there is a high pass filter calculator here http://www.mh-audio.nl/spk_calc.asp
The cap should be of a good quality : humblehomemadehifi site for example to try to choose one whch is not too bright. There are also good enough russian teflon or MKT which gives excelent results (many threads here). I tryed some polystyren from MIT on my speaker. You could find them on the american sites here on the vendor shops.
What about a tin foil which are inductive for a speeddy planar driver ?
The cap should be of a good quality : humblehomemadehifi site for example to try to choose one whch is not too bright. There are also good enough russian teflon or MKT which gives excelent results (many threads here). I tryed some polystyren from MIT on my speaker. You could find them on the american sites here on the vendor shops.
What about a tin foil which are inductive for a speeddy planar driver ?
Looks like to get the phase correct i need to use a 3rd order in conjunction with the protection cap - to get a full 360 phase change. Matching the slopes may be tricky. Looks like i need to invest some time understanding FIR crossovers if i want phase alignment.
FIR filters can result in flat phase, but using conventional filters, PEQ, underlap or overlap, differing filter types (LR vs BW) and delay can result in a smooth phase transition through the acoustic crossover region.
The introduction of the capacitor makes a smooth alignment more difficult to achieve, as it does not result in a 90 degree phase shift due to the driver's variable impedance vs. frequency. A series resistor between the capacitor and tweeter may help with that problem, the capacitor will "see" more of a fixed resistance.
I think the Beyma TPL is a pure resistive load, so not sure a series resistor will help. I understand why Ihave not had an issue previously as had a protection cap on my midrange compression driver.
After extensive listening and tweeking, i am not liking the presentation of the Beymas in sealed boxes, dont seem to have the air and attack of the midrange horns.
What to do next....
1) Do i try a smaller box lifting the qts to 0.5 and add more equalisation, maybe they are flat at a qts of 0.25? (easy may do anyway)
2) Revisit the horn - i have heard good thinks about the Yuichi horns with someones judgement i trust preffering the 290Hz to his Azura horns. Having done some scaling i could extend the 290 profile to make a 200hz Yuichi style horn, will only be 30cm tall so may give me that better integration with the TPL i am looking for.
Comments/ opinions please
What to do next....
1) Do i try a smaller box lifting the qts to 0.5 and add more equalisation, maybe they are flat at a qts of 0.25? (easy may do anyway)
2) Revisit the horn - i have heard good thinks about the Yuichi horns with someones judgement i trust preffering the 290Hz to his Azura horns. Having done some scaling i could extend the 290 profile to make a 200hz Yuichi style horn, will only be 30cm tall so may give me that better integration with the TPL i am looking for.
Comments/ opinions please
After extensive listening and tweeking, i am not liking the presentation of the Beymas in sealed boxes, dont seem to have the air and attack of the midrange horns.
What to do next....
1) Do i try a smaller box lifting the qts to 0.5 and add more equalisation, maybe they are flat at a qts of 0.25? (easy may do anyway)
2) Revisit the horn - i have heard good thinks about the Yuichi horns with someones judgement i trust preffering the 290Hz to his Azura horns. Having done some scaling i could extend the 290 profile to make a 200hz Yuichi style horn, will only be 30cm tall so may give me that better integration with the TPL i am looking for.
Comments/ opinions please
What to do next....
1) Do i try a smaller box lifting the qts to 0.5 and add more equalisation, maybe they are flat at a qts of 0.25? (easy may do anyway)
2) Revisit the horn - i have heard good thinks about the Yuichi horns with someones judgement i trust preffering the 290Hz to his Azura horns. Having done some scaling i could extend the 290 profile to make a 200hz Yuichi style horn, will only be 30cm tall so may give me that better integration with the TPL i am looking for.
Comments/ opinions please
Wow !
It can't but the smooth respons in the low end can be an advantage !
Maybe you can try a vented with it with a FIR corection (pos's soft) of the vented front port to allow it to play in phase with the cone ! Because the dopler effect of the cone you will have this tight dynamic behavior (I'm looking for too !) ?
