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I'm fascinated by the SEAS A26 kit, especially the woofer thar appears not to ring at the top of its bandwidth and rolls off naturally with no crossover. I know this is extremely rare and have not been able to find another driver with similar characteristics(smooth natural roll of from 2 to 3 kHz and able to reach the low 40s bass in a large closed box 3 to 5 cubic feet). Has anyone here ever come across such a driver other than the SEAS? I like the idea of running the lower driver of a 2 way direct coupled with no crossover parts. I know I'm hoping for a miracle. Thanks.
Follow Ups:
8" I think and naturally rolled off.
They sold me a new single replacement for a damaged driver in my DeCapo I.
They are marketed as custom made by Reference 3A and probably hand built.
So they might not sell as seperate unit. But the management/owners are nice people and might be worth an email.
You are correct because those 3A drivers were designed to roll off nicely without a low pass filter. But I don't think they'd sell me a driver unless I could fake 3A ownership of defective speakers. Plus I don't think it has the low frequency characteristics I'm looking for.I recall listening to a 5 way 3A speaker at a New Jersey audio club meeting( Harry Pearson suggested it to me) years ago. It was very open and very dynamic.
Thanks for the suggestion.
Edits: 12/25/23
Hi, My favorite speaker is the Dynaco A-25 Mark2. It came out in 1977 and was only around or manufactured for about a year in New Jersey not Denmark. The tweeter is mounted or centered right above the woofer and not a little to the left or right like the original A-25. This was probably done to improve imaging. The cabinet is the same size as the original .So my question is ....Why does the A-26 revert to the old style of off setting the tweeter from the woofer and not centering it for a better vertical alinement? Was this done to remind the masses who remember the original back? It seems like a backward step in the forward of a classic design.....take care, Mark Korda.
Hi, here is a Dynaco A25Mark2 with the grill off....The tweeter is centered and not off set...Mark Korda
Thar SEAS A26 woofer appears to be similar in design to 1960s drivers*. Take a look at it and you'll see that the voice coil is 1.5" or maybe 2" diameter - typical of those antique designs.
Now look at a top-drawer modern (21st century) driver of similar diameter. Take for example the 9" driver used by ATC
https://atc.audio/professional/loudspeakers/scm50a-pro/
Note that the voice coil is at least 4" diameter. Why is this so much better? The coil generates the movement of the cone requiring it to act as a piston, moving air at maybe a couple of thousand times per second. The laws of physics come into play and the distance between the coil and the cone surround becomes important here. The smaller this distance, the less "flabbiness" there will be in the cone's movement. The ATC driver will offer a much less distorted sound.
There's nothing wrong with using ancient driver designs, but you must appreciate that things have moved on in the last 50 years and this includes driver design. A modern driver with a much larger diameter voice coil should (if well constructed) offer a much better sound.
* PS - Just noticed since starting this post that this SEAS driver is in fact based on a 1968 design. Your consolation is that SEAS is a highly respected company that has been making drivers for decades. They build to high standards and even these old designs will be good compared with many other old designs and poorer-built modern ones that find their way into budget speakers.
Not much has changed, really, since Olson/RCA/Western Electric (etc.).
all the best,
mrh
Edits: 12/22/23
You can't tell from that photo as all it shows a big diameter magnet - it doesn't show the voice coil cover. It could well have a 2" coil.
No doubt there were very costly large voice coils decades ago, but most were small diameter like the SEAS. Same applies today - big coils (if well implemented) are superior to small ones - but more costly.
That's the mighty Altec 515, dating back to the 1940s and still in production at GPA. 3" edgewound voice coil. Used in large format VOTs and as the woofer in the 604 Duplexe. Best midrange and vocal reproduction of any woofer I've heard.
I'm listening to Linda Ronstadt's Christmas album over 604Es as I type this.
