www.acuhorn.pl
Now here's a question. What exactly is going on with these ludicrously expensive things? I reckon they look ripe for a cloning, but there isn't much information on their layout. The smallest 125, which we thought was an inverted BIB, is actually a normal rear-venting corner-horn (I suspect a big CC though -I found a picture which you can see on the BIB thread). It seems to be made of plywood, as you can see from the attached head-on picture.
The drivers appear to be based upon these cheap £10 things, albeit heavily modified with neodium magnets http://www.tvm-valmez.cz/index.php?id=110&catit=186&l=1&catg=27
Their huge top-end 155 uses two drivers. They claim it's a dipole, so I'm assuming they are out of phase with each other, otherwise it's a bipole, and in physically partitioned off sections, otherwise the cabinet won't be doing a heck of a lot. But exactly where is the second driver? On the tall 175, which is the other one of their 4 models to use two drivers you can see it's mounted on the rear baffle, but I can't see one on the 155. Thoughts on this and any general ideas re what the different speaker's layout could be?
Cheers
Scott
Now here's a question. What exactly is going on with these ludicrously expensive things? I reckon they look ripe for a cloning, but there isn't much information on their layout. The smallest 125, which we thought was an inverted BIB, is actually a normal rear-venting corner-horn (I suspect a big CC though -I found a picture which you can see on the BIB thread). It seems to be made of plywood, as you can see from the attached head-on picture.
The drivers appear to be based upon these cheap £10 things, albeit heavily modified with neodium magnets http://www.tvm-valmez.cz/index.php?id=110&catit=186&l=1&catg=27
Their huge top-end 155 uses two drivers. They claim it's a dipole, so I'm assuming they are out of phase with each other, otherwise it's a bipole, and in physically partitioned off sections, otherwise the cabinet won't be doing a heck of a lot. But exactly where is the second driver? On the tall 175, which is the other one of their 4 models to use two drivers you can see it's mounted on the rear baffle, but I can't see one on the 155. Thoughts on this and any general ideas re what the different speaker's layout could be?
Cheers
Scott
Attachments
Hi Nigel
Thanks for the views. I hadn't thought about the weight, but I reckon you're right: not much internal partitioning in there. That's significant -I've had a few ideas regarding what the layout could be, and it looks like the simple one is the most likely.
I've just taken another look at the Acuhorn site, and spotted something else I hadn't noticed before: the 155 is exactly double the depth of the 145 according to their site. So it looks like it's simply two of them joined together, and facing in opposite directions.
I'll get back once I've drawn up a few rough plans and checked them in MathCad. Makes a change from the BIB and my usual QWRs, love it / them though I do.
Best
Scott
Thanks for the views. I hadn't thought about the weight, but I reckon you're right: not much internal partitioning in there. That's significant -I've had a few ideas regarding what the layout could be, and it looks like the simple one is the most likely.
I've just taken another look at the Acuhorn site, and spotted something else I hadn't noticed before: the 155 is exactly double the depth of the 145 according to their site. So it looks like it's simply two of them joined together, and facing in opposite directions.
I'll get back once I've drawn up a few rough plans and checked them in MathCad. Makes a change from the BIB and my usual QWRs, love it / them though I do.
Best
Scott
I've been studying all the pictures of the Acuhorn 155 that I can find over the past couple of days. And I think it might look something like this, internally. About as simple as you can get really. Given the relatively light weight for the size, I suspect it's something like this anyway. Two horns, back to back, and separated by a central baffle, with the drivers wired out of phase. I ran a quick MathCad sim on this, assuming the old-type non 'E' FE208Sigma, and aside from a dip at ~150Hz, the FR looked decent enough. Could be as cheap or as expensive to build as the wallet could afford -anything from chipboard to the more expensive types of veneered birch ply or solid wood would be on. Could be a really interesting option if you have the space.
Attachments
acuhorn
Hi, I have been to a shop to see how the original (non modified) driver of the acuhorns look like.It has a very small magnet and it has a huge frame basket, very strange looking driver since the openings on the frame are relatively small compared to the frame surface.Maybe it is a good driver as a first driver for single-driver experiments.Some DIY-ers from Poland made a similar construction to the Acuhorn's.
Hi, I have been to a shop to see how the original (non modified) driver of the acuhorns look like.It has a very small magnet and it has a huge frame basket, very strange looking driver since the openings on the frame are relatively small compared to the frame surface.Maybe it is a good driver as a first driver for single-driver experiments.Some DIY-ers from Poland made a similar construction to the Acuhorn's.
