How about a vented box for the Beyma 12p80nd? Tune it to 50-60 Hz and then just cross it around 100 Hz or so... It may be what would make the mids 'breathe'. At least it would be worth a try before dropping the 12p80nd....
Best regards
Peter
Best regards
Peter
Steve
It seems we are all doomed to keep repeating the mistakes of the past .. going down the same road !
The Yuichi is a scaled one, by the way - 415Hz ( x0.7 from the A290S to use 1.4" driver ) .
In my thread you'll find maybe 3-4 years ago the efforts to find a lower-midrange match to the 288H/Azura was a hard struggle and left me with various set of surplus drivers. I concluded that if you don't want ( or fail ) to make a big 120-200Hz horn then the only option that gets you close is a low-mass midrange driver on OB - something like a Fostex FE208EZ , a B&C 8PE21 or ideally the AER Mk.1 that JamesD used to great effect on his perspex OB's. Qts needs to be something like 0.35 to 0.25 . Then I'd suggest using a 12" driver of suitable type ( maybe not the Beyma ) with 0.4 Q or thereabouts to make a decent-size sealed box bass for low group-delay . Depends how many amps you're prepared to use !
What compression drivers do you have ? It seems to me if you go for a 200Hz horn then you need something to take over beyond 1 or 2kHz with good tone in that area and extension to 15k or so . Something like a 1" driver on a 600Hz Iwata or something of that sort. I'd favour an asymmetric expansion - elliptical Le Cleac'h or Iwata after my experiences with the Yuichi .
So anyway , four-way seems to be the minimum once you've got even ONE horn in the system !
It seems we are all doomed to keep repeating the mistakes of the past .. going down the same road !
The Yuichi is a scaled one, by the way - 415Hz ( x0.7 from the A290S to use 1.4" driver ) .
In my thread you'll find maybe 3-4 years ago the efforts to find a lower-midrange match to the 288H/Azura was a hard struggle and left me with various set of surplus drivers. I concluded that if you don't want ( or fail ) to make a big 120-200Hz horn then the only option that gets you close is a low-mass midrange driver on OB - something like a Fostex FE208EZ , a B&C 8PE21 or ideally the AER Mk.1 that JamesD used to great effect on his perspex OB's. Qts needs to be something like 0.35 to 0.25 . Then I'd suggest using a 12" driver of suitable type ( maybe not the Beyma ) with 0.4 Q or thereabouts to make a decent-size sealed box bass for low group-delay . Depends how many amps you're prepared to use !
What compression drivers do you have ? It seems to me if you go for a 200Hz horn then you need something to take over beyond 1 or 2kHz with good tone in that area and extension to 15k or so . Something like a 1" driver on a 600Hz Iwata or something of that sort. I'd favour an asymmetric expansion - elliptical Le Cleac'h or Iwata after my experiences with the Yuichi .
So anyway , four-way seems to be the minimum once you've got even ONE horn in the system !
The test box particulars are as follows.
1 1/2" particle board. 17"x19"x10" )w x h x d (internal) driver mounted 2/3 way down from top in the middle of the baffle. Centre of driver is 25" off the floor. Cabinet has a 2 internal braces dividing the height up into 3rds. Baffle has no rounded edges.
As mentioned previously felt lined and the stuffed with BAF.
1 1/2" particle board. 17"x19"x10" )w x h x d (internal) driver mounted 2/3 way down from top in the middle of the baffle. Centre of driver is 25" off the floor. Cabinet has a 2 internal braces dividing the height up into 3rds. Baffle has no rounded edges.
As mentioned previously felt lined and the stuffed with BAF.
