New DIY Mid High (90deg) - AKA PM90

what configuration you decide on should be based on the amp power you will have.. Once you decide that then you can do the simple math of 1.5 times the rms power to ensure you are at the right place.. 1.5 times is just to get you in the right region and is subjective in itself..
 
jami schorling said:
Yes, and hence my question is: Are there any concerns with using 2x 16 Ohms in parallel = 8 Ohms for the mids, in contrast to 2x8Ohm=4Ohms?
I can get my hands on the 16Ohms version, but can't happen to find an offer for the 8 Ohms version. Just want to doublecheck before spending 700+ Euros on the wrong mids.
Click to expand...
Do you want to run 1 or 2 cabinets per side?

2x 16 Ohms requires a very beefy amp: it needs to be able to deliver > ~2.5 kW @ 8 Ohms if you want to utilize the full capability of the cabinet. Running 2x 8 Ohms can save you €€ on the amps.
 
Thanks for your answers. Amp power is definitely an aspect of consideration. If there isn't any other that could make a difference (e.g., different TS-parameters on the 16 Ohm version), that would not be my biggest concern. Though I read something somewhere sometime about sensitity issues with the 16 Ohms configuration, but I can't remember right.
 
This isn’t a PM specific question, but you guys will have the experience and data,

I’m swapping out my XT1464 for HF950s to broaden the horizontal coverage in my HT LCR build I did a few years back. Switched from 1st gen 4594 to DCX464s and due to the high freq narrowing of the 1464 I’m switching.

Two questions, has anyone run a DCX yet with the HF950, how has the performance been and;

How does the 950 load and perform in terms of distortion down to a 450Hz XO?

Thanks gang


Sent from my iPhone
 
Chris Burns said:
This isn’t a PM specific question, but you guys will have the experience and data,

I’m swapping out my XT1464 for HF950s to broaden the horizontal coverage in my HT LCR build I did a few years back. Switched from 1st gen 4594 to DCX464s and due to the high freq narrowing of the 1464 I’m switching.

Two questions, has anyone run a DCX yet with the HF950, how has the performance been and;

How does the 950 load and perform in terms of distortion down to a 450Hz XO?

Thanks gang


Sent from my iPhone
Click to expand...
I'm working on DSP settings for a speaker using HF950 with BMS4590.
Initial measurements suggests that the 500hz XO I target is doable in terms of dispersion, it's pretty even with the LF section there.
But, I haven't done any distortion measurements...
 
As one always keen to spend as little money as possible to achieve my goals (ok, a cheapskate...) I am using Behringer crossovers and EQ, lamenting the inability to implement phase correction. However, I came across three tantalising videos on YouTube - search 'All Pass Filter BEHRINGER DCX2496' - showing it used as an all-pass filter using just the individual channel phase adjustment features. It all appears to be in Portuguese with little on-screen activity, but I get the gist of it. Comments, please, good people.

​

 
Hi Guys. I don't want to be a party pooper but am I the only one who is concerned about really high 2nd harmonic distortion of BMS4594HE in the high frequency region, where it's most noticeable/audible? The THD is -20dB or 10%, huge! It's shown in green on the picture
1643226453814.png

There is a research that claims even -40dB distortion is noticeable at 10KHz:

1643226242041.png

The question is does single-point source worth living with this level of THD, especially considering the price of the driver? My much cheaper Selenium D3300TI for example has THD at around 2% or less in the same HF region...
 
Carl Klinkenborg said:
As one always keen to spend as little money as possible to achieve my goals (ok, a cheapskate...) I am using Behringer crossovers and EQ, lamenting the inability to implement phase correction. However, I came across three tantalising videos on YouTube - search 'All Pass Filter BEHRINGER DCX2496' - showing it used as an all-pass filter using just the individual channel phase adjustment features. It all appears to be in Portuguese with little on-screen activity, but I get the gist of it. Comments, please, good people.

​

Click to expand...
it looks like DCX2496 should support phase correction. From the user manual:
1643248346125.png
It's also possible to use CC caption on youtube, with auto-translation to english. I found is useful more than once.
 
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Victor Ruskovoloshin said:
it looks like DCX2496 should support phase correction. From the user manual:
View attachment 209559
It's also possible to use CC caption on youtube, with auto-translation to english. I found is useful more than once.
Click to expand...
Did exactly that, and from what I understood, it is an adjustable All Pass Filter that you can use to correct the phase. It applies a 360° shift at the frequency that the High Pass filter is set to, even If you dont use it. If put intelligently and depending on the phase behaviour, you could flatten out some of the phase by doing that. But quite surely you can't accomplish the same as with FIR?
 
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jami schorling said:
Did exactly that, and from what I understood, it is an adjustable All Pass Filter that you can use to correct the phase. It applies a 360° shift at the frequency that the High Pass filter is set to, even If you dont use it. If put intelligently and depending on the phase behaviour, you could flatten out some of the phase by doing that. But quite surely you can't accomplish the same as with FIR?
Click to expand...
The explanation of Polarity/Phase adjustement in the user manual is 0 to none. But it's definitely not a simple delay (delay is described in the next chapter, 4.5.5) so should be All Pass Filter with the phase control for all frequencies. Unfortunately for me I don't have enough knowledge of DSP to understand the implementation.
 
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i finally got round to firing up one of my PM90s after 2yrs or waiting but i have a question on the frequency response....this is BEFORE doing any corrections and just simple crossovers at 100hz and 650hz.....I'm using the DCX464 with the HD950 horn and 18Sound 12ND930 drivers.

I see a 10-12db drop between 2khz-5khz and then a complete cliff drop after 13khz all the way to 20khz....does that sound right to you?
I'm using the Behringer ECM8000 and it's old so it could be that the mic is finished but wanted to get other people's experience
 
That does not sound right. Do you have a picture of the measured response?
Also:
-What was your measurement setup?
-How did you hook ups the DCX464?
-What kind of 100H and 650Hz crossovers?
-Is the ECM8000 calibrated?
 
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Hey Stef, I really should've included all that info, apologies. I don't have the graphs anymore as i didn't save anything like an idiot!

measurement setup:
MacBook pro with REW, external audio interface which the ECM8000 is plugged into and then the audio interface going out into my Behringer x32.

Filters:
DCX464 (using Convair passive crossover) - FIR Sinc highpass @ 675hz
12ND930 - IIR lowpass LR-36 @ 725hz - highpass BW-48 @ 96hz

The reason for not using FIR for the bass drivers is because the active crossover I'm using (t-racks FIR 408 from Thomann) will only allow either both low and high passes to be FIR or IIR but the main issue is that i can't go lower than 150hz in FIR mode. Then again the drop offs are happening way after the crossovers.

The mic is not calibrated.

I wonder if the Convair passive crossover is faulty in some way? it's either that or the mic....i can't really think of anything else that could be going wrong
 
Yeah checked it multiple times and even tried different polarities just in case. I'll swap it with the other crossover I have and retest. I'll come back with the results as soon as I can. It would be amazing if anyone who's built these could supply a graph before correction to see what it should roughly look like!

Actually before I do that, I'm gonna test another mic as that's easier to do first.
 
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