John Curl's Blowtorch preamplifier part II

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#86,808
I was curious as to what the term might mean. I have not made or heard any DAT recordings in years, but did do quite a bit of work with them when they first come out. Sure beat using that big SONY PCM box fed into a U-Matic video deck.

Honestly don't remember much about the sound of DAT, just remember learning not to push the levels, like we did on analog tape.
 
#86,810
Pano said:
I was curious as to what the term might mean. I have not made or heard any DAT recordings in years, but did do quite a bit of work with them when they first come out. Sure beat using that big SONY PCM box fed into a U-Matic video deck.

Honestly don't remember much about the sound of DAT, just remember learning not to push the levels, like we did on analog tape.
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Do you remember the aural exciter? That thing does a fine job of smearing.
 
#86,811
Pano said:
I still don't know what that is, in audio terms. Can you describe?
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I don't have instrumentation to measure it, but I have heard it and smearing sounds like as good a word as any for it. Its probably something like a kind of phase noise. That is, if you took a very pure, stable sine wave at some fairly high audio frequency, and modulated the phase of it with noise and/or deterministically, you might end up with the original signal almost exactly if averaged over a few cycles, where averaging would LP filter out the phase modulation or phase noise. But if you took the wave and looked at it cycle by cycle, you would be able to measure phase or frequency variation, perhaps variation over a small fraction of a cycle. It sounds smeared in time, not in frequency, at least to me. Maybe the way human minds recognize or sense frequency is not particularly sensitive to that particular type of phase variation at high frequencies? I don't know.
 
#86,812
morinix said:
DAT tape recordings and Behringer actives! I'm trying not to spit my tea across the room from chuckles. Nothing really wrong with this level of audio but the unending haranguing of the likes of Curl and Marsh over ABX and all? I've heard a Constellation system. Heard M2 also.

I worked at Alesis all through the 90's so I've had a gut full of DAT and active speakers. SY and MAX sorry guys, it doesn't hold a candle anywhere near the level Marsh and Curl can reach.
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Robert, my focus is in bringing 'ordinary' systems up to par....the 99% of the audio market.
I have installed/heard the likes of Genesis 1 and matching line level gear and heard/repaired plenty of other Hi-End gear, so yes I do understand the difference.
And there has been nil disparaging of JC or RNM from me.
Interesting anecdote, I dropped into a friend's Hi-End store to return some repairs.
From the front room/counter area I could hear the main demo room system running.
I remarked that the sound was unusually good and sounded 'right', and 'what is it ?'.
The answer was, 'Oh, that's a new amp we have in, a John Curl Parasound amp.'

Anyway, the sound I now have is better than any other system I have heard to date, in terms of clarity, definition and imaging, both l/r and depth imaging......the speakers totally disappear.
Added to the above, is musical 'correctness' that I have not heard in any other system, and the result is a 'lens' in on the original master, without subtraction or embellishment....ie the PB system gets right out of the way.

No added glare, harshness, boominess etc or other signatures....recordings are presented as signed off on, and the recording chain is clearly evident on recordings, ie recordings can have subtle (andnot subtle) signatures that persists throughout the album.
The Redbird recording mentioned has a wrong vocals 'essing' glare that is common from track to track, is this the DAT 'smear' that you speak of ?.
None of the rest of the sources sound quite right either...it is a pleasant enough album but obscured by a layer of 'dirt' that don't belong.

I am awaiting confirmation, but I believe my filters are used in this THE HEAVY HITTERS Acoustic Project - A Little Bit Closer recording, and if so for sure on bass and guitars.
Do yourself and take a preview listen, better still fork out USD $8.95 and download the Wav file version.
I find there is something unusually 'right' and 'warm/solid' sounding about this album.
The guitar/vocals, bass and drums perform as Vdelli also...worth Youtube searching.

Dan.
 
#86,813
Max, I generally listen to B products, rather than A products. It is just too much trouble to get the A system running, it doesn't have remote control, and it often is annoying when it shows problems in program material. I now am using a 20 year old HCA-1000 (125W) 2 ch amp. I am driving 5 speakers with it at the same time. Two front, two back and a sub. Works OK for me, in fact, very balanced for the video and even most fm input material. It doesn't take a fortune to have pretty good hi fi, but it is not as good as my A system which might cost 10-25 times more.
 
#86,814
Markw4 said:
I don't have instrumentation to measure it, but I have heard it and smearing sounds like as good a word as any for it. Its probably something like a kind of phase noise. That is, if you took a very pure, stable sine wave at some fairly high audio frequency, and modulated the phase of it with noise and/or deterministically, you might end up with the original signal almost exactly if averaged over a few cycles, where averaging would LP filter out the phase modulation or phase noise. But if you took the wave and looked at it cycle by cycle, you would be able to measure phase or frequency variation, perhaps variation over a small fraction of a cycle. It sounds smeared in time, not in frequency, at least to me. Maybe the way human minds recognize or sense frequency is not particularly sensitive to that particular type of phase variation at high frequencies? I don't know.
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I'm hearing you, iirc JC has referred to this as PID (Phase Intermodulation Distortion).
This time 'instability' is not wholly due to system clocking, and the lousier (self noisier) the PB system is, the worse the subjective outcome is.
This PB system 'phase noise' manifests as an obscuring layer over the whole recording, and vocals and highs are in particular adversely affected/effected, causing hardness/glare/splashing.

