Born Again Vinylista Phono Stage

[IslandPink]

Ah OK, so the Cole is OK as a reference. It's quite a low gain unit then ? You must have plenty of gain on the power amp or a pre-amp. Mine has lots more gain, but my power amp doesn't !

There will be insertion loss from the eq of course, but not, I suspect, to the degree the LCR unit causes.

I didn't think there was any difference ?

[Nick]

you're basically fooked with 12AX7 or any high gain low u valve if you want a valve phono stage that isn’t going to be all warm and cuddly.

ECC83 will give you at most 150pf so a low cap cable can take that to maybe 250pf. Also, remember you can alter the resistive loading if you want to tweek the cartridge response. The world wont end if its not 47k.

Also, remember that you are making a device with a inherently high cut frequency response, so you have the perfect oportunity to add a bit of HF lift if you want.

And thirdly, I assume your CD player is flat, so all you need is a flat overall response from the phono and cartridge. Also, there are good low (ish) cost MC cartridges, if cost is a limit, I would build or buy a SS phono, and spend the money you save on the cartridge.

There will be insertion loss from the eq of course, but not, I suspect, to the degree the LCR unit causes.

Not sure what you mean by "insertion loss" in this context, but assuming you are talking about passive RIAA, then by definition, there is a 20dB loss at 1kHz, and a 40dB one a 20k, thats what the curve requires.

[Cressy Snr]

you're basically fooked with 12AX7 or any high gain low u valve if you want a valve phono stage that isn’t going to be all warm and cuddly.

ECC83 will give you at most 150pf so a low cap cable can take that to maybe 250pf. Also, remember you can alter the resistive loading if you want to tweek the cartridge response. The world wont end if its not 47k.

Also, remember that you are making a device with a inherently high cut frequency response, so you have the perfect oportunity to add a bit of HF lift if you want…

Thanks a million Nick.
That was damned useful
Need to think a little more, but I may change direction slightly and climb out of the hole I’ve been digging.
Thanks also Mark.

[izzy wizzy]

Sorry, my bad on the EQ

[izzy wizzy]

Thanks for simming that Stephen.
If the thing is drooping after 10khz it’s the last thing I want. My hearing is dull enough as it is after Bells Palsy damaged it a few years ago, without the equipment further exacerbating the situation. Although I know one should build rather than rely on SPICE sims, HF droop is absolute anathema in my own situation.

The Cole sounds less treble happy than either my CD player or streamer and the Cole is flat to within 1dB. A treble rise from a phono would probably be what I would look for, but then that’s also wrong in so many ways. MCs do the treble lift independent of the phono stage better than MMs do but they are not suitable for my SME arm, neither are they something I can easily afford.

It's very very small. Nothing to worry about. I think it not a bad thing esp with MCs. I know you've got MM. There's way more in life than to be worried by than a slight roll off in the 0.1s of dB above 10k

[Cressy Snr]

Interesting few days I've had in terms of both phono stage musings and the amplifier.
The Cole LCR was not really giving enough gain into the 45 amp as it stood, with its ECC88 input/driver stage. Although it sounded excellent, in the first instance, something began to bother me about the way it was performing, namely a distinct lack of dynamics. Soundstage excellent, detail excellent, tone excellent, texture excellent, dynamics and transient response, meh. That aspect of the Cole's performance was something that crept up slowly, but once fully on the radar, it spoiled my enjoyment of vinyl completely.

So, as Nick mentioned earlier about finding the things that matter personally about phono stage performance: dynamics and transient attack seem to matter a great deal to me. There might be a number of causes of the lack of dynamics, and gain was something I investigated, also I was concerned about the number of identical devices in the signal chain.

With the Cole in the system we have ECC88 - LCR unit - ECC88, into amplifier with ECC88 input stage, a veritable plethora of ECC88s in. Now, I'm aware that the late Mr Sakuma used to like that sort of thing, but a long chain of ECC88s (transistors that glow) are not what he was thinking about I'm sure.

So to cut to the chase, I looked at the amplifier and changed the ECC88 input stage to the ECC81 I'd proposed in the first place, in an attempt to boost the gain further down the line from the Cole.

Screenshot 2021-08-16 at 16.57.55.png (63.63 KiB) Viewed 2158 times

Boom! Fantastic result!
ECC81s are a great match with 45s! Believe me. Must be due to fortuitous distortion cancellation, but there is no denying the superb performance.
In the end, the Cole still doesn't really have enough gain to really drive the input stage of my amplifier. It probably needs a preamp after it, but it's attack and dynamics were certainly a lot better than before. It has now gone back to our Ant's. It works now, which was after all the initial objective.
Meanwhile, I'm enjoying my MoFi Studiophono with my records. The ECC81 has made such a difference to the overall performance of the amplifier, it's comical.

The hunt for a 2V output valve phono stage continues. I have a few possibilities to have a look at and have identified a characteristic that matters greatly to me. This will allow me to better judge the results of my endeavours.

