I should think anyone wanting to build upper bass/mid horns should start with Bruce Edgar's Positive Feedback interview, then try and read as many of JLH's ( in particular) and GM's posts as possible. Alongside that, try to read the relevant threads on Romy's 'knowledge tree' which is tougher but ultimately rewarding once you are actually building and listening .
Romy The Cat's Audio Knowledge Tree
I'm stalled on further measurements right now, as I think I've blown a cathode-by-pass cap on my output valve while doing measurements - fed in too much signal at the front end while I was using the big series resistance. Need to de-bug ...
Romy The Cat's Audio Knowledge Tree
I'm stalled on further measurements right now, as I think I've blown a cathode-by-pass cap on my output valve while doing measurements - fed in too much signal at the front end while I was using the big series resistance. Need to de-bug ...
You need to get hold of Rakesh on this ..
http://www.diyaudio.com/forums/grou...y-fane-8m-studio-50-units-production-run.html
...thread, when he comes back from holiday . He took the risk of funding a few more pairs to make up the order , expecting future sales .
Sorted out the amp problem - blown cap from clipping at low frequencies during testing . Back in business now .
Put some blocks of dense closed-cell foam in the corners of the box to further reduce the free volume to about 2 to 2.5L . Listening revealed :
(i) bit cleaner tone likely due to the box interior being a bit damped by the foam
(ii) obviously bass-light .
Tests with signal generator and ear suggested it's now rolling-off from eg. 160-170Hz and well down ( -20dB ? ) by 100Hz . Showing all the hallmarks of being too small a back-volume - and this agrees pretty well with sims on Hornresp .
So I just seem to disagree with you on this point JLH , sorry ;o)
Maybe we will be more 'aligned' when I try the Fane drivers .
In the meantime I must build a better back-chamber ( cylindrical most likely ) that is a bit bigger and easier to adjust . I will be checking out the houseware departments at the weekend .
MJ
Put some blocks of dense closed-cell foam in the corners of the box to further reduce the free volume to about 2 to 2.5L . Listening revealed :
(i) bit cleaner tone likely due to the box interior being a bit damped by the foam
(ii) obviously bass-light .
Tests with signal generator and ear suggested it's now rolling-off from eg. 160-170Hz and well down ( -20dB ? ) by 100Hz . Showing all the hallmarks of being too small a back-volume - and this agrees pretty well with sims on Hornresp .
So I just seem to disagree with you on this point JLH , sorry ;o)
Maybe we will be more 'aligned' when I try the Fane drivers .
In the meantime I must build a better back-chamber ( cylindrical most likely ) that is a bit bigger and easier to adjust . I will be checking out the houseware departments at the weekend .
MJ
I changed it to 10 liters and it didn't make much difference in the simulated SPL response.
One thing that has shown up in Hornresp is that if you take a 1/4 size tractrix horn and put it into 1/8 size space, the bass response extends to the designed cut off frequency whereas if you take that same horn and stick it in 1/4 size space the bass response does not extend to the intended cut off frequency. Bruce talked about how tractrix bass horns do not perform that well because they cut off at a higher frequency than the intended cut off. I think there's something wrong with the math such that it is off by a factor of 2.
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The frot loaded horn system
including not only the driver and horn after,
but
one chamber behind driver
one smaller chamber after the driver, with Sm
and horn.
That is not only for bass horns but for all horn
sys... These compression drivers already have the chamber inside...
read M. Leach articles on designing horns...
.
another thing, Rg is the value of internal resistance of the
generator + cables
(and if You using a tube amp that is somethig smaller than dc res of secondary
of OT...)
So consider this value different from like 0.05 ohms or so
cheers🙂
including not only the driver and horn after,
but
one chamber behind driver
one smaller chamber after the driver, with Sm
and horn.
That is not only for bass horns but for all horn
sys... These compression drivers already have the chamber inside...
read M. Leach articles on designing horns...
.
another thing, Rg is the value of internal resistance of the
generator + cables
(and if You using a tube amp that is somethig smaller than dc res of secondary
of OT...)
So consider this value different from like 0.05 ohms or so
cheers🙂
Have you actually measured the resonance frequency? Check to see where your peak is at before you draw any conclusions. If your tuning is still too low, the horn will roll off early because the reactance is choking it. You have to get the resonance close to the flare frequency or you'll never get full bass extension. When I got the tuning correct on Romy's 126Hz tractrix horns, the bass drum would shake my floor and you could feel a punch in the chest. It was very tight and powerful. And this was using a 1.5W 6AH4 single end amp. If you're not getting simular results, then there is something very wrong.
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Or just hold on patiently for a year or less when "grup buy" folks start to sell theirs at half price crying that wives don't let them build or put midbass horns in their living rooms. (thats what I'm gonna do hehe😉.
...When I got the tuning correct on Romy's 126Hz tractrix horns...
