Pass Labs B4 crossover questions

[adason]

I think Christmas will be coming early this year. 🙂

 

[woofertester]

The LXmini+2 or Studio version will do that. I have a couple prototypes
already, and the store is prepping a chassis with 8 RCA's.

A triamp diyaudio.com store chassis with PC board and transistors will be awesome.

 

[chrisb]

So, for folks wanting to run a pair of Georges in bridged mode in a multi-amped system with B4 crossover, there’d need to be some conversion of the latter’s output from SE to differential? Any suggestions for that?
I mean the answer could be just buy a cheap Ashly, DBX or Behringer, but there are some limits ? 😉

 

[mbrennwa]

I am trying to prepare my wallet for the kit. I guess the costs will depend on the number of channels, type of chassis, etc.; but it would be cool if we could get an order-of-magnitude guesstimate. Is it a bit like an ACA kit?

 

[Nelson Pass]

I think you will find these pretty inexpensive, with the base being pcb
and Jfets. I came up with a design which uses much cheaper matched
Jfets that still get some good distortion numbers.

 

[chrisb]

Could well be a case where the case costs more than the contents. To paraphrase what Paul Klipsch may not have ever actually said “what this country needs is a good $50 chassis”.

By the time you do the math on the customizaton, the mini-dissipante for the ACA is a helluva bargain. I built a chassis from scratch for a mini-aleph groub buy few years ago, and it was a royal pain in diaz.

 

[nzlowie]

I've been following this with interest and would!d like the thoughts of the experts here before jumping in to this build. (I know it's not available yet...)
I first tried the digital minidsp for my attempt at active, never liked it and always went back to a passive xover. When I built the 4 channels of ACA it was the intention of active, my latest incarnation of this uses a 2x4 analog minidsp with each pair of amps . Replicated for the other channel.

My question is , do the experts here believe that this style of active xover will outperform the minidsp? Yes we can eq in minidsp but I'm not sure that this doesn't introduce more problems than it solves...... I just don't like all the signal processing that happens within the minidsp, we spend thousands on DAC's to get purity of signal then use a hundred odd dollar board to do the next part.

My system has BMS coaxial compression driver's on LeCleach horns so really a good match for the ACA's.

Love to hear your thoughts. Also love building stuff so that's no excuse!

 

[Davey]

I just don't like all the signal processing that happens within the minidsp, we spend thousands on DAC's to get purity of signal then use a hundred odd dollar board to do the next part.

You buy a cheap signal-processing unit, but you don't like it because of all the signal-processing and it's not expensive enough?
Classic. 🙂

Dave.

 

[Soundhappy]

My question is , do the experts here believe that this style of active xover will outperform the minidsp? Yes we can eq in minidsp but I'm not sure that this doesn't introduce more problems than it solves...... I just don't like all the signal processing that happens within the minidsp, we spend thousands on DAC's to get purity of signal then use a hundred odd dollar board to do the next part.

You get the answer from the expert it's Papa show the filters curves graph etc.

start about DSP and analogue version at 29:29

Mr Pass at BAF 2017

Enjoy 🙂

 

[nzlowie]

You buy a cheap signal-processing unit, but you don't like it because of all the signal-processing and it's not expensive enough?
Classic. 🙂

Dave.

Didn't say I didn't like it (the analog one) just asking if this new active xover might be better.....

 

[ascaso]

Hi Mr. Nelson, Hi all,
I'm thinking of biamplifying my Tannoy Cheviot Loudspeakers, equipped with Dual Concentric HPD315 (12" Woofer with Xover frequency around 1000Hz and concentric compression driver for the HF).
I look forward the B4 Kit to disconnect the actual passive crossover and go with active bi-amplification.
In your opinion is a viable solution?
🙂
Lu

 

[Zen Mod]

for Tannoy squawker you need both boost (Newman constant boost) and notch filter

 

[ascaso]

Thanks ZenMod.
My current passive xover has a notch filter (3.3.uF + .7mH + 10R).
I thought I would keep it passive.I hope not to say nonsense.

Apologize, but I did not understand why you think the boost is essential.
Could you explain me better ?

🙂
Lu

 

[Zen Mod]

@ascaso

there is one series cell , made of cap and resistor in parallel

that's for linear boost of voltage , 6db/oct , because all compression drivers are declining in SPL with frequency , starting from frequency in strict corelation with diameter of dome, practically VC dia

I believe that corelation was established by Ray Newman , of JBL

 

[ascaso]

@Zen Mod
You are right.
I took a look at a crossover scheme
Thank you!
🙂
Lu

 

[Nelson Pass]

If you can post a curve of the voltage appearing across the drivers vs
frequency for the speaker, then I can come up with an opinion as to
whether the crossovers designed so far can do it.

If not, it might suggest another new design.

 

[Zen Mod]

same xover as you have in your Papatanns

 

[ascaso]

@Mr. Nelson @Zen Mod
Many thanks for the interest,
I apologize but for now I can't post that measures.
If I understood well, Mr Nelson Speaker are the HPD385 (15" woofer) the mine are HPD315 (12" woofer).
I'm not sure that the HF Drivers are the same both for 315 and for 385.
Anyway the xover regarding the HF seem to be very close or equal on both HPDs.
Here are both the xover.
Thanks alot another time !
Lu

tannoy

tannoy

 

[Nelson Pass]

The crossovers are similar, but ours are based on the Filton version,
which was adjusted for a more efficient horn driver.

Here is a picture of it.

For the best results we would want a filter response curve.

 

[ascaso]

@Mr. Nelson
Thank you !
I will try to make the measurements and post the curves.

Do you think it is not appropriate to use your B4 active crossover in place of the passive crossover?
Thanks.
Lu