Looking at the plans, the top of the driver opening is 7 inches above the bottom. The driver has to sit on a flat surface, So 7 inches from the bottom, there is still no expansion. Probably not for another bit, as the frame is a bit bigger than the membrane etc. so, the first measurement that we can absolutely rely on, is the next one,
This measurement, closest to the horn throat, is 163,7597531 cm^2. The mouth size was established earlier in this thread as 1089,161128 cm^2. The length between these two measurements is 73.66 cm.
Putting this into hornresp gives a tractrix horn with a flare frequency of 69.53 Hz.
This measurement, closest to the horn throat, is 163,7597531 cm^2. The mouth size was established earlier in this thread as 1089,161128 cm^2. The length between these two measurements is 73.66 cm.
Putting this into hornresp gives a tractrix horn with a flare frequency of 69.53 Hz.
The frontloaded horn section is now fully defined:
Ah: 136.29 cm^2
Am: 1089.16 cm^2
L: 80.3 cm
Flare frequency: 70 Hz
Ah: 136.29 cm^2
Am: 1089.16 cm^2
L: 80.3 cm
Flare frequency: 70 Hz
OK, next step is the bass pipe.
From the plans, grabbing numbers from various figures and the table on the final page:
Ah = 10.25 inch x 11.5 inch = 26.035cm x 29.21cm = 760,48235 cm^2
This is going to be interesting, because there are some numbers missing. Specifically, the pipe ends sort of mid air and how far that is above the floor does not seem to be in the plans. However, I have played around with the pipe tuning a bit in hornresp and pipe length does not seem too critical. Let's just see which numbers are in there and what can be inferred. It's likely that there is a logical compromise to be found.
To be honest my primary interest was how Voigt approached the frontloaded horn section, but that bass pipe is grabbing my interest. It appears to have almost no taper, varying length does not lead to very large peaks or dips, so it's pretty easy to adapt to a driver and/or roomgain.
Voigt is a legend for a reason, that much must be clear by now. 😎
From the plans, grabbing numbers from various figures and the table on the final page:
Ah = 10.25 inch x 11.5 inch = 26.035cm x 29.21cm = 760,48235 cm^2
This is going to be interesting, because there are some numbers missing. Specifically, the pipe ends sort of mid air and how far that is above the floor does not seem to be in the plans. However, I have played around with the pipe tuning a bit in hornresp and pipe length does not seem too critical. Let's just see which numbers are in there and what can be inferred. It's likely that there is a logical compromise to be found.
To be honest my primary interest was how Voigt approached the frontloaded horn section, but that bass pipe is grabbing my interest. It appears to have almost no taper, varying length does not lead to very large peaks or dips, so it's pretty easy to adapt to a driver and/or roomgain.
Voigt is a legend for a reason, that much must be clear by now. 😎
Aha. I think we actually have enough information after all. The top panel of the "bass chamber" fits up against the horn. It has a certain width, so we can determine the exact height at which it sits up against the horn. The plans say to be trimmed and to be fitted a lot, so I don't really want to calculate or eyeball this. A basic SketchUp model is in the works, which wil let me add the material thickness and will allow me to lay out these panels very precisely.
I think this will be helpful in determining the angle of the slanted panels as well. An interesting thing is that the horn is expanding, which means the expansion of the bass pipe is actually less in the middle of the pipe than it seems from the 2D view in the plans. Bruce Edgar has Voigt say it is a resonant pipe, but perhaps there is more to it. There is minimal expansion judging from the horn throat and horn mouth, quickly leading to the assumption of a barely expanding conical/parabolic/nearly straight transmission line. If the middle of the bass pipe is somewhat constricted, the pipe may actually have a little more pronounced curved expansion and could even be tractrix or exponential. The Hegemann reconstruction's rearloaded section, from the same person whose Domestic Corner Horn reconstruction is linked above, seemed very pipe-ish. But after careful laying out, he concluded it was a precise tractrix expansion.
A tractrix is mostly similar to a plain exponential horn, only the full mouth section is significantly different. At the mouth reductions and compromises at which most backloaded horns operate, the difference between exponential and tractrix is almost zero, and even parabolic can often have a very close volume and simulated frequency response. But there is about 1-2 dB difference in efficiency between the most and least efficient horn expansion, so it's still relevant to find out. I'm looking forward to finding this out over the coming weeks.
