audio-talk

Posted: **Mon Jul 13, 2020 12:38 pm**

You may as well go back to the origin

https://patents.google.com/patent/GB394325A/en

they only capture left-to-right level differences, not time differences

I would have thought the path length would allow them to capture the time difference as well as level difference.

Posted: **Mon Jul 13, 2020 3:55 pm**

Yep, there's a description of a few different stereo pickup techniques there, ranging from a Jecklin disc to Blumlein stereo, to mid-side using fig-8s for both. Some of those techniques are coincident, but not all of them.

The XY arrangement of mics you've mentioned, by design, cannot pick up phase information: Sound from any direction hits both capsules at the same time.
By contrast, if we were to space the mics out by 0.5m, sound coming from 90 degrees left would hit the left microphone 1.45ms before it hit the right. There would also be a level difference (from both inverse square law and aiming the directional microphones out a little).

It's my belief that level differences alone cannot convey an accurate stereo image, and the text in the patent appears to substantiate:

Directional hearing sense is due to phase and intensity differences between sounds reaching the two ears, phase differences being more effective for the lower frequencies and intensity differences for higher frequencies.

I'll do some digging around and see if there's any hard data.

Chris

Posted: **Tue Jul 21, 2020 12:39 pm**

For Owston next I'd love to see the 212 amp that Nick has up and running.

Posted: **Tue Jul 21, 2020 12:57 pm**

So would I, must try and see where it is as I never finished it, waiting on heater supply.

Posted: **Tue Jul 21, 2020 1:03 pm**

Nick wrote: ↑Tue Jul 21, 2020 12:57 pm So would I, must try and see where it is as I never finished it, waiting on heater supply.

Last time I was at your place it was on the floor under a pile of something or other.

Posted: **Tue Jul 21, 2020 1:35 pm**

That doesn't narrow it down much !

Posted: **Tue Jul 21, 2020 2:23 pm**

There is a diference, Nick’s building a professional project for which he wants the best filament supply so its not as if it’s a fun project for a not so busy or pressurised. diy enthusiast. Nick’s conceptions stand for solid reliability and hi end quality from first to last without compromise. You cant place your conscerns about whether he cna produce his amp out of a hat. He needs the filament supply which in turn has to meet Nick’s demanding standard of quality and reliability.

Posted: **Tue Jul 21, 2020 2:57 pm**

Actually, I have sent all the bits on to Ian who I was building the amp for and he is getting someone else to try and finish it off. I am working at about 110% of capacity at the moment and have been for the last couple of years. I have a list of things I need to finish off and I just didn't have the time to do something that would take so much time in design and build. Lockdown has made it simpler in that I didn't have to get ready for a couple of shows over that time, but sales of power supplies are up about 40% so that time has been used up. Not spending two hours a day commuting has helped, but still more things to do that time to do them.

Likewise Andrew L who was working on the high current heater supply for the last couple of years has had no time either what with being a Keysight Jet setter, visiting his kids and everything else. I still have a phono of Ant's that I need to get to but haven’t yet.

Posted: **Sun Jul 26, 2020 7:51 pm**

IslandPink wrote: ↑Tue Jul 21, 2020 1:35 pm That doesn't narrow it down much !

Posted: **Fri Apr 02, 2021 10:33 am**

Nick wrote: ↑Tue Jul 21, 2020 2:57 pm Actually, I have sent all the bits on to Ian who I was building the amp for and he is getting someone else to try and finish it off. I am working at about 110% of capacity at the moment and have been for the last couple of years. I have a list of things I need to finish off and I just didn't have the time to do something that would take so much time in design and build. Lockdown has made it simpler in that I didn't have to get ready for a couple of shows over that time, but sales of power supplies are up about 40% so that time has been used up. Not spending two hours a day commuting has helped, but still more things to do that time to do them.

Likewise Andrew L who was working on the high current heater supply for the last couple of years has had no time either what with being a Keysight Jet setter, visiting his kids and everything else. I still have a phono of Ant's that I need to get to but haven’t yet.

For those who might be interested, Colin Wonfor is now working on this amp for me. Because the PS was going to be so big and heavy he has designed a SMPS for it. It will be some time before I get the finished article.

Posted: **Fri Apr 02, 2021 10:58 am**

Number one rule of contract work. If you don't want to do what the customer wants. Convince him he wants what you want to do (or even better you have already done)

Posted: **Fri Apr 02, 2021 11:53 am**

Well there was a time when I would have thought, “SMPS, too noisy, can’t be any good “ However having seen the specs on the Benchmark AHB2 and having heard one, its clear to me there are SMPSs and there are SMPSs . . . .

audio-talk

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