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Old 16th May 2004, 05:32 PM   #21
Sheriff is offline Sheriff  United Kingdom
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Default Will you post a few comparitive graphs?

Dear Mr Madsen,

Lets try and compare apples with apples.

Leaving the subjective issue of sound quality to one side for a moment.

Why keep us guessing as to the detailed specs of your proprietary modules?

Put up a few graphs that compare specs of your modules using the same criteria as the ones detailed in the Hypex UcD pdf file as found on their website, the mueta data as detailed on their website - and the B&O data.

I assume that you posses an Audio precision to conduct the tests..?

Surely there is nothing to be ashamed of with the technical performance of your product..... Is there?

You never know you may get deluged with calls from people wanting to buy some from you.

Whatever the outcome, if you post the data or not, I believe that you are not helping your cause by being so secretive about the actual specs of your designs, and belittling the performance of other class D solutions.

Knocking the competition rather than promoting the benefits of your own product, is either the sign of a poor salesman, or a poor product. I hope that for your sake it is the former.

Nothing personal, just my outlook on things.

Cheers

Sheriff
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Old 16th May 2004, 05:38 PM   #22
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Dear Karsten,

...hm I find it very pitty you don't want to compare, by yourselve (!), the UcD with your own Class-D. Please feel free to take mine offer agin in consideration, I am really looking forward to your acoustical comments.

This is the best way to do a discussion, comparing A to B and vice versa. Otherwise we stay at the same level as "this amp does sound better the other one".

I agreed totally with Kuribo: Simple details like output filter/feedback take-off are also likewise provided by most designers, and discussion of such is not considered "giving away the store".

B&O, Mueta and in this forum links about the UcD patent, does tell a lot about this particuler designs. So they share the community with a lot of information. So I disagree with you that you share the same info as the above mention is companies.

Regards,

Jan-Peter

www.hypex.nl
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Old 16th May 2004, 06:02 PM   #23
km is offline km
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hi.

sheriff , yes we did measure thd , freq response ... with an ap and yes the specs are decent for sure.

we did send out the specs to oem customers but i still think there is little correlation between low thd and good sound quality.

this is based on real life experience comparing boards having much better specs (on paper) with our boards

too bad you could say you cant make you own comparison of sound quality.

jan-petter if you cant see from what i wrote long time ago what topology we are using regarding pre/post output fiter feedback you could be the only one (perhaps kuribo cant either...)

you may as you have done before make your own conclusions or asumptions based on whatever you like to think , im afraid i cant help you and im sure we dont want any cooperation with you either.

rgds karsten madsen - www.cadaudio.dk
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Old 16th May 2004, 06:21 PM   #24
Sheriff is offline Sheriff  United Kingdom
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Hi KM,

I realise that good specs do not always equal good sound quality.

After all how is it that there are so many valve amps out there - people enjoy the sound that they make.

Is this down to 2nd harmonic distortion...? Many customers dont know or really care - they just buy them because they enjoy them.

I do not doubt that your modules are good (I have not heard them so i am not qualified to comment). But it leaves a very bad taste in the mouth and gives me nagging doubts when you are backward in coming forward with any meaningful info.

Perhaps you could post the data that you sent to the potential OEM customer.

Combine this with the bashing that you tried to hand out re the ICE power modules in earlier threads......

From where i sit, it does not look promising.

I am sure that more people would consider your products if you were a little more open, and open minded about the way you do business.

Cheers

Sheriff
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Old 16th May 2004, 06:41 PM   #25
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Madsen,

When you have measurement data, please show it to us?

Probably it is secret, but I do not see why?

I can't remember myself that I saw something more technical info about your topic. But perhaps you can be so nice to repeat it again?

How can I make a conclusion about something where I don't know anything about?

In the past we have used the ICE500 a lot for several OEM customers, I am very satisfied about this product. Within a few months we will move to an own UcD 400-500W version.

In the past I have got a first version of the Zappulse from LCaudio (BTW for free!!!, Lars still many thanks), but there was somewhat too much EMC from this version. As far as I know LCaudio has this now very much improved, and this must be ok now. In one of the other Topics (Class-D versus Class-A) Lars did tell and show a lot of his design. He is one of the less designers who did design something by him self. Still mine compliments to him.

.....so I have some experience with other products.

If you don't have us something to tell/show we better stop with this duscussion, it has no sense anymore.


Regards,

Jan-Peter

www.hypex.nl
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Old 16th May 2004, 07:05 PM   #26
km is offline km
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hi.

sheriff, where is the so-called bashing of icepower you refer to?

and where is the >belittling the performance of other class D solutions>?

rgds karsten madsen - www.cadaudio.dk

ps. jan-peter you are right asuming that we dont wish to show or send you anything......
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Old 16th May 2004, 07:06 PM   #27
soren is offline soren  Denmark
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Quote:
Originally posted by km

i think its obvious for most of us that good specs tell only half a story (or less).
Well, I think it all depends... THD measurements at steady state operation will of cause only tell a part of the story, but it is a place to start. When THD, freq. response and maybe a 1kHz FFT is made, it's always interesting to try the real challenge: TIM, DIM, SMPTE, CCIF etc. Linearity under strongly transient operation tells a great deal about sound quality IMO. Music is often to be considered as transients.
But also other parameters are important/of great interest: Open/light/hard load operation. How much differs performance with e.g. an inductive load (quite important) etc.
Things as background noise doesn't matter much with a class d, as the noise flor often is a few V if implemented properly.

By the way, a THD vs. power at high frequencies, say 5kHz, with high measuring bandwidth, say 80kHz tells a lot about basic modulator linearity (and a lot of designs gives scary figures here).
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Old 16th May 2004, 07:24 PM   #28
IVX is offline IVX  Russian Federation
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Jan-Peter, you can just buy km's amps and make comparison vs yours, without any kind of permission. The truth is too much expensive? :-) I would be doing so, really.
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Old 16th May 2004, 07:27 PM   #29
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Soren,

I agree with you a good measurement is a place to start.
Flat frequency responce is very importend to have a neutral sound.

And something very importend is to have a flat THD curve thrue the whole frequency band. When the amp has a lot of feedback around 1K the THD is nice low but at 10K it is very bad because of the lack of loopgain.

The very nice thing of the UcD is has a flat THD curve. Thd at 100Hz is the same as 10kHz.

Are you not the designer of the Sorens Audio project?

BTW we get very far a way, at the moment, from the original topic;-)

IVX, ofcourse I don't mind to buy the Cadaudio amp, but I don't think I will get it when I order it personally.

Regards,

Jan-Peter

www.hypex.nl
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Old 16th May 2004, 07:29 PM   #30
km is offline km
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hi.

soren , did you have a chance to listen to different class-d amps?, if yes you have probably noticed that they sound quite different and the better spec type doesnt necessarily sound best (most natural , open or whatever way you want to describe it).

same goes for other types of amplifiers like sheriff points out , most tube amps dont really show good specs many of them sound better than transistor amps with far better specs

sheriff , im afraid that what you want to do is to substitute a real life listening experience with spec reading and im afraid i cant help you here (and im also afraid it wont say much after all).

listen to amps in real life and share your experience with the rest of us , ok?

what class-d amps did you listen to so far?

btw. feel free to email me if you have further questions.

rgds - karsten madsen - www.cadaudio.dk
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