[Nick]

Cant say I understand why changing the driver valve will have the effect you describe. Does it also change how you hear digital sources?

What you describe sounds like what I heard when the lower frequency RIAA was a bit off. Would maybe have been helpful to be able to measure the phono stage, but never mind.

[Cressy Snr]

Cant say I understand why changing the driver valve will have the effect you describe. Does it also change how you hear digital sources?

Yes, digital sources are also affected in a positive way.
To be honest, I originally wanted ECC81 as the driver as it has a gain of around 50 in this circuit, but as ruddy usual I got put off the ECC81 by too much reading around and believing the bollocks spouted about it. Small wonder Alex Kitic gets so frustrated. However I’m not Kitic and am not going to get into a decade long argument about it on DIYAudio. The bloody valve suits this amp better than the ECC88…end of!
I reckon it produces just the right amount of distortion to enable highly effective cancellation with certain output valves and the 45 just happens to be one of them: a bit like the WE harmonic equaliser, but in tube form.


Loads of edits due to piss poor typing.

[izzy wizzy]

Sometimes changing the source can give you an insight into how a piece of equipment downstream is behaving and where our priorities lie in curating "our sound". That's what I got from what Steve was saying.

[Cressy Snr]

Yes, I need the snap and twang basically. A phono stage needs to provide this, but not at the expense of getting all coarse and nasty. I had enough of that game with the Linn/Naim stuff thank you very much.It’s a difficult balancing act.
Asking for whip-crack dynamics and slam from a 45 amplifier producing 1.5W with a following wind is just being silly, but in the right circumstances ie a good driver and fed by good sources, it still does the best job on my music collection I’ve heard so far.
The MoFi phono stage I’m currently using, is a bit restricted in terms of soundstaging, although that could equally be the fault of the ancient SME 3009 S2 with cheap ass MM cart, but it has plenty of speed and tone and most importantly, nothing descends into nastiness.

So to summarise: I want a valve phono stage that puts out CD player line levels (2V rms) has plenty of snap, twang and doesn’t get nasty or muddled when the going gets tough. And as a Yorkshireman, I want all that for £50 in DIY cost.

[izzy wizzy]

I'm a bit puzzled by your gain requirement given the efficiency of your system. What gain setting are you using on the Studiophono?

I think you said you had ECC88s to hand. They work well as a cascode first stage. What other valves in the medium mu range have you got? I'm guessing you wouldn't want cascaded 88 stages.

[Cressy Snr]

I'm a bit puzzled by your gain requirement given the efficiency of your system. What gain setting are you using on the Studiophono?

I think you said you had ECC88s to hand. They work well as a cascode first stage. What other valves in the medium mu range have you got? I'm guessing you wouldn't want cascaded 88 stages.

With the digital sources, I turn the volume control to 10 o’ clock absolute maximum for realistic volume levels. With the Cole phono stage and ECC88 inputI couldn’t get near the same levels even with the volume control at maximum. My AT cart is specced at 3.5mV. The Studiophono is set at 40dB of gain for carts over 3mV. With 12AT7 power amp input stage, this does allow the same levels as the digital sources to be achieved, but the volume control still needs to be at 1 o’clock to match them exactly.
If I set the Studiophono gain to 46dB (1-3mV) output then the phono stage output matches the digital sources, ie same volume level for same control position. Crude I know but short of measuring, it’s the best I can do.

However I’m conscious that setting the gain to 46dB could cause overload of the Studiophono due to the nominal 3.5mV output of the AT cart. With the 40dB gain setting the cart output is towards the bottom of the allowed range. With the 46dB setting, it is 0.5mV too high.

[Cressy Snr]

As an aside,
When I entered teaching from industry and experienced the horrors of my first staff meeting, I went home and told Melanie that “there is nothing like fecking teachers for making a simple job ten times harder than it needs to be!”

I seem to have become one of those teachers with this project.

[Paul Barker]

There are so many more factors affecting sound that just making a phono package as a whole which matches the voltage drive of the dac or whatever youre digital is.

At home you most likely dont need the digital voltage amplitude into youre 45 amp.

I wouldnt be fixing my attention on just that factor. Id get the phono stage sounding how I like the sound at a reasonable level for the room its in, and not care that when Im on digital Im seeing the volume control at 10 oclock and on the phono stage Im seeing it at 2 oclock.

Tube rolling’s purpose in my builds isnt to match the position of the volume pot, its to achieve what I like the sound of.

[Cressy Snr]

I also want the best sound I can get Paul, but I also want convenience and ease of use. The qualities of ultra-low noise, RIAA accuracy, overload margins that will cope with scratches, decent gain and convenience, surely can’t be an impossible set of requirements. Commercial manufacturers achieve it. My WAD Phono II kit did it.

I accept that valves are noisier than transistors at these signal levels, but still….