built myself a 3-way with 2235 / 2123 / 2435 / pt-h1010

[Robh3606]

Just adding a bit to one of Ian points. If you look at the polars as far as matching the directivity at crossover you have a narrow window. Above 2K and things get a bit dicey. The driver starts to beam so above that you have a rather abrupt change in DI compared to the waveguide if you decide to crossover in the 2-3K range.

Rob

[grumpy]

Hi Rob,

Is this a modeled plot, based on parameters you've input for a 2123H
(and baffle or enclosure), or pre-canned actual measurements that come with Leap, or ???

[Robh3606]

Hello Grumpy

That is using the preloaded model in LEAP. It predicts the rising response as well. From experience using LEAP I would consider any modeling done by it to be fairly accurate. That's with an infinite baffle mount. You can change the modeling to go full anecholic or in room. With in room you can adjust volume and spacing inside the room as well 1/2, 1/4 and 1/8 space.

Rob

[Russellc]

It is the network Robh3606 is using in his similar design.
I believe he posted it somewhere on these forums.

Sorry, I wasnt clear I was looking for the circuit itself!

Still digg'in for it........I know 2123H must be handled carefully and figured this would be a good way.

The part of this thread that's got me is how the 2123H is treated.....I want this part right, I intend on either 2344A or some other waveguide/CD driver on top.....I figured Rob's would be the best way!
Russellc

[frank23]

I am still working on this project, slowly...

I re-mounted the waveguide for the upright position and tried the 2123 / 2435 again upright on top of the 2235 instead of lying down "on its side". I find this sounds better.

And I have sourced a 2nd hand M553 that I will pick up this weekend. And I ordered the Behringer UltraCurve DEQ2496 / ECM8000 mic with mic stand and cable to make some measurements and try eq-settings.

Now, I'll just have to build me the left cabinet, buy another few meters of speakercable, wait for the equipment to arrive, hook it all up with my 3 class-A musical fidelity amps and I'll have myself an incredibly complicated, power eating full active, digital-eq-ed, 3-way system!

For vertical alignment reasons, I might want to turn the 2235 cabinet on its side so the 2123 / 2435 sits a little lower. What do you think, the 2235 center is now 49cm above the floor and when on the side, this would be 27cm. It would make it more vulnerable to kids I guess, and there'd be more floor reflections, but the bass would probably also be stronger as there is more acoustic floor coupling.

[Robh3606]

Hello Frank

Since you are going to be using 24db L/R filters you may want to take a look at this Rane Tech Note

http://www.rane.com/note160.html

Your set-up is very similar to mine. Depending on the Voice Coil off set you may want to add a shim plate under the PTH1010 to get the alignment a little closer. I don't use one but it's an idea I have always played with. That aims your nulls but it may not be an issue for you as you are. I have another set-up using the 112A as a midrange and the step response in really good on the horns axis. The offset there is 1.45 inches between top plates 11 inches vertical.

A vertical stack would be the way to go. That way the nulls don't end up off to the side in a listening position if you don't listen on axis. As far as the 2235 spacing you can always put it back if it gets boomy.

Rob

[Robh3606]

Hello Russel

I have ran both the 2344 and the PTH1010 with the 2123 in an active set-up. I don't have a passive solution network worked out for it. The only passive componenets were the compensation networks used on the horn/waveguides. I don't have a schematic posted for those either. Pre LEAP so it was all done using an RTA/CLIO.

Rob

[frank23]

Hi Rob,

Would you know of a way to measure the step response without clio etc?

I have been looking for a impulse / step wav file to play on my cd-player and then measure the speaker output with audacity, but I haven't been able to find it. Is there another way? Maybe switch on a 1.5V battery on the amp input, that would sure be a step, just kidding, it would probably be blocked by the input capacitor :-)

From looking at it, it seemed that the acoustic centers for the 2123 and pt-h/2435 would be fairly aligned, how big do you think the difference is, 1cm max?

Frank

[Robh3606]

Would you know of a way to measure the step response without clio etc?

There is other software out there but I don't know if they will let you process a measurement in demo mode or if there is freeware or a trial set out there. They were playing with software over on DIY that a guy wrote and introduced there. I think its freeware might want to look for it.

From looking at it, it seemed that the acoustic centers for the 2123 and pt-h/2435 would be fairly aligned, how big do you think the difference is, 1cm max?

Well the rub is you can't tell by looking you have to actually measure to determine where the real acoustic center is. I used the line up the VC method when I did my 112A 2435/PTH1010 set-up. It's a passive crossover between the 112 and the PTH and biamped on the bottom. My alignment was more off physically than the 1 cm. If you look at the step response it look fine from what I did. I don't think you will have a problem with the 1 cm but I have never tried to measure what the real offset is.

