Copy of catalog / plans for a transmission line loudspeaker kit from Accurate Sound, Lincoln NE, circa 1977

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#21
planet10 said:
Why? I wouldn’t builkd any TL from before the time of, and modeled with a modern TL modeler by someone who knows what they are doing..
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Perhaps it is irrational nostalgia, but if I can find the plans for the Accurate Sound model 7, I would like to build another pair, and so would a friend of mine. Falcon Acoustics from the UK is producing the original KEF drivers (with improved adhesives and insulation) and my workshop is a lot better than it was fifty years ago, so this is easy for me to do if I have the plans in hand.
 
#22
jlinkels said:
This is not what you are asking for, but these 2 designs (Roger's Monitor and Atkins State of the Art) originally used the same speaker configuration. Both were excellent speakers. The bass of the State of the Art was clearly more extended on the low side.
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Indeed there are many designs like this. One of the best published ones from that era (available online) is B.J. Webb "A proven transmission line loudspeaker", Audio Amateur 1/1975 page 3 https://p10hifi.net/TLS/downloads/WebbTL-AA-1-75.pdf

However, my goal is to find the plans for the Accurate Sound model 7. These had a larger cabinet volume and a simpler divider concept to get the TL (one slanted board internally, rather than a baffle/labyrinth).
 
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#23
prairieboy said:
Can't speak for Dave, but I'd guess the modeling he was referring to meant the work of M.J. King. Transmission theory from then to now has changed dramatically, and for the better. (This from someone who, years ago, built a trans line based on Bailey's now disproved theories using those same KEF drivers plus a Coles super tweeter.)
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I'd be grateful for a link or citation to the work by King.
 
#24
perrymarshall said:
I grew up in Lincoln, Nebraska and it’s almost certain that these kits were offered by a guy named Richard “Dale” Pitcher who later had a company called Essence Speakers which made transmission line speakers using typically Morel and Dynaudio drivers.

Essence Speakers was in the 80s. For a little while he had a showroom at or near that M St. address. Before that, his products were sold through a local dealer called Sound Dimensions. I also sold my own brand of speakers through that same dealer for a short time. I was 17.
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Thank you Perry, that's very helpful. If you have any contact info for Richard “Dale” Pitcher, could you please share it with me via PM? I did find an email address for him, but it is from a decade ago, so not clear if it still works. Anyway, I'll follow through on that.

perrymarshall said:
I agree with others in this thread that you can build far better transmission lines with today’s knowledge than anything anybody was doing back in the 70s and 80s. I’ve built a lot of TLs myself. The mathematical modeling of programs like HornResp takes TLs to a whole new level. I also agree with the comments about KEF drivers. Modern units from leading companies are much better.
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As I've explained, I'd like to build a pair out of nostalgia. However, if I can get hold of the plans for the Accurate Sound Model 7, I will first use HornResp or similar to first build a mathematical model, and will share that with the group here, before proceeding.
 
#25
Turbowatch2 said:
If you want to build a transmission line, even if you are new to it, maybe do an own construction, based on a free simulation program. http://www.hornresp.net/ will be all you need. You may keep the proportion of a vintage construction, but do it right inside. Even simpler, build a newer construction, based on simulation, documented and measured. Just search a little. For most people the transmission line of today is the tapped horn, the basic construction is hardly much different.
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If I can get hold of a copy of the Accurate Sound Model 7 plans, before building another set, I will make a HornResp model and post it here for comments.
 
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#26
perrymarshall said:
So yes, I absolutely identify with your affection for speakers of this particular vintage. Depending on how technical you want to get, you can buy classic drivers of whatever time period you prefer, and end up with a system that has the romantic qualities, while at the same time exceeds those old designs in many respects.
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Perry, thank you for this sympathetic hearing (sic). The first step is to get hold of the plans for the speakers that I built in 1977. If I can succeed in that, I'll come back to this group, share the plans, and gather comments. I built my first pair in one weekend in my father's shop, and my own shop is quite a bit better. So it's not that much time invested, and fortunately after almost five decades the costs are not enough to deter me.
 
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#27
It's a hobby and hard to argue against doing what you want. Here is a link to a thread discussing the Falcon drivers and what was found by a hobbyist wishing to build a 50 year old design but expecting current tolerances and performance. BTW the B139 seems to have greatly increased power handling (needed for modern amplifiers) so not sure how much of a direct replacement it might be. Anyway you have the information to make a more informed choice and perhaps what might need checking if you do opt for Falcon drivers.

