There is a thread on doing the summing in mono going on. Basically for low level rumble removal. Once digital it might not make sense, but if you are filtering grot in the L+R signal worth investigating. MiniDSP very handily already gives you a SUM feed anyway.
Now I have to say I have never had a rumble or warp induced issues but I can see how it could make sense.
Now I have to say I have never had a rumble or warp induced issues but I can see how it could make sense.
My biggest worry is still the unequalized tick and pops, they are BIG. The Pure Vinyl guys sell very pricey flat preamps with ultrawide BW as a feature, this still seems like shooting yourself in the foot.
me too, but that's because I don't know how to design a gain stage with limiting that is linear.
good argument for one of the poles in analog in the preamp, in front of the digital
I would even guess offhand that the lower break is better for dynamic range - music power is already limited just above the 75 us so analog filtering that high wouldn't buy much dynamic range for music signal
the high frequency content of ticks, pops would be linearly knocked down with the preamp having a low audio pole in analog
and even the "flat feedback factor" rubric works with a low frequency low pass differentiating feedback giving a "constant feedback factor" with a high gain op amp's open loop gain roll off
I would even guess offhand that the lower break is better for dynamic range - music power is already limited just above the 75 us so analog filtering that high wouldn't buy much dynamic range for music signal
the high frequency content of ticks, pops would be linearly knocked down with the preamp having a low audio pole in analog
and even the "flat feedback factor" rubric works with a low frequency low pass differentiating feedback giving a "constant feedback factor" with a high gain op amp's open loop gain roll off
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Always seems like a good idea but this brings up the channel to channel matching issues from some. I'm still not sure the dynamic headroom/noise issues don't trump slavish adherence to RIAA anyway. Though digital keeps more of those evil caps out of the signal path. OTOH analog keeps all that information lost between samples, just can't seem to win.
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Hello!
Update of one of my GUI software (PEQGUI-10MC) for EqualizerAPO implements now RIAA pre- and de-emphasis filters. It's a biquad implementation ATM and supports 44,1/48/88,2/96 and 192kHz.
It's also possible to set the output level for the digital RIAA 'stage' (using gain coefficients):
- de-emphasis: -12dB - +40dB (0.1dB steps)
- pre-emphasis: -12.5dB - +3.0dB (0.1dB steps)
so, this implementation should work well with setups missing proper (flat) pre-amplifier (PEQGUI-10MC allows to set preamp ±12dB --> max gain is +52dB.
Update of one of my GUI software (PEQGUI-10MC) for EqualizerAPO implements now RIAA pre- and de-emphasis filters. It's a biquad implementation ATM and supports 44,1/48/88,2/96 and 192kHz.
It's also possible to set the output level for the digital RIAA 'stage' (using gain coefficients):
- de-emphasis: -12dB - +40dB (0.1dB steps)
- pre-emphasis: -12.5dB - +3.0dB (0.1dB steps)
so, this implementation should work well with setups missing proper (flat) pre-amplifier (PEQGUI-10MC allows to set preamp ±12dB --> max gain is +52dB.
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You could use a Townshend Rock (or a Well Tempered?) - no tone arm resonance, in fact no-subsonic info at all!
Just found this thread as I'm looking into running a Denon DL110 (on a Rock II) flat into my Essence STX and using DSP RIAA, to see if it's an improvement on any of the pre-amp options I have (the best currently being a Creek OBH-18SE).
Certainly plenty of headroom on the STX, I've measured the noise floor at -119 dB RMS (-105dB peak) on its line-in, and it is entirely 'white' or 'brownian', no trace whatsoever of any discrete artifacts, all of which I find quite amazing for an internal interface.
Heh. I've never given any thought to all that silliness (?), I was just impressed by the raw numbers for the Essence cards, and that S/N I measured is actually better than spec (which is -118dB).
It was after realising how amazing quiet it is that it occurred to me that flat vinyl transfers and DSP RIAA might be viable on my rig, and the Denon is a moving coil, so no (or minimal) super/ultra sonic crap to worry about.
Keep us informed, unfortunately their stand alone USB model gets a lot of bad reviews for drivers. Someone else recommended the Lynx Hilo but at $3000 it's not for the average person.
