replaced my 2420 + 2344A with 2435 + PT-H1010HF

[frank23]

Hi,

I'm sorry I am not posting too often, but with two small children my JBL hobby only gets so much time...

I just wanted to let you know I have finally hooked up the 2435 + 100x100 waveguide (the 338785-002, or PT-H1010HF). I have had this combination boxed in my garage for years. I have done much effort to get the right horns and then I had 2 children (or, my wife did actually) and then, nothing.

I have hooked it up to the existing crossover that my 2420 + 2344A combination has been playing on the past few years.

Out of the box it sounds fine, but the drivers have been in my garage for the last few years so they probably get better (or different) when they come up to room temperature and everything has setteled down a bit.

I'll try to see how they develop over the next days. I know there are threads about this driver / horn combi, I was following them a few years ago and decided to buy this combination. So now I'll be able to hear them for myself.

regards, Frank

[Robh3606]

Hello Frank

I did the same change out a couple years back. Curious to see what you think.

Rob:)

[Mr. Widget]

...and then I had 2 children (or, my wife did actually) and then, nothing.Then nothing audio related or nothing in your marriage?:D ;)


Curious to see what you think. Yes, please let us know how it turned out.


Widget

[frank23]

Hi,

After this one day I would say that:
+ stereo image is a little better
+ larger dynamic range
+ better pace
- the sound is a little harsher
- there are problems with S, T and F sounds

As things are now I'd prefer the old setup as it is nicer to listen to, but remember that I have just "plugged and played" this setup on the existing crossover, so perhaps it is not all fair to say so.

But I don't know how the slight harshness and STF problems would go away by changing the crossover values. They are quite obvious and in the old setup I got rid of them totally (and I mean totally, the Van den Hul The First Ultimate carbon interlink does wonders). Does anyone know the frequency range these problems occur in?

BTW I am a "high end" follower with class A amps, high end cd/da and carbon interlinks etc. Not from the "another 500W is better" school.

Regards, Frank

[frank23]

Then nothing audio related or nothing in your marriage?:D ;)

Yes, please let us know how it turned out.

Widget

Audio related! Although I did change components. But I didn't have time to rebuild my speakers as I liked.

Frank

[spkrman57]

You might need to attenuate the HF section a little to better match the overall efficiency of you system.

Just a thought......

Regards, Ron

[Robh3606]

- the sound is a little harsher
- there are problems with S, T and F sounds


Sounds like there is a peak in there. There may be a sensitivity issue as well I don't know if the 2435 on a 1010 is the same as a 2425 on a 2344??

Do you have any measurement capabillity like an RTA??

When I get a chance I will run a stock 2435 in LEAP with a 4430 crossover and see what it looks like. I have measurements of uncoated 2435's and Imp runs on the horn in the "library" so to speak so it should be a quick work-up to see what's up.

What components are you using from the 4430 network?? Is it stock or are you just going with the compensation in an active set-up??

When I did my own networks using that combo I needed a couple of notch filters to flatten things out.

Rob:)

[frank23]

hi,

I don't use any components from the 4430 crossover. It is a setup of my own design combining an 8" kevlar ticonal magnet woofer with a 2420/2344A combination all through a 1st order crossover with compensation for the 2344A high end fall off and an attenuation network for lowering the sensitivity to match the woofer.

So it is a little out of the ordinairy, certainly on this forum!

I'll post the crossover layout and values tomorrow.

Maybe the 2435 has peaks in different areas than the 2420 and the crossover match isn't optimal.

Regards, Frank

[Robh3606]

Maybe the 2435 has peaks in different areas than the 2420 and the crossover match isn't optimal.

Well lets see what you have.

Rob:)

[robertbartsch]

...Hey - I've owned many systems over 30 years and I am from the "500 watts is better" camp! ...Anyway, I would say this is not necessary for a high sensitivity system like most Altecs but for JBL big power is usually much better!

[frank23]

hi,

here is my crossover layout, the drivers are simplified by only a resistor which is about right for the bass driver as it has a very, very low induction, but of course is not right for the 2420/2344 combination

I know the real impedance can also be modelled, but I don't know how...

the 2420/2344 crossover can be highered or lowered in the graph by changing the resistor values around the opamp on the left, I don't exactly know what the right value should be, but this is how the setup sounds great

I just substituted the 2420/2344 for the 2435/waveguide now and found the sound a little harsh.

In the graph below the green is my current crossover. The red is the current, but without the high compensation. The blue is what could also be done as a simple alternative to the more complex green, but as you see there is a difference of a few dB's between them. But I could try it as I have the components [always difficult with paper-oil capacitors].

http://i200.photobucket.com/albums/aa253/frankvcp/20081224_2420_2344_co.gif

Frank

[frank23]

Hi,

Instead of taking a simple resistor to represent the driver I have now found out how to simulate the driver impedance peaks and have made a graph of the crossover-driver interaction for the 2425/2344A combination. Just to see what the calculated effects would be. Of course, I don't have a 2425, but I couldn't find impedance curves for the 2420 on the 2344A.

