Beyond the Ariel - Page 899 - diyAudio
Go Back   Home > Forums > Loudspeakers > Multi-Way

Multi-Way Conventional loudspeakers with crossovers

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 23rd June 2013, 09:12 AM   #8981
Kolbrek is offline Kolbrek  Norway
diyAudio Member
 
Kolbrek's Avatar
 
Join Date: Aug 2007
Quote:
Originally Posted by Lynn Olson View Post
It would be interesting to see Stephens Tru-Sonic revived; the old-timers I've met told me that they were the best-sounding drivers and loudspeakers of the early and mid-Fifties. My understanding is that Stephens was part of the Wente and Thuras team at ERPI in the late Thirties, and was the inventor of the multicell horn.
Stephens seems to have been running his own company at the time. It looks like he did some OEM work for W.E., and he worked on the muticell horn for the the Shearer system under John K. Hilliard. He designed and built the horn, probably on a licence from W.E., since Wente holds the patent.

Wente and Thuras worked at the Bell Labs, not at ERPI, which was a separate company. BTL/WE developed and produced the equipment, ERPI installed and maintained it in the theatres.

-Bjørn
__________________
Dynamics to the people!
  Reply With Quote
Old 23rd June 2013, 03:22 PM   #8982
limono is offline limono  United States
diyAudio Member
 
Join Date: Mar 2007
Quote:
Originally Posted by Kindhornman View Post
Lyon,
Extrapolating from what you are saying I will add in that JBL and Altec at the time just acted as if the crossover components were completely interchangeable, that is what you are seeing. As long as the value was electrical component met a minimum standard like it was plus or minus 10% it was the same and would sound the same. We all know now that isn't true and I bet they more than likely did also, but just ignored it as they could get away with that. The same guys designing those great drivers of the time we just as capable as anyone at designing better crossovers. As you say Heyser was in California and there were just to many others who knew what was going on. When you control the market for the products why change was the thinking.
Peter Snell was doing exactly the same thing and his standards regarding matching crossovers and drivers are said to be the highest in the industry. I heard from reliable source that it was incredibly tight . Yet , he mixed mylar and electrolityc caps only with regards to value . I found early Model K where
in one speaker there was a mix of bipolar and mylar caps in tweeters hf filter and in the another only electrolityc bipolar caps.. granted he used cheap drivers with poor tolerances and had to select them but still those old vifa woofers have tone which I miss in modern drivers.
  Reply With Quote
Old 24th June 2013, 12:49 AM   #8983
diyAudio Member
 
Lynn Olson's Avatar
 
Join Date: Jul 2004
Location: Northern Colorado
Quote:
Originally Posted by Truetone View Post
Hi Bud, Do you mean they used air core inductors? The old drivers I thought were forgiving of this basic approach. Particularly when horn loaded. Pio caps and air core inductors in 12dB primitive style sound pretty good, but hoping to learn more from Lynn.

martin
Well, I use (electrical) 2nd-order crossovers a lot myself, as a reasonable subjective compromise between group-delay error, out-of-band attenuation, and immunity to driver impedance variation.

The Altec A5 crossovers I saw were the "constant-power" type, with the same-value L's and C's for the high and low-pass sections, a 10-watt L-pad attenuator for the HF driver. That was it. There was nothing else in the cast-aluminum can except for lamp-cord type wire going to the binding posts.

Rather unexpectedly, Paul Klipsch was doing some unexpected things with autoformers as far back as 1959, and in following Klipschorns, La Scala's, Cornwalls, and Heresies, you see asymmetric 1st, 2nd, and 3rd-order networks, along with autoformers. But PWK's drivers were not easy to work with, with some pretty rough responses (particularly at the top of the range of the folded bass horn), so I can see why he and his staff were forced to be creative.

Speaking from personal experience, the one thing horns have taught me is they are much less tolerant of out-of-band operation (compared to direct-radiators). I don't understand how anyone is getting them to work satisfactorily with 1st-order highpass filters, whether active or passive.

The sound gets much grainier and harsher if the compression driver gets too much energy in the horn-cutoff region. I was surprised that differences between 2nd, 3rd, and 4th-order highpass filtering were as strikingly audible as they turned out to be. (Mylar diaphragms seem to be a lot more tolerant of out-of-band operation, which probably accounts for their popularity in small-format compression drivers.)

Bjorn, thanks for the additional information about the history and people of Western Electric, ERPI, and Altec; always appreciated.

Last edited by Lynn Olson; 24th June 2013 at 12:54 AM.
  Reply With Quote
Old 24th June 2013, 01:56 AM   #8984
diyAudio Member
 
Kindhornman's Avatar
 
Join Date: Aug 2012
Location: Los Angeles, California
Lynn,
I think you would be very surprised at the actual acoustical output of the surrounds on these compression drivers and that also really goes for direct radiators also. I tried to mention this to one of the other designers on another forum and was told that he only cared about sound in the far field but there is a large contribution to noise in some drivers from the surrounds. Compression drivers are most definitely not immune to this factor, the surround can be a very large area compared to the diaphragm surface area and many times this area is out of phase to the diaphragms output. I would say that the mylar surrounds are probably much more well damped than say a metallic surround, with or without diamond shaped reliefs that themselves can cause even more breakup modes in the surrounds signature sound output. When doing speaker development one thing I have been taught is to not overlook the surround. We not only look at the response at 1 meter but also at very short distances and it is amazing when using a 1/4" mic to actually analyze the output of the different sections of the cone, you can definitely look at the acoustical signature of the surrounds when working this close to a particular area, I am talking about almost touching the surface but far enough away not to get hit by the moving parts.
  Reply With Quote
Old 24th June 2013, 02:51 AM   #8985
Pano is offline Pano  United States
diyAudio Moderator
 
Pano's Avatar
 
Join Date: Oct 2004
Location: Milliways
Blog Entries: 4
Lynn and I have spoken about this subject and my take on it is that it's not the quality of the crossover parts that is the problem, but the design of the circuit. They were mostly just bog standard 2nd order crossovers with no regard for actual impedance or the acoustical targets. The results were not worthy of the drivers. A good crossover is more than just textbook values.

