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MV-55 - upgrades?

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RJKflyer
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MV-55 - upgrades?

Post by RJKflyer » Mon Dec 02, 2013 5:59 pm

I've just posted a Q in amps about what might need replacing on an MV-55, but thought I'd post here too and add "what would you look to upgrade whilst inside the box"?

Thoughts?

Thanks!

jeffreybehr
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Re: MV-55 - upgrades?

Post by jeffreybehr » Mon Dec 02, 2013 7:13 pm

I have a low-quality schematic of the MV-50 on which I can't read the cap numbers, but FWIW...
1. Replace the 2nd cap (in the '50, a pair of 'lytics in series) in the main-PS CLC filter with a 'propylene...a big enough 440VAC motor-run cap or a Solen or Axon 100uF/630VDC cap. If I used a MR, I'd add in parallel the biggest Mundorf silver/oil cap I could afford plus the biggest SoniCap Platinum I could afford. If I used a Solen/Axon (which I think are a little edgy), I'd use probably the biggest Jupiter HT I could afford.
2. Replace the last output 'storage' cap in the regulated supply with about the same value of Mundorf Silver/Oil plus SoniCap Platinum I could afford.
For both of these, if you're short of cash, add/replace with the Mundorfs now and add the Platinums or HT later.
3. Replace the 2 coupling caps per channel with something lots better. I'd start with at least a MultiCap RTX ('styrene; nicely detailed and, according to some golden-ears I know, a bit 'sweet'-sounding, whatever that means). A step up from that would be a Mundorf Silver/Oil, and the maybe-best cap you could use would be a SoniCap Platinum.
4. I'd replace the input RCA with a Furutech FP901...
http://www.soniccraft.com/products/conn ... _fp901.htm
...and the speaker binding posts with Cardas CCGRs...
http://www.soniccraft.com/products/conn ... s_ccgr.htm

Good luck in your project. :-)
Tin-eared audiofool, large-scale-Classical-music lover, and damned-amateur fotografer.
William Bruce Cameron: "...not everything that can be counted counts, and not everything that counts can be counted."

RJKflyer
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Re: MV-55 - upgrades?

Post by RJKflyer » Tue Dec 03, 2013 3:12 pm

Thanks Jeffrey. There's now a MV-55 schematic in the techdocs thread.

Will start looking into your suggestions.

jeffreybehr
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Re: MV-55 - upgrades?

Post by jeffreybehr » Tue Dec 03, 2013 6:11 pm

Got it; thx.

1. Output-stage powersupply, point A of the schematic:
A. Looks as if c-j is already using film caps in the Main-PS CLC filter. Merely add a big (2.2/1000 for $70?) Mundorf S/O (MSO)...
http://www.soniccraft.com/mundorf_silver_oil.htm
...in parallel with the 2nd main cap.
B. replace the 2 'propylene and (probably)-'styrene caps bypassing the choke in that CLC filter with one 2.7/1200 MSO, $77.
That takes care of the output-stage PS.

2. Frontend PS. There are 2 regulated and filtered supplies:
A. Point B. Replace the 4uF and 1uF output caps with a 5.6/1000 MSO, $126.
B. Point C. Replace the 4uF output cap with a 4.7/1000 MSO, $112.

In any of the above-discussed positions, you certainly can choose other high-quality caps. For instance, I might use a large-value Jupiter HT...
http://www.soniccraft.com/products/capa ... ter_ht.htm
...cap AND a 0.47uF SoniCap Platinum...
http://www.soniccraft.com/sonicap_platinum.htm
...instead of MSOs, which are excellent...what I call '5-star'...caps. A less-expensive alternative might be 400V. MultiCap RTXs...'styrenes...
http://www.soniccraft.com/multicap_rtx.htm

C. Active circuitry:
1. Replace the two 0.22/600 coupling caps per channel with the best caps you can afford. I probably woulnd use SoniCap Platinums, but there are many excellent caps to choose from. See comment above about PS-bypass caps.
2. Replace the 1/400 'propylene attached to the 6SN7 with a better cap. There I think I'd use a 1/400 RTX.

D. Fourth priority but while you're in there--replace the RCA input jacks and the output binding posts; see my earlier note. Also replace the IEC-15 power inlet with at least a Furutech F110.
http://www.soniccraft.com/products/conn ... h_fi10.htm

And I now see that Sonic Craft has many MultiCap RTXs on sale...
http://www.soniccraft.com/specials.htm
These are truly 5-star caps...better than anything in your amp now...and a steal at those prices.

Many of us would also replace lots of resistors with better ones, but resistors are, IMO, much-less audible than capacitors. YMMV.

Also, FWIW, if it's convenient for you to do, I suggest you do these things in stages with some time between them. That way you can determine if each change in sound was positive or not.

Again, good luck with your project.

Going somewhere else just reminded me that tube rolling could be quite audible in your amp. The absolutely-best-sounding 6SN7GT I ever heard is the Tung-Sol roundplate, and it might be worth digging up a pair. Second-best-sounding is the old (actually, BOTH of these tubes are OLD!) Ken-Rad 6SN7GT/VT-231.
Tin-eared audiofool, large-scale-Classical-music lover, and damned-amateur fotografer.
William Bruce Cameron: "...not everything that can be counted counts, and not everything that counts can be counted."

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