Mark
I already have a 200hz horn, which with my JBL 2482's i cross at 300hz running it up to around 1600hz where the Beyma TPL's take over. At the start of this thread i stated that i was concerned that i wasnt getting as good an integration as i could, as centre to centre the horn and TPL are around 400mm, which for 1600hz isn't ideal. So i started the experiment of using a cone driver to get better integration. At the time i posed the question about getting a non radial horn to reduce the centre to centre gap, without any recommendation. Similar ones to the Yuichi that go low enough i have seen for example are AOS - H220. My only worry is when you exceed a 90 deg mouth on the horn, alll the benefits of horns for small rooms are lost, and you might as well use a cone driver.
Back to tuning the sealed box for different Q's. Would it be a sensible experiment to put a variable resistor in series with the driver to change the Qts, and thus the box Q?
I reckon 5 ohms for Q=0.5 and 10 ohms for Q=0.71, in the 44 litre box.
I already have a 200hz horn, which with my JBL 2482's i cross at 300hz running it up to around 1600hz where the Beyma TPL's take over. At the start of this thread i stated that i was concerned that i wasnt getting as good an integration as i could, as centre to centre the horn and TPL are around 400mm, which for 1600hz isn't ideal. So i started the experiment of using a cone driver to get better integration. At the time i posed the question about getting a non radial horn to reduce the centre to centre gap, without any recommendation. Similar ones to the Yuichi that go low enough i have seen for example are AOS - H220. My only worry is when you exceed a 90 deg mouth on the horn, alll the benefits of horns for small rooms are lost, and you might as well use a cone driver.
Back to tuning the sealed box for different Q's. Would it be a sensible experiment to put a variable resistor in series with the driver to change the Qts, and thus the box Q?
I reckon 5 ohms for Q=0.5 and 10 ohms for Q=0.71, in the 44 litre box.
Ok, I think the Yuichi or something like it will help interface to the TPL which should work, as where the Yuichi starts to become less interesting eg. over 2Khz the TPL has good quality and can come in, and with closer positioning, which is nice ....
I am struggling to be enthusiastic about the Beyma, as it's a 700W driver - why will it sound good at eg. 1W for home use ? Why does it have an insanely low Q of 0.15 - what's the intended application ?
I don't think adding series resistance to drive this unit will do anything other than make it sound worse - but easy to try, or course.
What aspects of the sound are not working - can you put it into words ?
- what does the upper bass tone like ?
- how does the combo work at low listening levels ?
I am struggling to be enthusiastic about the Beyma, as it's a 700W driver - why will it sound good at eg. 1W for home use ? Why does it have an insanely low Q of 0.15 - what's the intended application ?
I don't think adding series resistance to drive this unit will do anything other than make it sound worse - but easy to try, or course.
What aspects of the sound are not working - can you put it into words ?
- what does the upper bass tone like ?
- how does the combo work at low listening levels ?
If I may interject ?
1600 Hz is simply too low of a crossover point to allow integration between the Beyma TPL and a compression driver/horn combination. Your better off running a mid range horn from approx 500- 5kHz, and then add the TPL in above 5 K.
Run a cone driven mid bass horn under the mid range horn, and then a sub woofer system for the foundation. Hence, a 4 way.
In my humble opinion, attempting to mate a large format 12 inch cone mid range to the TPL@ 1600 is somewhat of a compromise.
1600 Hz is simply too low of a crossover point to allow integration between the Beyma TPL and a compression driver/horn combination. Your better off running a mid range horn from approx 500- 5kHz, and then add the TPL in above 5 K.
Run a cone driven mid bass horn under the mid range horn, and then a sub woofer system for the foundation. Hence, a 4 way.
In my humble opinion, attempting to mate a large format 12 inch cone mid range to the TPL@ 1600 is somewhat of a compromise.
Havent had chance yet to tweek and measure.
With regard to the question of whats not working for me and what is, here goes...
1) Imagining, it like i have crossed the polarity of one of 12P80's by mistake, i have checked and double checked - i havent neather pyshically or electronically.
2) Bass tone, not clear it i have a one note peak, doesnt show up on measurement, or whether the sealed configutation transients reveals detail that i havent heard, i assuming the later currently.
