• Registered: 2014-12-11
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Topic: Phono / Vinyl with UFX

Finally, I revisited the option to use the mic pre's of the UFX as phono preamp. The load impedance for a Denon DL-103, specified with >100Ohm, is readily implemented by a parallel load resistor across pin 2 and 3 for balanced lines.  So I started with that, fitted a small utility enclosure with XLR inputs and outputs and a resistor or potentiometer parallel to the signal path. The enclosure is earthed, the shield is not, the cartridge is floating. The mic pre's gain is adjusted in Total Mix, the vacuumsound RIAA-Phono Equalization plugin in Reaper does the RIAA de-emphasis. The 65dB of gain of the UFX mic pre's is more than enough (for the DL-103). [Watch out for phantom power] DIGICheck comes in handy for metering of proper gain and spectrum, both the record and the de-emphasis spectrum.

In fact, 100Ohm load seems a little low on the DL-103. Depending on the record, I vary the load up to 400Ohm, which gives a fuller sound in the lower end. A very simple solution would be a dedicated cable with a resistor in the XLR plug!

If you are concerned about truncation, I recommend R. S. Robinson's paper in Audio Engineering Society Convention Paper, 123rd Convention, 2007, New York.

The UFX mic pre's are extremely clean and transparent, the sound is simply amazing! Sounds just like the best phono-preamps I have heard!

  • Jeff
  • Jeff
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Re: Phono / Vinyl with UFX

Very interesting, thanks for posting this info.

Regards,
Jeff Petersen
Synthax Inc.

Jeff's Website

  • ramses
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Re: Phono / Vinyl with UFX

Do you know a "ready for use" solution for MC systems ? I have a Dynavector Karat 23 RS.

BR Ramses - UFX III, 12Mic, XTC, ADI-2 Pro FS R BE, RayDAT, X10SRi-F, E5-1680v4, Win10Pro22H2, Cub14
  • Registered: 2014-12-11
  • Posts: 47

Re: Phono / Vinyl with UFX

If you can find the recommended load impedance, use this value as parallel resistor. I could not find it easily. Alternatively, use a potentiometer within the recommended load range, than you can tune R on the fly. Many low impedance low output MC systems, like the DL-103, are somewhere in the 50-500 Ohm region.

5 Reply by MC

  • MC
  • MC
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Re: Phono / Vinyl with UFX

Note that the much more popular Moving Magnet (MM) systems require a load of typically 47 kOhm, plus a small but individual  capacitor (around 220 pF) to make them sound good in the treble range. The best solution here is still to get an external (inexpensive) RIAA preamp.

Regards
Matthias Carstens
RME

MC's Website

6 Reply by cyberkul (edited by cyberkul 2019-08-07 08:37:19)

  • Registered: 2018-08-24
  • Posts: 33

Re: Phono / Vinyl with UFX

Soundwunder wrote:

Finally, I revisited the option to use the mic pre's of the UFX as phono preamp. The load impedance for a Denon DL-103, specified with >100Ohm, is readily implemented by a parallel load resistor across pin 2 and 3 for balanced lines.  So I started with that, fitted a small utility enclosure with XLR inputs and outputs and a resistor or potentiometer parallel to the signal path. The enclosure is earthed, the shield is not, the cartridge is floating. The mic pre's gain is adjusted in Total Mix, the vacuumsound RIAA-Phono Equalization plugin in Reaper does the RIAA de-emphasis. The 65dB of gain of the UFX mic pre's is more than enough (for the DL-103). [Watch out for phantom power] DIGICheck comes in handy for metering of proper gain and spectrum, both the record and the de-emphasis spectrum.

In fact, 100Ohm load seems a little low on the DL-103. Depending on the record, I vary the load up to 400Ohm, which gives a fuller sound in the lower end.

I have done the same with my UFX and DL103R. The RIAA-correction is done in Audiolense "convolution filter", together with XO, frequency and time correction. Playback through Jriver convolution engine. Gain in mic pre about 55dB seem to be max before I get clipping in Totalmix. Noise is very low, but it is a bit thin sounding. Did the parallel resistor make a big difference? Did you also add a parallel capacitor? I`ll try to add a potmeter to check for myself..

Gunnar

  • Registered: 2014-12-11
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Re: Phono / Vinyl with UFX

Thin sound can result if the mechanical resonance frequency of the cartridge is too high. The resonance frequency can be checked with a test record. Adding weight to the cartridge down-shifts the resonance frequency (adjust counter balance appropriately).

A variable resistor is a good idea for testing. I did not use a capacitor, to the best of my knowledge MC does not need a capacitor.

In the mean time I use a balanced step-up transformer (Lundahl). Gives extra gain@no noise, smooth transformer sound and a better match of the cartridge to the balanced mic input of the UFX+. Sound is amazing. Noise is better than high-end phono-pre.

It is too bad RME won't implement a software phantom power protection eg with a modifier key or preference setting to avoid accidental phantom power on the mic ins.

Cheers

  • ramses
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Re: Phono / Vinyl with UFX

Similar to this request: https://www.forum.rme-audio.de/viewtopic.php?id=29052

BR Ramses - UFX III, 12Mic, XTC, ADI-2 Pro FS R BE, RayDAT, X10SRi-F, E5-1680v4, Win10Pro22H2, Cub14
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Re: Phono / Vinyl with UFX

Soundwunder wrote:

Thin sound can result if the mechanical resonance frequency of the cartridge is too high. The resonance frequency can be checked with a test record. Adding weight to the cartridge down-shifts the resonance frequency (adjust counter balance appropriately).

