John Curl's Blowtorch preamplifier part II

[keantoken]

Keantoken, you might find this post interesting (as well as the whole thread): http://www.diyaudio.com/forums/power-supplies/226070-network-analyser-measurements.html#post3340903
I can't compete with Elvee, though ;-)

I have always been fascinated with the inductance cancellation. My question is how feasible would it be to do on a PCB? How hard is it to get at least a 50% reduction in inductance? Probably easier with SMD devices. And then, do the extra coils couple to other fields in the vicinity and pick up interference?

 

[Kastor L]

If its not part of the original signal then its distortion .....

Then a V-shaped frequency response is distortion as well, this only leads to severe confusion, imho.

 

[fas42]

Look up linear vs. non-linear distortion ...

 

[KSTR]

I have always been fascinated with the inductance cancellation. My question is how feasible would it be to do on a PCB? How hard is it to get at least a 50% reduction in inductance? Probably easier with SMD devices. And then, do the extra coils couple to other fields in the vicinity and pick up interference?

See the linked thread for these question if you haven't already. Papers from the original authors there.

 

[fas42]

Every now and again one bumps into a website which is very satisfying to visit - 100% meat so to speak - and this is one of them ... Fourmilab

Just thought I'd throw that in ...

 

[a.wayne]

Then a V-shaped frequency response is distortion as well, this only leads to severe confusion, imho.

Only if you want to take it out of context , want confusion , why are really low distortion amplifiers least liked and 1% can be considered good sounding ...

 

[vacuphile]

I use these :Mundorf - Inner Excellence
I am happy with the result but why that is i did not research in detail.
I also used DNM slit foils.
I am a friend of Dennis Morecroft. the inventor.
He told me it is because it avoids eddy currents.
I do not have any data though.
This needs more research i guess.

Referring to the Mundorf link: I always think it is self-derogatory to call capacitors 'audio grade', this in view of the very limited frequency range audio covers.

What I find curious about these slit foil capacitors is that the manufacturer does not provide the data which would allow one to form a well based decision, that is, ESR or allowed ripple current. If the slit foil would work, it should translate into a lower than usual ESR. What also makes me wonder is that the patent has expired, but no other manufacturers produce them.

 

[Pano]

... but i cant get past (horns)their coloration, shout and lack of coherency ....

That a lot like someone saying he doesn't like cone drivers because of ABC and dome tweeters because of XYZ, planar because of whatever, etc.

In each of those categories there is good and bad. If you once hear a horn system with decent horns and the right crossover - you may may become addicted.

 

[a.wayne]

I'm audio agnostic , never rule out anything ..

 

[gerhard]

I was meaning at 1MHz and up. I've never actually seen measurements of electrolytic impedance in the MHz range before. I'm curious what the losses look like, if the ESR remains constant up to 10MHz or so.

The Black Gate ad said that electrolytics go "dead" above 200MHz. I'm curious about that too, but at the same time I'm wondering who would try to use a lytic to filter frequencies that are only typically filtered well by feed-thru caps?

I have measured it some years ago.

< http://www.hoffmann-hochfrequenz.de/downloads/experiments_with_decoupling_capacitors.pdf >

to 180 MHz, though not many types.
adresses in the .pdf are outdated.

regards, Gerhard

 

[john curl]

Very nice work, Gerhard!

 

[keantoken]

Thanks for that info Gerhard.

 

[john curl]

We once talked about hi end audio (design) on this thread for years, so I might remind people in the SF Bay Area that there is a hi end audio show this weekend, located near the SF Airport. I doubt that I can make it, due to the hassle of not being able to drive that far, but I hope others will go, if only to be exposed to what I have discussed here for more than 10 years. It is actually possible to hear great hi fi today, still.

 

[gpapag]

Thank you Gerhard

George

 

[Joachim Gerhard]

Another subjective review :Parasound JC 3+ Phono Preamp | The Absolute Sound
How did you do it John ?
Buying a full page add in colour ?
I do not think so.

 

[john curl]

I haven't seen the review yet, Joachim. My copy of TAS should come soon.

 

[a.wayne]

Another subjective review :Parasound JC 3+ Phono Preamp | The Absolute Sound
How did you do it John ?
Buying a full page add in colour ?
I do not think so.

Ahhh come on you know this is an afternoon work for John and represents nothing to what can be done when he's serious ..

 

[simon7000]

Actually the thing that first struck me was how quiet the design is. So it to me is an accurate review. So maybe there may be a future for all IC designs.

(Of course JC did use an interesting technique to reduce the noise, so simple, yet so effective.)

 

[a.wayne]

Why fixed MC and variable loading John , advantage with straight fix ..?

 

[a.wayne]

Thats what Scott said ....

Actually the thing that first struck me was how quiet the design is. So it to me is an accurate review. So maybe there may be a future for all IC designs.

(Of course JC did use an interesting technique to reduce the noise, so simple, yet so effective.)