The best place to ask about plans is perhaps Martin King's facebook group on transmission line speakers. Here is a link though I am not sure it will work. Alternatively try following links from his web site here.
 
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#28
Although I am not familiar with the company Accurate Sound, from the picture in post 1 it looks asif - not for the first time- a smallish US speaker manufacturer basically made copies of the various 70ties British TLS designs as published in WW, Hifi News, Practical Hifi etc. etc. and sold in kit form. The early years of Speaker Builder contained comparable ad's by US "cottage industry" manufacturers.
 
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#29
andy19191 said:
It's a hobby and hard to argue against doing what you want. Here is a link to a thread discussing the Falcon drivers and what was found by a hobbyist wishing to build a 50 year old design but expecting current tolerances and performance. BTW the B139 seems to have greatly increased power handling (needed for modern amplifiers) so not sure how much of a direct replacement it might be. Anyway you have the information to make a more informed choice and perhaps what might need checking if you do opt for Falcon drivers.

The best place to ask about plans is perhaps Martin King's facebook group on transmission line speakers. Here is a link though I am not sure it will work. Alternatively try following links from his web site here.
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Andy, these links are very helpful, thank you. It is discouraging to read about the poor quality of the "new production" Falcon drivers.
An addition to your links is the nice website put together by Dave (Planet10) here:
https://www.t-linespeakers.org/
 
#30
Boden said:
Although I am not familiar with the company Accurate Sound, from the picture in post 1 it looks asif - not for the first time- a smallish US speaker manufacturer basically made copies of the various 70ties British TLS designs as published in WW, Hifi News, Practical Hifi etc. etc. and sold in kit form. The early years of Speaker Builder contained comparable ad's by US "cottage industry" manufacturers.
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At the time I built these speakers, I had studied all of the transmission line designs published in Audio Amateur and Wireless World and another UK publication whose name escapes me now. [The MIT technical library "under the dome" had a very good collection of audio related magazines from around the world.]

The model 7 from Accurate Sound was a somewhat larger than the other designs, and simpler to construct. As far as I was able to tell at the time, it was not a 1:1 copy of another design.
 
#33
BruceAllen said:
It is discouraging to read about the poor quality of the "new production" Falcon drivers.
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Problems happen particularly if 50 year old driver designs are assembled in tiny numbers using 50 year old tooling, 50 year old manufacturing and assembly methods and possibly by people unfamiliar with the drivers manufacturng issues. Without further information on why there were fairly significant issues with those particular drivers it may be unwise to draw any general conclusions. The drivers themselves were always standard range (e.g. stamped rather than case frames, hand doped,...) rather than premium/prestige range and they always had pretty wide tolerances. After KEF moved on to technically superior drivers in the 80s I think some of the tooling for the old drivers moved to a manufacturer like Harbeth, Spendor or similar which was selling into the retro/audiophile market segment that highly valued speakers like the LS3/5a and BC1. Anyone?
 
#35
If you update a vintage design, at what point have you departed from the original spirit of the design?

Everybody's gotta answer that question for themselves.

Well.... If this were my project, I'd go for an Accurate Sound Model 7 "2.0." I'd build a HornResp model incorporating Martin King's best TL practices and alter the internal cabinet geometry to cancel the "Fbx3" second resonance of the TL.

I'd see if I could lay my hands on the Tang Band W8Q-1071 12"x8" subwoofer instead of the B139; and instead of the B110 I'd use a Focal 5N401, 5N412, 5N411 or 5N412; and instead of the KEF T27 I'd pick one of SB Acoustics 21mm domes. Or if it needs to be vintage, the Audax TW025.

VItuixCad and measurements to dial in the crossover.

The end result will have a strong family resemblance, and honor the original idea, while picking up major improvements.

Most of my "nostalgia projects" have approached things this way, and I've always been extremely happy with the results.

To me, every speaker project is a "game" with some restraints. Every time my best buddy comes over and sees one of my new speakers, he knows to ask "So what was the constraint this time??"