And some old Trusonic's , looked a lot like JBL's
Fwiw, loudspeaker engineer folk lore in the 80's was that the 4 inch coil size came about because of a winding form originally made from a coffee can.Curiously, the Voice coil's figure of merit can be stated as BL^2/Rdc, that is not tied to the diameter and that's why there are all kinds of VC diameters. A large diameter does allow for more surface area and that's tied to the thermal power capacity.
When a very large VC force is desired, a large diameter coil made from square copper tubing with water cooling can be used to make a big driver.
Here is an example of a large voice coil, note it is sitting on a full size shipping pallet
Edits: 12/23/23
I almost get the same feeling if I were looking at an unfused artillery shell.
I fear the potential acoustical output of that completed and installed unit.
I know what you mean AND the motor assembly was so impressive that although it was cheap, i passed on it. It was VERY heavy for it's size and it was big, that's also on a reinforced pallet. It has a water cooled field magnet as well as water cooled VC.
If you zoom in, you can see it's rating and if attached to a radiator, it can reproduce music or anything else in that frequency range.
I was at a vibration tests a couple times at Wyle labs where a bigger brother to this one was used to vibrate a Sounding rocket payloads.
That was driven by the biggest amplifier i have ever seen, a 250KW tube amplifier also made by Ling that took up the entire wall of the room floor to ceiling, literally like a huge radio transmitter. It had two giant glowing red output triodes and two BIG driver tubes.. One of the operators saw i was interested and showed me some of it, I was speechless looking at the proportions of all the bits.
The operator told of one year they made up and 8 foot square thick plywood piston and attached it and rolled the assembly on the rail tracks to the open garage door and played Christmas music to Huntsville / Marshal / Redstone.
He said it sounded good but was "kinda loud inside", yeah inside the cabinet you mean.
BTW, loudspeaker building advice, if you ever make a large loudspeaker, never let yourself be closed inside one because your curious what it sounds like no matter how your friend says he will let you out right away.
I know what you mean AND the motor assembly was so impressive that although it was cheap, i passed on it. It was VERY heavy for it's size and it was big, that's also on a reinforced pallet. It has a water cooled field magnet as well as water cooled VC.
If you zoom in, you can see it's rating and if attached to a radiator, it can reproduce music or anything else in that frequency range.
I was at a vibration tests a couple times at Wyle labs where a bigger brother to this one was used to vibrate a Sounding rocket payloads.
That was driven by the biggest amplifier i have ever seen, a 250KW tube amplifier also made by Ling that took up the entire wall of the room floor to ceiling, literally like a huge radio transmitter. It had two giant glowing red output triodes and two BIG driver tubes.. One of the operators saw i was interested and showed me some of it, I was speechless looking at the proportions of all the bits.
The operator told of one year they made up and 8 foot square thick plywood piston and attached it and rolled the assembly on the rail tracks to the open garage door and played Christmas music to Huntsville / Marshal / Redstone.
He said it sounded good but was "kinda loud inside", yeah inside the cabinet you mean.
BTW, loudspeaker building advice, if you ever make a large loudspeaker, never let yourself be closed inside one because your curious what it sounds like no matter how your friend says he will let you out right away.
"This requisition from Huntsville Alabama says the need a 250kw audio amplifier, maybe we should sent them two just in case"
JBL was using 4" voice coils 70 years ago. And not just on woofers but on compression drivers too. Altec used 3" woofer voice coils but went to some with 4" coils about 50 years ago.
sorry I didn't read your post until after I posted (nearly) the same thing, Tom.
Merry Christmas!
all the best,
mrh
Good info that I already knew. But you ignore the main point. I want to build a 2 way without a low pass on the woofer, preferably one that works in a closed box. The important factor is no crossover on the woofer to eliminate the reactance of a crossover. The A26 woofer works but I would like to find something even better. I have searched lots of manufacturers and nothing quite works. There seems to be a Morel driver but it's ultra costly. And there's a SEAS nextel 8 inch but it rolls off too high.
You might not find any others and it might not be work so well if you do.
