I didn't "accept" this. I TESTED it. In 1980, there was at least one codec which was completely transparent to the best ears in the business. I repeat, a DBLT is a measurement.. You instrument is your DBLT panel. It has an accuracy that you can determine & should check regularly.Hans wrote:The tested very low noise preamp might be just a better design with a higher overload margin and maybe even a balanced design with a high CMRR compared to the other one in the test.
Apart from two ZTX bipolars, being steadily improved with modern production techniques, all active components in Wayne´s circuit can be modern components from today´s industry, not comparable what was available some 30 years ago.
The circuit is balanced, I agree with Wayne the "magic" advantages of that topology, and CMRR will be very high too.
There is just one thing of concern. The overload margin being only ca. 16dB ref 5mV@20kHz, exactly in the high frequency region where scratches causing sharp clicks, may cause a serious overload.
Reducing the gain of the head amp quite a bit, would inversely increase the overload margin at the higher frequencies.
Last but not least, I'm amazed by the ease you accept positive listening results from an ultra low noise preamp, yet having great difficulties in accepting that A/D/A in the signal line of a Pick-Up may change the listening experience.
Here's more from DBLT101.
For something like the effect of a codec on your vinyl playback chain, you do ABC tests. 2 of these 'presentations' are the same but you NEVER tell your panel this or say they are to find the odd man out. You just ask them to rank the 3 presentations and give them a score without telling them what the test is about or what they are listening too. The true golden pinnae will rank the odd man either top or bottom and say the differences are small for the other 2.
You repeat the test 3 times. Each test may take up to 1/2 a day and only 1 person is tested at a time. Anyone who gets the same odd man in the same position 3 times is not deaf. There is a 1:9 chance of him guessing. Apologies to the statisticians reading this but this is probably the quickest way to get useful statistical significance.
You IGNORE the results of anyone who puts the odd man in the centre. They are deaf for the purpose of this test and not worth testing the 2nd & 3rd time.
THEN you ask which of the 'presentations' is preferred ... and sometimes this gives the most surprising results of all. Only the opinion of true golden pinnae counts. For da wannabe Golden Pinnae, you just tell them LOUDLY AND REPEATEDLY, your stuff is Hand Carved from solid Unobtainium by Virgins.
I tested the effect of brickwall filters in those days and found that off those who could tell the difference, ALL preferred the bandlimited signal. I was surprised to find all other properly conducted tests also came up with the same result.It can only be regarded as astounding how music still sounds after all this "deformation" of the original sound, especially because of all the steep digital filters.
Some 30 yrs later, I was amused to find that ALL Bandwidth Limitation tests conducted since then came up with the same results. (including one with a 17kHz bandwidth)
Maybe I should market a black box which I'll guarantee to improve the performance of any chain in a DBLT. Nay. Only a very small population can actually hear the difference and practically none are audiophools. The Hand Carved from solid Unobtainium by Virgins label is a lot cheaper and lends itself to more marketing BS.
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BTW, I did say I thought the good performance of my device could be due to other stuff besides its ultra low noise .. eg its overload performance.
Remember, a vinyl playback system has HUGE distortion which goes up with level & frequency. The HF distortion goes up at 18dB/8ve. In this situation it is highly likely that a device with complementary characteristics might result in better sound.
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Hans, I'm interested to know which OPAs you feel are superior to 5532/4 and for what applications.
And you are certainly wrong in thinking good 1980's MC cartridges like the EPC100, AT37, Koetsu, the better Ortofons are worse than present day Golden Pinnae product.
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Paul, you are right about RFI/EMI etc.
Based on my listening tests on EVIL digital systems, I'd say 20dB below the 'theoretical' (?!) noise floor for everything else is worth aiming for. I've dabbled with phono cartridge design but with much less success than speakers & microphones. I worked with a couple of guys who had designed MC cartridges for LEAK in pre-Jurassic times.
They had quite a large collection of lacquers, some done direct to disc .. all stored (like Test Records) with detailed notes of how many times each was played and with what equipment. The noise level on these was certainly a lot quieter than on commercial records. No. I didn't use these for my listening tests as one of its precepts is the listener ALWAYS chooses his own music.