John, where that odd cut off frequencys of your horns are coming from? I remember you were selling your 142 Hz trax midbass
Regards L
John, where that odd cut off frequencys of your horns are coming from? I remember you were selling your 142 Hz trax midbass
Regards L
Physical size restrictions mostly. I've built several large mid bass tractrix horns. Sometimes the person asked for a certain frequency response, other times they would tell me I have "X" amount of space and I would build the biggest that would fit.
Hello all, I'm hoping to implement a upper bass tractrix in my system as well. I have a 5 way horn system right now and I assume adding a 6th channel would do wonders. 😀
First, a little info on my system. I built this system from the ground up with my father, it is our first attempt at horns and we're slowly improving it. The 5 way system is digitally crossed and used to consist:
TAD ET-703
TAD 4003 on 400hz Stereolab Tractrix with 1.5in throat
GOTO 505TT on GOTO S150 Horn (150hz exponential)
TAD 1101H 11" driver on DIY 1/2 space 9ft 53hz Horn
TAD 1603 16" driver on DIY Tapped Horn
Over the past couple of years we slowly learned about implementing horns and the problem we've always had was mismatch between our DIY 53hz midbass channel and the GOTO channel. GOTO claims their 505TT driver does 200hz-1khz and we believed it, afterall it is the most expensive channel in our system, right? It wasn't until we had access to a RTA that we realized the "hole" we heard was caused by GOTO's huge drop in output between 200-400hz 😱 We also tried moving the xover frequency to 400hz and things got a little better but ultimately the 53hz midbass horn just wasn't performing up to par into the upper bass region...
Fast forward to a few months ago, we were looking for something to replace GOTO's 200-1.2khz channel with and came across this thread. We chose 2 drivers from JLH's list of recommended drivers:
"The following drivers are ones that I've either built with, or know first hand that work very well in horns.
Eminence Delta Pro-8A or 8B, the 8A is 8 ohms, the 8B is 16 ohms
Ciare 6.38NdW
Ciare 8.50NdW
Faital M5N12-80, it is 12 ohms
Faital W6N8-120
Beyma 6MI100
18 Sound 6ND410
18 Sound 8M400
18 Sound 10M600
B&C Speakers 8PE21
B&C Speakers 10MD26
Your overall goal will determine which driver will meet your needs the best."
We finally decided on Faital M5N12-80 and Beyma 6M100. As a temporary solution, we mounted the drivers on a section of GOTO's S150 Horn. We were lucky the point where the two GOTO horn sections meet is around 4 inches in diameter 😉 Please refer to the photo below on how the drivers were mounted. Anyway, the 6M100 performed very well between 200-1.2khz and is in agreement with JLH's comment "The most articulate of the drivers I listed is the Beyma 6MI100. The 6MI100 can approch high dollar GOTO drivers if it is equiped with a good phase plug." After this change, we finally heard some sort of completeness in our system. Most importantly, we learned the importance of the upper bass frequencies.
So why do we want to try a 6th channel if things are working out? There are a few reasons. 1) Although the 6M100 approaches high dollar GOTO drivers, the speed/transients/attack for the higher frequencies between 200-1.2k is a bit softer than GOTO's. We'd like to keep the good parts of GOTO and mate it with a proper sounding upper bass horn. 2) Our 53hz midbass is okay at 200hz but we'd like to see if things will be even better with a lower xover point. 3) Vertically align the upper channels. We plan to rotate the midbass horn 90 degrees and setup a vertical horn rack next to or in front of it. By doing so I can couple the upper bass channel to the floor as well. 😀
So the big question is which 8-12" driver will sound "best" between approximately 100-600hz loaded into a 120hz tractrix? (120hz tractrix horn should be 36" high and will allow us to set our 400hz tractrix above it at ear level. The supertweeter and GOTO loading into 250hz tractrix will go above ear level.) My father and I listen to all kinds of music but really enjoy classical and jazz on this huge system! 😀
Thanks!
Keith
First, a little info on my system. I built this system from the ground up with my father, it is our first attempt at horns and we're slowly improving it. The 5 way system is digitally crossed and used to consist:
TAD ET-703
TAD 4003 on 400hz Stereolab Tractrix with 1.5in throat
GOTO 505TT on GOTO S150 Horn (150hz exponential)
TAD 1101H 11" driver on DIY 1/2 space 9ft 53hz Horn
TAD 1603 16" driver on DIY Tapped Horn
Over the past couple of years we slowly learned about implementing horns and the problem we've always had was mismatch between our DIY 53hz midbass channel and the GOTO channel. GOTO claims their 505TT driver does 200hz-1khz and we believed it, afterall it is the most expensive channel in our system, right? It wasn't until we had access to a RTA that we realized the "hole" we heard was caused by GOTO's huge drop in output between 200-400hz 😱 We also tried moving the xover frequency to 400hz and things got a little better but ultimately the 53hz midbass horn just wasn't performing up to par into the upper bass region...