Rob

[pos]

I don't understand why the voice coil is allways refered as being the acoustic center. The cone (or dia) is moving at exactly the same time as the VC, and that is what actually produce the sound, so this is what has to be considered the center (geometrically at least).

[4313B]

You might want to check out Mark's work here:

http://www.aes.org/e-lib/browse.cfm?elib=8194

http://www.aes.org/e-lib/browse.cfm?elib=8424

If not, just move the horn forward or backward until the sum at crossover point looks best.

[frank23]

Well, after days and days of building, the speakers are about finished. All that's needed are a few input panels for the rear. The amount of time involved has been far greater than I expected, but it turned out that even with an active system, you cannot ignore things like panel and cabinet resonances. So while the cabinets look about the same as in the first pics, they have been built to a much higher standard than before. Before they where just "driver placeholders" whereas they are now cabinets, braced and damped.







In the proces, I put the 4507 cabinet on its side to reduce the height of the system. The compression driver is now slightly above ear listening height, the total system being 114cm high. It doesn't look too big, I think people from outside of this forum seeing these pics will think "I can accommodate that", but it remains massive with the 15" and 10" setup.

Listening now, I think I have to analyse and retune the parametric EQ on the behringer that I use, it sounds slightly harsher now than when the 4507 were standing upright. The m553 crossover points are set at 160Hz and 1400Hz (taking the polar graph above into account).

Linkwitz has written very interesting things about this: http://www.linkwitzlab.com/frontiers_5.htm

This is one of the pics on the Linkwitz page, I just put it here to make you go there and read it :-)

[frank23]

So, how does it sound?

That was the question for me too. I had all the components and decided that I'd either had to sell them or try them out. I need to do a lot more critical listening, but for now I have to say that the system sounds very, very impressive. Dynamically it is on a different level than I am used to, it is kind of strange to listen to sometimes, but you know it is right when you hear it.

Luckily it can still do "small", I am now listening to the Oscar Peterson trio in a 1957 recording and this is about as small and intimate as it is on my other passive 1st order system. For me timing is very important and I was afraid that the EQ-ed multi amplifier / multi driver system would not turn out to be good in this area, but all seems fine.

And as for scale, large orchestral work is just "large" with a big L and a lot of low frequency extension.

Katie Melua also sounds ok, apart from the sssses which are always a problem on her piece by piece album and the music which is problem by itself. But the sound image is fine, a bit up front maybe but very powerfull.

I think I'll be hooked most on the low frequency extension and the clean dynamics of this system. What remains though is to try out different decoupling capacitors and maybe the 2420 / 2344 combination instead of the 2435 / PT-H1010. And what remains is trying it out a bit louder when the rest of the family and the neighbours are away...

[frank23]

after about two weeks of critical listening, the sound is much better now, due to a number of things:
- bas and mid drivers were almost new of just reconed so the suspensions are a little looser now
- I changed the amp configuration and with the different amp / driver combinations my mid is much sweeter and the bass is tighter and goes lower
- I went "all carbon" on the interlinks and used the same speaker cabling for all speakers to apart from the ams themselves, the whole chain is using the same equipment
- I optimised equipment polarity for best sound stage (yes, this can be easliy heard in a good setup)
- I added a thick carpet in front of the speaker to minimize reflections from my hard stone floor

"the cd of death" that I know can sound fantastic on an all tube high end system with zingali speakers, now even sounds bearable on my system!

this is "the cd of death" by the way: http://www.amazon.com/Peter-Tchaikov.../dp/B000000SJP

[frank23]

I will keep updating my listening experiences here. Last week I did a modification that really affected the sound.

I always used a DC coupling capacitor (of about 40uF) to block DC from the amp output on my 2435 that I use from 1800Hz and up. I always figured DC was bad for compression drivers so I tried different capacitors and settled on a Russian paper-wax capacitor that gave the juiciest sound. But then someone told me that with the DC on my amps of only 24mV, I could connect them without a DC blocking cap, just like cone drivers.

I first connected a 2440 2" driver and listened to noise and switch on clicks, but there was total silence. So I connected the 2435's without DC blocking cap and never looked back. This was the final tweak my system needed. The emotional connection to the music has improved in a great way.

Classical is great, Jazz is great, great recordings are great. I am convinced (I know, I know I am in over my head here) my setup now sounds as good as can be extracted from JBL drivers.

I put high-end friends through a solo bach cello piece and they all mumble something about that the system sounds amazingly coherent although it looks quite thrown together and then say something about that they also want a big living room and paper coned drivers.

So, was I the only one being so stupid using a DC blocking cap on my compression driver when the low DC from my amp made it unneccesary?