kipman725

I think for a small box you would be better off looking at reflex as high excursion 12" drivers are usually capable of overloading most practical port designs. The main limitation to SPL is port compression and 'cuffing' due to the high air velocity near tuning. To this end what I think you need to look at more complex port designs that incorporate flares rather than designs using more ports that take away volume that could be used for your fundamental tuning. Here are some guidelines on ports: https://www.subwoofer-builder.com/flare-testing.htm Saying that tapped horns are series 6th order bandpass boxes with huge ports so it might be worth looking into a tapped horn design if you want a bandpass response. You're using DSP so attenuating out of band issues (which are never as bad as Hornresp predicts due to losses) should be trivial.

I've built subs out of cheaper hardwood ply and MDF before. The cheaper ply works but is more vulnerable to damage than BB ply, this can to an extent be made up for by rounding (and filling if there are voids) the corners and using a tough coating. MDF is horrible to work with, heavy and vulnerable to damage at any exposed edge. I would use cheaper ply rather than MDF. I don't use screws I use a brad nail gun and glue, this way you can build a cab very quickly!

I had similar subs to this, I found I needed a lot of amp power to cope with the massive low end EQ boost and had problems with heat accumulation in PA applications. But for home use they should be great.

Prices lower than expected but should be there only really for people who can move big subs around but are still restricted on overall truck space (top end touring). If you can afford the volume you can match the IPAL system output using more cheaper subs like ~1000L FLH. saying that if you could buy a finished EDM sub for 10k I think it would be decent value compared to the brands like Funktion one.

Regarding pascal modules they are available in the STA-1000D and STA-2000D amplifiers from img stageline.

Sounds good. A lot more comprehensive than what I can do!

Hey @h3idrun looks like you got decent results. You could try power compression (see testing methods on this site) testing to see how close your actually getting to a 21" (Sweeps increasing in level until your getting 3dB compression). The umik-1 tops out around 120dB so if you will probably need to move it back a few meters to reduce the level. I like the idea of running the Prius as a generator. I have a 6 channel DSP amp box running off a 16S lithium battery I built for portable stuff.

Hi @lowerFE, First time I have seen this thread. I'm quite interested in your measurement methods, when you perform the ground plane measurement do you perform baffle simulations of both the elongated and normal size baffle and then find the difference for your compensation factor? Also does anyone know of a 35mm pole stand that could lift a large 30kg speaker high and stable? something more substantial than the usual tripod stands and with a crank for lifting.

ha ha I think I saw your FB post in speaker freakers

New M-Force transducer (M-Force 301P02): https://www.powersoft.com/en/applications/oem-solutions/m-force-sub?fbclid=IwAR0wy-1oH0yKVQTpaRNLrEOLRJoQA0ryqIiblr2LZnp_KTbaVI6sojCIa78 https://www.powersoft.com/en/products/transducers/m-system/m-force-301p02/ https://www.powersoft.com/wp-content/uploads/datasheet/PS_MFORCE301P02_DS.pdf

They seem to be sealed boxes won't they work fine into the 100Hz+ range? I have seen infra subs that are very narrow band using tuned pipe enclosures arranged in an array of varying pipe length to cover a frequency range not possible using a single pipe.

Got a link? few companies called Ascendo but non of them seem to do 32" woofers.

not in the market but would love to see Kipple data on these under hung subs. I saw the BL curve for this type of driver though: http://www.eighteensound.com/en/products/lf-driver/21-0/8/21ntlw5000 which was impressively flat so I wonder if underhung coils are just a waste of magnet in comparison?

I meant in a DJ playback situation to increase the mud intentionally but only during the most bass heavy parts, using a long attack time. I guess in audiophile terms to add 'warmth'. well live I would always have a compressor on the bass drum mic and possibly, depending on mic technique on vocal mics. Good speakers you should always want to turn it up, only wanting to listen quietly indicates faults.

Regarding the mud issue sometimes in a high headroom system at high SPL (and you don't want to increase the SPL further) putting in a compressor with a medium knee that engages during the loudest passages to increase the harmonic content of the bass is worthwhile as the expectation is that the sub bass system will be limiting (intentionally or not) during those passages. Without the limiting it can sound a bit weird. Its all really easy to do with modern DSP!

I would go for corner placement for the reasons SME states but if you could do 1+2 this would be better. Regarding eq/room correction the best curve tends to be genre/album specific due to the lack of standardization in the frequency response of control rooms so quite often you have a situation where one EQ sounds better with one genre but worse with another.

I have made subs that are long like this and yes you need a lot of stuffing to combat standing waves, the higher you can push the first standing wave up in frequency the more effective the stuffing will be: Another thing to consider is your driver placement is a worst case scenario for standing wave generation (mid pipe). If you consider possible standing waves in the pipe you can have a maximum at the driver and two minima at either end at 86Hz (fundamental modes. You would be better off putting the driver at one end.

