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Old 12th May 2012, 05:21 PM   #5401
bcarso is offline bcarso  United States
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Quote:
Originally Posted by nigel pearson View Post
I recently tried Spice . I got so bogged down . I still use a spreadsheet . A calculator is useful , often my phone as an idea comes to me sometimes miles from home . I an terrible at arithmetic and have to recheck . Like when pico or nano farads . It matters a lot and sometimes .........! I often get people to check my stuff after , usually nothing is changed as by then I have built it . I use Burr Brown Filter Pro freeware ( I bought it originally ) . I lost my fear of Chebishev filters with that . Sometimes the best solution a Chebishev . .

http://www.ti.com/lit/an/slyt113/slyt113.pdf
I dodged computers in general for many years, after I realized I'd quickly wind up a programmer. When I got an HP-25 I spent the next two weeks doing nothing but writing programs for its ludicrously limited capacity. Some years later I started to play with one of the early Compaq luggables and once again was spending huge amounts of time.

One prof I knew well at UCLA bought each new HP offering, and spent almost all of his time for the next two years (!) writing programs for the 65 and 67, all the while maintaining how sensible this was, as the resulting tools would be so powerful and save him so much time (he did a lot of optical design). After a while the code he developed with a grad student, far beyond the limits of the HP calculators, took over, and he spent a lot of time on the main machine at the university, an IBM 360 mod 91KK, iirc. At one point the astonishing amount of fast memory with that machine was about 2 million words!

But I managed to design and build a lot of equipment before embracing simulators. It's fun to go back now, and dig out some of the schematics and plug them into Spice. Generally the design decisions are vindicated, though I'd do a lot of things differently today. One of the things that made my UCLA position so educational: there was a budget of <50 dollars a day for buying things without going through the UCLA highly-bureaucratic purchasing dept. As a result, I could buy transistors but not modules, unless the latter went through purchasing and of course as well were approved by the Chair.

By the time the particular instrument was completed, it had exactly two off-the-shelf modules in it: an ADC and a sample-hold. Of course time could have been saved with more modular opamps, power supplies, etc., but much of the required circuitry really did need to be custom.
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Old 12th May 2012, 05:49 PM   #5402
a.wayne is offline a.wayne  United States
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Originally Posted by Pano View Post
Bad crossovers are the more likely culprit, IME.
Ahh , usually the culprit in all speakers and not having design nor built one myself , you might just be right .
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Old 12th May 2012, 06:08 PM   #5403
Pano is offline Pano  United States
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Well, Hi-Eff drivers do have their quirks, that's for sure. It takes a good bit of crossover skill to tame those quirks. But once you have, it's well worth it.

Medium efficiency drivers often seem much easier to build crossovers for. I mean the crossovers are closer to textbook.
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Old 12th May 2012, 07:08 PM   #5404
a.wayne is offline a.wayne  United States
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@Pano ..... Does your pass the headphones test .... ?
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Old 12th May 2012, 07:49 PM   #5405
dvv is offline dvv  Serbia
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Originally Posted by john curl View Post
Loudspeakers are interesting, to be sure. One thing that DOES count with speaker efficiency, is improved magnetic path and magnet, which, like compression ratio in an automobile, gives you more efficiency, no matter what else you do. Unfortunately, really good magnetic assemblies, this includes the magnet and the steel cost REAL money, and are not the first choice of 'practical' designers.

Also, horns, which will make ANY loudspeaker much more efficient, do give improved 'internal clarity' because the speaker cone has to do so little to get so much sound output. One weakness of horns, unfortunately, is that it is almost impossible to make a full range one, therefore, a 2 or 3 way horn speaker having a stepped arrival time, normally, the K-horn being an excellent example of this.
I was once told by a professional loudspeaker designer from UK, staying nameless as he still works in the LS company, that their design goal was to spend 10-12% of the FACTORY sales price on drivers. Top models were stretched to 15%.

When you calculate backwards, the remaning sum for the drivers is generally pitiful. It makes you want to cry.

