PSU for SL-1210 with pics

[Marco]

Perhaps also Paul Hynes could 'sell' me what he considers are the benefits of his best PSU design (since I note he's on-line now) over those of his competitors?

This is not an excuse for a 'battle' between our respective trade members, incidentally, merely an opportunity for any members interested (and of course the whole of the Internet) to get the full 'low-down' on what they might consider (for them) as being the 'best' PSU for the SL-1200/1210.

I should point out that AOS (or me) is completely impartial on the matter. It's all about competing manufacturers/dealers promoting their respective products fairly and squarely and having an effective (and constructive) platform to do that. This is what being a trade member here is all about

Marco.

[leo]

What were you using before? Just the techie's own power?

Hi Hamish,

I've not had the Technics long so this psu upgrades the stock version. I could have drawn something up onto copper clad using something like a circuit based around an LM1084 and etched my own board but tbh it wouldn't have been half as good as the discrete PH module, for less than 200 quid you get an excellent performing psu which is why I posted details into the diy room

Cheers,
Leo

[anthonyTD]

hi all,
well,,, i'l break the ice and give my take on the requirements needed to control and hence stablise the requirements of the 1210 motor.
first of all we need to understand why the power supply is so important on a turntable motor in the first place.
from the moment the needle hits the record the motor of any turntable wether it be direct drive [1210] idler drive 301, 401 etc or belt drive is under a constant battle to try and keep the turntable at exactly the right speed in order to maintain the pitch impact and acuracy of the recording, this is not an easy task as the record grooves are exerting a constantly varying drag on the needle hence having the affect of trying to slow the turntable down, my example, when you were a kid did you ever turn your bike upside down and turn the pedals until the back wheel was up to speed? if so did you ever try to grab at the wheel and try to stop it? well if you can imagine thats what the needle is trying to do on the record,,, all be it at a minute amount but at many, many times a second and at varying amount of severity! this is why it is important that you have a power supply that can cope with the varying amounts of current needed to keep the motor up to exactly the right speed at all demands of signal amplitude and complexity.
if your using a direct drive turntable as in the 1210 it is of the utmost importance to get this right as unlike other turntable designs where they can to a degree use the weight of a heavy platter hence taking advantage of the flywheel affect the 1210 dosent realy have that advantage, idler drive turntables can be somewhere in the middle of the two.
i hope this helps.
as stated this is my take on things, others may have their own ideas, lets wait and see.
A...

[leo]

Hi marco,

I think some folks prefer to let the performance of their product do the talking rather than go around hyping things themself

I used the 2 x 80vA traffo for a reason, its probably way overkill for the Techie but I intend trying this psu with other things too, the trimmer pot allows adjustment to the output voltage making it quite handy, the regulator is also capable of driving heavy loads without breaking a sweat, its not just good at driving heavy loads but also very low noise and output impedance which makes it ideal for many other app's I want to try it with

Cheers,
Leo

[leo]

hi all,
well,,, i'l break the ice and give my take on the requirements needed to control and hence stablise the requirements of the 1210 motor.
first of all we need to understand why the power supply is so important on a turntable motor in the first place.
from the moment the needle hits the record the motor of any turntable wether it be direct drive [1210] idler drive 301, 401 etc or belt drive is under a constant battle to try and keep the turntable at exactly the right speed in order to maintain the pitch impact and acuracy of the recording, this is not an easy task as the record grooves are exerting a constantly varying drag on the needle hence having the affect of trying to slow the turntable down, my example, when you were a kid did you ever turn your bike upside down and turn the pedals until the back wheel was up to speed? if so did you ever try to grab at the wheel and try to stop it? well if you can imagine thats what the needle is trying to do on the record,,, all be it at a minute amount but at many, many times a second and at varying amount of severity! this is why it is important that you have a power supply that can cope with the varying amounts of current needed to keep the motor up to exactly the right speed at all demands of signal amplitude and complexity.
if your using a direct drive turntable as in the 1210 it is of the utmost importance to get this right as unlike other turntable designs where they can to a degree use the weight of a heavy platter hence taking advantage of the flywheel affect the 1210 dosent realy have that advantage, idler drive turntables can be somewhere in the middle of the two.
i hope this helps.
as stated this is my take on things, others may have their own ideas, lets wait and see.
A...

Nice one A ! Thank you for the info, these are the posts we want

Sorry I posted short, the site is running extremely slow for me at the moment

[Marco]

Excellent, Anthony - now all I need to know is whose PSU design best optimises what you've just described!!!

Hi Leo,

I think some folks prefer to let the performance of their product do the talking rather than go around hyping things themself.

