John Curl's Blowtorch preamplifier part II

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TeraHertz VNA? That's impressive. And even ADI only rents the stuff. Does anyone actually buy it?


At the time I think it was over $200,000, we frequently rent things like 22G BERT's since some are over $300K each. Yes, Corning for one buys this stuff to qualify long haul fiber, etc. I haven't seen it but someone here said they have a complete 140G lab setup that spares no expense.
 
TeraHertz VNA? That's impressive. And even ADI only rents the stuff. Does anyone actually buy it?

Then there was the fellow who figured he would put that kind of stuff into his annual budget, so when he got only part of it, he could still buy everything he really wanted. Well the budget went through without any cuts. After 2 years even his boss figured out he hadn't even opened the boxes! He went and the gear went to a surplus sale. They got almost 3% of the purchase price!
 
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Ah, that's what it is ?
You've been reading the brochure ?

Decorating an already fetishistic (*) piece of equipment is indicative of the way they think (Kitsch).

On the commercial part of it, the “return” of the open reels (used equipment) will generate a lot of money. Only the restoration/repair of the transport mechanism, replacement of parts, alignment and testing, promises a business with a very high profit margin, for they are few that know how to do it properly. Good for them.

A wealthy customer (**) will not be hurt by the milking of some thousands from his wallet. He will pay for having the equipment delivered and connected, he will have a precious tape correctly rooted through the capstans and heads, he will have been shown which knobs to press for the miracle to start. The tape will last for the whole social meeting.
Someone will ask there: “Where did you get it?” The answer will be: “20 grands from XX. They custom rebuilt it for me. And I had to wait for 3 months”.
The one that asked the question, will gladly pay 40 to the same XX for another piece, custom decorated of course, set-up and delivered for his -next week-social meeting. He will expect to be asked the same kind of question.

That’s life, but what all this has to do with diy?

If one here has an open reel, he knows very well what it is capable of, despite all it’s technical (mechanical) shortcomings. Just like vinyl TT.(***)

Master tapes? Well, how many are available, at what price and of which musical content? Just like vinyl reference recordings.

R2R for live recordings? Yes and no. The majority of practitioners have started with open reels. Some continue to do so, some use it in parallel with A/D recording, some have abandoned using R2R altogether.

Magnetic tape (beneficial?)compression?
High freq. extension?
30ips?
Diy?

Why not turn to home video recorders?
Magnetic tape compression, High freq. extension, rotating heads, much less mechanical issues.
Take off the electronics you don’t like and stuff it with your own good guts.(****)




We have these capabilities but usually you need an expert driver for the tools. Garbage in garbage out. Our modeling folks are now supporting us at up to 50G with some amazing fits to the data. I think they rented a 90G network analyser at the time to verify, I think there are 1050G ones now.

Sure you do.
But I was expecting :) some response on the highlighted phrases (lack of displacement current terms and wave behavior).

George


(*)Size, shape and positioning of the reels :D

(**)Not the case of vinyl or tape collectors who listen to their collection.
I have yet to meet one that is sitting unconfortably in his chair when thinking of his playback (good but not top)equipment. I would like to hear of your experience with serious music collectors.

(***)It becomes a bit of irony that in both cases –vinyl and tape- most (both in number and severity) of the technical problems are of mechanical origin. Yet the focus is on the electronics side.

(****)But whatever can be done, a VCR will never become the wonder of the evening. And a video cassette has it’s bobins smaller and well hidden.
 
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(**)Not the case of vinyl or tape collectors who listen to their collection.
I have yet to meet one that is sitting unconfortably in his chair when thinking of his playback (good but not top)equipment. I would like to hear of your experience with serious music collectors...........................
An older "audiophile" died. His estate included a very large collection of albums and his TT based system was at the highest level of cost. When his widow asked a serious music friend to catalog the collection, it was found that the 'collection' was chosen almost entirely for the attractiveness of the female models/performers illustrated on the covers!! There were less than a couple of dozen records lacking such covers.....and they were of typical singalong crooners. :whacko:

I am not suggesting that many collectors fall in this category!
 
