be expensive though but hopefully within reach. I know that Peter believes there is nothing better than the BG.
On the first go-around, I didn't realize that so many folks would have difficulty sourcing the 2N5457 NJfet. The equivalent is available in surface mount. The through-hole device does show up from time to time.
I think it was Richard himself who suggested twiddling with the resistor values...and that was at least a year after the article was published in LA.
You'll probably find that careful adjustment of the two potentiometer values, getting the output devices relatively close will swamp any effort to tweak a bypass cap here or there.
I find them regularly on eBay. Today they have many.... typical price is $7 USD for twenty.
THx-RNMarsh