John Curl's Blowtorch preamplifier part II

Status
Not open for further replies.
We have often found that German/Swiss standards of mechanical perfection higher than typical American standards. That seems to come from early training and expectations.
However, when it comes to electronics, often the reverse is true, probably because we had so much early development in Silicon Valley and elsewhere, with military standards parallel to industrial and consumer because of the 'cold war'. Today, Germany might be caught up, being such a strong industrial society, where, I hope, engineers are still highly respected. I could be wrong about this, what do the rest of you think?
 
As for German engineers, I don't think the public is blind enough to blame them for the design issues. I will say that the quality of German branded cars seem to be a slight downward spiral. Having an issue with a Mercedes Benz in 1985 would have landed an engineer at your local dealership to note and address the issue, where as today it's treated as just another shop repair like the American brands, to the tune of $120hr. BMW and Audi can be very pricy to fix, and many of the problems are petty and should have never been allowed to happen. I won't elaborate beyond this.

There are some very bright out of the box thinkers, but they are not the Yes, Ma'am types and place interest in quality and design above high profit margins. Also, if they do not have a Masters degree at minimum and fifteen years experience in a F500 company, they do not get the job as paper seems more important these days than originality or capability. US companies marketing departments have the final say on all matters.
 
Last edited:
You are right, kouiky. They don't make Mercedes or BMW's necessarily like they used to, is what you are telling me, I presume, and you are probably right.
Cycles come and go. Once, long ago, the Japanese studied American cars and almost gave up in despair of catching up. And look where they went!
Americans used to make pretty good cars, and they lost it by 1960 or so. Hopefully, they might be coming back.
The overall quality does seem to be driven by the executives, upstairs. '-)
 
Everybody try to make PA systems as good as possible, and, sometimes, it is not so bad.
Seems to be very little interest here in making audio better, shame about that ... ;)

Anyway, I shall be very boring, and continue this theme ... . The most impressive audio systems I've ever heard have been PA systems, and obviously the worst have also been such. There are 2 or 3 that stick in my memory for the absolute clarity at high SPLs that they achieved, vastly superior to any high end setup I've come across. One was amplifying a full big band, with trumpets blazing, and I couldn't fault it. In contrast to a Sinatra tribute concert, similar big band running through a setup, and for most of the time I was hanging onto my seat, thinking it will be over soon, this dentist's chair can't last forever ... :)

So, one can get the extremes, meaning that the gear can do it if set up correctly, by someone who has a bit more than one or two brain cells. Which indicates, as far as I'm concerned, that pro gear can do high end sound if sufficiently finessed; and that the only thing holding back conventional domestic gear is that insufficient attention is paid to enabling high volumes to be reproduced cleanly. IMO, there should be a continuum of equipment that essentially differs only in the maximum sound levels that be achieved.

Frank
 
Let's be realistic, the vast majority of people have migrated to video, and tend to think of their audio as a less important than decades ago.
This happened with American car radios, when they first went solid state, and when people went from their radio listening to TV watching, in the USA, about 1950.
This doesn't mean that quality high fi listening and design is not still going on today. It is just a much smaller group of enthusiastic supporters, than it used to be.
I was contacted today with a fellow engineer, and we are going to 'swap' engineering projects, in order for both of us to be able to improve our mutual hi fi systems. It will take a bit of work on both our parts, but I a pretty sure that it will be worth it. Hi end design is not dead, it's just not here on this website. '-)
 
Fas42, one of the major problem is PA is live performance. Means the sound engineer is mixing in real time, while the same 3mn had been mixed during hours with automated consoles when you listen to CD.
Second, musicians, don't often offer a volume coherency between each others during live shows, both because the scene is large and they do not hear themselves, and because they sometimes need high volume to get their sounds (saturated guitars with sustain).
More, musicians want high levels of feedback and this destroy awfully the original sound, so near from Larsen.
Last, each night in a different place, both the PA team and the musicians don't have enough time to take their marks and make enough rehearsals.

There is some very good live performances from time to time, where both the PA is very good and the musicians grooving, you can consider those nights like miracles.
 
We have often found that German/Swiss standards of mechanical perfection higher than typical American standards.
Europe was not so rich than US, so, we were obliged to use as little raw (import) material as we could. This obliged-us to have very good steel and advanced technology etc. While US used to oversize everything, with quality of the materials way under. At the end, with resource reductions, the US had joined the same technology we used in Europa, with little light cars, good quality and finish, good breaks and good road holding. The result is we buy some American cars in Europa, now, while it was no way in the 60/70s apart some for the look, like Ford Mustang.

About actual overall quality, we are now all on the same level all over the world: planned obsolescence in a little planet.

About audio, the major problem is the size of the market: Hifi for the few in little countries. Public audio is mainly highly industrialized Japanese, nowadays, except for stuff not industrial, like loudspeaker's baffles. And for those, Europa is not so bad on the market (Cabasse and Focal for France, as an example).
Last, in France we were absolutely not aware of business, commercial and export. A country of artisans. Now we copy US business with ten years late, and the result is our lives have become hell.
 