3) Positives - has good Slam and PRAT
Listening at low levels - not to bad, but i think that atributed to replacing the OB bass, I think with OB bass you have to put more power in for the same "slam" effects, and as the x -over to the mids is lower.
With regard to the question of whats not working for me and what is, here goes...
1) Imagining, it like i have crossed the polarity of one of 12P80's by mistake, i have checked and double checked - i havent neather pyshically or electronically.
2) Bass tone, not clear it i have a one note peak, doesnt show up on measurement, or whether the sealed configutation transients reveals detail that i havent heard, i assuming the later currently.
3) Positives - has good Slam and PRAT
Listening at low levels - not to bad, but i think that atributed to replacing the OB bass, I think with OB bass you have to put more power in for the same "slam" effects, and as the x -over to the mids is lower.
It doesn't sound like the bass driver is working out to me . Lack of presence I see somewhere , and not enough tone . I think you need to stand back from the problems a bit and decide what are the most sensible crossover points and how you can use some of what you have there to move forward.
I think ( after seven years working on my own horn/OB system ) that once you have even one horn in a 'full-range' system it has to be a four-way. If you take a conservative 40Hz - 16kHz and divide it geometriclaly for a 4-way then you end up with crossovers at something like 200Hz, 800Hz and 4kHz . These can be pushed/pulled a little bit, but not too much .
I think ( after seven years working on my own horn/OB system ) that once you have even one horn in a 'full-range' system it has to be a four-way. If you take a conservative 40Hz - 16kHz and divide it geometriclaly for a 4-way then you end up with crossovers at something like 200Hz, 800Hz and 4kHz . These can be pushed/pulled a little bit, but not too much .
I am not sure if its the midrange/bass, i may get a chance tomorrow to play with the lower crossover point, its currently at 100hz (using a single sealed sub currently) I will reconnect the previous bass configuration and inch up the crossover freq, and see what happens. Regarding the crossover point for the TPL, i know this needs to be around 1800Hz or higher. (Marc Cohn cd's are a good way of working out how low you can go with compression drivers and AMT's in the 1000hz to 2000hz range - his shh's are very sharp)
The TPL can run to 20khz with contouring, but cutting in a HF unit adds sparkle. I only have some JBL 2405's around at present, i reckon a smaller AMT would have better synergy with the TPL though.
Interestingly you mention tone, i am not sure if the Beyma 12p80nd has any tone, very neutral when i compare it with the Altec 414'z i have. Obviously the midrange horn has loads of tone, so maybe this is what i am missing?
The TPL can run to 20khz with contouring, but cutting in a HF unit adds sparkle. I only have some JBL 2405's around at present, i reckon a smaller AMT would have better synergy with the TPL though.
Interestingly you mention tone, i am not sure if the Beyma 12p80nd has any tone, very neutral when i compare it with the Altec 414'z i have. Obviously the midrange horn has loads of tone, so maybe this is what i am missing?
20 pages
Greetings ! In few that this thread is now 20 pages, could you please be so kind as to restate where you are at, and what you wish to achieve, with any restrictions involved ? Thanks, kindly.
Greetings ! In few that this thread is now 20 pages, could you please be so kind as to restate where you are at, and what you wish to achieve, with any restrictions involved ? Thanks, kindly.
The original intent of this thread and the last years waste of time and money was to replace the mid range horns which due to there size i didnt feel integrated well with the Beyma TPL's. I started out following other peoples positive experience of using the Beyma 12P80Nd with the Beyma TPL, i wanted a sure thing as i have been messing around with speakers too long, and wanted to just have a stable platform to listen to music on. ( the reason we build speakers - i think)
I am at a point of not really understanding, where to go other than back to my mid range horns. Maybe changing from a round to a rectangular horn to improve the integration.