That's fine - I understand that, but how then does someone like me choose what he thinks will best do the job without any 'sound quality information' with which to make an informed choice, prior to purchase, other than buying all the available options and comparing them, which is of course impractical and also expensive!

What I need is for the likes of Paul Hynes or Dave C to put forward a 'case' as to why they consider their designs best for the job - in effect, what their design aims/principles were for their products, so that I can then use that information to decide which PSUs to buy or audition.

Do you see my point? I like to know something about a product before I buy it, other than just a list of what's inside. It's no use saying what components are used unless I know what they're designed to do, sonically.........

With no disrespect to Dave, making a statement such as:

This achieves an instantaneous 60A peak current delivery with absolutely no negative feedback at all

...means bugger all, unless it's explained to me how that translates into improved audio quality, which at the end of the day is all I'm interested in.

So..............

Until Dave's back on-line after he's finished with Martin T and Hamish visiting him today, could either Anthony or you have a stab at explaining the above statement of his and what relevance it has with regard to improving the sonic performance of the SL-1200, especially in terms of the likely effect of the new heavy platter?

Cheers!

Marco.

[Paul Hynes]

Hello Marco,

I am not at liberty to deliver too much detail about how the regulator design works as I have entered into non-disclosure agreements, for most of my power supply designs, with my consultancy clients. I do, of course, retain the right to use these designs in my own products whether stand-alone power supplies like the SR3 or the DIY equivalent the PR3.

I no longer have access to the test equipment I used when measuring the circuitry at the design stage in the 1980’s, so I cannot give you hard and fast figures for the current specification. The circuit topology has remained the same as my original design although it has been refined a number of times since then.

The latest incarnation of the regulator topology, used in the above two products, was designed to give a fast transient response and a very low impedance over a wide bandwidth which obviously necessitates using wide bandwidth circuitry. The supply line rejection is also very good over an equally wide bandwidth. The error amp devices are noise specked at 0.5 nanovolts root Hz with a noise corner of 1 Hz and the low noise voltage reference has a further 60 dB of noise filtration, all in all, making this one of the quietest regulators around.

Current versions of both products use heavy-duty Mosfet output devices. I am not sure how much transient current is actually available, but the Mosfet manufacturers spec pulse current ratings exceeding 100 Amps with enough gate drive, and there is enough gate drive to achieve this. The limiting factor with transient current would be how much voltage sag would occur under these conditions in the energy storage capacitance I have included with the regulator designs. The wider the time period of the load transient the more the energy storage capacitance voltage would sag. It would have to have quite a long duration to affect the dropout voltage of the output mosfet, which calculates out at 2.4 volts at 100 Amps. Whether such prodigious current delivery is required for the SL1200 remains to be seen but both the SR3-21 and the PR3-21 will certainly provide more than enough current for the SL1200 motor/servo circuitry under all real world load transient conditions.

Of course the continuous current ratings would be much lower and as they would depend on the transformer rating, rectifier ratings and how fast you could remove heat from the output device. The rectifiers are rated at 5 amps continuous, 5000 Amps surge. The rectifiers will run hot at 5 amps continuous so I tend to de-rate them to 3 amps continuous for design purposes. I have had this topology running at 20 amps continuous with suitably rated components and a largish heatsink on the output device.

The most important parameter of all is the effect the SR3 power supply had on the sound of your music when fitted to your SL1200. It doesn’t really matter what the power supply measures like as long as it delivers sound quality.

Marco, I can provide you with a SR3-21 if you want to do a AoS power supply bake-off, provided you don’t mind waiting for around a month or so as my product build schedule is fully booked for a month at present.

Hi Leo, Nice build. Glad you are enjoying the results.

Regards
Paul

[anthonyTD]

a very informative and honest post paul!
A...

[leo]

Indeed! thank you for taking the time Paul , its much appreciated

Certainly agree regarding the most important parameter and for me its doing a grand job in that area

[Marco]

Hi Paul,

Thanks very much for taking the time to supply that information. However, I'm afraid that most of it went over the top of my (non-technical) head, so............

Marco, I can provide you with a SR3-21 if you want to do a AoS power supply bake-off, provided you don’t mind waiting for around a month or so as my product build schedule is fully booked for a month at present.

Yes please, as that would be very useful. It will mean I can form my own conclusions without incurring any expense. Is this the one that Hugo has bought?

Perhaps Dave would also provide an HE PSU for the same purpose and I can then review both products (using my SL-1210) for all the Technics users on AOS?

This will then also allow me to decide which one to buy from a position of extensive listening experience.....

Marco.

P.S Where in Scotland are you? I'm going up to Glasgow in about a month to visit my parents, so perhaps we could meet somewhere then?