4x RSS264 is overkill to me... and highish lowpass needed for crossing to 3" dome would create interference challenges.
Passive .5 operation for the lower woofer?
M74A Fs is 400Hz... (see post #2) and H2 rises below 1kHz https://hificompass.com/sites/default/files/zamer/afc315/m74a-6_315mm_2v83_hpf2-300_0.png
Most of music energy and fundamentals will be on woofers then!
Passive .5 operation for the lower woofer?
M74A Fs is 400Hz... (see post #2) and H2 rises below 1kHz https://hificompass.com/sites/default/files/zamer/afc315/m74a-6_315mm_2v83_hpf2-300_0.png
Most of music energy and fundamentals will be on woofers then!
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That is actually a different project using the Zoudio AIO438 amp board, a blue tooth desktop type speaker. I will probably do that one next year sometime. This current project is one I have been pondering since April 2023, doing a lot of simulations and conceptual sketches...
The only 8" driver that comes close to meeting my low distortion volume displacement requirements is the PTT8.0x08-NAB. If I absolutely had to use 8" drivers for some reason, I would pay the price and use them (they are slightly higher cost than the Dayton)... but I think I can make the slightly wider bass cabinets look right.
It will be a challenge to connect Bliesma mid with these subwooferish monsters....or not.
I would go to 3 way pyramid, Purifi 8 inch plus Bliesma 74 plus Bliesma 25 or 34. Down two 10 inch SB's SW26DBAC76. in small boxes All black aluminium. It would be stealth dynamite. Price for everything would be explosive also I guess.... but it would be near end game...🙂
I would go to 3 way pyramid, Purifi 8 inch plus Bliesma 74 plus Bliesma 25 or 34. Down two 10 inch SB's SW26DBAC76. in small boxes All black aluminium. It would be stealth dynamite. Price for everything would be explosive also I guess.... but it would be near end game...🙂
The 8 inch Purify is slightly higher priced? You made me check to see if there was a massive price drop, no such luck, they are $600.00 more per unit. I looked back and you are going to use RSS subwoofers, not RS woofers, do you think a subwoofer will be able to play up to 500 hz to meet the mid dome?
Here is my latest simulation of the system sketched in post#35. I have sized the trapezoid for a 70 mm chassis tweeter with 110 mm CTC spacing. These simulation use the baffle dimensions of the two woofer boxes, and the trapezoid. The simulation models the drivers as perfect flat discs.
First I show it with both woofers fully in parallel over the whole bandwidth
Now I show it with a passive rolloff applied to the lower woofer (3.9 mH very low DCR inductor)
The above sims use a 25 mm disc tweeter model, which has very wide dispersion up to almost 5k. The Bliesma T25B has this kind of pattern. However, I get different system level results depending on the assumptions I make about the M74A radiation pattern. In the above some, I have modelled the M74A with a smaller dome to match the radiation pattern as measured by @HiFiCompass (2k-5k range). This is why my next step is measuring the polar response in a trapezoidal prototype. If the M74A pattern is closer to an ideal disc with an Sd of 50 cm^2 (the spec), then this kind of tweeter is not optimal, and a more narrow tweeter pattern would be more useful... such as a Satori TW29TXN-B or TW29BN-B.
j.
First I show it with both woofers fully in parallel over the whole bandwidth
Now I show it with a passive rolloff applied to the lower woofer (3.9 mH very low DCR inductor)
The above sims use a 25 mm disc tweeter model, which has very wide dispersion up to almost 5k. The Bliesma T25B has this kind of pattern. However, I get different system level results depending on the assumptions I make about the M74A radiation pattern. In the above some, I have modelled the M74A with a smaller dome to match the radiation pattern as measured by @HiFiCompass (2k-5k range). This is why my next step is measuring the polar response in a trapezoidal prototype. If the M74A pattern is closer to an ideal disc with an Sd of 50 cm^2 (the spec), then this kind of tweeter is not optimal, and a more narrow tweeter pattern would be more useful... such as a Satori TW29TXN-B or TW29BN-B.
j.
Some 10" Woofer Tradeoff in Basta! according max. output Level on FA253 or FA503 channel:
2x 10" in 60l CB. Both driver in parallel on one Fusion module channel. Linkwitz EQ on FR.
Power Amplifier limit is set to 35V RMS for FA253 ( --> 150W@8Ohm, voltage limited) and 53V RMS for FA503 ( --> 350W@8Ohm, voltage limited).
PMax is set to 125W per driver for FA253 ( --> 250W@4Ohm, current limited) and 250W per driver for FA503 ( --> 500W@4Ohm, current limited) OR the driver's PMax datasheet value if smaller than Fusion module power limit.