Will do.
And yes, I gather that the USB Essence didn't impress.
I have to say, I'm somewhat attentive to detail, and I think that's why my STX has met, and actually exceeded its specified S/N.
For example, I have the IEC lead to the PC held in a coil of several loops via zip-ties.
I have ferrite beads on various power-leads (AC and DC - LoL), such as on the lead from the PC's PSU to the Essence.
I adhere to a philosophy dictating that;
if it's worth doing, it's worth over-doing.
ASUS Xonar Essence ST/STX soundcards Measurements | Stereophile.com gives some measurements. Now I know nothing about what specs matter for an ADC for music recording, but the spectrum from a 1Khz sine wave at -90dB looks pretty darned clean to me. Anyone experienced in the art able to comment?
The analog output looks pretty SOTA as well. Certainly good enough for its intended function.
The analog output looks pretty SOTA as well. Certainly good enough for its intended function.
I guess I'm going to find out soon enough, but out of curiosity, what kind of peak-levels are people aiming for with flat recordings to allow the headroom needed for RIAA EQ?
a problem is the clicks and pops, tone arm resonance that are not "music" that can be very large
I think one pole in the preamp is a much better choice even if quality caps can be big and pricey - having a pole in analog up front knocks down the impulses and allows a fair amount extra headroom over flat gain
implementing the low pass in feedback hugely reduces slew rate requirements and higher frequency distortions - the feedback factor becomes constant above the low pass corner frequency for typical high loop gain op amps if that argument floats your boat
the matching issue seems irrelevant given the ease of calibrating with the soundcard - not at all hard to calibrate for corner frequency as well as gain in the DSP
I think one pole in the preamp is a much better choice even if quality caps can be big and pricey - having a pole in analog up front knocks down the impulses and allows a fair amount extra headroom over flat gain
implementing the low pass in feedback hugely reduces slew rate requirements and higher frequency distortions - the feedback factor becomes constant above the low pass corner frequency for typical high loop gain op amps if that argument floats your boat
the matching issue seems irrelevant given the ease of calibrating with the soundcard - not at all hard to calibrate for corner frequency as well as gain in the DSP
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Well, I'm not really experienced in anything but hobbyist audio, but I've been mightily impressed with the recording and line-out quality of the STX. I even found the drivers to be stable/usable ,apparently it's not always plain sailing (I used the 3rd-party 'Uni Xonar' ones from the get-go).
Anyway you look at it, if the specs are accurate (which they seem to be), the only way to better it would be buying pro studio gear from someone like RME (although it can't be used as a studio recorder thanks to massive latency, but that's moot in this context).
One issue which I just noticed in that review is that it has rather low impedance on the line in - I've always taken it as given that any and all decent gear presents at least 10Kohms.
I forgot that the idea being discussed here is using a PC, effectively, as an 'always-on' RIAA stage, rather than for recording/archiving.
That is something the Asus card's drivers and (rather toy-like) user interface might get in the way of.
That is something the Asus card's drivers and (rather toy-like) user interface might get in the way of.
One thing is a given - gain into the digital interface would need to be adjusted per disc on the pre-amp to use the available bit-depth maximally but avoiding clipping, as levels will vary wildly - 12" 45's and LP's of string quartets?
I guess after a while it would become second nature to know where the knob/slider on the preamp needs to be set. Maybe just another part of the vinyl-spinning ritual?
I guess after a while it would become second nature to know where the knob/slider on the preamp needs to be set. Maybe just another part of the vinyl-spinning ritual?
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You figured it out fast, serious vinyl archiving can be a very tedious process/ritual. 🙂 If the card connects to SoX as an I/O device you are done, as you say for home use the latency is a don't care. You can record from SoX and pipe the result to the RIAA plus any other filter and pipe that to the play feature.
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EqualizerAPO is quite easy way for digital RIAA. My playback system ATM is quite simple: TT --> flat pre-amp (fixed ESI DuaFire audio interface) --> digital RIAA using EqualizerAPO --> ESI Duafire output. RIAA filter creation and output level controlling is done using PEQGUI-10MC + Peak Meter.
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