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

[MartinT]

Marco - the Technics main DC power rail must be run at 21V. This is why most external PSUs (such as yours) are set to 21V.

My deck now has internal 21V regulators so this is why an external 27V rail is required (this is two-stage regulation). You could not now use my PSU on your deck.

[Marco]

H'okey cokey... So, apologies for being dense, but what was Paul getting at with his suggestion of a new lead?

Anyway, there's one sure way to sort this...

I'd forgotten that I still have my SR5, therefore all we have to do, is for me to bring it down (along with my T/T) and let you hear the comparison between the PSUs, using my T/T in your system, which will easily show up the differences!

All you have to do then is listen to the sound of my T/T with both the SR5 and SR7EHD, using your system as the reference point, and judge from that.

Job done

Marco.

[MartinT]

I don't doubt that the SR7EHD sounds better than the SR5 when used as a single external power supply on your deck. However, working out whether it will sound better on my deck (with, eventually, triple stage regulation) is more complex than that and necessitates the use of 27V external PSUs - with my deck, of course

This is why Paul is suggesting the adapter cable - so that we could adjust your SR7 to 27V and use the cable to connect it to the 4-pin flying lead from my deck.

[Paul Hynes]

Hi Marco,

Martin has answered your questions but for technical reference I have added some more information below.

The output voltage should only be adjusted to 27 volts if the SL1200 internal regulator upgrades are in place. All regulators have what is called a dropout voltage, which is the required voltage between input and output to maintain voltage regulation. The regulator will not regulate if the input to output voltage is reduced below the dropout voltage. The PR3 regulators fitted in the transformer well of the chassis have dropout voltage of around 4 to 5 volts in this application so the external power supply needs to be set higher to ensure correct regulation.

Martin’s SR5 was fitted with a 4 pin XLR originally. You have changed the SR7EHD XLR to a Furutech XLR which, I believe, is a 3 pin XLR. Unless Martin has also changed to a Furutech 3 pin XLR your connectors will not be compatible. I will have to make a 3 pin XLR cable the same length as his 4 pin cable for Martin to patch into his deck wiring. This will provide the minimum number of contacts in the DC path. I will need to know which pins have been used on the three pin XLR to ensure correct polarity.

Charles,

The case arrived yesterday. I have not checked the parcel yet as I have only returned to work today and there is a very large e-mail in box to get through. Many of the materials orders that were delayed by bad weather during December and the holidays have also arrived and I have to get these unpacked, checked and sorted for the various build projects in the build schedule. It will probably be Monday before I get into the workshop and I will be working through the build schedule in chronological order as usual.

Andrew,

The Teflon printed circuit board has arrived. I will be building a large batch of regulator modules for a variety or power supplies including yours next week and then working through the outstanding power supplies.

Regards
Paul

[jostber]

Great to see that good craftsmanship is in demand!

[Artifolk]

Paul,

Thanks for confirming delivery.

Happy New Year

[Wakefield Turntables]

Lol - I'm not after anything, dude. I'm more than happy with the 'mere' standard SR7EHD!

All I was suggesting is that it might be interesting swapping PSUs for a week sometime later on, as that way we can analyse the sonic effect of the 'posh bits' you've had put inside yours

Marco.

I'll be doing a slow upgrade over the next six-nine months starting with a new cart, new SUT and some lovely new reference power leads for my ATC's. I'm gonna see what each bit adds to the system, I'll probably also put in the new internal regs that Paul's designed but we'll have to see about that later! I'm very much up for fetching the PSU to you at some point. Probably meet you half way somewhere at a hifi show??

This upgrading lark is very infectious.

You poor dude! You have techy1210itis which is a commonly known disease amongst the bretheran of AOS. There is no known cure and you'll always be skint but you will have a wonderful deck.

Hi Marco,


Andrew,

The Teflon printed circuit board has arrived. I will be building a large batch of regulator modules for a variety or power supplies including yours next week and then working through the outstanding power supplies.

Regards
Paul

NICE! Now, when can we start to buy the internal regs from you

[Artifolk]

You poor dude! You have techy1210itis which is a commonly known disease amongst the bretheran of AOS. There is no known cure and you'll always be skint but you will have a wonderful deck

Who needs a cure when fully blown techy1210itis is the outcome

[MartinT]

I rushed home tonight to get Paul's latest wonder PSU installed. The SR7-27 (set for 27V because I have the full dual-stage regs fitted internally) is a big beast, fitted into a silver chassis but with the mammoth heatsink deleted as I needed it to fit into the tight space available in my system rack. It's quite a lot larger and heavier than the SR5.

Now I must admit to wondering whether the SR7 would really yield any improvements over the already over-spec SR5, however I remembered the very significant uplift in performance of the SR5 over the SR3 and Timestep PSUs, so I went ahead and ordered it knowing what it was doing for Marco's deck.

I am not disappointed. There are improvements across the board (no night-and-day stuff, this is subtle) and, interestingly, the first thing I noticed was a cymbal in the opening to Gaucho that I hadn't really focused on before. There is more authority, more of that rhythmic-metronomic punch that the Technics does so well, more detail in the soundstage, more slam.

I am listening to it connected via the 4-pin XLR connector, just to get the thing going. I have yet to fit the 3-pin Jaegar connector that Paul assures me delivers an even lower output impedance.

I can't begin to figure out how a hugely over-spec PSU can better an over-spec PSU when there are two further stages of regulation down-line, driving a turntable motor. All I can say is that the SR7 is the best PSU I have heard on my deck, taking its performance even higher and representing (in my book) good value for money.

[Wakefield Turntables]

Welcome! Did you get the XL version??