What Hypex Fusion module do you exactly own already? If it is "only" FA253, Scan Disco 26W will kick the Daytons by >6dB max output >60Hz:
2x 10" in 60l CB. Both driver in parallel on one Fusion module channel. Linkwitz EQ on FR.
Power Amplifier limit is set to 35V RMS for FA253 ( --> 150W@8Ohm, voltage limited) and 53V RMS for FA503 ( --> 350W@8Ohm, voltage limited).
PMax is set to 125W per driver for FA253 ( --> 250W@4Ohm, current limited) and 250W per driver for FA503 ( --> 500W@4Ohm, current limited) OR the driver's PMax datasheet value if smaller than Fusion module power limit.
What Hypex Fusion module do you exactly own already? If it is "only" FA253, Scan Disco 26W will kick the Daytons by >6dB max output >60Hz:
The RSS265HF-8 is marketed by Dayton as a subwoofer, but it has a nice frequency response all the way up past 1k, and the Le inductance is 1.57 mH, which is a little high, but not unreasonable. To me, it should be called a woofer.
Since this is a modular design, if I don't like this pair of woofers, I can switch to something different in the future.
Your analysis is interesting, and you are correct that above 60 Hz, the higher efficiency scan speak woofer has the advantage.
On a system which is used primarily for music, my max spl design point is 40 Hz. If the system will be used for both music and video/movie soundtrack, which is how this system will be used, then my max SPL design point is 30 Hz. With this being a sealed box system with LT EQ, volume displacement capability is rather important.
According to my analysis using VituixCad:
At 30 Hz, a pair of ScanSpeak 26W8534G driven to max displacement will generate 100 dB SPL with about 100 W into the combined 4 Ohm load. This is less than the capability of my current woofer, which can do 102.4 dB SPL at max excursion. One of my requirements is that the new woofer system has to at least equal the current woofer.
At 30 Hz, a pair of Dayton RSS265HF-8 driven to max displacement will generate 107 dB SPL with about 510 W into the combined 4 Ohm load. This is more power than the Hypex FA253 can produce into 4 Ohm, so with this combination we are power limited rather than displacement limited. At the max 250 W amp capability, we get 104 dB SPL at 30 Hz, and 108 dB SPL at 40 Hz.
Both the ScanSpeak 26W8534G and the Satori WO24P-8 were drivers I evaluated closely. I am not committed to any woofer at this point, so I welcome all suggestions for 10" woofers.
j.
that was my attempt at dry humor. Yes the PTT8 is rather spendy.
I couldn't decide it it was an attempt at humor or you were saying that ONE PTT8 was slightly higher priced than a quad of RSS drivers using a generous PE discount code. 🤔 🤣
I crossed mine at 250Hz to an OB 8" Peerless (NE225-8). No problems there.
My measurements of 2 RSS265HF-8 samples show FR flat within 1-1.5 dB to ~800Hz where roll-off begins. -3dB occurs around 1.2kHz. Didn't measure off axis, but at 5-600Hz, I doubt there's any narrowing.
I come with data:
System with equivalent 2.83V "sensitivity". Also N.B. For horizontal measurements, past 90 degrees I capture only ie. 120, 150, 180, hence the inaccuracy behind the speaker (and DI)
Maximum (excursion limited) SPL, with 26V (240W to 4 ohms) to the pair of 12" XXLS-P830845 woofers:
Real life reference:
Peak SPL during fireworks show:
I would NOT build this again:
System with equivalent 2.83V "sensitivity". Also N.B. For horizontal measurements, past 90 degrees I capture only ie. 120, 150, 180, hence the inaccuracy behind the speaker (and DI)
Maximum (excursion limited) SPL, with 26V (240W to 4 ohms) to the pair of 12" XXLS-P830845 woofers:
Real life reference:
Peak SPL during fireworks show:
Reference: Class 2 (+/-2dB) Sound Level Meter app for your phone:
I would NOT build this again:
This is more appropriate:
Reference:
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About woofers, my aim is for a GD of 5ms at 50hz and under 2ms at 100hz. A QTC of .5 too. There does not seem to be much perception below 50hz as far as timing.
The group delay is based on headphone perception I found in an paper. (no link). So maybe in a room it is different. (My 15" you head way back when had this GD).
The group delay is based on headphone perception I found in an paper. (no link). So maybe in a room it is different. (My 15" you head way back when had this GD).
For their top models both KEF and B&W have long followed the path of a minimal baffle mid and high enclosure, accompanied by a bulky woofer(s) enclosure. Amongst others no doubt. Your findings on small baffles for mid and high shouldn’t surprise us, there’s quite some heritage on that. I only would hesitate to go the mid dome way for this concept, unless that Bliesma does a solid and loud 500Hz. One doesn’t have an awful lot of clearance to play with.
M74 is capable of doing 500Hz at well above 110dB system level. By my calculations it's able to do even 400Hz at 113dB system level. It's worth to remember that calculated level for mid is one octave above crossover, as at crossover driver is already 6dB down.
