flat MM/MC amp?

[Jim Audiomisc]

I've been considering the pros/cons of digitally capturing LPs etc *without* having RIAA correction applied before the ADC. There are apparently plugins for Audacity to do the correction after the user has removed clicks, etc. But it set me wondering:

Are there any reasonably-priced non-RIAA i.e. 'flat gain' preamps for MM/MC carts that can easily be bought and used by domestic users for this? Or is this only the realm of pro kit or DIY amps?

 

[wd40addict]

Presume you've seen this:

http://pspatialaudio.com/flatpreamp.htm

 

[Werner]

http://www.channld.com/seta/bridge_seta.html

So yes, there are a few of them. Predictably costly.

Throwing a pair of AD797s into a box, for fun, is on my to-do list. And has been there for 10+ years.

 

[al2002]

I've been considering the pros/cons of digitally capturing LPs etc *without* having RIAA correction applied before the ADC. There are apparently plugins for Audacity to do the correction after the user has removed clicks, etc. But it set me wondering:

Are there any reasonably-priced non-RIAA i.e. 'flat gain' preamps for MM/MC carts that can easily be bought and used by domestic users for this? Or is this only the realm of pro kit or DIY amps?

If you don’t mind DIY have a look at:
https://proaudiodesignforum.com/forum/php/viewtopic.php?f=6&t=783

Ripping LPs then de clicking them using a program is quite labour intensive. Here is an alternative (not cheap):

https://sweetvinyl.com/

 

[paulfromcamden]

Presume you've seen this:

http://pspatialaudio.com/flatpreamp.htm

That was my first thought as well. A pair of low noise microphone preamps with 50-60dB of gain could work. Maybe something like this: http://www.lineaudio.se/2MP.html

 

[The Bish]

I think the Graham Slee Accession provides the capability to do flat gain and various other settings and is a nice phono stage, but doesn’t provide any software for post processing. About £900 and there’s one on auction on eBay uk at the moment.

 

[Michael J]

A pair of low noise microphone preamps with 50-60dB of gain could work.

I have a TASCAM 4-track cassette recorder with a nifty mixer section that has four jack socket line inputs, two of which have extra boost for microphone level signals. It can take 3mV inputs at max trim.

 

[Arkless Electronics]

I've been considering the pros/cons of digitally capturing LPs etc *without* having RIAA correction applied before the ADC. There are apparently plugins for Audacity to do the correction after the user has removed clicks, etc. But it set me wondering:

Are there any reasonably-priced non-RIAA i.e. 'flat gain' preamps for MM/MC carts that can easily be bought and used by domestic users for this? Or is this only the realm of pro kit or DIY amps?

If you get stuck and if MM is enough and if you can arrange a power supply I'll sort you something for a few beers

 

[gints]

Korg DS-DAC-10R can record LP to computer without RIAA and you can apply a few versions afterwards.

 

[Achim]

As it happens, I have a Korg 10R for sale...

This should do the amplification trick respectfully:
https://www.thomann.de/gb/behringer_mic2200_v2.htm

Have used such with direct in bass guitar, very clean results.

 

[davidsrsb]

How about a simple single pole amplifier?
The two problems with flat gain are handling the high level spikes from scratches, that easily trigger slewing and clipping and the poor performance of many ADCs in handling the still tiny bass signal

 

[Jim Audiomisc]

If you don’t mind DIY have a look at:
https://proaudiodesignforum.com/forum/php/viewtopic.php?f=6&t=783

Ripping LPs then de clicking them using a program is quite labour intensive. Here is an alternative (not cheap):

https://sweetvinyl.com/

Thanks to all for the various URLs pointing at choices.

Personally, I'd DIY this as I've built low noise preamps before. But it occured to me to wonder how practical it might be for someone who wishes to buy a suitable amp. Seeing the options is quite useful.

 

[Jim Audiomisc]

If you get stuck and if MM is enough and if you can arrange a power supply I'll sort you something for a few beers

Thanks! Noted. Yes a PSU I could provide as things stand. And I am interested in experimenting with this sometime. In my case I'd be using a Shure V15/III with an HE profile. So classic low-output MM.

 

[Jim Audiomisc]

How about a simple single pole amplifier?
The two problems with flat gain are handling the high level spikes from scratches, that easily trigger slewing and clipping and the poor performance of many ADCs in handling the still tiny bass signal

The point of flat is, nominally, to avoid any time-speading of the click energy. Converting RIAA to single pole could be done after RIAA capture, but so could flat. I'm not sure how well it would work either way, though. But worth a ponder

In my case the clicks tend often to be ones that 'hide in the grass' when viewed with a conventional rip. I tend to deal with that by using sox as a high pass filter to reduce the LF of the music (turnover 5kHz 2nd order) and put that on show in Audacity alongside the main recording. Lets me pinpoint the small clicks. Big ones are obvious. And if really bad, need excision anyway. But I assume that doing a flat recording helps here to reduce the timespan of the click. So making interpolation repair easier.

 

[davidsrsb]

I agree that is much easier to correctly identify clicks, remove them and repair from a flat recording

Some well regarded equalized designs use video opamps to avoid slewing issues, stretching clicks

 

[Jim Audiomisc]

I agree that is much easier to correctly identify clicks, remove them and repair from a flat recording

Some well regarded equalized designs use video opamps to avoid slewing issues, stretching clicks

So how fast are the max measured slew rates? I did do some stats years ago on the output using a good RIAA amp, and I can't say the results indicated high slew rates would emerge from a cartridge, but I'll have another look...

 

[Jim Audiomisc]

I didn't look at clicks, just the audio. Got these results
http://www.audiomisc.co.uk/HFN/LP2/OnTheRecord.html
http://www.audiomisc.co.uk/HFN/LP2/Gallery.html

I'll see if I can find some nice clicks and correct for flat.

 

[Werner]

In my case the clicks tend often to be ...

Do you know this https://clickrepair.net/software_info/clickrepair.html, made by a fellow academic.

(* Fellow of you, not me. I've only ever been addressed once as 'Professor' ...)

 

[Jim Audiomisc]

Do you know this https://clickrepair.net/software_info/clickrepair.html, made by a fellow academic.

(* Fellow of you, not me. I've only ever been addressed once as 'Professor' ...)

Thanks. I think I've probably seen references to them before. However I'm not at this point trying to do any actual click removals, etc. My interest is in how easy it might be for people to do it using non-RIAA corrected recordings and if that is advantageous. Matter of curiosity.

 

[Arkless Electronics]

Thanks! Noted. Yes a PSU I could provide as things stand. And I am interested in experimenting with this sometime. In my case I'd be using a Shure V15/III with an HE profile. So classic low-output MM.

If you need such a thing let me know what gain, loading and PSU options you want. I'm assuming that if I made you a suitable circuit up on veroboard with flying leads present for all inputs, outputs and power you could take it from there yourself....? Straight 40-45dB gain, low noise op amp and can put a pole in at say 50KHz if you like but if you need high order anti aliasing filters etc that would be too much of a PITA I'm afraid.