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Old 1st January 2010, 08:21 PM   #631
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Syn,
I feel you are critiquing something you don't fully understand. You have seen a schema of the RTP phono stage, but I suspect know nothing of the overall design and full specs.

I suggest you check out:

http://www.vacuumstate.com/fileuploa...brochure_b.pdf

and see that there has been some serious engineering taken place. And look carefully at the distortion numbers and graphs on Page 4. If you can prove you can hear the difference in distortion between the RTP3D and one of your designs, I'll buy you lunch anywhere you choose.

You critiqued my use of 22ohm stopper R's in the MAT02 inputs, saying they add noise, and I replied it stops oscillation. You said I should be able to fix that with layout - maybe you could, but after two weeks of work it was easier to add the R's. The preamp has significant gain at 3MHz, and the phono and line stages are in one box and all inputs and outputs are at the same end.

Last point, I assure you I can clearly hear the difference between regular magnetic end cap R's and the Dale/Vishay non magnetic R's - we heard it first in our SACD player Upgrade module, and proved it in our tube gear. For someone who mostly uses the PC to simulate circuits, how can you critique my perceptions? Would you not use the best possoble parts, costing allowing?

Or am I just wasting my time talking with you?

Regards, Allen
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Old 1st January 2010, 09:09 PM   #632
syn08 is offline syn08  Canada
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Quote:
Originally Posted by Allen Wright View Post
Syn,
I feel you are critiquing something you don't fully understand.
Or am I just wasting my time talking with you?
Allen,

You have conveniently answered only the questions you felt comfortable with, avoiding some and without specifying the conditions. Not that it really matters, but care to specify distortions to allow an apple to apple comparison I specified the distortions at 20KHz and 20Vp output, you did at 1Vrms out and (not really sure, the graph is unclear) 1KHz. Though, no doubt a nice product and I'm sure it also sounds great.

Otherwise, if you put it this way, then yes you are wasting your time with me. Good luck listening to the non-magnetic resistors and make sure you better advertise this technological breakthrough finding, together with the "atomic power station quality primary signal path capacitors" which I'm sure also make a huge difference.
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Old 1st January 2010, 11:45 PM   #633
brianco is offline brianco  Ireland
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[QUOTE=syn08;2031049].........;... and then you praise non-magnetic resistors, and other such, for their superior sound.

I (and I dare to say, anyone of my EE breed, not involved in the audio industry) would tell you that there are 1001 reasons, some of them many orders of magnitude larger, impacting the sound in your designs, before you can talk about (non)-magnetic resistors.


I cannot see that this sweeping statement is really justified. The requirements of EEs in non audio sectors are not automatically applicable in total to the audio sector's needs. Although I agree that there are a large number of factors to be addressed in the implementation of an audio design, there is no evidence that these considerations HAVE to be applied in any specific order. What may be a very small difference between components in a well equipped lab scenario, may have a disproportionate effect in the relaying of recorded sound to the ears via an audio equipment chain, whereas a large lab measurement differential may have a rather insignificant sonic impact.
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Old 2nd January 2010, 12:04 AM   #634
syn08 is offline syn08  Canada
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Quote:
Originally Posted by brianco View Post
I cannot see that this sweeping statement is really justified. The requirements of EEs in non audio sectors are not automatically applicable in total to the audio sector's needs. Although I agree that there are a large number of factors to be addressed in the implementation of an audio design, there is no evidence that these considerations HAVE to be applied in any specific order. What may be a very small difference between components in a well equipped lab scenario, may have a disproportionate effect in the relaying of recorded sound to the ears via an audio equipment chain, whereas a large lab measurement differential may have a rather insignificant sonic impact.
Maybe, but statements like in Allen's brochure (quoted above) are extraordinary, therefore the burden of proof, as having any support other than marketing tactics, is on the authors.

I've said this over and over again: I'm fine with statements like "according to our marketing studies, this spec [THD, noise, you name it] is good enough for 99.9% of our customers". I'm not fine with inflating the price by using expensive components, only for the purpose of filling in the product brochure with technobabble **. In this sense, I fully agree that open loop MC headamps are feasible and, as long as the vinyl distortions are not better than 0.1% anyway, they may offer all that customers are looking for, but I'm not fine with claims there's anything sonically fundamentally superior in such a configuration. Or that BJTs cascoded with a tube have some undisclosed superiority. Or that non-magnetic resistors make a difference here. Or about "atomic power station quality primary signal path capacitors".