Last edited:
Christophe,
I understand what you are saying about touring sound systems and the difficulty with sound checks and getting the sound correct in so many different venues. You never know what you are going to have to deal with. It could be indoors one night and outdoors another and these are very different situations to deal. Then you have the size of the venue to deal with, one very large and a bowl and another small and intimate clubs with some good acoustics and others that are more of an echo chamber than anything else. On the other hand if you got to work with a fixed installation then you had the time and hopefully the equipment to get things right over time. Some of the best sound are these fixed installations. I know that you have been in all of these situations and can appreciate the difficulty of the constant changes from place to place. Same thing goes for the engineer who has to work in different facilities with different monitors and electronics, you don't know what you are going to walk into and what you will be able to accomplish with all the changes. I guess that today with digital recording it may be a bit easier to get the basic tracks down and then take them somewhere that you can do a final mix on equipment that you know and understand.
 
Live recording is an other stuff. We used big trucks with a real comfortable studio inside, big mixing desk, in the street or parkings, far away from the stage. As the musicians know they are recorded, and that is important for them, sometimes more than the public performance itself, they agree to have less feedback and more rehearsals.
That makes often the best sound for the audience, and, in the same time the best records, as it brings better conditions, and the real excitement and atmosphere brought by the public. Too, the musicians play together, not always the case in studio recordings. This make the music true and 'living' as each musician react in function of the other's play. This does not prevent to re-record some parts in studio after the show and before mixing, to correct errors, or try to get better singer's parts, or better solos, as an example, but the basis is there.
Too, with the use of 'rythm boxes', they can play the same tunes at the same exact tempos several days, so we can mix parts of the same tunes from different days, sometimes.
Of course everything is recorded with close miking, so the "room" is artificially recreated during the mix.
 
Last edited:
Just out of curiosity what type of plastic did you use for the suspension? TAD uses the beryllium itself but to try and get down to 2.5Khz I feel will not be practical for that much excursion.
It was a thermoplastic material which we were alerted to by Heco, who were also part of Rank in those days.

Hostaphan variant springs to mind but that can't be right cos that's Mylar. Excuse my senile memory but it was more than 20 yrs ago.

Using Be for the suspension is a no no. I'm surprised Andy Jones even considered it. The surround provides the only damping except for a miniscule amount from the air load.

If you are only making a few, the woven fabric surrounds used by many manufacturers today for soft domes are worth trying but need to have damping applied. Liquid latex dissolved in ?? is as good as anything more sophisticated. However, this type of surround construction isn't really appropriate for consistent production.

The material we used is no longer made cos the EU regulations on WHS.

We had similar problems with surrounds for cone speakers cos the 'rubber' mixes available were always dictated by tyre manufacturers but then the quantities we used made it worthwhile to stockpile.

The Accuton page brings back many memories and I see they use a 'fabric' surround. Ferrofluid is important and they improved a lot over the period we used them.
 
Member
Joined 2005
Paid Member
Look at JBL now run by marketers and accountants rather than engineers, their classic products and engineering drive of the 50s through the 80s gone, except for their top of the line Japanese export market product , has lost it's soul. Closed up shop in California and now just a brand name to sell more Chinese and Mexican produced lo and mid fi. Looks good on a balance sheet somewhere.

http://audioheritage.org/
 
Last edited:
Finally, you make sense, Esperado. I have heard both bad and good sound from the same PA, and it is often bad luck with the acoustics at a particular venue.
You have to take very fast decision about the setting, in places you don't know, and with the heavy stuff involved and assembly time, it is a no way back.
When you realize you had made a mistake, it is too late, you have to do with it.
Worse, when you decide the set-up, the theater is empty: acoustic change a lot with the audience (good damping material) in a way difficult to guess.
And so many unexpected incidents and disasters from outside or your own stuffs , you have to get around instant with no room for error!
I would not have the courage today to take such risks and such responsibilities, it is scary and exhausting.
 
Last edited:
Kgrlee,
Thanks for the information. Yes I agree about the damping of a metallic surround and especially one where there is no discontinuity between the surround and the dome. I am looking at using a thermoplastic urethane surround for the specific reasons that you sighted. I am looking at serial production so I do not want to deal with doping a cloth surround, as you say to inconsistent for production. The adhesive used at the joint is just as important as the surround itself and so many make the mistake of using a rigid adhesive like a CA and then we are right back to having a reflective material sending vibration directly back to the dome before the surround can even attenuate those vibrations. As you learned most of the butyl rubber or natural rubber compounds also have poor damping properties. I would think the same about the mylar suspensions. I know some companies use that material as a surround for there compression driver surrounds but there we are looking at extremely low excursion and I know that it can be the cause of some nasty noise production. Thanks for trying to jog your memory. The beach can do that to you!
 
ticknpop,
I can attest to the fact that JBL was a stickler for products heading to Japan. I did contract work for them, including development, tooling design and manufacturing, on their highest end product at one time that was destined for Japan. If there was the tiniest flaw that you had to go out into the sun and look for they would reject a product. It was insane but we did meet the requirements. Even then most of their products were being made in the orient except for the pro-audio devices. This was all done with the Northridge facility on Balboa Blvd. But even then the quality of what was done in-house was shoddy some times, this was during the time that Harmon was out of Sidney Harmon's hands and the company was run by a bunch of MBA's as you said. I forget who owned them at the time but I want to say it was a large food conglomerate. They were a mess.
 
Christophe,
One of the problems that I remember doing concert sound in different venues was the ac power source. Some places would have enough power, others would blow breakers and have nothing but noisy ac sources. How many times did we have to bring in portable power generation to separate the audio from the house power and especially the lighting systems. The more you make me remember the more I want to forget.
 
Status
Not open for further replies.