The impedance curves of the 2435 on a H9800 horn that I found showed very low impedance peaks. Does anyone know the impedance peaks for the 2435/waveguide combination?

In the graph below the green line is the crossover vs a 6ohm resistor. The blue and red graphs represents the impedance simulations for about 500Hz and about 1200Hz peaks.

The graphs show that the impedance peak causes the level at 1246Hz to be about 1.4dB louder than with a normal resistive value. It also shows that the rising impedance due to self inductance causes the high compensation to come out about 2dB louder at 20kHz which isn't a bad thing.

http://i200.photobucket.com/albums/aa253/frankvcp/20081224_2420_2344_co_effects.gif

Frank

[Beowulf57]

h
I just substituted the 2420/2344 for the 2435/waveguide now and found the sound a little harsh.

In the graph below the green is my current crossover. The red is the current, but without the high compensation. The blue is what could also be done as a simple alternative to the more complex green, but as you see there is a difference of a few dB's between them. But I could try it as I have the components [always difficult with paper-oil capacitors].



Frank

You found the sound harsher with the 2420/2344? Below you noted that the 2435/waveguide was a little harsher...which is it?

Do you get the same STF problem using the setting without compensation (Red)?

I found the 2420/LE85/HL92 combo a bit harsh/hard/glaring and sibilant until I added the 2405H HF drivers with 3106 (8000Hz) crossovers. The upper response (above 8KHz) of the 2420's was ragged and the sound improved noticeably when they were rolled off above 7KHz and the 2405H's took over.

[frank23]

I had the 2420/2344. When I changed it to the 2435/PTwaveguide the sound became harsher.

Frank

[Beowulf57]

I had the 2420/2344. When I changed it to the 2435/PTwaveguide the sound became harsher.

Frank

Okay...now I got it. So, does the STF problem decrease without the HF compensation?

[Robh3606]

Hello Frank

Here's what it looks like in Leap. One is just with a 6 ohm load Green. The original in Red and a Cap leg repositioned in Blue. Well have to run too much to do with the holiday. If I don't get back have a nice one.

Rob:happyh:

[Mr. Widget]

BTW I am a "high end" follower with class A amps, high end cd/da and carbon interlinks etc. Not from the "another 500W is better" school.OMG!, you mean to say you actually listen to this stuff?! :applaud:

I am not sure you'll be able to get the quality of sound out of the parts you are using... you might succeed with some work. I have heard variants on this theme at Zilch's place and never thought they quite made the grade for the, "Not from the "another 500W is better" school." ;)


Widget

[Zilch]

My results were considerably better sounding once I abandoned the pursuit of comping them flat to 20 kHz, and just let them roll off in the VHF, as Giskard suggested. That came with using a modified version of the Timbers filter, elsewhere documented in this forum.

It's been over a year since I worked with these; I'm confident I could do a more competent job of it now, and that it would be a worthy pursuit.... :yes:

[frank23]

Okay...now I got it. So, does the STF problem decrease without the HF compensation?

The STF's decrease in volume slightly when taking out the hf compensation, but not in the sense that they are not there. I don't know exactly how to put this as I am not a native English speaker, but taking away the compensation does not take away the problem, it only lowers the volume of it slightly. It wasn't there with the 2420/2344 combi.

Frank

[Mr. Widget]

It wasn't there with the 2420/2344 combi.I know exactly what you are saying... when over at Zilch's place every time he would go back to a pair of LE85s from one of the 2431s or whatever, I had a similar feeling... the top end is simply lighter and more delicate sounding with the LE85/2420. There was a hard quality at Zilch's that I heard with every 243X driver on every horn. As he has mentioned, Giskard and others did suggest lowering the SPLs up top, but that is only a magnifier... the underlying problem is still there.

The Array 1400 does have a similar HF driver, however it does sound good, so I think if you dial in the network and use the right horn you can make these things sound good... I just don't think it is easy.


Widget

[frank23]

Well, it looks like my crossover and the 2435/PTwaveguide are not too incompatible. The overall level is a few dB too high compared to the 2420/2344 combination, but I can hear "through" that to assess the 2435/PTwaveguide sound. It definately has the pace, but is also a little too rough for my taste.

As Mr. Widget is saying, there might be something about the 2420 that the 2435 just cannot do?

To make things even more insane at my house, I just carried my 2440 / 2382 combination from the second floor [I know, I have too many driver/horn combi's, but there is more!] and hooked them up to the same crossover.

The overall level is a few dB lower than the 2435's and the high's are not there, but the sound is sweeter again. These 2440's have JBL titanium diaphragms though, not the aluminium originals. I'll listen to them for a few days and see what I think.

Frank

[Robh3606]

I would dump the compensation or modify it. It is making a broad peak in the response worse as well as increasing the driver level at 10-15K. You have a peak about 2 octaves wide from what I see with LEAP. That very well could be what you are hearing. You may want to try and notch out that 4-8K peak in the response possibly leaving the comp in. These drivers have different mass break points so the compensation won't be the same.