A woofer I seriously considered is the SB34NRXL75-8. Unlike my current SB34NRX woofer, the SB34NRXL has a more advanced motor with shorting rings. There are various test data which show that the NRXL version has about 10 dB less harmonic distortion than the NRX version. @profiguy has spoken highly of using the SB34NRXL75-8 up to 500 Hz, and @IamJF has used this driver in combination with the Bliesma M74A link in a very impressive design.
However, a single SB34NRXL75-8 would have slightly less deep bass capability than the NRX, due to a slightly lower Xmax value, but also because the NRXL has a Qts=0.28 which is more optimized for a vented box. As a result the NRXL version requires more LT EQ in the deep bass to get the response I am looking for. So all in all, a little less capability in the 30 - 50 Hz region than my current NRX.
A pair of NRXL's would of course be magnificent, and the combined 4 Ohm load would match well with the Hypex Ncore amp, and 96 dB/2.83V sensitivity would be a perfect match with the M74A. However, this would be a much larger (and heavier) speaker than I want.
I decided that a pair of RSS265HF-8's would be more than enough bass capability in a smaller box.
As I said recently in another thread... I wish that SB would make a larger version of the WO24. Perhaps a WO28, in both a paper and Textreme version, with a real 350 cm^2 Sd.
However, a single SB34NRXL75-8 would have slightly less deep bass capability than the NRX, due to a slightly lower Xmax value, but also because the NRXL has a Qts=0.28 which is more optimized for a vented box. As a result the NRXL version requires more LT EQ in the deep bass to get the response I am looking for. So all in all, a little less capability in the 30 - 50 Hz region than my current NRX.
A pair of NRXL's would of course be magnificent, and the combined 4 Ohm load would match well with the Hypex Ncore amp, and 96 dB/2.83V sensitivity would be a perfect match with the M74A. However, this would be a much larger (and heavier) speaker than I want.
I decided that a pair of RSS265HF-8's would be more than enough bass capability in a smaller box.
As I said recently in another thread... I wish that SB would make a larger version of the WO24. Perhaps a WO28, in both a paper and Textreme version, with a real 350 cm^2 Sd.
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I think @USXX of SB Acoustics has explored larger Satori woofers, even going as far as making prototypes.
If almost everyone thinks that a pair of 5x8" woofers in a ported cabinet suffices as a "subwoofer", what can the manufacturer do?
I'm guilty as the next person. A pair of twelves in cabinets barely 14" wide is considered too big, so I will "need" to downsize...
Manufacturers follow the market.
If almost everyone thinks that a pair of 5x8" woofers in a ported cabinet suffices as a "subwoofer", what can the manufacturer do?
I'm guilty as the next person. A pair of twelves in cabinets barely 14" wide is considered too big, so I will "need" to downsize...
Manufacturers follow the market.
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SB34RNXL is around 50L sealed (lowisch QTS) if a LT. The problem is to know how much loud one is listening. And what is the room gain and close hard surfaces reenforcment.
That certainly deserves a deeper study. Many lesser diameter will do worse in the low end cause higher Fs and at the end higher group delay and bad flatish alignments sealed as well as vented. Max flat is often max boring to the ears.
Could be cool to have a sim of low end cut off of the SB34RNXL related to the SPL; when I look the blue curve in Vituix it is not that bad (at least for non party listening).
That certainly deserves a deeper study. Many lesser diameter will do worse in the low end cause higher Fs and at the end higher group delay and bad flatish alignments sealed as well as vented. Max flat is often max boring to the ears.
Could be cool to have a sim of low end cut off of the SB34RNXL related to the SPL; when I look the blue curve in Vituix it is not that bad (at least for non party listening).
@hifijim -- if a more capable deep bass SBA 12" driver is of interest, have a close look at https://loudspeakerdatabase.com/SB/SB34SWPL76-4 A key spec is 15mm Xmax. That plus 79 liter Vas, 19 Hz Fs, and 0.33 Qts combine to allow
Vb = 0.78 ft3 = 22.01 lts
f3 = 40.71 Hz
fb = 40.71 Hz
Easy DSP EQ to get F3 well below 30Hz.
A single driver max SPL is 104dB at 30 Hz. Only real downside is low sensitivity of 84-85 dB/W
Factory FR curve shows reasonably flat response to around 600Hz, so it could work with your mid dome.
Vb = 0.78 ft3 = 22.01 lts
f3 = 40.71 Hz
fb = 40.71 Hz
Easy DSP EQ to get F3 well below 30Hz.
A single driver max SPL is 104dB at 30 Hz. Only real downside is low sensitivity of 84-85 dB/W
Factory FR curve shows reasonably flat response to around 600Hz, so it could work with your mid dome.