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Rega and phono capacitance

moomaloo

pfm Member
Evening all. Now, this is by no means meant as any criticism of Rega (longtime Rega fan here with an almost entirely Rega system). But… why do they appear to have increased the capacitance value of the MM phono stage within the Brio and Elex R to 220pF when the ratings for their standalone MM phono stages is 100pF?

I’ve just bought a used Elex R from these pages (and I’m looking forward to receiving it) but didn’t look into this before buying it; thinking it would be the same as the phono stages and my current Mira3 (100pF)…

I’m now worried about how this will work with my cart (AT VM 740 ML). It doesn’t seem a good match, unlike the phono stage in the Mira3.

Could the quoted specs online for the Elex R possibly be a misprint? If not, I’m puzzled at this seeming discrepancy? (But it might sound fabulous anyway…)

Thanks
 
The whole capacitance thing is a mystery to me. The Aria has switchable capacitance between 1000 and 4200 pF and I have no idea what I'm supposed to set that too! :0(
 
Just to add to this - according to the specs online at the Rega website the Exact cart (which was my ‘go to’ before the AT) wants to see 100pF. That isn’t going to happen even with the standalone phono amps, when one adds in the capacitance of the cabling, and will be a long way off the 220pF capacitance of the Brio / Elex R…

Rega know what they are about so there must be a reason for this…

Maybe the whole capacitance lark makes so little audible difference that it isn’t worth bothering with..? I’m just hoping that my cart, which works so well with the Mira3, isn’t going to turn into an ear bleeder with the Elex R…
 
Just to add to this - according to the specs online at the Rega website the Exact cart (which was my ‘go to’ before the AT) wants to see 100pF. That isn’t going to happen even with the standalone phono amps, when one adds in the capacitance of the cabling, and will be a long way off the 220pF capacitance of the Brio / Elex R…

Rega know what they are about so there must be a reason for this…

Maybe the whole capacitance lark makes so little audible difference that it isn’t worth bothering with..? I’m just hoping that my cart, which works so well with the Mira3, isn’t going to turn into an ear bleeder with the Elex R…
I gather that the capacitance spec of Exact refers to that of the phono input, not the total including tonearm wiring.

With respect to the 220pF of the io, Brio, and Elex-R phono inputs, keep in mind that increasing capacitance not only lowers the resonance peak frequency but also the peak amplitude with it. This lowering of both frequency and amplitude can subjectively fill in the natural rolloff that can begin as low as 1kHz due to coils being inductive (i.e. they act as low-pass filters).

It is also possible that when combined with the integrated amps own sound signature, 220pF was the best compromise with everything from Rega's own A-T OEM derived Carbon to their own built MM models. After all, it is highly unlikely that they didn't spend some time listening to their own decks, tonearms and cartridges through these amplifiers.
 
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The input capacitance of this and indeed any other amp/phono stage can easily be changed by anyone who knows what they are doing with a soldering iron. I of course can do this for customers who would rather not try it themselves.
 
The input capacitance of this and indeed any other amp/phono stage can easily be changed by anyone who knows what they are doing with a soldering iron. I of course can do this for customers who would rather not try it themselves.
Careful Jez, you might burn a finger on this one.

elex5.jpg
 
It looks like the recommended loading capacitance for the AT VM740ML is 100-200pF.

https://www.audio-technica.com/en-gb/vm740ml

Ideally you need to know the capacitance of your tonearm plus tonearm cable/interconnect. This alone could have sufficient loading capacitance without needing any 'extra' built into the amp.

My hunch would be that the loading caps are the two red polybox caps top right but don't quote me on that!!
 
Terry Bateman, the designer, is a big Leak and valves fan (was very active on the Leak forum 12-14 years ago ish...maybe still is but I'm not now so I don't know) hence the text on the PCB I would guess.
 
Terry Bateman, the designer, is a big Leak and valves fan (was very active on the Leak forum 12-14 years ago ish...maybe still is but I'm not now so I don't know) hence the text on the PCB I would guess.
I recall seeing some photos of a classic tube amp bakeoff that Terry had organized in Roy's barn.

IIRC, there were a pair of ELA 2000 and lots and lots of lovely old amps lined up to go.
 
My money is on the two small blue caps. Dual opamp, two stage, mc followed by mm. At a guess.
 
I really appreciate very low capacitance phono inputs -but 47 pF is about It for my sense of adventure. We have to realize that Rega has to design for worst case situations. I spent decades living and working in our local antenna alley (two hospitals ,a University, multiple TV towers with multiple radio,public safety and microwave transmitters on each tower , etc.) . Audio equipment that was dead silent anywhere else in town was noisy in those few square miles. RF input snubbers have a function. But I'm as confused as anyone else as to why it's so high in the new Rega 's ? A shame because the Rega arms mate well with the newer AT cartridges.
 
I'm running a borrowed Dynavector 20X2L right now. I've tried all of the loading settings on the Aria, all of the capacitance settings and both of the gain options. The effects are subtle at best with some changes being effectively inaudible. Is this issue really an issue?
 
Hmmm....

MM's are often very sensitive to capacitive loading. MC's are pretty much unaffected by this.

MM's OTOH are intended to work into a standard resistance of 47K whilst MC/s are somewhat affected by the resistive loading , with figures from around 60R to 560R being the typical range of values likely to be found most suitable.
 
I recall seeing some photos of a classic tube amp bakeoff that Terry had organized in Roy's barn.

IIRC, there were a pair of ELA 2000 and lots and lots of lovely old amps lined up to go.

If I recall correctly one of the photos showed the Ela's being hooked up to a pair of Stereo 20's. So I'm guessing Terry was bi-amping the Ela's or using them as monos.
 


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