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At the time I think it was over $200,000, we frequently rent things like 22G BERT's since some are over $300K each. Yes, Corning for one buys this stuff to qualify long haul fiber, etc. I haven't seen it but someone here said they have a complete 140G lab setup that spares no expense.

I thought you said (and meant) 1040G.

In my world it seems the sales guys can buy the good stuff (we have a 7Gb Bert and Tek DSA that spend more time on the road in front of stereo sales guys than in the lab). Engineering must make do with whatever they can squeak out.
 
For completeness: The entire repro circuit for a 30 ips analog recorder.
 

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I thought you said (and meant) 1040G.

In my world it seems the sales guys can buy the good stuff (we have a 7Gb Bert and Tek DSA that spend more time on the road in front of stereo sales guys than in the lab). Engineering must make do with whatever they can squeak out.

Aglient lists a 1050G network analyzer (extension on a 110G one actually) no price which probably means made to order. Just a comment on the most extreme stuff around. There are several instruments that we have been unable to rent because there are none made without someone paying the full price.
 
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(**)Not the case of vinyl or tape collectors who listen to their collection.
I have yet to meet one that is sitting unconfortably in his chair when thinking of his playback (good but not top)equipment. I would like to hear of your experience with serious music collectors...........................
An older "audiophile" died. His estate included a very large collection of albums and his TT based system was at the highest level of cost. When his widow asked a serious music friend to catalog the collection, it was found that the 'collection' was chosen almost entirely for the attractiveness of the female models/performers illustrated on the covers!! There were less than a couple of dozen records lacking such covers.....and they were of typical singalong crooners. :whacko:

I am not suggesting that many collectors fall in this category!

Remember the Volkswagen hubcap cover on the Ring cycle?
 

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diyAudio Member RIP
Joined 2005
:yell::yell:
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(**)Not the case of vinyl or tape collectors who listen to their collection.
I have yet to meet one that is sitting unconfortably in his chair when thinking of his playback (good but not top)equipment. I would like to hear of your experience with serious music collectors...........................

Remember the Volkswagen hubcap cover on the Ring cycle?

:yell:
 
For completeness: The entire repro circuit for a 30 ips analog recorder.
Thanks for sharing it, John, that's very generous of you.
I remember, you once told us how MoFi put a pressure on you to acquire full details of your design and now you're giving it away to the world. Lets hope that someone will look at it for inspiration, when designing his own repro.
At the same time I'm wondering how many people would be willing to do that these days, because it's quite a bit of work. Copying your circuit 1:1 won't work, unless someone uses the same Studer heads under identical conditions. I haven't investigated it yet, but it is very much possible that different head designs that Studer used for the same machines over the years (1.216.xx/1.316.xx/1.317.xx) might have different 'head bumps'.
 
Mag eq

schematic

Man John,

When faced with the unenviable job of setting up equalization for a system that produced millions of tapes a month, I ended up modding my reference Nak 1000ZXL with an almost identical eq solution. There are several differences, my solution was implemented using passive feedback around the existing preamp eq stage and was nowhere near as elegant as yours. As you also stated, at 1-7/8ips using those extended pole-piece Nak heads, the problem was nowhere near as severe as with the Studer heads at 30ips. The results were similar, and I will try to find and scan a ST1510A printout of the results. We could, with extreme reliability, high-speed record and reproduce cassettes flat within +-1dB from 15-25kHz. S/N was nowhere near that of a 30ips R-R, but it was what it was given the paucity of domains/second passing by the gap...

Memory lane, here I come...

Howie

Howard Hoyt
CE - WXYC-FM 89.3
Chapel Hill, NC
www.wxyc.org
1st on the internet
 
Interesting input, everyone.
As it is obvious, it is a bit of 'cut and try' for each tape head type, BUT at least it is stable for a given speed, so: Adjust once and fits forever, if you keep the tape machine in good tension, etc.
Of course, lower speeds may not necessarily need such extreme head bump correction, AND Studer heads are actually smoother, so they don't need the EXTRA compensation for the higher frequency ripples.
30 ips full track mastering, done right, was found to be the next best thing to direct disc. Actually, direct disc, being one step closer in the vinyl record chain, is noticeably better than even 30 ips transferred to vinyl. However, direct 30 ips playback, done right, can be wonderful sounding.
 
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