I have run between one and 4 subs at home and much prefer 4 subs, they are mostly corner placement. I take a frequency response measurement at each seat of my sofa and vector average the results. After I have dialed in the sub crossover I fit the response to a target curve below 500Hz as my main speakers are close in to the corners and designed to be flat in free space so this has to be compensated for and there are some large peaks in the lower bass that need to be cut to avoid the whole thing been boomy. Works well but I wish there was a more scientific method. SME when you say flattest possible response do you mean an actually flat response? as from my understanding a constant directivity speaker in a domestic room which has a flat free space response should have a tilted downwards response in room (and will sound natural in this condition) so equalizing to flat in room will make a speaker sound overly bright.

Ah ok I thought it might be a double bass setup but was thrown off track a bit. I see a few issues: 1) double bass setup should launch a plane wave which relies on the point sources on the opposed walls been within 1/4 wavelength of each other and there to be point sources within 1/4 WL of the walls. At say a crossover 80Hz this is 1m, however real world this can probably be pushed up a bit: https://www.avsforum.com/threads/double-bass-array-dba-the-modern-bass-concept.837744/ So definitely in your configuration there is no plane wave due to the geometry. 2) Another issue I see is that your room has unequal absorption on each wall due to the french doors. Even considering this I still think it would be better to run two subs rather than one even if running them as double bass array doesn't work due the smoothing effect on room responses: https://data-bass.com/#/articles/5cb5fb285389a80004c7e58a?_k=ymaw45

Placement looks fine, the main thing is to have more subs and place them in a diverse set of locations around the room, they don't care which direction they point. Real rooms differ from the research (in your case you have a large lossy door on one wall) so its not necessarily true the best locations would have been mid wall anyway. Box volume isn't very important (as long as your using EQ) as what produces the sound is the cone moving in and out a larger box is just requiring less power to reach a given SPL when operated below Fc.

You may want one to remove content in the low region the sub doesn't have useful output in to increase usable output in the region it does. EG. if your sub is -3dB @ 30Hz and you play back the TELAC 1812 recording with 11Hz fundamental cannon fire you would be better off not just going to maximum excursion on the 11Hz and instead reproducing the harmonics*. Only applies if your hitting excursion limits though, if the sub stays in the linear region I don't see an advantage to HPF. *As the harmonics will be distorted by the sub been pushed out of the linear region

I think these area good points I also had some skepticism about the statistical basis for saying that the the small signal values can be used. High crest factor signal is interesting and only reporting 2nd and 3rd harmonic distortion, this suggests some gaming of the results. I think the practical implementation uses voltage and current sensors to inform the model along with reference data obtained from the kipple system of the transducer. There are a few demo videos floating around like this one where parameter variation over time is shown:

I have been reading these papers by Kipple: http://www.klippel.de/fileadmin/klippel/Files/Know_How/Literature/Papers/Green Speaker Design Part 1.pdf http://www.klippel.de/fileadmin/klippel/Files/Know_How/Literature/Papers/Green Speaker Design Part 2.pdf In the second paper they improve the efficiency of an overhung driver by reducing the coil height to the top plate thickness and then compensate for the resulting non linear behavior. The benefit of this in their example is a 39% in voice coil temperature for a given output compared to an overhung driver (~3dB output gain in the non excursion limited region for the same driver). Considering the IPAL driver already is designed to be a transducer with dedicated amplifier and it has a huge coil overhang it would seem that with just shortening the coil a bit and a new version of the IPAL mod that implements the kipple DSP work they could increase the efficiency/output substantially (IPAL2?). There would also seem to be benefits form changing reducing kms but I understand that this is required to have small clearances in the voice coil gap due to rocking modes.

I have a couple of 15TBX100, yet to go into a box and can confirm its a pretty serious driver. It has many of the features of the more expensive drivers like shorting rings, double silicone spider and a 4" voice coil . What it lacks compared to the top end drivers is excursion capability with an xvar of 11mm VS 19mm xmax for the 18N862 (comparing xmax numbers is difficult between manufacturers as some report geometric xmax and others report 70% Bl and others are just pulling a number out the air almost and other factors such as compliance often limit excursion before BL on high excursion drivers), unless your aiming to get every last dB out of the sub the reduced excursion capability is not going to be important. These videos from B&C show some of the kipple data for the 18TBX100 which show a nice parameters that should result in a low distortion bass like a flat BL curve:

I also wouldn't bother with an additional mid bass cab initially as you will be adding quite a bit of cost and complexity to the system that will run without it, going from 4 amp/dsp channels per side to 5. Saying that I am (slowly slowly) building a midbass horn for the 100-500Hz range which is an unfolded exponential horn so it might be worth looking at what I did: https://www.diyaudio.com/forums/pa-systems/349105-mega-midbass-straight-horn-139db.html This horn was designed for outdoor usage The paper you should read before designing a bass horn is " 11. "Low-Frequency Horn Design Using Thiele/Small Driver Parameters," Presented at the 57th Convention of the Audio Engineering Society, Preprint No. 1250 (K-7), (May 1977). " http://xlrtechs.com/dbkeele.com/papers.htm The changes I would make to my horn in covering say 60 - 120 Hz would be to no longer bother having a smooth straight horn profile and instead folding the horn. I would also reduce the mouth area to less than half the ideal mouth area and use multiple boxes per side. The HD15 has quite a short path length so if you can tolerate a larger box you can get much closer to true horn performance.