Fast forward to a few months ago, we were looking for something to replace GOTO's 200-1.2khz channel with and came across this thread. We chose 2 drivers from JLH's list of recommended drivers:
"The following drivers are ones that I've either built with, or know first hand that work very well in horns.
Eminence Delta Pro-8A or 8B, the 8A is 8 ohms, the 8B is 16 ohms
Ciare 6.38NdW
Ciare 8.50NdW
Faital M5N12-80, it is 12 ohms
Faital W6N8-120
Beyma 6MI100
18 Sound 6ND410
18 Sound 8M400
18 Sound 10M600
B&C Speakers 8PE21
B&C Speakers 10MD26
Your overall goal will determine which driver will meet your needs the best."
We finally decided on Faital M5N12-80 and Beyma 6M100. As a temporary solution, we mounted the drivers on a section of GOTO's S150 Horn. We were lucky the point where the two GOTO horn sections meet is around 4 inches in diameter 😉 Please refer to the photo below on how the drivers were mounted. Anyway, the 6M100 performed very well between 200-1.2khz and is in agreement with JLH's comment "The most articulate of the drivers I listed is the Beyma 6MI100. The 6MI100 can approch high dollar GOTO drivers if it is equiped with a good phase plug." After this change, we finally heard some sort of completeness in our system. Most importantly, we learned the importance of the upper bass frequencies.
So why do we want to try a 6th channel if things are working out? There are a few reasons. 1) Although the 6M100 approaches high dollar GOTO drivers, the speed/transients/attack for the higher frequencies between 200-1.2k is a bit softer than GOTO's. We'd like to keep the good parts of GOTO and mate it with a proper sounding upper bass horn. 2) Our 53hz midbass is okay at 200hz but we'd like to see if things will be even better with a lower xover point. 3) Vertically align the upper channels. We plan to rotate the midbass horn 90 degrees and setup a vertical horn rack next to or in front of it. By doing so I can couple the upper bass channel to the floor as well. 😀
So the big question is which 8-12" driver will sound "best" between approximately 100-600hz loaded into a 120hz tractrix? (120hz tractrix horn should be 36" high and will allow us to set our 400hz tractrix above it at ear level. The supertweeter and GOTO loading into 250hz tractrix will go above ear level.) My father and I listen to all kinds of music but really enjoy classical and jazz on this huge system! 😀
Thanks!
Keith
Attachments
A good 11 slit radial phase plug can help get the 6MI100 a little bit closer to the GOTO performance, but in the end it will be giving something up because it can't quite match the GOTO's powerful motor structure. However, as you found out, it is one of the best values in audio when you consider its level of performance. Also, within the confines of what your system is now, adding another horn makes perfect sense. I would suggest a 10" or 12" due to the scale of your current system and room size. Most of the low Qes pro sound woofers with light cones should be fine. I've worked with the B&C 10MD26 and it does very well in the 100Hz to 600Hz range. But, once again you might find some "softness" compared to the GOTO driver. A good phase plug design will help close the gap. You can also over dampen the tuning to increase the "attack".
Missing peak
OK JLH, advice noted, I'll try to find a resonance peak , but I did find it impossible with the back-volume ( empty) fitted, before, to find a peak anywhere in the expected 80-130 Range - just a couple of small ripples around 150 and 170 as I recall . I might try Romy's method of opening up a few mm of gap at one side of the back-chamber and see if I can locate a peak that way .
MJ
OK JLH, advice noted, I'll try to find a resonance peak , but I did find it impossible with the back-volume ( empty) fitted, before, to find a peak anywhere in the expected 80-130 Range - just a couple of small ripples around 150 and 170 as I recall . I might try Romy's method of opening up a few mm of gap at one side of the back-chamber and see if I can locate a peak that way .
MJ
Tell me how you'd measure the impedance curve, Dirk . I described my difficulties finding the peak a few posts back . If you have a better method then that would be very useful .
hi Keith
i made the same experience as you, after i replaced the Fane Studio 8m with Radian 950pb. The difference of the Radian to your Goto is , that it goes lower. Vincent Brient measured useful output down to 220hz.
In my setup, i choose 300hz crossover point. And my bass horn keeps up well up to that frequency. Instead of inserting another horn channel, with all the difficulties to integrate it etc., why do you not try a compression driver in the lower midrange, that goes lower, to fill the gap ?
Angelo
Look at the size and scale of his sytem. A Radian 950PB is a toy compraed to the GOTO 505TT. If the GOTO driver isn't cutting it, what makes you think the Radian can do it? The span between the 53Hz horn and the 150Hz is too great due to the high horse power design of his system. You can't do things the same way - the scaling and requirements are completely different. You should never use any compression driver below its Fs. It's a poor design choice.
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