A variable resistor is a good idea for testing. I did not use a capacitor, to the best of my knowledge MC does not need a capacitor.

In the mean time I use a balanced step-up transformer (Lundahl). Gives extra gain@no noise, smooth transformer sound and a better match of the cartridge to the balanced mic input of the UFX+. Sound is amazing. Noise is better than high-end phono-pre.

It is too bad RME won't implement a software phantom power protection eg with a modifier key or preference setting to avoid accidental phantom power on the mic ins.

Cheers

Thanks! A test record would be nice. I use a Jelco 750L with the DL103R. I think peaople use this combination without adding weight? I added a 1k pot today to lower the load impedance of the cartridge. I hear no difference, except when impedance get so low that the volume level decreases.

  • Jas0_0
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Re: Phono / Vinyl with UFX

I am also interested in using a microphone amp to take an MC cartridge signal (with appropriate resistance), then convert in my ADI-2 Pro FS and apply software RIAA EQ on my Mac.

However, I have read old posts on other forums that suggest AD conversion of an unequalised turntable signal results in loss of dynamic range, because the bass response is 20dB down at point of conversion.  Is this still a valid concern with the AD converter in the Pro FS?

And are there any other potential disadvantages in using a mic pre for MC cartridges and digital RIAA EQ?

Many thanks,

James

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Re: Phono / Vinyl with UFX

Considering the available dynamic range on vinyl, I wouldn't worry. Other than that, I have no specific feedback on this kind of setup. Might just work fine.


Regards
Daniel Fuchs
RME

Regards
Daniel Fuchs
RME

RME Support's Website

  • Registered: 2014-12-11
  • Posts: 47

Re: Phono / Vinyl with UFX

Jas0_0 wrote:

I am also interested in using a microphone amp to take an MC cartridge signal (with appropriate resistance), then convert in my ADI-2 Pro FS and apply software RIAA EQ on my Mac.

However, I have read old posts on other forums that suggest AD conversion of an unequalised turntable signal results in loss of dynamic range, because the bass response is 20dB down at point of conversion.  Is this still a valid concern with the AD converter in the Pro FS?

And are there any other potential disadvantages in using a mic pre for MC cartridges and digital RIAA EQ?

Many thanks,

James

Please check: R. S. Robinson's paper in Audio Engineering Society Convention Paper, 123rd Convention, 2007, New York.
The integrated spectrum of most music genres of the turntable output is more or less flat, so AD conversion will not cause loss of dynamic range. You can use a resistor or even better a balanced transformer. Only problem left is phantom power. Accidental phantom power may destroy cartridge. Unfortunately, RME has not implemented any protection scheme in its software, which would be so helpful.

  • ramses
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Re: Phono / Vinyl with UFX

Soundwunder wrote:
Jas0_0 wrote:

I am also interested in using a microphone amp to take an MC cartridge signal (with appropriate resistance), then convert in my ADI-2 Pro FS and apply software RIAA EQ on my Mac.

However, I have read old posts on other forums that suggest AD conversion of an unequalised turntable signal results in loss of dynamic range, because the bass response is 20dB down at point of conversion.  Is this still a valid concern with the AD converter in the Pro FS?

And are there any other potential disadvantages in using a mic pre for MC cartridges and digital RIAA EQ?

Many thanks,

James

Please check: R. S. Robinson's paper in Audio Engineering Society Convention Paper, 123rd Convention, 2007, New York.
The integrated spectrum of most music genres of the turntable output is more or less flat, so AD conversion will not cause loss of dynamic range. You can use a resistor or even better a balanced transformer. Only problem left is phantom power. Accidental phantom power may destroy cartridge. Unfortunately, RME has not implemented any protection scheme in its software, which would be so helpful.

And you are sure that such a "protection" would technically be possible ?
How should the circuit know whether phantom power is possible or not if the user turns it on ?
If it would be that easy, why is phantom power not enabled by default in cases where needed.
Auto Micro type detection, hurray ! ...

BR Ramses - UFX III, 12Mic, XTC, ADI-2 Pro FS R BE, RayDAT, X10SRi-F, E5-1680v4, Win10Pro22H2, Cub14
  • Jas0_0
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Re: Phono / Vinyl with UFX

Soundwunder wrote:

Please check: R. S. Robinson's paper in Audio Engineering Society Convention Paper, 123rd Convention, 2007, New York.
The integrated spectrum of most music genres of the turntable output is more or less flat, so AD conversion will not cause loss of dynamic range.

Many thanks for this - interesting.  Though I'm slightly wary that it was published by a member of Channel D who make flat phono preamps and digital RIAA software.  Perhaps I'm too cynical?!  On another forum I've been told that a loss of SNR in bass regions comes from using a flat preamplifier, rather than at the AD conversion stage.  Not being technical I have no means to challenge this and I wondered what you thought.

Soundwunder wrote:

You can use a resistor or even better a balanced transformer.

Thanks, though again not being technical, I'm afraid I don't know what this means - what is a balanced transformer?

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Re: Phono / Vinyl with UFX

RME Support wrote:

Considering the available dynamic range on vinyl, I wouldn't worry. Other than that, I have no specific feedback on this kind of setup. Might just work fine.

Thanks for your reply.  Is this because the dynamic range of a record is so much lower than that of the preamp/AD converter that it would result in no loss of fidelity when amplifying/converting a signal from a record?