Rob:)

[4313B]

My results were considerably better sounding once I abandoned the pursuit of comping them flat to 20 kHz, and just let them roll off in the VHF, as Giskard suggested. That came with using a modified version of the Timbers filter, elsewhere documented in this forum.;)
It's been over a year since I worked with these; I'm confident I could do a more competent job of it now, and that it would be a worthy pursuit.... :yes:Most likely.

*****

Like I posted years ago, the 243x drivers do not behave the same way as the 242x drivers. Once you get them dialed in they sound quite nice. In fact, it really takes a 476BE or TAD to top them.

The 242x/2344 combination is a tough one to beat, JBL reiterated that a few years ago.

[frank23]

The 242x/2344 combination is a tough one to beat, JBL reiterated that a few years ago.

? I am curious, can you please explain?

Frank

[4313B]

? I am curious, can you please explain?We were sitting around one day talking about horns and we started ranking them. The 2344A ended up third from the top. That was a few years ago.

The biggest gripe with the 2344A/242x was the "small" 1.75" diaphragm. It just doesn't have the steam that the 3" and 4" diaphragms have. The consensus was that the "low" 1 kHz crossover frequency of the 4430/4435 was pushing it. For normal volume levels it works just fine though.

[Robh3606]

Here it is with a single notch filter in place added to the filter with compensation.

Rob:)

[frank23]

ok, I have found some formulas and simulated a compensation circuit after the crossover for correcting for the 6.000Hz centered +5dB level for the 2435

it seems to come to a series circuit of a coil of 0.15 mH, a capacitor of 5 uF and a 1.21 Ohm resistor [where the resistance will of course partly be the resistance of the coil]

this series circuit will be placed in parallel to the existing 1.21 Ohm resistor

rob, is it possible for you to enter this in your simulation software? I have entered it in mine [microcap], and it looks ok, but I am not too sure about my work here...

Thanks, Frank

[Robh3606]

Here you go, the R value is the coils DCR.

Rob:)

[frank23]

thanks!

frank

[frank23]

hmm, that compensation looks too narrow, what values did you use in your simulation to get the brown line?

[Robh3606]

Hello Frank

It's in the schematic put it's not all that easy to read. Its a 3.3 in series with the driver with a .040mh and a 17.8uf in parralel. Look at V2 and R17, L2 and C10.

Do you have any measurement capability at all?? I am using my measurements, it sure would be nice if you could actually confirm what curve you are actually getting from your drivers. Even an RTA would help feel kinda blind on this end.

Rob:)

[frank23]

I have some capability, but it is so bad, we'd better consider it as "no measurement capability", I'll try your values tomorrow, it's already midnight here

thanks again,

Frank

[Robh3606]

Well Good Luck I hope it helps you.

Rob:)

[frank23]

its june now and I have recently rearranged my system to include the 2435 / pt-h1010 combo again, but now in a active setup

as I am a bit of an high-end afficionado, I have been trying to get the best out of the combo in this setup and I have found a really fine capacitor for the 2435

I have set up the M552 active crossover in 236x series compensation and am crossing over to the 2435 at 1300Hz using all class-A amplification (50W low-mid and 10W on the 2435)

to protect the 2435 from DC at the amplifier output, I had to include a capacitor between amp and 2435 that had no attenuating effect in the passband of the crossover, and I have tried several

the best sounding on the 2435 is an NOS (new old stock) sovjet paper-oil (or paper-wax?) capacitor (30uF, 160V), it really makes a difference compared with top-notch MKP capacitors, it takes away the last bit of harshness from the 2435, so sweet!

they can be had on ebay for about 10$, here for instance (I have no connection with the seller, just an example): http://cgi.ebay.com.sg/30uF-160V-30-0uF-MBGO-2-CAPACITOR-5-NOS-CAPACITORS_W0QQitemZ390039173053QQihZ026QQcategory Z4193QQcmdZViewItem

just sharing this with you, I know most of you don't consider capacitors like these, but they definately make a big musical improvement over the slightly cold MKP's most use, just listen...

frank

[spkrman57]

I have not tried out the Russion paper in oil (PIO), but a friend of mine has in his tube amp builds and he likes them.

I acually like to use vintage oil caps in my 1st order crossovers as they have smoother sound than the metalized polypropolene (MPP) types as high efficiency horns are very revealing and I like the sound characteristics.;)

So, yes some of us do like the "oil" type caps!!!:applaud:

Regards, Ron





just sharing this with you, I know most of you don't consider capacitors like these, but they definately make a big musical improvement over the slightly cold MKP's most use, just listen...

frank

[4313B]

I acually like to use vintage oil caps in my 1st order crossovers as they have smoother sound than the metalized polypropolene (MPP) types as high efficiency horns are very revealing and I like the sound characteristics.;)I'll buy that. I had a similar discussion with Jeff at Sonicap many years ago.