Very usefull measurements.
So we can expect around 92 dB efficienty if my understanding is correct. Hopping we can reach 110 dB peaks ! I assume a smoothing by "down EQ" is better for keeping all the transcient qualities of this driver 🙂 !
I assume if you full the cabinet at 100% with a fiber, you're comming to +10/20% liters volume virtually !
So we can expect around 92 dB efficienty if my understanding is correct. Hopping we can reach 110 dB peaks ! I assume a smoothing by "down EQ" is better for keeping all the transcient qualities of this driver 🙂 !
I assume if you full the cabinet at 100% with a fiber, you're comming to +10/20% liters volume virtually !
Ended up filling the cabinet up with loads of paper back novels to reduce the volume down to around 60 ltrs. Legend for attached trace is a before, was going to show a direct comparision to highlight effects of changing volume and lowering q, but Holmimpulse crashed half way through and i haven't removed all the books to re-do original measurements. Seemed to be very little difference maybe the loss of a couple of db around 60hz, which is as expected. Diificult to see if distortion increased as room modes over shadowing.
Going to listen in mono with a TPL crossed at 1600hz to see how it integrates with the 60 ltr test box.
Going to listen in mono with a TPL crossed at 1600hz to see how it integrates with the 60 ltr test box.
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I'm curious why you are using such large enclosure. I believe it's sealed, right? Running UniBox for the 12P80Nd in a 140 liter sealed box returns Qtc of 0.178 and F3 of 307 Hz, while running it for 60 liter returns Qtc of 0.215 and F3 of 302 Hz.
Sincere question here. No challenging intended. I was told very low Qtc deliver dry bass, but maybe that's not your experience? I was told to aim for Qtc = 0.707.
I bought my midbass drivers and want to start experimenting with boxes as well, so this is pretty relevant to me 😕
Cheers!
The PHLs are being considered as midranges. For midbass I purchased Beyma 10G40, planned 2 per side in independent sealed enclosures.
Regarding a low box qtc - giving dry bass, how would you define dry bass? Without equalisation yes you would get less upper bass, if all you did was increase the cabinet size. But the system is being designed to be equalised. You get about 2db more response at the cross over freq and about 6 db down at hz compared to a 0.7 qtc cabinet, which means less amplifier power required. From a quality perspective you are compressing the air in the cabinet less - which has to be a good thing.
Next phase is to build a a 55 ltr TTL (2.4m long line) test cabinet to see if the TTL has any benefit over a simple sealed box.
Also wi
Next phase is to build a a 55 ltr TTL (2.4m long line) test cabinet to see if the TTL has any benefit over a simple sealed box.
Also wi
A combination of factors, with the 12P80 being a close second option:
- two drivers allow more flexibility in mitigating baffle step.
- using two drivers allows for a very small displacement compared to Xmax, minimizing distortion. At 80Hz & 105 dB: 20% of Xmax vs 28% for a 12P80
- Volume displaced by two 10G40 at 80Hz & 105dB is 106 cm3 which is very close to what a single 12P80 delivers at 116cm3
- 10G40 has the lowest Le (0.6mH) of all midbasses I looked at except AE TD12M (0.2mH). 12P80Fe has 1.5mH. I've seen a very interesting article arguing Le was the best predictor of "speed", and I plotted Le vs Mms/BL (a popular indicator of speed in the forum) and it correlates pretty nicely.
- 10" drivers will be easier to accept in the living room by my wife than 12"
I presume cause those test´s were made 2009 could be standard lambda motor speaker.
Those apollos could be even better.
Those apollos could be even better.
Seems your message was cut off. Thanks for the perspective. I will try a box with Qtc around 0.4-0.5 and develop a point of view. I will be applying DSP as well, so got to try it.
FWIW, a while back I looked into TTL for midbass (80-400Hz) and exchanged with Martin King. The conclusion was at those frequencies there was little to be gained from TTL vs sealed. If you will run this further down in frequencies I would think there would be an advantage to TTL.
I am sitting listening to a single speaker, dipole bass to 100hz 12p80nd upto 1600hz then the TPL. The sound isn't a disappointment but is different from what i am use to. Not as much bottom end body - but a lot better integrated, (used to have 2 X 15" drivers upto 350hz) i think a sealed bass is needed to match the tightness of the 12" sealed driver. Integration to the TPL was easy as both traces are flat.
With respect to the TTL back chamber, it looks as if i can easily integrate it into a cabinet all i sacrifice is a couple of ltrs. The big ask will be going a TTL for an 18" bass driver!
BTW - interestingly i am hearing midrange detail, i haven't previously heard with the JBL 2482's, must have been lost in the 350hz xover range. Sound abit like BG neo 10's on steroids, or what i imagine a few pairs in an array would sound like.
With respect to the TTL back chamber, it looks as if i can easily integrate it into a cabinet all i sacrifice is a couple of ltrs. The big ask will be going a TTL for an 18" bass driver!
BTW - interestingly i am hearing midrange detail, i haven't previously heard with the JBL 2482's, must have been lost in the 350hz xover range. Sound abit like BG neo 10's on steroids, or what i imagine a few pairs in an array would sound like.
Vinylnvalves... are you interested in performing polar SPL measurements around the 1600Hz Xover? Time-alignment..How many milliseconds between TPL-150H and 12P80Nd_v2 square waves? You have the first pair of version_two 12P80Nd, and many diy'ers are using your data to help write letters to Santa Claus.
I am happy to provide/undertake more measurements. However I will need some guidance in how to, as I haven't invested much time on understanding the fine art of measuring beyond the simple SPL and phase traces.
I am happy to provide/undertake more measurements. However I will need some guidance in how to, as I haven't invested much time on understanding the fine art of measuring beyond the simple SPL and phase traces.
I am happy to provide/undertake more measurements. However I will need some guidance in how to, as I haven't invested much time on understanding the fine art of measuring beyond the simple SPL and phase traces.
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