A rather obtuse post, ji?
Do you mean a single ended setup - ie. + 'X'v (not +/- 'Y'v) - doesn't go well with a passive RIAA network? In which case, I'd like to know why you think this - as it's not my experience.
Andy
I wholeheartedly agree with you, per, that 'lytics have no place in the signal path. But I can't see any reference to them in jack's post.
Andy
It's MM, and I was thinking of using one chip per channel.
For the record, many amplifiers have been built using electrolytic caps in the signal path that sound perfectly fine. Even my line amp uses 10uF Chengxing caps (Because they are cheap and work fine) bypassed with 0.22uF X2 MKP caps. Sounds great.
My RIAA tube based amp uses a 4uF polycarbonate cap on the output, and a 0.1uF X2 MKP cap in between stages. Also sounds excellent.
A rather obtuse post, ji?
Do you mean a single ended setup - ie. + 'X'v (not +/- 'Y'v) - doesn't go well with a passive RIAA network? In which case, I'd like to know why you think this - as it's not my experience.
Andy
Electrolytic's can "hang" in a phono preamp if the first stage is overloaded by a click or pop (or Canon Blast in Telarc's version of the 1812 Overture). I think SY pointed this out in his discussion of His Master's Noise.
The noise difference between the single supply and bipolar is imperceptible, at least according to LTSpice.
If we insert ESL of 25nH onto each 100uF capacitor, here's what the output of the two phono preamps look like (the Lipshitz caps are removed).
Attachments
Thanks Kodabmx, just wanted to ensure we weren't going down the wrong hole.
I've heard of what jack mentioned also, the hanging. I'm not sure what the correct
terminology is, I have a paper that describes it somewhere but can't find it
at the moment.
The MM design I'm going to build uses the LME49710HA in the first stage and
can use different opamps in the second stage. Here is the output using an
MM cartridge using the LT1115, it has an additional 10pf cap for stability.
I've heard of what jack mentioned also, the hanging. I'm not sure what the correct
terminology is, I have a paper that describes it somewhere but can't find it
at the moment.
The MM design I'm going to build uses the LME49710HA in the first stage and
can use different opamps in the second stage. Here is the output using an
MM cartridge using the LT1115, it has an additional 10pf cap for stability.
Attachments
I can believe that. The important thing with the power supply in a phono stage is that it needs to be not less than +24v ... or +/-15v, to provide enough headroom to deal with clicks & pops.
Andy
SPICE is its own private fantasy.
When we run single-supply, we may also be cheap, the supply may be nasty. The chips have good CMRR at 120Hz, but a little filtering is always wise. But the "bias reference", dead-zero on good bipolar supply, must now be split from the main supply. Done badly, half the power crap is offered to the amp input! There may be 20dB loss due to 47K against pickup impedance, but there's 55+dB gain after. That's why I sketched double filtering on the bias supply.
Yes, but guitar-amps grid-block just fine with film caps; I'd have to find SY's words to see how electrolytics are special.
I measured some 220u/35V Silmics -- 40nH ESL -- I used 25nH in the simulation.
I thought that the single supply amp would be a touch noisier owing to the bias resistor on the front end. It isn't. The only way for sure is to measure. The sim showed a difference in the low hundreds of pV/RtHz which is less than triviality.
I thought that the single supply amp would be a touch noisier owing to the bias resistor on the front end. It isn't. The only way for sure is to measure. The sim showed a difference in the low hundreds of pV/RtHz which is less than triviality.
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