Or reduce the volume sealed cabinet ??? (not with stuffing as it gives the inverse effect : more sealed volume according V. Dickason 's book) !
If you are talking of the classic bi-radiall profile : 290 is too low as you really need to move more air here ! It can be a trap ! 700/800 is near the better trade off (according my ears at least !) if you use a horn.... a 15" to move too 700/800... you should find it's lacke of refinment and lightness although horn are too thin here 🙂
It can't but the smooth respons in the low end can be an advantage !
Maybe you can try a vented with it with a FIR corection (pos's soft) of the vented front port to allow it to play in phase with the cone ! Because the dopler effect of the cone you will have this tight dynamic behavior (I'm looking for too !) ?
Or reduce the volume sealed cabinet ??? (not with stuffing as it gives the inverse effect : more sealed volume according V. Dickason 's book) !
If you are talking of the classic bi-radiall profile : 290 is too low as you really need to move more air here ! It can be a trap ! 700/800 is near the better trade off (according my ears at least !) if you use a horn.... a 15" to move too 700/800... you should find it's lacke of refinment and lightness although horn are too thin here 🙂
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Sorry to read this. I've been wondering how things might have turned out for you.
It seems trying a smaller box would be rather easy to do. I would try Qtc of 0.71 to have a reference too. I'm actually going through this myself, with a different driver.
Could this stem from attempting to cover too many octaves with one driver? I know it has worked for others, but also know some experienced folks favor 4-ways. The 12P80Nd is a midrange driver at the end of the day.
I WISH... I lived down the block from you and could get all of your hand-me-down speakers. 🙂
Very interested in your listening impressions of the 12P80nd_v2 in a smaller box volume with Qtc~0.6 - 0.7.
Very interested in your listening impressions of the 12P80nd_v2 in a smaller box volume with Qtc~0.6 - 0.7.
Considering one of the comments, about over stuffing the cabinet. I am wondering if I have stuffed the cabinets incorrectly. What would be best practice, I have lined the boxes with felt and then have filled the remainder of the void with BAF, leaving a few inches of air space around the back of the driver.
Sir,
Could you share with us the details of the enclosure construction?
Materials used, dimensions, etc. ?
The thread title contains the word "mid" - a 12" can do a lot, quite low, in domestic environment.
One get 105 dB at 100 Hz on a narrow baffle. Thats loud.
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vinyl, I have been following your thread with interest. I have a 3-way active system with 15" in a large sealed cab (think Klipsch Cornwall size) digitally XO'd at 500 Hz to a Selenium D405 2" compression driver (similar to your 2" JBL 2482 compression driver) on not such as nice horn as you have (JBL 2380a flat front bi-radial) and XO at 5kHz to a BMS 4540ND mated to a QSC waveguide (love that combo - top end is sweet and crystal clear).
I have tried a couple of mid-range cone drivers a while back, certainly not as nice as the Beyma's, but I gave up almost right away as the attack is nowhere as fast as the compression driver. Even then the D405 compression driver I am using is of the same ilk as your 2482 in that it has a phenolic diaphragm, is not the fastest compression drivers either. The BMS 2492 mid driver I thought would be an upgrade, but have not sprung for it yet. Interesting to hear your comments on that versus the 2482...
I am happy with the transition between the Crites woofer in a sealed box to the compression driver with an XO of 500 Hz. Sounds seamless to me. But I have been on the lookout for a different compression driver (like the BMS 4592 mid) or a different horn or both for the mids for more attack.
I don't know about you, but I can't go back to cone midranges. For my ears, just don't have the attack like a compression driver. Maybe it is as simple as moving the XO up to 500 Hz? I don't know what you have for the bottom end, but my large coffin box was vented and I ended up plugging the ports to go with sealed and had a much better transient response that better matched the compression drivers.
As an aside, I run fully active with digital XO, driver time alignment, driver linearization, and room amplitude and excess phase correction. So playing with different XO points is easy to do.
Hope that helps in some way and looking forward to your next moves.
Cheers, Mitch
In any other way than a SPL loss? It has been accounted for in the calculation above!
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