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Old 21st July 2011, 03:03 AM   #301
Tea-Bag is offline Tea-Bag  United States
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Carl,
You can build a different type of power supply ~ +/- 15v.
On the caps, I think there are plenty of other choices, not sure how they will affect sound - but the film caps here need to be close to spec for the RIAA to work right.
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Old 21st July 2011, 03:18 AM   #302
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For el cheapo version, check the phonoclone thread: The Phonoclone and VSPS PCB Help Desk

It is similar circuit, although not exactly the same, however, parts substitutions should work here equally well.
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Old 21st July 2011, 03:19 AM   #303
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Quote:
Originally Posted by BigE View Post
I just noticed that Nichicon Muse is not on this list. Are Silmics preferred?
I don't know, din't try any of them
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Old 21st July 2011, 03:43 AM   #304
Carlp is offline Carlp  United States
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Thanks so much Peter, Tea-Bag and Byron. Very helpful.
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Old 22nd July 2011, 10:55 AM   #305
slawney is offline slawney  Germany
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As far as cheapo parts for the build, go ahead and use WIMA MKSs and carbon comps. The sound will be different, but it will still sound "good." I wouldn't be surprised to find cheapo parts in the product that inspired this all. Tip: I once laid this circuit out with SMD resistors and WIMA MKS2s with 2.5mm pitch, to get the shortest feedback loops, and the results were also very impressive. Much faster, tighter, preciser and dynamic, if lacking in the clarity and detail of the boutique build. So, please, experiment, and report back.
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Old 22nd July 2011, 04:50 PM   #306
BigE is offline BigE  Canada
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Interesting observation. I changed the input signal wire from 26 awg mundory silver/gold to 24 awg neotech legenburg UPOCC copper with exactly those results:

Faster, tighter, more precise and much more dynamic. Also an improvement in depth of soundstage. It lacks the detail of the silver/gold, but sounds *so* much better -- there is no contest.
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Old 23rd July 2011, 12:35 PM   #307
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So...due to having to replace one of the op-amps in my phono stage a couple times, and making a bit of a mess of it (desoldering is NOT one of my skills), I decided to rebuild the phono using a new PCB which peter kindly provided me.
Anyway, in the meantime I have had a system change. I went from the Harbeth SHL5 to a 'three-way' horn system using a JBL E145 in a 4560 cabinet, a 2420 compression driver in a 511b horn, and a JBL 2405H slot tweeter, bi-amped with xindak monoblocks for bass and a 45 based SET amp for the mids/highs.
The point is, my speakers went from not-so-sensitive 86dB, to an extremely sensitive +105dB...
Now I have completed the phono stage yesterday and it seems as if I have WAY too much gain, and I am hearing a lot of hiss from the phono stage. I thought it may have been solder flux or something and so I cleaned it with isopropyl to no effect...I have the feeeling that I am hearing noise from the op-amps, but I am not sure.
The hissing noise is definitely coming from both channels.
Thanks for any suggestions,
Byron
edit: btw, I bought the op-amps off of ebay (china), and I am wondering if they are really OPA637/627. Could be that they are fakes? Dunno

Last edited by mantisory; 23rd July 2011 at 12:56 PM. Reason: more information
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Old 24th July 2011, 03:48 PM   #308
slawney is offline slawney  Germany
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I am afraid that this circuit is not a "low-noise design." Even with a low-noise PSU and regulators, there will always be a bit of ambient hiss. Because of the way the inner impedance of the cartridge is an active part of the circuit setting the gain of the first stage, the first op-amp "sees" on its Vin+ and Vin- legs (the most sensitive legs of the op amp) quite alot of extension into the HFI and RFI environment through the tone-arm cable. That does not keep the circuit from sounding excellent, but it will never be perfectly quiet, unfortunately, just as a Gainclone is never perfectly quiet, and always has a little low level hum, but for different reasons.
**
My experience with Chinese 627/637s is that there is no problem with noise (as long as they are authentic) but I have noticed some older production code numbers and greater variation in the DC offset sometimes.
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Old 24th July 2011, 03:51 PM   #309
slawney is offline slawney  Germany
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Tip: always shield this circuit in a metal enclosure with the PSU star ground connected to case. Connect the turntable earth to the grounded phono unit case.
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Old 25th July 2011, 01:27 AM   #310
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Finally got around to taking a few pictures of the phono stage that Peter put together for me a while back. I had built this circuit in one of the integrated enclosures over a year ago, compared it with a few other phono options in my system and decided that this was the one for me; however, my circuit was not quite as quiet as I would have liked with my Lyra Delos. I asked Peter to rebox it for me in a small enclosure that I could mount right were the interface box is on a VPI table and run the tonearm cable right to the phono circuit. Peter put together a dual mono PS in the integrated enclosure.

Results - phenomenal, can't see myself ever giving this one up, my ears aren't that good to notice an improvement from here!

Thanks Peter!!

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