Guesstimating 2-way crossover circuit...

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03-16-2021, 12:30 PM
eso

3 Attachment(s)

Guesstimating 2-way crossover circuit...

I need help from the brain trust here. I've combed the internet, searched the archives here and made some phone calls all without finding what I think I'm looking for.

In the course of my work I've come across a set of components that look to be Westlake but the more I've studied it things don't quite add up.

Starting as a built-in pair of high power 2-way monitors they had been modified and then abandoned. I'm looking to put them in new cabinets and build new passive crossovers.

Here's what we have:

4 Gauss 4583A 8Ω 15" woofers
2 TAD 4001 16Ω drivers
2 solid oak Westlake Radial horns.

While the original baffles have the circular cutout where you would normally find an L-pad an also the location where a terminal strip once was those had been removed and there is no trace of a passive crossover. So they were converted to bi-amping at some point. Also, while the baffles had T-nuts for mounting the woofers with JBL style clamps, the Gauss woofers were mounted with screws. Lastly, the holes in the mounting mounting flanges for the compression drivers would fit 1/4"-20 screws even though the TAD drivers mount with small M6 screws.

All of that makes me think the original configuration was gutted and replaced at some point. Also, if these were original to the building they were in then they were installed before the TAD drivers were even made.

So I'm looking for a baseline passive design. The gauss specs I can find recommend crossing 800Hz or lower and TAD recommends 600Hz minimum. Enclosure with be ~11 cu. ft. with 2 3X6 ports or equivalent which should give pretty good response to ~36-38Hz.

I had toyed with the notion of adding a midbass driver, but these are not the right woofers for that approach so 2-way it is...

Any thoughts? Input on a bassline 2-way passive network?

eso
03-16-2021, 01:02 PM
Mr. Widget

Here is a decent on line crossover calculator:

https://www.v-cap.com/speaker-crossover-calculator.php

Plug in the impedance and the desired frequency for a 2nd, 3rd, or 4th order network and this should get you going.

Widget
03-16-2021, 01:34 PM
macaroonie

Nice barn find , some good potential there.

FWIW not to contadict Widgets sound advice I would beg borrow or steal the equipment to achieve a full active arrangement , not the least of the reasons being that you can derive the parameters ( from a DSP aka LMS ) that will allow you to build a passive x/o
with a good chance of a successful outcome. Think of it as a tool , if you like it stick with it if not , move on.

Haven't heard of Gauss for a few years , strong drivers.

M

I see you have some interesting speakers to evaluate against , fancy sharing some pics for the folks in the gallery
03-16-2021, 01:55 PM
eso

Quote:

Originally Posted by Mr. Widget

Here is a decent on line crossover calculator:

https://www.v-cap.com/speaker-crossover-calculator.php

Plug in the impedance and the desired frequency for a 2nd, 3rd, or 4th order network and this should get you going.

Widget

That is a handy little calculator.

Off hand do you know the slopes used in the big JBL Monitors?

eso
03-16-2021, 02:24 PM
eso

5 Attachment(s)

Quote:

Originally Posted by macaroonie

Nice barn find , some good potential there.

I see you have some interesting speakers to evaluate against , fancy sharing some pics for the folks in the gallery

These things?

Attachment 88438 Attachment 88439

Nothing else I've ever heard compares to them, except the 3 other sets like this I know of.

I've also got this thing for rebuilding old Urei monitors and making custom horns for them:

Attachment 88440 Attachment 88441

And just recently was able to clone the Urei A series horns for the flawed 604 8K duplexes:

Attachment 88442

I've been battling audiophilia nervousa for ages and seem to be losing the battle...

eso
03-16-2021, 02:43 PM
macaroonie

Hot tamale !!! I'd keep that quiet or the tent people from Venice will be up to help you with your removal :D
03-16-2021, 02:53 PM
JeffW

Maybe copy the TAD 2401 (? I think - I can never keep those systems straight) crossover, it was a pair of 15s and a horn.
03-16-2021, 02:57 PM
eso

Quote:

Originally Posted by JeffW

Maybe copy the TAD 2401 (? I think - I can never keep those systems straight) crossover, it was a pair of 15s and a horn.

Do you know where I could find a copy of that?

eso
03-16-2021, 03:58 PM
JeffW

Quote:

Originally Posted by eso

Do you know where I could find a copy of that?

eso

Not right off hand. I have the stuff to build the single woofer version, but those crossovers are also hard to nail down.
03-16-2021, 08:04 PM
eso

4 Attachment(s)

Quote:

Originally Posted by JeffW

Not right off hand. I have the stuff to build the single woofer version, but those crossovers are also hard to nail down.

I got Lucky… Not too deep of a rabbit hole.

The Gauss 4583A T/S are pretty similar to the TAD 1601B except the Qms is quite a bit lower on the Gauss. I’m not sure how that would affect the network.

This is the TN-2 for the single 15"

Attachment 88443

Attachment 88444

And this is supposed to be the TN-1 for the dual 15"

Attachment 88445

That's a pretty complicated network. But, I think I have enough NOS Soviet PIO caps on hand to build a pair and charge couple them.

This is my very simple charge coupled network for the Cogents...

Attachment 88446

eso