After reading so many good things about the Buschhorn, I built a pair of MKIIs using Fostex FE103En. I got them together yesterday afternoon and they really do disappear. Unfortunately, they sound bad. I mean not just bad, but terrible. Horns (ironically) sound great, but otherwise the closest thing they resemble is the sound of an old transistor radio, my radio alarm clock, speaker in a plastic box, etc.: it's a thin, hollowness with very little low frequency.
I have one side clamped tight to them while I play around with the sound. I've added polyfill damping in the compression chamber (which brought some instruments forward), the upper and lower voids, and added a bit in the throat as recommend by some. I even plugged them in out of phase with very little change. I've tried a variety of amplifiers and the speakers pretty much sound the same. Could this simply be a problem with the clamped seal? They have about 30 hours on them so do the drivers need to break in...a lot? This is my first DIY speaker project and any mods, tips, advice is welcome.
I have one side clamped tight to them while I play around with the sound. I've added polyfill damping in the compression chamber (which brought some instruments forward), the upper and lower voids, and added a bit in the throat as recommend by some. I even plugged them in out of phase with very little change. I've tried a variety of amplifiers and the speakers pretty much sound the same. Could this simply be a problem with the clamped seal? They have about 30 hours on them so do the drivers need to break in...a lot? This is my first DIY speaker project and any mods, tips, advice is welcome.
I just started playing them about two days ago and have about 25-30 hours on them. They sound so thin I wonder how much break-in will help; the change will have to be significant to enjoy anything but the most simple music. I'm curious too, if there is something I'm supposed to do to get rid of the hollowness or bring out a bit more low frequency (apart from adjusting tone controls)...Be patient?
I haven't looked at the Mk2 for a while, & certainly not with the 103En, but I have a nasty feeling that what applies to the Mk1 Buschorn also applies to its successor: viz. that (IMO) it's tuned too low for the given bulk / box size, with the result that the useful gain BW tends to be concentrated above ~100Hz. I could be wrong. Hope so. I've got some teaching to do this evening, but if I get chance, I'll take a look at it later & see what it's general behaviour is like / if I can make any suggestions.
Meantime: get some hours on the drivers. Those units were not anticipated by their designers to come on song until several hundred hours had passed (that's coming from a source in Fostex). Make of that what you will, but it should help a bit.
Meantime: get some hours on the drivers. Those units were not anticipated by their designers to come on song until several hundred hours had passed (that's coming from a source in Fostex). Make of that what you will, but it should help a bit.
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Frankly even though it's smaller and might not model as well. I found the MkI far superior to the MkII - the latter definitely has issues with the driver chamber. When properly corner situated the MkI with FE126 is quite nice.
Hey guys. Update: I let them play all weekend and I'm getting more low frequency now. I guess patience is a virtue...I played around a bit with the compression chamber based on what Scottmoose and hm mentioned, reducing the volume by about 2/3. What a change that made. I think I lost some openness (which was spooky) but the sound is now much more forward. Before (and in the one I have left unaltered) it seems as if instruments were buried in the cabinet somewhere and that high, nasal, hollowness has mostly been eliminated. As they break in, I'll cut some nice fitting pieces and continue to tune the CC. Since I put a fair amount of time into these, I'm still open to suggestions about mods to fine tune.
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Low pass chamber, the room is the compression chamber for a back-horn. I took a look the other night; in principle it's not too bad for what it is & reasonably flexible in terms of tweaking. FWIW, I'd concur in reducing the depth of the filter chamber to ~3.5in - 4in & then lightly damp. The box will be tuned a little higher since that long chamber is likely to be forming part of the horn expansion in practice (probably unintentionally), but it should result in a little more gain & probably kill some resonances without severely affecting the upper corner frequency (providing they're corner loaded, as intended). You might want to try adding a very light layer of damping as indicated in green lower down on this page: Serge's Home Page which should help kill any unwanted midrange that's still passing through the horn.
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Thanks. I believe the chamber is right around 4" now which smoothed the sound considerably. I'll continue to tweak it. I noticed on Serge's Home Page he used a Notch Filter. Anybody have experiences with these on the B-horn?
The BH is a very small horn so do not expect it to beheave as horn below 100 Hz.Then there is the baffle step f(3) = 115/W(B) (where W(B) is the baffle width in meters) so below 700 Hz the driver has its front radiation going from 1/2 space radiation to full space and a 6 dB loss. In general increasing the lowpass chamber volume increse the low bass but also increase the amplitude of the peaks and "uneveness".
So you have a severly compromised horn more like a resonant quarter wave pipe with some horn features thrown in. It still can sound good but it is a juggling act of getting it right.
So you have a severly compromised horn more like a resonant quarter wave pipe with some horn features thrown in. It still can sound good but it is a juggling act of getting it right.
The BHs have been running for about a week now, 10-14 hours a day. The drivers have continued to develop, and they seem to be using the horn now (sound comes out of it whereas before nothing). Overall, there is much more low end, and the highs have mellowed substantially. Those folks that say drivers don't need a break-in, obviously don't know what they are talking about. Like I said, out of the box these just sounded downright terrible.
I did some mods to the cabinets as suggested, and added a plate in the upper chamber about 6" from the front baffle and damped the area behind the driver with polyfill. This eliminated a lot of the hollow treble sounds I heard and gave me a better bottom end. One mod I tried was eliminating the upper chamber by adding a plate tilted forward at about a 45 degree angle toward the driver so what chamber was left, functioned like a mouthpiece. This was cool looking, but I lost some top end, soundstage/space, and even a little LF. Ultimately, it created a veiled, flat response.
I also added wool felt to the sides of the throat as indicated by Scottmoose. There was no negligible change, but left it in place for now because it didn't seem to hurt. I'll let these break in another week or so, seal them up, and make 'em pretty...And as far as the seal goes, I found it's gotta be tight or you will loose LF.
I did some mods to the cabinets as suggested, and added a plate in the upper chamber about 6" from the front baffle and damped the area behind the driver with polyfill. This eliminated a lot of the hollow treble sounds I heard and gave me a better bottom end. One mod I tried was eliminating the upper chamber by adding a plate tilted forward at about a 45 degree angle toward the driver so what chamber was left, functioned like a mouthpiece. This was cool looking, but I lost some top end, soundstage/space, and even a little LF. Ultimately, it created a veiled, flat response.
I also added wool felt to the sides of the throat as indicated by Scottmoose. There was no negligible change, but left it in place for now because it didn't seem to hurt. I'll let these break in another week or so, seal them up, and make 'em pretty...And as far as the seal goes, I found it's gotta be tight or you will loose LF.
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