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Old 27th April 2009, 03:25 PM   #631
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Quote:
Originally posted by bluegti
I have one board stuffed with Silmics and 22nF WimaFKP2. Unfortunately, I have to go out of town for 10 days so I won't have time to report back for a couple of weeks.
Any news?
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Old 27th April 2009, 11:04 PM   #632
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SPECTACULAR MY REF FAILURE!

Just kidding. Yes, I already did have a failure, and I couldn't figure out the problem. I had a pair of spare boards, so I built a pair of new amps. I incorporated all of the previous upgrades and included some more. One of them is playing right now along with one of the older amps. The differences are subtle but meaningful to anyone who values good sound.

The new configuration:

All active components (chips, diodes, rectifiers, transistors) remain the same. Power supply caps reused from failed amp.

All electrolytics except C9 are Panny FM caps: C1, C2, C6, C11, C14, C15, C16.

All ceramic caps are Kemet Golden Max.

All other small value caps are now metallized polypropylene or film and foil WIMA MKP or FKP. C21 is 0.022uF WIMA FKP.

Most resistors, including R5, R6, R8, R9 (0.1%) are now PRP or Caddock. R1 and R4 are Caddock 2 watt 1%. R3 is now Caddock MP-930 with heatsink. R10 and R12 are Shinkoh tantalum.

C17, C18, C19, and C20 not used.

C9 is Blackgate Standard polarized, 220uF.

C13 is Mundorf Silver-in-oil, 0.68uF.

Binding posts are Vampire solid copper/gold plated.

I wanted to use a better relay, but I couldn't find any others that fit the board. I could have used one off-board, but decided against it. I guess that might be the only area I neglected.

Some of the parts are a tight fit, but only the input cap is off the board. I use it with one lead directly soldered to the RCA and the other lead soldered to the board, so it does not require any additional wire or joints. I used teflon tubing to insulate the leads.

So there is my fully "tricked out" My Ref. It is actually quieter than the already quiet original amp. With all equipment on and my ear directly at the speaker, I hear NOTHING without a music signal present. Once the music starts, it is incredibly beautiful, detailed, smooth, three-dimensional, dynamic, robust. Bass is very powerful and tight. Midrange is present and clear and has realistic tonality without coloration. Highs are airy, sweet, extended. Thick instrumental textures are properly delineated and distinct. I recently sold my previous reference amp, an ARC 100.2. These amps are now, indeed, my ref. They are very nearly the equal of the BAT VK60 monoblocks I once owned; actually, much better in some ways.

I have one more experiment to perform, and then I am off the upgrade merry-go-round. I want to try one more input cap: a Fostex film and copper/tin foil cap. I heard some things with the AudioCap Theta that I really liked that the Mundorf doesn't do as well, and I believe it's a result of the film/foil construction. The AudioCap was very three dimensional, but the Mundorf doesn't have quite the same width and depth. The AudioCap was a little too bright with etched detail, while the Mundorf has beautiful detail without any harshness or edge. I hope the Fostex will do it all correctly because it uses copper along with the tin that is in the AudioCap. I will report the results here.

Peace,
Tom E
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Old 28th April 2009, 09:17 AM   #633
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Quote:
Originally posted by madisonears
The new configuration:
...
All other small value caps are now metallized polypropylene or film and foil WIMA MKP or FKP. C21 is 0.022uF WIMA FKP.
...
C17, C18, C19, and C20 not used.
I think we can all agree that this is the starting point for improving the MyRef.

Get rid of all AVX BQs, use Wimas instead:

C30 FKP2 1nF 63V
C21 FKP2 22nF 63V
C4, C5 MKP4 100nF 250V 7.5 mm lead spacing
C7 MKP2/MKS2 100nF-220nF 63V
C17, C18, C19, and C20 not used

I encourage everyone that wants to improve the amp to start with these mods.

Regarding C9, C13, C6, C11 there's no general agreement.

It would be nice if someone else apart me and Tom could experiment with C9, C6, C11 and report back to the forum their impressions.

Quote:
Originally posted by madisonears
I have one more experiment to perform, and then I am off the upgrade merry-go-round. I want to try one more input cap: a Fostex film and copper/tin foil cap. I heard some things with the AudioCap Theta that I really liked that the Mundorf doesn't do as well, and I believe it's a result of the film/foil construction. The AudioCap was very three dimensional, but the Mundorf doesn't have quite the same width and depth. The AudioCap was a little too bright with etched detail, while the Mundorf has beautiful detail without any harshness or edge. I hope the Fostex will do it all correctly because it uses copper along with the tin that is in the AudioCap. I will report the results here.
I do agree, film/foil caps are best here IMHO, when I've compared C13 caps the best were Mundorf Zn and Obbligatos, both film/foil ones.

Tom, have you tried a 10nF FKP2 bypass here?

I've had great results with it.