A modern 8" two way in a tower is hard to beat in a normal household living room. Snell E 4. Dayton has some decent 8s and even a 10. Adding the Wavecore TW030WA12 around 1500 for great results. A DIYer can even get Xsim files for both and tweak crossovers till they pass out, finding a design to maximize (compromise) impedance. Furthermore, there are several independent measurements for each to confirm published data, response and distortion.
Anything more is more expensive and complex and maybe only a little better. Anything less will compromise something.
Although aware of the Wavcor brand but have no experience with either.
The TW30 is interesting for bigger size low Fs type projects, have you any experience with either company or driver ?
Maybe a line or url for a Europe based DIY forum with Wavecore experience?
Yes I use the TW030 in a project. I like it alot.
Been tossing around for a larger dome low fs tweeter, most are 34 or 35 mm and so I associated the 30mm Wavcor n that group , but it's just 1mm more than say the Scanspeak 29 series and some SEAS.
Funny that 29 is small, but just a 1mm larger 30 is big.
Thanks for the experience shared
These tweeters cover a lot of bases: Wide range > 1500, low distortion <.5%. smooth response, 92DB or more and decent wave guide off access. Hifi compass and Voice Coil Test Bench verify the numbers. I think they sound great. I like the JBL 2431 slightly better and the SEAS 27TDC (no ferofluid) slightly less. I got rid of everything else.
The ATC,DYNAUDIO,MOREL,and SKANNNING are about the only ones, vast majority are 1 to 2 inch voice coils
The A26 driver is a Dynaco A25 driver design upgraded updated with design and measuring tools not available when the original driver was designed. It is specifically a 10 driver made to have no crossover and run to a smoothish roll off. Not possible with a 4 inch dome covering the voice coil.
The driver is both a throw back and a bit of a technical marvel to behave as well as it did. Far outclasses the original Dynaco A25 and think they sold many 10,000 of them world wide of the originals.
I've just looked up my own bass drivers' voice coils. They are 4" but the latest version has coils of 6" (153 mm) on their 12" drivers. I don't know who Avantgarde source their drivers from or whether they manufacture them themselves, but AG certainly do the design work.The better modern drivers have large diameter voice coils as they can much better control the movement of the cone as a truly rigid piston. The cone is what agitates the air and allows us to hear the music. The less the cone "waves" as the centre is pushed in and out, the less distortion there will be.
I don't doubt that the Dynaco A25 was a great speaker in its day, nor that the new version is not a good driver for DIY projects, I'd suggest that it isn't a great driver.
The argument about its need or otherwise for protection from higher frequencies is not really relevant, as few drivers of that diameter will deliver high frequencies, so it's generally best to filter them out at the XO stage. Far more important of course is to protect the tweeter from bass frequencies.
Edits: 12/21/23
Or what's left of Vifa , Audax Hi-Vi and only in some subwoofers from Peerless lineThese makers often have drivers used in some of the finest speakers on the market, with far fewer having the large coils of dynaudio, ATC, Accuton or Morel. The first two are now solely proprietary to only one brand, so that limits their availability, but no doubt would be in many more finest products to be using them.
So although some advantages to a oversized voice coil, the diameter of such is not the single factor that defines modern leading edge drivers, demonstrated by the manufactures and buyers of the marks that many consider SOTA.
Edits: 12/21/23
Only $79 in 1973! :)
Image from 1973 Lafayette Radio Electronics catalog, from the link below.
Still a very pleasant to listen to loudspeaker is the A25. :)
all the best,
mrh
Edits: 12/22/23
prefer listening with grilles on or off? Thanks.
per the US Bureau of Labor Statistics' CPI inflation calculator.
Still slightly cheaper than the current A26 (especially given that the latter is sold as a kit only, AFAIK).
Just sayin'. ;)
all the best,
mrh
for a speaker with a tube-friendly, minimal x-over and is a perfect match for a tube-based PP amp.
First they came for the dumb-asses
And I did not speak out
Because I was not a dumb-ass
It's wonderful for the money but I was curious about doing the same minimal crossover design but even better than the A26.
