Shuggie's SL-1210 Blog Revived

Quote:

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Originally Posted by Dave Cawley

Paul
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Trying to deflect the argument by retrospectively asking the same questions is bizarre!

Dave

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There is no argument.
Dave you had a right old 'go' at Paul, for which he is asking quite politely for you to substantiate.

Somebody else assessed the different power supplies..and made a subjective judgement.

Dave,

I notice that you have updated your web site again. It is a start, but unfortunately you are still basing your comments on erroneous information.

I have re-read the posts you allude to from July 2009. The fact that someone mentions my name or my product, in a forum thread, and then proceeds to compare it with your product is hardly my fault. Maybe I have missed something but also I see no mention of my citing bandwidth limitation, RF rejection, or transient response for any reason either. Perhaps you could post a link directly to this information to better help me understand what is going on here.

Regards
Paul

Hi Steve

Not really, the words on this thread were originally supplied by Paul. Alex has answered his question, and now I'm simply asking Paul about his various statements. I'm sure he can give good answers for us all to learn from?

Dave

Hi Alex,

Using a switch would be fine if a couple of specific voltages were all that were required, But Shuggie wanted some variable adjustment and the customer is always right.

Regards
Paul

Hi Guys

Not taking sides here ( I have not had any dealings with either Paul or Dave, nor do I have any vested interests in either company or products. )and purely in the interest of moving this series of posts on, it would perhaps IMHO be a good idea to answer the first set of questions from post 110 and then tackle any subsequent questions.

Otherwise this thread will end up going round in a circle and going know where fast.


Regards D S D L

Yep, agreed. And just to remind everyone of what it was, here it is:

Quote:

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Originally Posted by Paul Hynes

Following posts on this thread, it has been brought to my attention that a certain person who makes power supplies for the Technics SL1200 has posted information on his website that is factually incorrect. This information is copied from his website below ;-

Note 30 June 2009: PSRR has been mentioned by some people, but it is the end result that tells all on our PSU, quite simply we measure noise on a HP400F voltmeter with a noise floor of 2.5uV, remember too that most equipment rejects power supply noise by at least 60dB. Theorising is OK, but measurements tell all! Another manufacturer of PSU's normally used for preamplifiers decided to have ago at us, and about how his PSU reacted to differing loads and how much feedback he used. Well we all know about the pitfalls of excessive feedback and a motor control has different requirements to a preamplifier! The last we heard of it was that " is back with **** for the moment for some adjustments" yes indeed! We are professional designers with a long pedigree.

Now lets examine these comments.

1] “ another manufacturer of PSU’s normally used for preamplifiers decided to have a go at us”. Hmm, I don’t think so. If I decided to enter your market area, with serious intention, you would know about it by now. If someone asks me for a power supply for a specific function I will provide this whether it encroaches on your market or not. The power supply in question has been used for a wide variety of power supply applications since 1984 and is not just suitable for preamplifiers. In fact I was using this regulator topology in it’s early incarnation to power the Pink Triangle DC motor version of their record deck in the 1980’s very successfully. It has also been used for powering the origin live DC motor many times and every one has been very pleased with the resulting sound quality improvement.

2], “about how it reacts to differing loads”. It reacts a lot less than an LM317 to differing loads over a much wider bandwidth.

3], “about how much feedback he used”. Actually I don’t recall mentioning how much feedback I use in this circuit topology. For the record it is 20 dB less than the LM317 below 1 KHz but crucially it has a much wider open loop bandwidth than the LM317 with much better transient response than the LM317, which gives better control above 1KHz than the LM317 can achieve. It is also way quieter than the LM317. The voltage reference I use is a low noise device, which is well filtered, and the error amplifier device noise specification is 0.5 nanovolts root Hz with an LF noise corner of 1 Hz. This is a damn quiet power supply and it is very stable.

4], “Well we all know about the pitfalls of excessive feedback”. With this I do agree. You have to know what you are doing when you design wide bandwidth circuits. I test my designs on a 250 MHz scope with a wide variety of loads to ensure that the design is unconditionally stable and therefore suitable for any load.

5], “Motor control has different requirements to a preamplifier” I would be pleased if you would explain these different requirements.

6], “The last we heard of it was that “is back with **** for the moment for some adjustments”. Actually it was returned to me for checking as Hugo was getting strange voltage readings on his multimeter. On receiving the power supply I put it through a rigorous test procedure to see if I could reproduce the readings that Hugo was getting. The power supply was fine and was operating correctly for a whole week of soak testing and the general abuse I subject my power supplies to under test. Hugo then informed me that his multimeter was faulty and I sent the power supply back. He also mentioned this in his posts on this forum yet you have still suggested the power supply was faulty on your website. This is clearly untrue and very unprofessional.

7], “Yes indeed! We are professional designers with a long pedigree”. I cannot comment on this statement, as I do not know you. However I do question the professional integrity of the statements you have made about my power supplies on your website as they are erroneous.

Perhaps you would show me that you are capable of acting professionally by removing the erroneous comments from your website.

To the site moderators.
I am sorry to have to bring this issue to this forum thread but I feel that having been the subject of the above issues, that are related to posts on this thread, I have a right of reply.

Paul Hynes.

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Over to you guys now... Can we please have it so that one set of questions is answered properly in their entirety before another set are asked? :)

Otherwise, the discussion is impossible to follow.

Cheers!

Marco.

Guys

I don't see any direct questions there. I have changed my website for the fourth time though (!)

I assumed that ( 04-07-2009, 09:57 AM "I can only go on what he (Paul) has told me" and later 04-07-2009, 01:10 PM "eg bandwidth limitation, RF rejection, transient response. " ) must have been fed from Paul. But I can see that it may not be, although it was a reasonable assumption. On that basis I apologise to Paul and have changed my website for the fourth time!

The integrity of the SL1200 and all it's future developments are more important than mere semantics! However my comments on the Timestep Power supply, it's inherent suitability, and it's design for the SL1200 are correct, and we are totally committed to the SL1200. Onwards and upwards!!

Regards

Dave

Dave,

I now understand how you assumed certain information came from me. In fact it did not with any direct relation to your power supply. Shuggie asked me for a power supply and I provided him with one. He has been using my regulator modules for years, for various functions, and he has also been active on forums discussing power supply regulation from time to time. He has compared the results of using my regulators against other regulator types and formulated his opinions along the way. You can understand why I was so concerned that I was being quoted as saying things I had no comprehension of.

Thank you for changing the website.

Regards
Paul

Thanks to all the forum members for their mediation efforts.

Regards
Paul

Yes, thanks from me too! I think we or I was getting lost in the woods. Thanks to a certain person (you know who you are) who pointed out that the assumption I had made, may not have been as clear cut as it once seemed!

Regards

Dave