Paul Hynes SR7EHD PSU - unlocking the latent potential of my Technics SL-1210

[MartinT]

SR7-27 EHD.

[Wakefield Turntables]

mines stupidly over specced but useless at this moment in time Paul has my deck and he's waiting for me to send him a replacement PCB, just you guys wait till my baby comes back!

[MartinT]

We're waiting, Andrew. Seems like an age since you were last playing it. Expensive mistake

[synsei]

Expensive mistake

Which is why you won't catch me doing such things to my Techie. When it comes to electronics mods I'm best kept well out of the way as I'm likely to blow something up just by being near it I'll pay someone to do it for me if or when the time comes...

[MartinT]

Paul has set up agent(s) in order to have the mods performed for you, when you're ready Dave.

[synsei]

Cheers Martin, but I've a long way to go yet. I do have an external PS now which has made a huge difference. I can't stop listening to my vinyl these days...

[MartinT]

Me too - that's what it's about!

[MartinT]

The SR7 has certainly brought its prize to my consciousness over the last couple of days, a combination of a) having run-in for 48 hours and being thoroughly warmed through, and b) my listening to a goodly selection of great music, hearing much of it in a new way.

As I first stated, it seems to be the treble that reveals itself first, being ultra clean, pure and filigree detailed. Then comes the incredible punch to anything percussive. Just now I've been hearing more and more that my speakers simply disappear, there being no sense of two channels of sound, just a deep and wide stage in front of me. My insight into the music is the best I've heard, a very strong sense of presence in the best recordings and at the very least something interesting about the worst recordings always coming through.

I don't know how he does it or exactly what's different about the SR7 over the SR5 (I would guess tighter regulation and more instantaneous current capability, possibly lower noise), but Paul has created yet another great enhancement to the Technics turntable. The very fact that the Techie keeps responding to these upgrades by getting ever better is a real testimony to how good the basic design is. Perhaps the improvement in treble is down to a further reduction in flutter? I'll also lay more than a little of the quality of the overall sound at my Dynavector arm's door. More fool HFN who gave it a so-so review. It is simply in a different class from the various SMEs.

So thank you, Paul. I am extremely happy with the SR7 and consider it to have been money very well spent.

[Marco]

Sorry I'm late to this one, Martin. Well done!

It's amazing how Paul's internal reg mods and the SR-7 work together so symbiotically, isn't it?

Marco.

[Paul Hynes]

Hi Martin and Marco,

Both of you are well aware of the benefits of a larger power supply and Marco is right about the symbiosis of the whole power system.

This particular regulator circuitry responds well to cascading in series and using this technique provides enormous supply line rejection making the deck circuitry much less susceptible to mains borne interference. Cascading regulators can add the regulator sonic signatures but in this case the regulator signature is benign so the technique is beneficial. This is not true for all regulator circuits and cascading some of them can add sonically obnoxious characteristics.

The regulator modules and power supplies are very quiet so they are not introducing high levels of additional noise on the motor board. They also operate over a much wider bandwidth than the typical regulator circuits used in audio power supplies, so RFI rejection is good and the regulators are still effectively regulating the digital control circuitry in the SL 1200, where lesser regulators like the LM317, and it’s clones, have stopped regulating as they have run out of bandwidth.

Not only that, the internal regulator modules are closer than any external power supply can be to the load circuits, so the load regulation is more effective.

Most people would consider the SR7 to be grossly over-specified for the SL1200, however there are audible gains to be had by the improved regulation and lower impedance of the larger mains transformer, the reduction in output impedance by increasing the size of the output stage and up-rating the rectifier diodes. More power under the bonnet, so to speak. There are also a few little tweaks to the circuitry that I am not at liberty to disclose at present.