That's more than a thousand $$$ just in drivers and all of that for a sub $2000 set of speakers?
Those same drivers, or comparable valued ones, in a commercial offering would run you $6 to 8$ thousand, based on normal markups.
First they came for the dumb-asses
And I did not speak out
Because I was not a dumb-ass
I understand. I do know something about drivers and speakers. I just want to know if there are drivers to make a super A26. There seem to be multiple tweeters I could investigate. But I'm unable to find a better driver than the A26 woofer with similar roll off characteristics. I was hoping someone here might have suggestions. I suspect there are few, if any -fingers crossed.
Ain't many, most older, and modern marks are $$$$$
Seems like about every ten years or so I too get interested in a large format midbass with very well behaved roll off to make an updated Dynaco A25.
Seas is still the manufacturer who has had offerings over the last 50 years that fit your interest, but most of the older offerings are, well old and few. Many with the RE code in the model number, with some TV code but most are 8"
PHY-HP and PHL companies offered large format wide band drivers made for very smooth roll off, but have trade offs in required large enclosure size and very costly.
Human speakers have some offerings but think their real winners are the 8 inch offerings
Vifa, scan speak, dynaudio, morel, etc don't offer any 10 that is a large format wide band not requiring a high order low pass. I tried the vifa m26 but it was too beamy and rolled off not as smooth as the SEAS 25TV or 25vw.
GRS claims to have a replacement, but being 6 ohms I'm skeptical. It's also got some roll of issues but not severely. I have not heard it.
The SEAS A26 kit uses a fairly expensive 35 mm tweeter, but a cheaper version could use the AUDAX TW034X0
Vintage paper cone drivers generally are very well behaved -- only when crossover design became very straightforward did woofers with awful out-of-band behavior become "reasonable" for loudspeaker design.
A classic example of a purpose-built woofer with well-behaved HF rolloff was Winslow Burhoe's 8" "EPI" woofer (and its kin). Huy Powell still builds replacement drivers (and whole loudspeakers) using a modernized version of the Burhoe woofer(s). See website below.
all the best,
mrh
Didn't Burhoe make a floorstander with slanted top with drivers on the slope. Forgot the name. It got good reviews from inmates here. Don't see it anymore.
Bill
EPI M201/Epicure 20 is the one I remember.
I have a friend in the Silicon Valley who still, AFAIK, has a pair. They were quite nice to listen to.Epicure 20/20+ image from Humanspeakers (link below).
EDIT: I believe Burhoe may have made similar loudspeakers later, under one (or more) of his later brand names, too!PS I think I mentioned this, but both Burhoe and Powell are on LinkedIn.
all the best,
mrh
Edits: 12/22/23
Thanks but unfortunately he doesn't show frequency response so I don't know how it performs at the top of his drivers' band width.
I can tell you empirically (only) tha the rolloff is smooth. XO on the "Burhoe modules" was first order on the tweeter (only) with a 10 uF capacitor (nomiunally 1800 Hz). I didn't calculate the XO frequency, it is from the link below, and may not be accurate. :-p
all the best,
mrh
Someone's measurement of the same woofer in the slightly larger EPI 110 enclosure. Not exactly what you're looking for (and, obviously not a laboratory measurement, nor a modern "spinorama"), but at least a little data to support the subjective impression (and the prevailing wisdom) about these drivers. HTH!
For reference, here's a photo of one of a pair of EPI 110 with woofers hich I re-surrounded with generic (three dollar) surrounds.
Proper replacement surrounds for these woofers are available (from Rick Cobb, e.g.) and are well worth the additional cost (still quite reasonable, less than $30 the pair).
Here's an EPI 100V that I re-surrounded with Rick Cobb's surrounds. The performance of this woofer should :) pretty well match the original performance.
I kept the 100Vs. Everyone should have a pair of these for reference, I'd opine :) They're epochal, and they don't take up very much space!
all the best,
mrh
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