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Post by Chris on Jul 18, 2014 21:53:00 GMT
I'm due to meet up with eduardowobblechops soon who has very kindly agreed to show me around the inside of an amplifier - not something I'm up on at all.
As part of this visit he has suggested a couple of improvements to an AVC EL34 amp I have including changing out anode resistors and coupling caps.
After a quick hi fi collective search I'm still unsure what would be a good option for me. Eduardo has offered to help and I'm more than happy to let him make the decisions.
Couple of questions though;
If I'm using Audio Note speakers do I use Audio Note capacitors?
How many will I need?
Anode resistors - Shinkoh seem good,any opinions?
Again how many?
Are there any bargains to be had in this sort of area? Russian maybe?
Is there any sort of synergy to be had in the components?
Anything else I should consider?
As always your answers are much appreciated.
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Post by Eduardo Wobblechops on Jul 18, 2014 23:06:54 GMT
For the resistors I'd go for Mills wirewound, get what you pay for with these IMHO. As for coupling caps, lots of choice. ClarityCap are very good for the money. For a bit more, AN copper foil are lovely caps. On the pricey side, SCR teflons are very good to my ears. Diminishing returns set in though, I reckon you get 90% of the rest from the CC's.
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colin14
Rank: Duo
Co-fonder of Tellurium Q, Designer and Director of TOCA, and Inca Tech, Magnum, ProAC Magnum, etc
Posts: 39 
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Post by colin14 on Jul 19, 2014 5:33:55 GMT
The problem with wire wound is the inductance, you can get Bi-Fillar from Welwyn or use a large ceramic type. Or better still lots in parallel of smaller type but high value i.e. 10 off 100R for a 10R, this in high value above say 10K does give some thermal noise cancellation.
What value is the Resistors?
What value are the caps? and working voltage?
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Post by pre65 on Jul 19, 2014 5:52:08 GMT
I think the Mills resistors that Ali was referring to are the MRA12, which are non inductive.
"The Mills resistor is a non-magnetic, non-inductive wire-wound that was specifically designed for high-end electronics, loudspeakers, and audiophile upgrades. The all weld axial construction boasts an alumina ceramic core, Cuprum/NiCr (low/high value) element, Silver/Copper alloy end-caps, and Tinned Copper leads. Aryton-Perry winding greatly reduces inductive reactance and signal loss. These resistors exceed MIL-R-26E specs and are applicable for MIL-STD-202, method 208. All resistor values are 1% tolerance.
The MRA-12 (12 watt power rating) possesses a big power handling for its size. It will handle overloads 10X its power rating (120 watts) for 5 seconds with operating voltages up to 1,000 VAC. The body measures 1.188" +/- 0.062" in length by 0.312" +/- 0.031" in diameter. The leads measure 1.500" in length minimum by 0.040" in diameter."
The MRA5 are even lower inductance.
"The MRA-5 (5 watt power rating) exhibits even lower inductance than the MRA-12 due to its very compact size. It will handle overloads 5X its power rating (25 watts) for 5 seconds with operating voltages up to 500 VAC. The body measures 0.562" +/- 0.062" in length by 0.167" +/- 0.031" in diameter. The leads measure 1.500" in length minimum by 0.032" in diameter."
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Post by Eduardo Wobblechops on Jul 19, 2014 8:04:00 GMT
Thanks Phil, yes, that's the ones I was referring to. Found any good caps recently?
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Post by Eduardo Wobblechops on Jul 19, 2014 8:05:05 GMT
The problem with wire wound is the inductance, you can get Bi-Fillar from Welwyn or use a large ceramic type. Or better still lots in parallel of smaller type but high value i.e. 10 off 100R for a 10R, this in high value above say 10K does give some thermal noise cancellation. What value is the Resistors? What value are the caps? and working voltage? Thanks Colin, yes, Welwyn are another good choice. |
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Post by Eduardo Wobblechops on Jul 19, 2014 8:06:18 GMT
Oops, forgot to say, not sure of values yet, need to see the amp.
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Post by pre65 on Jul 19, 2014 8:36:02 GMT
. Found any good caps recently?
Total for 11, inc shipping (UK) was £16.78.  |
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Post by pre65 on Jul 19, 2014 8:57:24 GMT
As regards capacitors, I find Clarity caps ESA to be a good compromise between cost and performance.
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Post by Eduardo Wobblechops on Jul 19, 2014 9:10:11 GMT
Yep, agree on the CC, they are very good for the money.
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Post by yomanze on Jul 19, 2014 10:14:44 GMT
There are some NOS Russian PIO and Teflon combinations available on eBay that cost relative peanuts in fact I have a box of spares that I will never use if you want some for free? I sent some to Synsei who fitted some to his amp he was pleased!
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Post by yomanze on Jul 19, 2014 10:16:12 GMT
On DIYAudio Salas rates them with Mundorf's top end caps. Indeed some NOS bargains to be found out there.
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Post by Chris on Jul 19, 2014 15:32:43 GMT
Bloody hell - that's a very kind offer yomanze! Not sure of values but if they are suitable I will let you know.
Maybe eduardowobblechops will be along soon - he will know better than me in this one!
Much appreciated.
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Post by Eduardo Wobblechops on Jul 19, 2014 16:26:53 GMT
Need to have a look at the amp for the values, usually 0.47 or 0.22uF. Probably 600v.
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Post by pre65 on Jul 19, 2014 16:31:21 GMT
Need to have a look at the amp for the values, usually 0.47 or 0.22uF. Probably 600v.  They are marked PIO but the P does not stand for "paper". |
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Post by Eduardo Wobblechops on Jul 19, 2014 16:36:55 GMT
Aye, tried a few myself, good caps.
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Deleted
Deleted Member
Posts: 0
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Post by Deleted on Jul 20, 2014 11:28:48 GMT
For the resistors I'd go for Mills wirewound, get what you pay for with these IMHO. Those Mills 'MRA-12' are very good resistors, whenever i need a power resistor these are the babies. |
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Post by pre65 on Jul 20, 2014 17:55:53 GMT
12W is quite low power.
100W is what I call a POWER resistor. 
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Post by MartinT on Jul 22, 2014 11:00:41 GMT
Mills MRA-12 are good, I used them in my Gale crossovers. You could look at Supersound caps, too. Good value and available from Wilmslow Audio.
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Post by yomanze on Aug 6, 2014 16:05:16 GMT
Supersound caps are great.
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They are marked PIO but the P does not stand for "paper".
