Is it possible to cover the whole spectrum, high spl, low distortion with a 2-way?
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 Multi-Way Conventional loudspeakers with crossovers

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 20th June 2019, 01:05 AM #1101 Ro808   diyAudio Member   Join Date: Mar 2010 The 105dB is for incidental peaks I presume? This is for a single 8 ohm woofer (one of my woofers in approx. 190l cab.): 114.5 dB at 1 m. Xmax = 2.5 mm. P = 36.0 W. Max. current through the VC varies between 2.67 and 2.74A Calculated thermal attenuation: 1.9 dB For me this is irrelevant though, I cherish my hearing. Last edited by Ro808; 20th June 2019 at 01:12 AM.
 20th June 2019, 01:33 AM #1102 Ro808   diyAudio Member   Join Date: Mar 2010 Same (theoretical) exercise for a single Faital 15PR400 - 8 Ohms (same cab. and port tuning): 120.0 dB with 1 speaker at 1 m. Xmax = 5.8 mm. P = 157.3 W. Max. current through the VC varies between 5.74 and 6.89A Calculated thermal attenuation: 3.1 dB The 114.5 (for my woofer) and 120.0 dB (15PR500) are theoretical max. levels without thermal attenuation. Last edited by Ro808; 20th June 2019 at 02:00 AM.
diyuser2010
diyAudio Member

Join Date: Jun 2018
Quote:
 Originally Posted by Ro808 The 105dB is for incidental peaks I presume? This is for a single 8 ohm woofer (one of my woofers in approx. 190l cab.): 114.5 dB at 1 m. Xmax = 2.5 mm. P = 36.0 W. Max. current through the VC varies between 2.67 and 2.74A Calculated thermal attenuation: 1.9 dB For me this is irrelevant though, I cherish my hearing.

105 dB / ch peak is reference, though I would never watch a full movie at those levels.

I also cherish my hearing, I wear earplugs daily, and also around home for tasks like mowing lawns, grinding, sawing, hammering, drilling, etc.

Ro808
diyAudio Member

Join Date: Mar 2010
Quote:
 Originally Posted by diyuser2010 105 dB / ch peak is reference, though I would never watch a full movie at those levels.
That's what I figured

FWIW:
"P" in my comparison above, is the minimum (calculated) peak power from the amp for the impedance of the woofer in the cab at Fb.

 20th June 2019, 05:29 AM #1105 camplo diyAudio Member   Join Date: Feb 2019 Great discussion, I really don't have much to add at this this point or ask =/ I was wondering how to measurements that to result o the polar response charts. I see the guys angle guide above, I'd that, that, has something to do with it. Ro808 I am concerned about distortion, this project and pretty much the jbl M2 is designed around IMD, and avoiding it. HIgh efficiency woofer, result in the lack of thermal compression right? I aimed at originally finding a 16ohm driver, because, once again, less distortion. I might run the woofers in series just to get there. You'll have clue me in. The Jbl 2226 would of been a nice driver for this project, I really would have appreciated the smaller cabinet. The AE TD15m does have the specs in the order that I wanted them, lower mms, higher bl, lower inductance. Add the 2216ND to the list and the 15PR400 (16ohm) and a few others; they all plot almost identical, on the excursion plot when the forced to flat response tab is used. I based my choices off of the excursion of the the 2216nd to begin with, IMD vs excursion vs bandwidth is the name of the game and the M2 has set the "standard" in so many words for the popular crowd, I'm sure the more elite crowd knows better. Then for good measure, and the potential to run a 3 way or 2.2 system, depending on how you look at it, I added another woofer The JBls, I think, may have better control in the bass region, and AE, a little better top...either way, for the money, AE has jbl beat.
diyuser2010
diyAudio Member

Join Date: Jun 2018
Quote:
 Originally Posted by camplo Ro808 I am concerned about distortion, this project and pretty much the jbl M2 is designed around IMD, and avoiding it. HIgh efficiency woofer, result in the lack of thermal compression right? I aimed at originally finding a 16ohm driver, because, once again, less distortion. I might run the woofers in series just to get there. You'll have clue me in.