We just bought a new house and things will inevitably slow down. Unless I need some distraction from it all, then it will speed up... 🤭
I think this will be helpful in determining the angle of the slanted panels as well. An interesting thing is that the horn is expanding, which means the expansion of the bass pipe is actually less in the middle of the pipe than it seems from the 2D view in the plans. Bruce Edgar has Voigt say it is a resonant pipe, but perhaps there is more to it. There is minimal expansion judging from the horn throat and horn mouth, quickly leading to the assumption of a barely expanding conical/parabolic/nearly straight transmission line. If the middle of the bass pipe is somewhat constricted, the pipe may actually have a little more pronounced curved expansion and could even be tractrix or exponential. The Hegemann reconstruction's rearloaded section, from the same person whose Domestic Corner Horn reconstruction is linked above, seemed very pipe-ish. But after careful laying out, he concluded it was a precise tractrix expansion.
A tractrix is mostly similar to a plain exponential horn, only the full mouth section is significantly different. At the mouth reductions and compromises at which most backloaded horns operate, the difference between exponential and tractrix is almost zero, and even parabolic can often have a very close volume and simulated frequency response. But there is about 1-2 dB difference in efficiency between the most and least efficient horn expansion, so it's still relevant to find out. I'm looking forward to finding this out over the coming weeks.
We just bought a new house and things will inevitably slow down. Unless I need some distraction from it all, then it will speed up... 🤭
Anything here?
https://www.worldradiohistory.com/UK/Wireless-World/30s/Wireless-World-1939-11-S-OCR.pdf
advertisements p15
"Home Constructor's Corner Horn with Bass Chamber"
from https://pinkfishmedia.net/forum/threads/p-g-a-h-voigt-a-great-audio-inventor.78278/page-2
===========
https://www.itishifi.com/search?q=voigt
https://www.itishifi.com/archives//2010/04/early-voigt-speaker-ads.html
https://www.itishifi.com/archives//2011/06/voigt-labratory-report-may-1939.html?rq=voigt
https://www.itishifi.com/archives//2012/09/voigt-corner-horn-mahogany.html?rq=voigt
https://www.itishifi.com/hifi/vjt3n6ewyae190lk3q7z9o6nhmkfds?rq=voigt
====================================================
https://pinkfishmedia.net/forum/thr...reat-audio-inventor.78278/page-2#post-1205965
from
" eguth
post#35
Further research has led to my finding an article in Wireless World-[issue of 28 December , 1934, p.561- entitled ‘Voigt Domestic Loud Speaker- Construction and Performance of the Latest Corner Cabinet Type Horn’]
The article is anonymous but I surmise that it was written by Voigt himself. It contains a photo of the exterior of the cabinet and a cutaway side view diagram. Most importantly, there is a photo of the INTERIOR with Front Panels removed. This shows alternative sound paths.
I believe that this article, and especially the photo, would be of use to anyone constructing the speaker or the simplified Home Constructor’s version, and would suggest that constructors obtain a photocopy.
I have also found a photo of the finished Home Constructor's Horn, but it is not as useful as the photo in the 28 December 1934 issue (abovementioned). It shows only the front exterior. The front exterior photo is inside the back cover in the 7 June 1935 issue. "
Anyone find this?
https://www.worldradiohistory.com/UK/Wireless-World/30s/Wireless-World-1939-11-S-OCR.pdf
advertisements p15
"Home Constructor's Corner Horn with Bass Chamber"
from https://pinkfishmedia.net/forum/threads/p-g-a-h-voigt-a-great-audio-inventor.78278/page-2
===========
https://www.itishifi.com/search?q=voigt
https://www.itishifi.com/archives//2010/04/early-voigt-speaker-ads.html
https://www.itishifi.com/archives//2011/06/voigt-labratory-report-may-1939.html?rq=voigt
https://www.itishifi.com/archives//2012/09/voigt-corner-horn-mahogany.html?rq=voigt
https://www.itishifi.com/hifi/vjt3n6ewyae190lk3q7z9o6nhmkfds?rq=voigt
====================================================
https://pinkfishmedia.net/forum/thr...reat-audio-inventor.78278/page-2#post-1205965
from
" eguth
post#35
Further research has led to my finding an article in Wireless World-[issue of 28 December , 1934, p.561- entitled ‘Voigt Domestic Loud Speaker- Construction and Performance of the Latest Corner Cabinet Type Horn’]
The article is anonymous but I surmise that it was written by Voigt himself. It contains a photo of the exterior of the cabinet and a cutaway side view diagram. Most importantly, there is a photo of the INTERIOR with Front Panels removed. This shows alternative sound paths.
