John Curl's Blowtorch preamplifier part III

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Bill,
Okay, I see the claim about pink noise as an imaging test, which is something I could try.
Regarding LEDR, I am skeptical that that particular illusion would work for me. I have previously tried listening to simulated vertical, overhead, and behind effects played through stereo speakers and through headphones. It never sounded like motion to me, just sounded like varying EQ and an phase stuff, but always coming from the speakers, or stationary inside my head with headphones.
 
Mark4... The reverb tails you refer to - if this is what it sounds like it is, it should be readily measurable? Did I miss some measurements?

In principle, everything must be measurable. Still need to know what and how.

In this matter, I believe the need is to measure the accuracy of the levels of the first bits. A long work. Do we have to fear any dynamic recovery problems ?
 
Does anyone know who designed the IC inside the Apple lightning or USB-C headphone dongle? It appears to be a custom part for Apple. Maybe Cirrus?

I find the performance impressive for the size and power consumption.

That might be true about the chip but... The dongle, it's the stupidest blitheringly **** slap in the face to the late Steve Jobs as you could possibly make. I can't imagine a more repugnant, anti-apple ethics, thing to do. It's the equivalent of making a Tesla car that has to tow a trailer that's the battery it won't run without.
 
I believe the need is to measure the accuracy of the levels of the first bits.

One of the DACs that loses low-level reverb tails is DAC-3. Measurements performed at Stereophile show ENOB = 21-bits. There are no missing bits as measured however Sterophile does it, and 21-bits is pretty much SOA.

It seems from my experiments with adjustments to dac registers and or AK4137 DSD sample rate, that reverb tail loss is linked to I2S/DSD clock jitter and or dac VCO jitter as function of DPLL bandwidth, at least for S-D dacs of the type most of the tested dacs are. Also, Allo Katana RPi hat DAC reproduces the tails pretty well. Interestingly, the best reverb tail reproduction of dacs included in the listening tests came from a TDA1387T based dac named phiDAC by its designer, our own diyaudio member Abraxalito (Richard). It was clocked by a Chinese CM6631A USB to I2S board. The dac chip itself is obsolete, but Abraxalito has some in stock. He is offering full kits for assembling 10 dacs for $50. So, a nominally $5 dac won that particular competition.
 
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It's hard to describe - I can sort of hear what it's supposed to do, but the illusion collapses to 2 speakers as soon as I try and listen to it.
I assume it's that something in my brain knows it's a fake, and won't play ball. A bit like, once you have seen past an optical illusion, you can't see the illusion any more.
 
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someone here mentioned a DAC that can be had as just pcb all the way up to completed unit without case.
I cant find it ... which was it?

It had some characteristics that should help with low level details like reverb/room sound and decay.

The lack of low level detail of DAC3 might be related to a dynamic range shift upward with the bits to achieve their greater head room at peak levels.



-RNM
 
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TNT

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Mark4... The reverb tails you refer to - if this is what it sounds like it is, it should be readily measurable? Did I miss some measurements?

On the localisation (soundstage, stereo image...) point - people hear differently. The illusion works well for some, not so much for others, it's very much a subjective phenomenon. Same with surround sound stuff. Perhaps it's no surprise that small effects would make a difference to different people therefore - but that should still be measurable.
Have you tried running mono information in dacs?

Is there any reason why this is not level linearity? If you have 9 technically well behaving ones, and the 10th one expose more "reverb tails" I would guess it is because it's compressing (as appose to expanding or linear).

//
 
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It? DAC-3? I did not mean that DAC-3 has linearity problems - my understanding is that it hasn't.

Your understanding is correct, it does not have linearity problems. It also does not reproduce audible low level reverb tails. Clearly the problem is not due to linearity. You appear to me to be thinking like an analog guy, no offense intended, understanding analog is a good thing. However, with S-D dacs it might help to try thinking like a DSP guy.
 
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