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current input phono stages (MC) with switchable EQ curves

slavedata said:
Can the Original Poster clarify what they are trying to achieve and what they want to play? I'm with GT Audio on this keep a phono stage simple and low noise.
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matt j said:
Steve, I think current/transimpedance phono stages are already a niche product, finding one with variable EQ sounds like find a needle in a haystack made of chicken teeth.

Probably something you'd need to have made bespoke for your needs I'd have thought.
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I’ve got a decent collection of fifties, sixties and seventies classical vinyl, all sorts of labels, and am building a similar collection of jazz from the fifties on. I heard the same record played on RIAA and on the DG curve through the CH Precision phono stage and the DG. curve was just massively, obviously better. Not just tone control, significantly more dynamic and musical. The recording dated from the late fifties, as do a fair few of mine.

The CH Precision stage can be voltage or current input, and has various curves built in. No need for bespoke if you’ve got £25k. Which I haven’t, alas. :(
 
Sue Pertwee-Tyr said:
I’ve got a decent collection of fifties, sixties and seventies classical vinyl, all sorts of labels, and am building a similar collection of jazz from the fifties on. I heard the same record played on RIAA and on the DG curve through the CH Precision phono stage and the DG. curve was just massively, obviously better. Not just tone control, significantly more dynamic and musical. The recording dated from the late fifties, as do a fair few of mine.

The CH Precision stage can be voltage or current input, and has various curves built in. No need for bespoke if you’ve got £25k. Which I haven’t, alas. :(
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Is it something Jez could retro fit to his phono stage, or possibly build from scratch?
 
Possibly daft question: is there a reason why a unit with these EQ curves couldn't be designed to fit between phono stage and pre-amp?

It could even have a bypass switch.
 
A good way to hear a whole slew of these curves would be to get a loan of a Devialet Pro and you can even change them on the fly. It’s quite striking how different they sound.
 
Just buy an old QUAD 22 Pre-amp. That has all the curves built in and its valve based so the best of both worlds. Some even came with a hard plastic card telling you what buttons to press to obtain the EQ you wanted to use. As has been said earlier tone controls provide exactly the same function.

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Note the rectangular buttons on the front of the 22. These correspond to the different switchable EQ settings (Time constants 3180uS, 450uS, 318uS, 100uS, 75uS, 50uS & 25uS) shown on the left side of page 20 of the 22 manual.
 
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OT but it may interest some: GT raises a very valid point re noise from micro processor (uP) and displays. I say this as somebody who works in instrumentation that can measure small currents (say a few mA) from a reasonable distance (say a few metres). The instruments are based on a uP and have a display. The display tends to be the noise limitation in the design. While the uP may run at 100s of MHz the processing tends to be periodic at rates that will be in the audible band - multiples of operating system tick rate or interrupt / batch processing data rate. Displays are typically in the order of 60Hz refresh over several 100s of lines and several 100s of pixels per line. Noise tends to be worse in and around teens kHz at half line rate. Unless there is an essential reason to put a uP and display in a low signal instrument, it is best avoided. Which doesn't mean they can't have done their best to screen, shield, ground and filter away as much as possible but I would ask is the display essential to the product?
 
The Gold Note was excellent. I demoed one for a week and nearly bought it. It’s considerably better than the Aria I ended up with, albeit more expensive too. Definitely better than my modest vinyl setup deserved. Maybe….
 
anubisgrau said:
are we talking that various RIAA curves and EQing is the same?
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The RIAA curve is a particular equalisation that is necessary to apply to the replay of LPs and singles to get a flat response. This is to match an EQ applied during cutting. The broad intent is to make the stylus excursion after EQ roughly similar for all frequencies.

RIAA has been standard since the early 50s. So unless you have a collection of very early mono LPs and singles it's the only one you need.

Some hifi enthusiasts are keen to find novelty, so non-RIAA eq for vinyl, the 'Neumann' pole, I think this is mostly to avoid admitting they would like to make use of an actual tone control. It's quite an odd phenomenon.

If you're a serious archivist and collector the best way to implement appropriate equalisation for records from the last 120 years is via digitisation, because once you go pre-vinyl the opportunities for adventure multiply.
 
The Sutherland Engineering SUTZ, which appears to be a transimpedance head amp with no eq of its own but intended to feed into a MM stage which can be one with a variety of them would seem to be the answer. It does look like Sunderland don’t sell into Europe though as they list no agency here.
 
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