I believe that this article, and especially the photo, would be of use to anyone constructing the speaker or the simplified Home Constructor’s version, and would suggest that constructors obtain a photocopy.
I have also found a photo of the finished Home Constructor's Horn, but it is not as useful as the photo in the 28 December 1934 issue (abovementioned). It shows only the front exterior. The front exterior photo is inside the back cover in the 7 June 1935 issue. "
Anyone find this?
Last edited:
?
old audio asylum post
http://www.lowthervoigtmuseum.org.uk/voigthc.html
old audio asylum post
RE: Voigt Home Constructors Horn
- Posted by Bruce Edgar (M) on January 15, 2009 at 08:36:59
In Reply to: Voigt Home Constructors Horn posted by DanK tubes on January 14, 2009 at 13:34:18:
http://www.lowthervoigtmuseum.org.uk/voigthc.html
I don´t have a lot of time at the moment. We are about to move to another house and getting the old house ready to sell. It´s constantly in the back of my mind though.
I just had some time to read the Voigt patent for the reflector used in the big Domestic Cornerhorn. The diagram below shows what he very clearly describes as a horn pointing down, with a reflector placed below it. As in, the reflector is separate from the horn. Bruce Edgar wrote it as Voigt´s own words in the quasi interview, but this is directly from Voigt himself. I thought that was good to add.
I suspect that the drawing in the patent is to scale and can be a decent basis for deducing relevant sizes and curves from. I have seen some pictures of a home constructor´s cornerhorn with a similar reflector added, Which is not a bad idea. Something for the list of things to sort out perhaps.
I just had some time to read the Voigt patent for the reflector used in the big Domestic Cornerhorn. The diagram below shows what he very clearly describes as a horn pointing down, with a reflector placed below it. As in, the reflector is separate from the horn. Bruce Edgar wrote it as Voigt´s own words in the quasi interview, but this is directly from Voigt himself. I thought that was good to add.
I suspect that the drawing in the patent is to scale and can be a decent basis for deducing relevant sizes and curves from. I have seen some pictures of a home constructor´s cornerhorn with a similar reflector added, Which is not a bad idea. Something for the list of things to sort out perhaps.
I have no time to work out the outstanding questions about the rear bass pipe at the moment. I suspect now it´s mostly a straight pipe. Considering Voigt ostensibly says the horn had response to 100Hz and the pipe expands it to 50Hz, I think we can assume a straight TL with 1/4 wavelength of 50Hz, at least until I have that more exactly worked out. Knowing is nicer than assuming, but...... Quickly simming some drivers in a hornresp model can be very relaxing after a day of clearing out the attic. 🤣
Anyone have any suggestions for a currently available 6" fullrange drive unit?
Also, does anyone have any clue about the range of TSP the originally used field coil drivers had?
Anyone have any suggestions for a currently available 6" fullrange drive unit?
Also, does anyone have any clue about the range of TSP the originally used field coil drivers had?
But, uh.... They are definitely bigger than your average Sonos offering, but they are not giant horns and they are not giant enclosures in the context of its era. I read in another little interview with Voigt that the simple home constructor's cornerhorn was greatly simplified due to material shortages, but performed amazingly well. (I should have remembered which article, to add it here.) From his wording, I got the impression that Voigt was actually a bit sorry for making the original corner horn so complicated, as the home constructor's cornerhorn gets basically the same thing done.
Not up to date re drivers, but FC were all about impedance matching, so assuming an 8 ohm resistor in series with a modern 8 ohm driver, a max flat alignment = 0.707 Qt on the high side and ~0.3 to allow for amp, in room tuning flexibility, though IIRC some modern FC drivers allow for as little as 0.2 Qt.