Scottmoose,
Interesting analysis. When you ran the sim did you use the original dims with the 208 Sigmas?
If you are correct about the internals, then somewhat similar to doubled up BiBs (with mouth pointing forward/backward)? I guess the next question is what does it sound like? And would doubled up BiBs, bipole/dipole, be a feasible proposition (how would it sim)?
Regarding BiBs,
Actually, the BiB is based on a "Japanese horn fanatic" design by Tetsuo Nagaoka.
Interesting analysis. When you ran the sim did you use the original dims with the 208 Sigmas?
If you are correct about the internals, then somewhat similar to doubled up BiBs (with mouth pointing forward/backward)? I guess the next question is what does it sound like? And would doubled up BiBs, bipole/dipole, be a feasible proposition (how would it sim)?
Regarding BiBs,
Actually, the BiB is based on a "Japanese horn fanatic" design by Tetsuo Nagaoka.
Hi guys
Interesting to hear from someone who's seen the original unmodified TVM / Tesla driver. Thanks for that.
I used approximately the original dimensions with the Fostex sim I ran. It's only educated guesswork, but the mouth area was exact, & I'm pretty sure the throat area was very close too. The rest of course is up in the air -you say some Polish DIYers have built something similar? Any details? The internal baffle I assumed for my sim went down further and at a shallower angle, creating a big CC in effect coupled to a short, more rapidly flared horn. Of course, these could just be big, positive tapered pipes, with the internal baffle at a steeper angle, terminating higher up, with no CC and giving a longer horn length, though that would mean the initial horn flare would be pretty straight. Given that each horn actually would have to be pretty shallow (~11in), I can't see there being physically room for anything else to be honest.
I don't think a doubled version of the BIB would work sadly as it relies on the room to complete it's horn mouth, and is designed for corner loading, which wouldn't sit too well with bi or dipole operation. Yes, similarities to the Nessie in some ways. Now, the 175 on the other hand looks to me from the website pictures like it is simply 2 Voigt pipes, back to back (the rear one inverted). I think I can see a front vent near the bottom, and there looks to be another at the top on the back, though the pictures aren't clear at all, and I could be way off the mark. Having said that -it'd work, no question. And very well too, providing the vents were properly designed.
Interesting to hear from someone who's seen the original unmodified TVM / Tesla driver. Thanks for that.
I used approximately the original dimensions with the Fostex sim I ran. It's only educated guesswork, but the mouth area was exact, & I'm pretty sure the throat area was very close too. The rest of course is up in the air -you say some Polish DIYers have built something similar? Any details? The internal baffle I assumed for my sim went down further and at a shallower angle, creating a big CC in effect coupled to a short, more rapidly flared horn. Of course, these could just be big, positive tapered pipes, with the internal baffle at a steeper angle, terminating higher up, with no CC and giving a longer horn length, though that would mean the initial horn flare would be pretty straight. Given that each horn actually would have to be pretty shallow (~11in), I can't see there being physically room for anything else to be honest.
I don't think a doubled version of the BIB would work sadly as it relies on the room to complete it's horn mouth, and is designed for corner loading, which wouldn't sit too well with bi or dipole operation. Yes, similarities to the Nessie in some ways. Now, the 175 on the other hand looks to me from the website pictures like it is simply 2 Voigt pipes, back to back (the rear one inverted). I think I can see a front vent near the bottom, and there looks to be another at the top on the back, though the pictures aren't clear at all, and I could be way off the mark. Having said that -it'd work, no question. And very well too, providing the vents were properly designed.
TVM speaker Quality
I am tempted to note that TVM speakers are of quite poor quality, perhaps not that bad for the price (usual price here is some 11-12 Euros). A friend of mine built a pair of speakers using tvm drivers, he is quite happy with them but direct comparison with my boxes (using seas excel) immediately revealed a horrible lack of detail from TVM. Also once we sought a replacement driver for some old revox speakers, out of 12 speakers nine rattled using a tone generator.
I am tempted to note that TVM speakers are of quite poor quality, perhaps not that bad for the price (usual price here is some 11-12 Euros). A friend of mine built a pair of speakers using tvm drivers, he is quite happy with them but direct comparison with my boxes (using seas excel) immediately revealed a horrible lack of detail from TVM. Also once we sought a replacement driver for some old revox speakers, out of 12 speakers nine rattled using a tone generator.
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