Prove it, or keep it at the marketing level only. For the rest, see the Cable thread.
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Old 2nd January 2010, 12:35 AM   #635
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I use the LC audio low noise supply with 25mH coils in the supply pass to the ECHO with 4 BC550c. Hum is not audible, ear on speaker. As far as i can see you syn08 use also one coupling capacitor at the output. I do not like a lot of coupling capacitors in the chain because they take away some micro detail in the extrem treble. There are some coupling caps that are very transpatent though. I use Riva-Evox PHE450 and Vishey-Röderstein MKPs that are not super expensive. Michael will have no problem with coupling caps if he likes the sound as far as i know him and has given praise to cap coupled designs. Sometimes a cap adds safety or is an easy solution in a circuit with very high DC gain like my inductive shelve RIAA. The Echo is not state of the art in any way but sounds very good to my own surprise. It also costs very little so i thought it is a good beginners circuit for people that whould like to explore transimpedance solutions. I will try with higher bias but will not eleborate the circuit any further. I will now concentrate to find a way to DC couple the MPP Low Z to the inductive shelve RIAA and then develop a High Z version with fets. I have also an idea to lower noise in the Low Z MPP and will ultimately go back to fully balanced, also in the RIAA. That soution has a 3dB noise penalty of cause. My goal is 0.5nVQHz. I think with "normal" sensitivity speakers in the 86 to 91dB range that is fine to be not audible in the listening seat. Any improvement is wellcome. I said it before, i see no reason why your more aleborated phonostages should not sound exemplary. I just have not heard them in my home and you already found out that for me subjective apraisal is more importand then exeptional measurements. P.S. : my commercial phonostage for Spiral Groove is totaly DC coupled from input to output.
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Old 2nd January 2010, 01:28 AM   #636
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I connected the first time the MPP Low Z to the Inductive Shelve RIAA. For the time being
AC coupled with Rifa PHE450 2.2uF and 0.1 Uf Röderstein MKP bypass. How does is sound compared to the Echo? Well the Echo is very transparent and has a lot of speed but the MPP Low Z is more natural and easy on the ears. I am very happy with that combination and will listen more tomorrow.
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Old 2nd January 2010, 02:13 AM   #637
Pano is offline Pano  United States
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Sorry to butt into the thread (I've been reading, but not posting) however...

I am confused as to why speaker sensitivity would matter to hearing noise in a phono stage. Noise in the power amp, sure, because there wouldn't be any attenuation of that noise.

But the phono stage is ultimately going to be amplified then attenuated (volume control) to some nominal listening level. Whether that level is produced by speakers that are 86dB@2.83V or 98dB@2.83 volts the acoustic level is going to be the same - E.G. 84dB average. Noise is going to be XdB below that, no matter what.

Or am I missing something?
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Last edited by Pano; 2nd January 2010 at 02:18 AM.
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Old 2nd January 2010, 07:17 AM   #638
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Quote:
Originally Posted by panomaniac View Post
I am confused as to why speaker sensitivity would matter to hearing noise in a phono stage.


It doesn't matter to most grown ups. Younger "audiophiles" though sometimes turn the volume up to the max, glue their ears to the tweeters and demand that no hiss is heard. Playing some music at that very moment would probably teach them well.
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Old 2nd January 2010, 12:13 PM   #639
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We have discussed this here before. Whereas i agree with Panomaniac, syn08 takes his 97dB sensitive speakers, cranks the volume and then hears no noise over his ultra low noise phonostages. Impressive, isn´t it ?
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Old 2nd January 2010, 12:42 PM   #640
SY is offline SY  United States
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Problem with me doing that is that the overwhelming noise source is the thermal noise of the cartridge, and that's not something a phono preamp can do anything about.

Because of the power summing of uncorrelated noise contributors, as long as the preamp has a S/N 6dB below the cartridge, its contribution is negligible. That also goes for the RIAA compensation- I hear what Joachim is saying about Johnson noise from the inductor, but really, an RC network will not degrade the overall S/N if it's designed competently. For my own preamp, it causes less than a 0.1dB change in the noise, and doesn't suffer from the severe non-idealities of real-world inductors (and is a boatload cheaper, too).
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