(Qts'): (Qts) + any added series resistance (Rs)
Whoops... We get the keys to the new house on April 1st, and we just had the photographer in our old house to put it up for sale, so there is a little boring gap. I ordered a pair of Sica 6D1,5CS and hope to get a bit of ply tomorrow. I will be cutting the project in bits. I am building the horn portion without reflector. If I have more time, I will make an extension with the reflector section. It will be fun and I also think the plans are set up for the bass chamber parts to be made in situ, rather than planned and cut ahead of assembly. I think finishing the reconstruction will be easier working from a physical specimen.
https://www.hifi-selbstbau.de/index.php/hsb-datenblaetter/breitbandchassis/sica-6d1-5-cs4
I admit that the first attraction was its price, but it has a rising response and the specs are ballpark. They like Sica drivers in the German diyaudio magazines for FAST, backloaded horns, TQWTs etc, so I'll find a way to put them to use if they don't work out very well in the Voigt horns.
https://www.hifi-selbstbau.de/index.php/hsb-datenblaetter/breitbandchassis/sica-6d1-5-cs4
I admit that the first attraction was its price, but it has a rising response and the specs are ballpark. They like Sica drivers in the German diyaudio magazines for FAST, backloaded horns, TQWTs etc, so I'll find a way to put them to use if they don't work out very well in the Voigt horns.
I have some outstanding business with the front horn, actually.
In the first 6 inch section, starting at the bottom, there is no expansion. The end of the second 6 inch section is wider. The driver needs a flat baffle to mounted to. I don't think that stretch of 6 inches flat baffle is enough to mount the driver. There is obviously a square frame around those original field coil drivers. I can't find exactly how large that square frame is, but I did find that information for the Lowther PM1, which could be fitted to the Voigt corner horns.
If the baffle cutout would be a simple round hole or a square, I would just place the drive unit over it, centered. Obviously Voigt wasn't so kind to me, so I am looking for some indications about where to place the driver on the baffle/the curved section.
So far I haven't been able to find a photograph of a driver in situ in a home constructor's corner horn. One or two from what I suspect is a PW1 corner horn, but no clear reference points. Another one or two from what looks like homebrew and adapted to a different, non-Voigt/Lowther drive unit.
And then I found the image below, of a Voigt domestic corner horn with a Lowther PM1 drive unit. As far as I understand, the early 6 inch Lowther drive units were backwards compatible with the Voigt corner horns, and I assume this means they had the same outer dimensions.
What is noteworthy to see, is that the driver is sitting on the lower panel of that chamber/start of the line. The square frame at the front of the driver is also sitting on that panel. I guess the weight of the assembly requires that sort of supporting frame and requires that frame to sit on a surface. I conclude that the driver in the Voigt home constructor's corner horn probably also sat... Well...
The horn itself is all on the front side of the driver, the bass chamber is an afterthought. So there is no bottom panel underneath the driver, I think. So to determine the length of the flat stretch of baffle, I will use the height of the square driver frame: 7.5 inches.
https://www.radiomuseum.org/r/lowther_lowther_voigt_driver_unit_pm1.html
In the first 6 inch section, starting at the bottom, there is no expansion. The end of the second 6 inch section is wider. The driver needs a flat baffle to mounted to. I don't think that stretch of 6 inches flat baffle is enough to mount the driver. There is obviously a square frame around those original field coil drivers. I can't find exactly how large that square frame is, but I did find that information for the Lowther PM1, which could be fitted to the Voigt corner horns.
If the baffle cutout would be a simple round hole or a square, I would just place the drive unit over it, centered. Obviously Voigt wasn't so kind to me, so I am looking for some indications about where to place the driver on the baffle/the curved section.
So far I haven't been able to find a photograph of a driver in situ in a home constructor's corner horn. One or two from what I suspect is a PW1 corner horn, but no clear reference points. Another one or two from what looks like homebrew and adapted to a different, non-Voigt/Lowther drive unit.
And then I found the image below, of a Voigt domestic corner horn with a Lowther PM1 drive unit. As far as I understand, the early 6 inch Lowther drive units were backwards compatible with the Voigt corner horns, and I assume this means they had the same outer dimensions.
What is noteworthy to see, is that the driver is sitting on the lower panel of that chamber/start of the line. The square frame at the front of the driver is also sitting on that panel. I guess the weight of the assembly requires that sort of supporting frame and requires that frame to sit on a surface. I conclude that the driver in the Voigt home constructor's corner horn probably also sat... Well...
The horn itself is all on the front side of the driver, the bass chamber is an afterthought. So there is no bottom panel underneath the driver, I think. So to determine the length of the flat stretch of baffle, I will use the height of the square driver frame: 7.5 inches.
https://www.radiomuseum.org/r/lowther_lowther_voigt_driver_unit_pm1.html