The spectral nature of this 'phase noise' also causes a subjective EQ/timbre change that tone controls/graphic/parametric don't/won't fix.
Further changes include reduction of precision of image l/r and depth placement and size.

My filters address this problem directly.

Dan.
 
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#86,815
john curl said:
Max, I generally listen to B products, rather than A products. It is just too much trouble to get the A system running, it doesn't have remote control, and it often is annoying when it shows problems in program material.
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Hi John, hmmm, ime that 'annoying' revealing of programme material can be due to system 'reactiveness'...ie slight but wrong/false emphasis on transient sounds that ultimately draws attention to itself.
I am sure we have all heard gear that sounds wrongly 'transparent' and 'detailed'....on initial listen sounds 'impressive' but ultimately drives the listener out of the room.
I'm not accusing your system of this of course, just sayin'.

BTW apart from Tv/Video and FM, what kinds of music do you listen to ?.
Could you give some examples of your favorite tracks for evaluation, and for enjoyment please.

I now am using a 20 year old HCA-1000 (125W) 2 ch amp. I am driving 5 speakers with it at the same time. Two front, two back and a sub. Works OK for me, in fact, very balanced for the video and even most fm input material. It doesn't take a fortune to have pretty good hi fi, but it is not as good as my A system which might cost 10-25 times more.
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I am most interested to hear your A system one day, I have heard one of your JC amps and it unsighted impressed me favorably from the next room.
I get your point of 'pretty good' is good enough most of the time, and same for me.

My endeavors are with 'common/real world' lesser systems, of next to zero outlay, and the results I have are disarmingly good, and in absolute terms right up there with the best that I have heard in the terms I have described.

I find that your approach/criterion of minimal noise (of all kinds) and low IMD/lowish THD is the correct way of course, BUT I also find that the subjective problems of 'normal' systems can be also ameliorated at a stroke, very interestingly.
Caps, resistors, wires all have influence, and these 'signatures' can be 'erased' all the way back to the master.
Well designed gear does this, but there is another method.

Regards, Dan.
 
#86,816
morinix said:
BS. Go here The Secret Society of Lathe Trolls • View topic - 100% analog and start about the 12th post down.


As far as studios equipped with preview decks that can do all analog mastering in the USA there is:
Salt Mastering - Mastering for CD and Vinyl - Brooklyn, NY
Masterdisk - Your music deserves the best.
STERLING SOUND - Audio Mastering Studio - New York City
The Mastering Lab | closing - The Mastering Lab

...and possibly a few more I've forgotten in that list as well. "
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While all analog mastering with a preview head has been common for a long time the digital systems were used more simply because of the need for high volume production and the most streamlined processes when vinyl (LP?) was king. It was possible to use a preview head + 1/2 speed mastering etc. and I believe a lot of the British stuff was 1/2 speed mastered. However for Capital records to get 1 million disks out in very short order its about fast production so the same track was cut many times. Often from dubs of the final mix/master tape with the mastering eq's baked in.
 
#86,817
jneutron said:
The issues I see:

1. That meter is incapable of separating out the in phase resistive losses caused by proximity effect from the in phase losses caused by skin effect. Had they used a true loop instead of a flattened parallel wire construct, it would be better, the send and return conductors are communicating magnetically. (see below for proximity effect elimination).
2. For that length of wire loop, there will be magfield enhancement caused by the length to spacing ratio, this will also modify the inductance vs frequency, therefore the proximity effect losses vs frequency will be a function of frequency. (this enhancement is noted as one of the three components of the terman equation.)
3. A truly scientific evaluation (which was NOT the purpose of that specific writeup) would have used several different gauges of copper, several aluminum, entirely round loops, and variation of loop diameter. That would have allowed a rigorous verification of the accuracy of the measurement.

All that said, it was a very good writeup nonetheless. Thanks for it.

If I were doing that test again, I would made a coaxial cable using a #10awg core conductor and 3mil thick tefzel heatshrink insulation, short it at the end, perhaps 10 foot long.

Did it so long ago, I'm not sure where that wire is anymore. Probably tossed it.
Edit: Forgot to mention: Since the outer braid of a coax has no internal magnetic field caused by the outer braid, the coaxial construction will eliminate proximity effect altogether on the core wire. Also, they did not mention that the loop CANNOT be near any metal at all, magnetic and non-magnetic. Eddy currents in any nearby conductive object will be interpreted by the meter as an increase in the DUT resistance.

John
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I own own several network analyzers. Depending on what I find, I will use either the single channel Anritsu MS3401A and/or HP 8753D for higher freq resolution and accuracy.

years ago I used 75 ohm coax - 10 cables in parallel - for a speaker cable. Worked very well.

Thnaks for the extra details --- RNMarsh
 
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#86,819
RNMarsh said:
I own own several network analyzers. Depending on what I find, I will use either the single channel Anritsu MS3401A and/or HP 8753D for higher freq resolution and accuracy.

years ago I used 75 ohm coax - 10 cables in parallel - for a speaker cable. Worked very well.

Thnaks for the extra details --- RNMarsh
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Makes no sense if it's balanced though... unless you mix them up half and half.
 
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