To have low IMD, you need low cone excursion. Horn loading, or large radiation area is key here. Vented cabinets can also help compared to sealed cabinets.

Thermal compression: Tom Danley has a vast array of posts on different forums on this subject, to condense it down, thermal compression starts to set in around 1/10th of the AES power handling.

Higher velocity ( higher losses, too! ) ports exhibited better cooling of the enclosure, exchanging more air from inside the enclosure. This has been documented in an AES paper, IIRC from JBL.

I'd suggest a large port cross sectional area instead, a too small port has losses and the trade-off of output for cooling isn't necessary in most applications.

Why would an arbitrary impedance number like 16 ohms reduce distortion? Is there any factual basis? A real world amplifier has voltage and current limits, and as long as you aren't hitting them, life is good.

Higher impedance will require higher voltages for the same sound pressure level, but again unless you are running the amplifier in a region where it's not happy, life is good.

phase_accurate
diyAudio Member

Join Date: May 2002
Location: Switzerland
Quote:
 Why would an arbitrary impedance number like 16 ohms reduce distortion? Is there any factual basis? A real world amplifier has voltage and current limits, and as long as you aren't hitting them, life is good.
I'd say the difference lies mostly within the amp performance because the linearity of the output devices is usually better at lower output currents.

Regards

Charles

mark100
diyAudio Member

Join Date: Dec 2010
Quote:
 Originally Posted by Ro808 mark100, do you have a thread somewhere? Which woofers do you use? Personally, I would prefer series because of efficiency/easier load on (low power) amps. Many of today's pro amps take a 2R load, but the better ones tend to be quite expensive. If I understand correctly, diyuser2010 opted for parallel considering heating of the VCs.
Hi Ro808, I use the 4594/1464 in boxes designed for mandatory use with sub...so 100Hz up. That's why I've never introduced them in this thread.
The MTM config is the Peter Morris design on soundforums, the PM 60 and 90.
(I'm mark wilkinson in those threads.)
There is also a thread about a modular system I've been developing. Modular Mid-High | Sound Forums

Maybe I'm still off with ohms law, but I get the voltage and current to two drivers in either series or parallel, is exactly the same when the same overall wattage to both drivers is held constant.
So I don't see that voice coil heating is any different for diyuser2010 whether going 2R or 8R.
My guess, and pls correct me if i'm wrong diyuser, is that the 2R decision is more about the plx 2502 amp's 1250w 2R vs 450w 8R specs.

I'd vote for getting another smaller amp for the BMS and running each 4R driver off a channel of the 2502...

Ro808
diyAudio Member

Join Date: Mar 2010
Quote:
 Originally Posted by camplo Ro808 I am concerned about distortion, this project and pretty much the jbl M2 is designed around IMD, and avoiding it. HIgh efficiency woofer, result in the lack of thermal compression right? The JBls, I think, may have better control in the bass region, and AE, a little better top...either way, for the money, AE has jbl beat.

Don't worry Camplo, all woofers you mentioned comply with your requirements.
Provided, the 'system' is designed properly and unless you would permanently play at PA levels (which you won't), or operate drivers outside of their comfort zone (which you won't), distortion, thermal compression etc. are mostly of academic relevance.

That's why the world's best known studios (also) use large format monitors, like the Auspurgers, Strauss, JBLs etc.

Brett referred to AEs as the woofers that 'bettered' his benchmark 2226s.

I would (strongly) recommend to wire the TD15Ms in series to maximize efficiency, reduce the amp load and thus minimize the mentioned artefacts.

Last edited by Ro808; 20th June 2019 at 02:24 PM.

 20th June 2019, 02:30 PM #1110 camplo diyAudio Member   Join Date: Feb 2019 Most amps are most efficient at higher ohms, I thought that was a well known thing. By efficient I mean that, more of the signal gets turned into sound, as opposed to, heat and distortion, for given power level. The numbers cited in my manual seem to agree to this trend. It has been speculated that transient response is also better at higher impedance though it may not be true. Other wise, all the attributes you describe, this project has addressed so I think all is well. I think... Though I don't like the look, I was considering a 26" wide driver baffle to help match the radiation pattern of the 26" horn. Sounds good in theory. Does any one have a guide on how to create polar charts?

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