PS

The MCAP Zn bypassed with FKP2 is quite as transparent as DC coupling, no harshness and it preserve the original soundstage.
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Old 1st May 2009, 04:33 PM   #634
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I've some news on a new position suitable for cap swapping

When I've ordered the kits and began the quest for alternative components I've considered also C32 as a cap that could be upgraded (it is directly in the signal path) and bought some 150 pF 100V FKP2s.

I've made a quick test on the beginning of this long adventure and it seemed to me that FKP2s in that position bettered the sound but in some way restricted soundstage.

Today I've been trying 150 pF CDE Silver-Mica in C32 position and found that they were better than COG ceramics, so I gave another try to FKP2s too.

Well they're even better than SM with both FMs and Silmics in C9 position but in different ways.

FMs gains a better soundstage and firmer bass while Silmics gains weight in the midrange (that they were lacking a bit) and a 'rounder' bass, both gains clarity and transparency.

With FKP2s in C32 the quality difference between FMs and Silmics is even more evident, IMHO.

I think that the other mods created the right context for C32 upgrading (particularly C21).

I suggest this mod to everyone in addition the the others baseline mods of the previous post.
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Old 1st May 2009, 05:52 PM   #635
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Dario,

I have not started to build my kit yet. Would you be kind enough to reiterate a summary of which caps should be changed to what in order to optimize the performance of this amplifier?

Thanks,
Steve
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Old 1st May 2009, 06:09 PM   #636
udailey is offline udailey  United States
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Try his second to last post
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Old 1st May 2009, 06:16 PM   #637
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Quote:
Originally posted by audiosteve
Dario,

I have not started to build my kit yet. Would you be kind enough to reiterate a summary of which caps should be changed to what in order to optimize the performance of this amplifier?

Thanks,
Steve
As Uriah stated it's just two post upper but no problem...

Get rid of all AVX BQs, use Wimas instead:

C30 Wima FKP2 1nF 63V
C21 Wima FKP2 22nF 63V (to be mounted in the bottom side of PCB)
C4, C5 Wima MKP4 100nF 250V 7.5 mm lead spacing
C7 Wima MKP2/MKS2 100nF-220nF 63V
C32 Wima FKP2 150 pF 100V
C13 Mundorf MCap 1.0uF 250V (low cost, perfect fit)
C13 Mundorf MCap Zn 1.2uF 250V (best but outboard)

C13 has to be bypassed by a 10 nF Wima FKP2

C17, C18, C19, and C20 are not used (leave positions void)

And finally the controversials:

C9 Elna Silmic II 220 uF 35V (tight fit)
C6,C11 Elna Silmic II 100 uF 35V

Uriah, any news?
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Old 1st May 2009, 06:37 PM   #638
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Unfortunately yeah. Mine broke during my move to Texas. I was not careful with the heatsinks and they are light so they were only held in place by the fact that the LM3886 chip was bolted to it. So in the move of course they bounced around and broke the chip off of the board. It can be fixed but I am selling it to a friend and building an F5. Of course now there is a BA1 to build When will it end. I am also thinking that it might be easy to do a DAC since many manufacturers have eval boards I could use as a starting point. In the meantime I bought a TAmp from PartsExpress and run it from the computer. Its awesome for $40. Sound is nowhere near the MyRef but the soundstage is very large. I opened it up to see if I could mod it. That will be a hopeless endeavor except that I could replace the pot which I am sure would be a good improvement but I think I will just be happy with it and build the F5 then be ecstatic with that
To me if anyone is going to mod this MyRef you HAVE to remove C13 and put a wire in place of it then measure for DC. If it is still acceptable this is probably the best change you can make as it is very dramatic increase in quality. Then from that point get some LDRs and build a Lightspeed to drive them. After that I have not tried anything but removing a few 220nf caps from around the LM318 that I have mixed feelings about. Its different but the enhancements were offset by the negatives I guess. I suppose I was as happy with it as before I removed those caps, it just sounded different and the mid-soundstage was a bit pinched.
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Old 1st May 2009, 07:35 PM   #639
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Quote:
Originally posted by udailey
Unfortunately yeah. Mine broke during my move to Texas.
...
To me if anyone is going to mod this MyRef you HAVE to remove C13 and put a wire in place of it then measure for DC. If it is still acceptable this is probably the best change you can make as it is very dramatic increase in quality.
...
After that I have not tried anything but removing a few 220nf caps from around the LM318 that I have mixed feelings about. Its different but the enhancements were offset by the negatives I guess. I suppose I was as happy with it as before I removed those caps, it just sounded different and the mid-soundstage was a bit pinched.
What a pity!

Well, I think that with the Aleph you'll have some good time too

I agree that DC couple is better than any cap but MCAP Zns bypassed are quite as good and all my tests were done with DC coupled MyRef...

and differences were HUGE
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Old 1st May 2009, 09:16 PM   #640
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Quote:
Originally posted by ClaveFremen
....and differences were HUGE
you mean the differences between DC coupled and using a Mundorf?
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