However, do bear in mind that many of highly touted European driver manufacturers have VERY different prices for wholesale buyers, like loudspeaker companies. Thus, driver you may be asked to pay 220 (app. $300) for a driver, but an LS manufacturing company can have it for 86 (app. $112). If they do well, everybody will know they use X's drivers, and sales will be good.

My own 10" bass driver cost some 350 on the street, but I got it for 210, which was the manufacturer price from Audax at the time.

Just one remark on the automoile engine analogy, John - my dad, a mechanical engineer who worked in development of engines for around 12 years just after WW2 used to say that NOTHING eats up the engine from the inside as high compression ratios after wild revving up to 7,000+ rpm. Combining the two was u asure fire way to eat up your engine quickly, unless you resorted to superior materials, in which case it became very costly.

The entire US muscle car era is based on 11.5:1 and greater compression ratios, but this was compensated by extremely large capacities, which allowed them to work at below 4.000 rpm. Kind of a petrol fuel diesel approach. At the time, Europeans preferred faster revving engines with much smaller compression ratios and always outsold their cars in the US as compared to US cars in Europe by something like 10,000:1, or some such.

Just a remark, if you like we can expand on it in the car thread.
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Old 12th May 2012, 07:53 PM   #5406
Pano is offline Pano  United States
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@Pano ..... Does your pass the headphones test .... ?
Don't know what you mean.
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Old 12th May 2012, 08:00 PM   #5407
dvv is offline dvv  Serbia
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@Pano ..... Does your pass the headphones test .... ?
Would you be alluding to a direct comparison with a pair of cans?

That's a thankless road to go on, Wayne. The industry creates headphones outputs by using series 220 Ohm or so resitor, with another one to the ground, to act as a voltage divider. Cheap and cheerful, also tend to kill the sound dead.

If on the other hand you do use a specialized headphone amplifier, and have half-decent headphones, you live on another planet. My own amps operate in pure class A and have an output impedance of 0.1 Ohms 0...20,000 Hz, etc. THAT really shows what headphones ara capable of, and it digs up the wealth of information in the signal.

I have never seen or heard any loudspeaker which could stand up to that, but on the other hand, some people plain hate headphones, and having the sound all around you IS a bit more natural than just on your ears. Yet, it's only then that you discover what kind of ultra high quality bass some cans are capable of. Cases in point - Sennheiser 598, Koss Pro4AA Titanium, etc.

Yessir, you'd be surprised what a fully complementary, pure class A headphone amp can do for your musical pleasure, with two 50W devices in a SEPP confuguration.

Oh yeah - it doubles down to 5 Ohms.
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Old 12th May 2012, 08:15 PM   #5408
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Originally Posted by dvv View Post
I was once told by a professional loudspeaker designer from UK, staying nameless as he still works in the LS company, that their design goal was to spend 10-12% of the FACTORY sales price on drivers. Top models were stretched to 15%.
It was 10% the retail price for everything as I knew it . Still they did not make money as the sales teams were often not so very red hot . Naim I know made considerably less as R&D gobbled it up . I think Naim sited that recently as the reason for the merger . Simply not having enough R&D money , forgive me Paul if I am wrong ?
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Old 12th May 2012, 08:17 PM   #5409
SY is offline SY  United States
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Quote:
Originally Posted by dvv View Post
I was once told by a professional loudspeaker designer from UK, staying nameless as he still works in the LS company, that their design goal was to spend 10-12% of the FACTORY sales price on drivers. Top models were stretched to 15%.

When you calculate backwards, the remaning sum for the drivers is generally pitiful. It makes you want to cry.
Rule of thumb for any successful manufacturing operation is retail price is 5x cost of BOM. You need drivers, crossover, cabinet, packing material, and box, so that's about the right allocation for drivers.
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Old 12th May 2012, 08:20 PM   #5410
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My own company is 4.75 as we are honorable people ( I think so ) . Most money goes to distribution . We aim higher but never get there . If we do the quality is always an issue .
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