FWIW, the UK Westrex drivers were better (IMO) than the same vintage Altec. Rare finds, tho, at least on this side of the pond.
__________________
Take the Speaker Voltage Test!
  Reply With Quote
Old 24th June 2013, 10:03 AM   #8986
diyAudio Member
 
Joshua_G's Avatar
 
Join Date: Nov 2008
Location: Small village, Israel
Quote:
Originally Posted by Pano View Post
Lynn and I have spoken about this subject and my take on it is that it's not the quality of the crossover parts that is the problem, but the design of the circuit. They were mostly just bog standard 2nd order crossovers with no regard for actual impedance or the acoustical targets. The results were not worthy of the drivers. A good crossover is more than just textbook values.
"A good crossover is more than just textbook values"
It sounds so true and so familiar. Though I have zero experience with speaker drivers and crossovers, from my experience in electronics, including RF filters, it sounds very true.
  Reply With Quote
Old 24th June 2013, 07:07 PM   #8987
diyAudio Member
 
Lynn Olson's Avatar
 
Join Date: Jul 2004
Location: Northern Colorado
Quote:
Originally Posted by limono View Post
Peter Snell was doing exactly the same thing and his standards regarding matching crossovers and drivers are said to be the highest in the industry. I heard from reliable source that it was incredibly tight . Yet , he mixed mylar and electrolityc caps only with regards to value . I found early Model K where
in one speaker there was a mix of bipolar and mylar caps in tweeters hf filter and in the another only electrolityc bipolar caps.. granted he used cheap drivers with poor tolerances and had to select them but still those old vifa woofers have tone which I miss in modern drivers.
Back in the Seventies, I would give the nod to licensed BBC monitors and the studio-grade KEF products. Although you'd see things like electrolytic caps for the larger values, they were selected to 1% precision, and the final product matched against the approved prototype.

We did this at Audionics too ... in fact, we have been the only US manufacturer foolish enough to apply for a BBC license. It took the BBC about 9 months to answer ... no. That didn't stop other US manufacturers from making LS3/5 copies, and selling them as minimonitors.

One little tip I picked up from Laurie Fincham when I visited KEF was phase-matching each production loudspeaker against the original prototype by placing the two speakers side-by-side, reversing the phase of one of them, and measuring the combined pair with a spectrum analyzer. If the null was 20 dB or more across the entire spectrum, it would pass QC as a match. For this to happen, you had to trim the driver levels (which usually vary by 1~2 dB in production) and have caps pre-matched within 1% tolerance. Since we and the Brits were using notch filters as a matter of routine, tight tolerances were pretty much required for the response-shaping portion of the crossover.

This is what we and the high-end Brit manufacturers were doing in the mid-to-late Seventies. At the time, many US manufacturers thought a "crossover" was a series cap to protect to protect the mid and tweeter (look at the crossover for the JBL L100 if you don't believe me, or many of the "East Coast sound" loudspeakers).

The US manufacturers started using more sophisticated crossovers in the Eighties, but I didn't follow the market closely since I spent the Eighties out of the hifi business ... Audionics had burned me out on hifi. I didn't re-enter until 1989, and things had changed a lot during that time. I never did understand why Wilson Audio became so popular during that time; they weren't flat, there was no diffraction control, and the drivers, particularly the dreadful Focal tweeter, were not that good.

Last edited by Lynn Olson; 24th June 2013 at 07:09 PM.
  Reply With Quote
Old 24th June 2013, 07:11 PM   #8988
Face is offline Face  United States
diyAudio Member
 
Face's Avatar
 
Join Date: May 2007
It appears Tannoy was way ahead of it's time.

As for Wilson, they appeal to the "appearance" first crowd. Although, they recently started the to transition to soft dome tweeters, and now are much less annoying to listen to.
__________________
"He who fights with monsters should look to it that he himself does not become a monster. And when you gaze long into an abyss the abyss also gazes into you." Friedrich Nietzsche
  Reply With Quote
Old 24th June 2013, 07:14 PM   #8989
diyAudio Member
 
Lynn Olson's Avatar
 
Join Date: Jul 2004
Location: Northern Colorado
Quote:
Originally Posted by Face View Post
As for Wilson, they appeal to the "appearance" first crowd. Although, they recently started the to transition to soft dome tweeters, and now are much less annoying to listen to.
Only took them twenty years to discover soft-domes. Progress.
  Reply With Quote
Old 24th June 2013, 07:56 PM   #8990
jpak is offline jpak  United States
diyAudio Member
 
jpak's Avatar
 
Join Date: Jun 2007
Location: NH
They still sound like the old Wilson speakers. Just the treble doesn't make you want to scream
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



New To Site? Need Help?

All times are GMT. The time now is 08:36 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2