One variation of the game I enjoy is "You have to build this project with parts purchased on EBay that you could have bought in 1983.... that you could have got from the McGee or Madisound catalog when you were a teenager... you are not allowed to use any "nuclear weapons" like DSP, only "bow and arrow"... but you ARE allowed all of the measurement and modeling technology of 2025 when you design your 1983 crossover and apply your 1983 woofers and tweeters."

So for example in this thread you'll see a photo and measurements a JVC HSA1014 woofer. That was in the McGee 82 catalog when I first started building speakers and I always wanted to try it. Didn't get around to it until 2024. The design went through a few iterations and I ended up using a modern Dayton 16mm tweeter. Yeah, I could have used the venerable Audax 10mm polymer dome but I had the Dayton on hand and it still scratched the "inner child work with 13 year old Perry" itch. Which I might add is 100% legit and speaks to an emotional need.

PS - Once a few years ago I was in a business meeting doodling, and made a list and time line of all the speaker projects I tackled in high school, which was over half dozen. Upon closer inspection I realized that every time I was immersed in one of those projects, our family was going through a major crisis. My mom developed mental illness; my dad had 2 different bouts with cancer and died at age 44; he had some serious problems with his job.... so my way of dealing with the chaos was to escape into my world of electronics and music.

It was the only corner of the universe that I had any real control of. I developed my thinking skills and engineering chops that way. Then got an EE degree.

I've been through a lot of therapy to sort out the teenage trauma. My counselor is a huge fan of inner child work, and I am too. It does the trick. One of the things I do is I imagine that 55 year old "Professor Perry" goes over to 14 year old Perry's house in Lincoln Nebraska. He brings his Macbook pro and microphone and measurement software... and notebooks and specification sheets and engineering formulas. All the benefits of an EE degree and years of experience.

Stuff that 14yo Perry LONGED to understand but had zero access to at the time. They sit together and Professor Perry teaches younger Perry everything he ever wanted to know. (My dad didn't have a technical bone in his body... there were a couple guys at the stereo shops that knew more than me, but they were busy with other stuff and their job was to sell equipment, not give a DIY guy an acoustics degree.)

We make stuff I dreamed of making when I was 14, but couldn't afford and didn't know how to do. We produce designs that even KEF engineers in the 1980s with all their state of the art equipment would be envious of. These designs retain that vintage sound, but enjoy 21st century technical advantages.
focal-audax_4585 Medium.jpeg
focal-audax_4586 Medium.jpeg


One last thing - this also puts me into a state of flow, which spills out into other areas. I've had a number of intellectual and career breakthroughs, insights to thorny problems that dropped on me while I was blissfully unaware of the passage of time, going through the ritual of building or optimizing a system. Just had a major epiphany about 3 weeks ago, tailing on this project pictured here.

It's very valuable head space and I've learned to just follow the muse and not try to rationalize or justify why I'm doing a particular thing.

In other words... if your younger self is yearning for an Accurate Sound Model 7, then go ahead and build it, and follow YOUR instincts and YOUR muse and just go where your heart leads.
 
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#36
I looked for your TML, but found this one: "Audimax -TL 28.3" It is a reference class DIYS speaker from a German developer. While I personaly find the upper parts too expensive, the bass part may be nice to copy. I will have a look for the plans.
On the cover of the magazine you can see how it is build inside. Has noting to do with "your" TML, but avoids all the problems. This is how you can do it today. It is a so called "Fuzzy TML".
 

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#37
Turbowatch2 said:
I looked for your TML, but found this one: "Audimax -TL 28.3" It is a reference class DIYS speaker from a German developer. While I personaly find the upper parts too expensive, the bass part may be nice to copy. I will have a look for the plans.
On the cover of the magazine you can see how it is build inside. Has noting to do with "your" TML, but avoids all the problems. This is how you can do it today. It is a so called "Fuzzy TML".
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I would like to first try to find the plans for the Accurate Sound Model 7 that I built in 1977. But, the next time that I visit the Technische Informationsbibliothek in Hannover, I will read through the August/September 2018 issue of "Hobby HiFi". Thanks for the pointer!
 
#39
At the cover PDF of that magazine you see the internals of this "fuzzy" line. It is very simple to build, using only straight cuts and takes care of unwanted resonances. Quite large too and very capable with the 10" woofer.
Just to show the huge contrast to the old "Bailey style" transmission line constructions, that had quite some problems.
 
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