I am disappointed that the 12P80nd's havent lived up to the hype. My last experiments with it in the sealed cabinet will be to make sure i havent screwed up the inplementation in the oversize box, having a low Q which i could overcome with the DSP. Which a number of contributors to this thread suggested was the best approach.
I am at a point of not really understanding, where to go other than back to my mid range horns. Maybe changing from a round to a rectangular horn to improve the integration.
I am disappointed that the 12P80nd's havent lived up to the hype. My last experiments with it in the sealed cabinet will be to make sure i havent screwed up the inplementation in the oversize box, having a low Q which i could overcome with the DSP. Which a number of contributors to this thread suggested was the best approach.
Now we're talking ! This is the perenial problem of these sort of systems - how to get the upper bass and lower mids right. Please substitute 'toneless' for 'neutral' in the above sentence !
I have been struggling myself to get something that matches the compression driver in speed and tone . A bass driver that can work below 100Hz will not do this .
I have noticed that a nice 4-way system would have roughly the following diaphragm masses :
Bass : 100g
Lower-mids : 10g
Uppermid/treble : 1g
High treble : 0.1g
Maybe with your tpl150-based system you can lower the upper crossover and 'stretch' to 300Hz for the mid-driver but it sounds risky. Can you re-cap on your amp/crossover options ? - remember you can driver an upper-mid/treble combo very easily from a low-power SE amp like a 45 .
I'm beginning to suspect that square arrays of direct-radiator drivers are the only way to approach (not equal) the speed and tone of midbass horns. The acoustical matching between air-load and moving mass improves, which keeps excursion low and substantially decreases IM distortion. If this approach is used, it's probably useful to give each driver its own sub-enclosure, rather than share a common volume.
2x2
This is true. In the classic design days, a 2 driver by 2 driver was the preferred arrangement, and yes, it does take about 4 direct radiators of comparable size to equal what the mouth area is, of a horn.
"Style" has dictated modern line arrays, but they do NOT work as well.
This is true. In the classic design days, a 2 driver by 2 driver was the preferred arrangement, and yes, it does take about 4 direct radiators of comparable size to equal what the mouth area is, of a horn.
"Style" has dictated modern line arrays, but they do NOT work as well.
Sounds a lot like one idea that our guru JamesD ( in the UK ) was suggesting before he went off for an extended work contract overseas - to make a small array of 3" to 4" FR drivers in a circle or diamond pattern , to form the lower-mid or midrange driver for a three-way . Nobody has yet tried this as far as I'm aware, but I reckon it could work rather well, at least for efficiencies in the 95dB/w range. James reckoned the lobing would disappear by 5 or 6 feet away, I didn't get chance to quiz him on what the trade-offs are on this.
This was intended as an OB-based idea. One could imagine also combining two different sort of drivers in this array, to smooth out some of the individual driver idiosyncrasies.
This was intended as an OB-based idea. One could imagine also combining two different sort of drivers in this array, to smooth out some of the individual driver idiosyncrasies.
Update
I have tested the 12" drivers in a variety of cabinet sizes with a Q ranging from 0.2 upto 0.7. As far as my ears and measurements are concerned, once equalised there is no difference in how the driver performs. I can say that a more powerful amp makes a difference, so i assume that the electrical damping is swamping the air damping.
Before i assign the drivers to the pile of audio mistakes i should try them vented, to see if i can recreate any of the magic that Angelo claimed from these drivers!
I have tested the 12" drivers in a variety of cabinet sizes with a Q ranging from 0.2 upto 0.7. As far as my ears and measurements are concerned, once equalised there is no difference in how the driver performs. I can say that a more powerful amp makes a difference, so i assume that the electrical damping is swamping the air damping.
Before i assign the drivers to the pile of audio mistakes i should try them vented, to see if i can recreate any of the magic that Angelo claimed from these drivers!
I'm sorry to read this.
After all your trials, do you sense the shortcoming in the lower operating range, higher end (beaming?), or simply overall? And this is compared to your existing horn, right?
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