It looks like you have not followed the topic, me and Demian were talking about solid state device amps with zero feedback loop.
The tube amp has a THD of 0.8% at 8W power output while the Pass F1 design has around 3% THD at the same power output.
Do you think you can get much lower THD with zero feedback loop solid state power amp?
Then, if you care about IMD probably both have low IMD since there is no feedback loop.
And finally, do you think the Pass F1 sound so bad? Worse than a 0.00001% THD amp with tons of negative feedback?
I don't believe, I suggest a listening comparison, you might have a big surprise.
Back to AK4499, which values of capacitance between VREFL and VREFH you folks think appropriate? Datasheet suggests 2200 uF // 0.1 uF, but the eval board uses only 220uF. And which kind of capacitor is most suitable for this position, normal electrolytics or low-leakage ones like Nichicon UKL?
I can do it, provided you specify who is the beneficiary of the "sound chaacteristics" results. I can do it for myself, but not for you and your customers, with any degree of confidence.
IMD has nothing to do with the feedback loop. It exists with or without feedback and is the result of the same nonlinearities in charge with HD. Enough feedback decreases IMD together with HD.
trung224,
AK4499 eval board is actually populated with single 470uf caps, what appear to be UCC standard types. The schematic shows two 220 uf in parallel.
What those caps do depends in part on whether or not the 10-ohm resistors are there. In any case, its a sensitive location for caps. To the extent they have a characteristic sound, IME it can be heard at the dac output.
AK4499 eval board is actually populated with single 470uf caps, what appear to be UCC standard types. The schematic shows two 220 uf in parallel.
What those caps do depends in part on whether or not the 10-ohm resistors are there. In any case, its a sensitive location for caps. To the extent they have a characteristic sound, IME it can be heard at the dac output.
As I said I have not measured THD and IMD (F1 data is from PASS website), I assume the IMD is low enough because there is no phase shift between input and output since the loop is open.
If you are interested in the IMD of the F1 please ask Neson Pass and not me.
BTW, I have never listened to the Pass F1 but surely I would get it with its high THD rather than a 0.00001% THD power amp with lot of negative feedback.
Sorry but I'm not interested in such that speculations.
Maybe Evenharmonics could be interested.
And I have no customers, sorry.
I have a different idea on this, the phase shift in the feedback loop IMHO increases the IMD, I'm with Nelson Pass.
Then why asking for?
No, only a business official registration for the purpose of handling DIYAudio Group Buys.
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I have read the paper several times before you linked it, but maybe I was not clear: I don't own the F1 amp so I cannot measure anything.
But then again, I would choose Pass F1 on trust.
Possible only for small amounts of feedback (that's why I said "enough"), and has nothing to do with the phase shift, but with your co-national Volterra series.
Please, read carefully my post.
I did ask Evenharmonics to predict the sound characteristics because he claimed to be able.
I don't believe in such that speculations, then I asked him to share his conclusions.
And yes, handling DIYAudio Group Buys.
Maybe you have not read carefully so I repeat:
"Usually I have lost money with these GBs rather than get a profit.
If I had a commercial interest I certainly wouldn't sell a better oscillator than the NDK DuCuLon (around USD 2000), in the region of the BVA 8607 and the BT ULN (several thousands of USD), and in class with the MSB Tech Galaxy Femto Clock (USD 19000) for EUR 228 (149 for the board + 79 for the crystal)."
It might be ok for sackbut music
Or for classic midwest music Boy Dirt Car - Forms Forced Surrender - YouTube (courtesy of SW).
And I said I am able to do it too, and volunteered to do so, what's the problem, are you interested specifically in EH results?
Please avoid insults, as until now I have avoided insulting your fetishist measurements.