John Curl's Blowtorch preamplifier part II

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By way of an example, I have some Caro Mitas recordings (SACD) of Pratum Integram using B&K mics and custom electronics. These recordings are pristine and I just dont see that they are sterile, or need any added ingredients. I have quite a few other very good recordings - no extra sauce needed IMV. I'm using an Oppo BDP103 - which was a big step up from my Marantz (old player from 1998 low end) Pioneer and Sony CD players.
 
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I also have some very 'organic' recordings - one of them is Paul Simons 'Rythm of the Saints' and some of Ry Cooder's recordings - very good to my ear. There are sterile recordings - Fourplay can fall into that and Gordin Goodwin recordings sound just too perfect. But, adding something on top of that isnt going to help IMV - they are just plain overcooked!
 
If I can get some ferrite beads I'll measure the distortion induced. They will cause some distortion, the questions are how much, under what conditions and is it audible.
Ok, looking forward to that.

IME, fitting a ferrite power cable clip-on filter, to a line level interconnect adds a low level nasty distortion.
Yes, a layer of dirt is removed, and there is improved clarity.
However, this perceived clarity may be partly due to higher order distortion harmonics.
Extended listening with these ferrites fitted ultimately drives me out of the room.

Different ferrite formulations may differ, and their distortions would be interesting to quantise.


Dan.
 
Quick question.
Typical amplifiers have a capacitor in the shunt arm of the NFB signal attenuator.
This cap is typically a standard polarised electro.

Has anybody substituted a Bipolar (NP) electrolytic cap in this circuit position and measured differences ?.

Dan.

PS - Are NP and Bipolar correctly interchangeable terms ?.
 
Quick question.
Typical amplifiers have a capacitor in the shunt arm of the NFB signal attenuator.
This cap is typically a standard polarised electro.

Has anybody substituted a Bipolar (NP) electrolytic cap in this circuit position and measured differences ?.

Dan.

PS - Are NP and Bipolar correctly interchangeable terms ?.

If you check the datasheet, IIRC the LME circuits used an NP cap there at least sometimes. In one case it looked a 100uF film cap at first:eek:.
 
Dont have to agree Scott, still no justification to say the man is not grounded... :rolleyes:

That's what I said. Case in point the wooden blocks, tried it heard nothing and eventually either my components were not up to it or it was the wrong wood.

As I remember there was a tightly knit posse at Ayre that heard just about anything "within minutes of walking into the room". Isn't Boulder in almost the same place? I'd love to see the two posse's get together, you know, for a little of the no peeking. This will never happen, and if it did it would end up a non-commital draw with smiles all around.

They both make what appears to be good products for sure.
 
If you check the datasheet, IIRC the LME circuits used an NP cap there at least sometimes. In one case it looked a 100uF film cap at first:eek:.
Thanks, ok so somebody there knew something,.....perhaps ?.

My question was more regarding typical mid-fi stuff.
I have read the argument that the NFB voltage will never be sufficient to cause reverse breakdown/leakage of the NFB shunt cap.


Dan.
 
I discussed it with Ovidos when he was doing his preamp. One SMD inductor (.06 Ohms DC) for each 4 - BF862's and there were no problems. No sure of the exact ones he used. It's not just RFI, massively parallel devices can be underdamped and make (usually) something like an RF Colpits oscillator with the interconnects acting as L's. The lossy L on the gate kills the forward gain at MHZ. If you obsess 10 turns of #32 wire on a 1K might work too.

A customer had a 1024 channel EGC (JFET op-amps) board spontaneously oscillate which was immediately fixed by gate dampers.
Understand the need and purpose of the grid stop resistor how big do they need to be based on what ?
 
magic sells better than science

That's what I said. Case in point the wooden blocks, tried it heard nothing and eventually either my components were not up to it or it was the wrong wood.

As I remember there was a tightly knit posse at Ayre that heard just about anything "within minutes of walking into the room". Isn't Boulder in almost the same place? I'd love to see the two posse's get together, you know, for a little of the no peeking. This will never happen, and if it did it would end up a non-commital draw with smiles all around.

They both make what appears to be good products for sure.
Agreed the block thing may have an effect if say the carpet is wool and humidity is low generating a static electric field . How different wood would effect the sound is maybe the moisture content and natural oil but that is a very long leap that Kierkegaard would have said WTF. Placebo work for some. :deer:
 
I also have some very 'organic' recordings - one of them is Paul Simons 'Rythm of the Saints' and some of Ry Cooder's recordings - very good to my ear.
I'm talking of audiophile in the sense that they are marketed as such, the label has made a fetish of it. Some peculiarities of the few I have - all 2nd hand, bought el cheapo - is the treble being heavily butchered, and the bass pumped up - a classical CD has remarkably anaemic violins, every ounce of zest has been excised, perhaps from fear the listener will be offended by shrieking tones ...
 
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