Hi Richard, I have observed rumble on some records using the Emerald, I can see the woofer cone drifting slowly and in some cases pulsing. My Emerald has the 2.2uF output caps specified in the schematic. Wouldn't higher value capacitance like 3.3uF work well to clip the rumble (0.48Hz instead of 0.72Hz)? I'm mostly asking in case such a substitution would have unintended consequences. Thank you.
Edit: oh, nm. Flawed logic.
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Yes, flawed logic. 
The reverse - making the coupling cap smaller - would work in principle, but since the 1st order filter slope is shallow it will also start to cut into your bass frequency response. A true rumble filter has a much sharper response so as to cut infrasonic more with less impact on audio.
That said you are welcome to try reducing to 1 uF or 0.47 uF as there is no risk involved outside of losing a little bass.
The source of rumble is cantilever/tonearm resonance + record warp. If it can be addressed at the turntable side you don't need to band-aid fix the problem at the preamplifier end.
The reverse - making the coupling cap smaller - would work in principle, but since the 1st order filter slope is shallow it will also start to cut into your bass frequency response. A true rumble filter has a much sharper response so as to cut infrasonic more with less impact on audio.That said you are welcome to try reducing to 1 uF or 0.47 uF as there is no risk involved outside of losing a little bass.
The source of rumble is cantilever/tonearm resonance + record warp. If it can be addressed at the turntable side you don't need to band-aid fix the problem at the preamplifier end.
Emerald is truly versatile! I I tried changing the output to full bipolar discrete and it sounded great, sounded more energy, bass, musical and juicy . Probably put stress on the supply and I may have to bypass the s reg shunt.
But it's sure a quick way to try different stuff sometimes with very interesting results.
But it's sure a quick way to try different stuff sometimes with very interesting results.
A quick update to note that airmail shipping from me in Japan to the United States is now possible again.
UK and Canada are still surface only however.
Elsewhere it's all over the place: The Netherlands yes, Sweden, Denmark and Finland no, Germany no, Belgium yes, France no.
You can confirm the current status at the Japanpost website, here.
UK and Canada are still surface only however.
Elsewhere it's all over the place: The Netherlands yes, Sweden, Denmark and Finland no, Germany no, Belgium yes, France no.
You can confirm the current status at the Japanpost website, here.
My humble contribution -- a dual mono approach [shortly with two PSU] -- using what I had handy.
https://photos.app.goo.gl/z7AMP1SV7gsjXpmy6
https://photos.app.goo.gl/z7AMP1SV7gsjXpmy6
From a quick perusal of the datasheet, it appears to be designed for instrumentation rather than audio. As such it's optimized for operation at frequencies somewhat above the audio band. The bandwidth at 30 dB gain would be 2 Mhz, making it more sensitive to RFI and such than an audio-specific op amp like the OPA27. There's also something odd about the power design, it appears to have asymmetrical current draw with the V+ current is 7.5 mA and the V- current 0.1 mA.
In short, it should probably be safe and functional but I doubt it will sound exceptional.
Step-up transformers increase the signal, but adhere to the well-worn electrical engineering principle of "there is no such thing as a free lunch".
As a general rule single-ended amplification will yield lower output noise than differential amplification.
The reason to use differential amplification in the first place is that you need to cancel out high common-mode noise, so you accept the trade-off of the higher self-noise. Common-mode noise is not normally a concern in phono stages, so there is no point in taking the hit.
As a general rule single-ended amplification will yield lower output noise than differential amplification.
The reason to use differential amplification in the first place is that you need to cancel out high common-mode noise, so you accept the trade-off of the higher self-noise. Common-mode noise is not normally a concern in phono stages, so there is no point in taking the hit.
With the cartridge-loading PCB module [aka "The SwitchBoard"] , you can customize your loading options by stuffing it differently , so "yes" you can accommodate the Audio-Technica AT-100E 'easily'.
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@captain pugwash
Sorry about that, my Yahoo mail spam filter seems to have been tweaked recently and sending some legit emails to spam.
I've sent you an invoice for the boards.
Richard
Sorry about that, my Yahoo mail spam filter seems to have been tweaked recently and sending some legit emails to spam.
I've sent you an invoice for the boards.
Richard
