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Robh3606
11-06-2007, 06:14 PM
I have been messing around with various drivers sets of the last couple of months. I have been trying to combine some the older drivers with some of the newer drivers to see what works for me and what doesn't.

I tried an MTM for a while and decided to move back into more familiar territory. I stumbled into a very nice sounding combination using 121A woofers and 2108A's in sealed enclosures with a 2435 on a PTH1010 horn. It's not perfect but it sure does sound good and gives me a nice balance of performance. It has really good transient response, tonality and clarity. They can also disappear with the right source material:hmm:.


I was wondering what driver sets you guys have tried and what some of your personal favorites and combinations are. Pictures would be nice. We have not had a Project thread up for a while it would be nice to see some of what you guys have been working on for the last year or so.

Rob:)

4313B
11-06-2007, 06:51 PM
Yeah, the 121 and 112/2108 make a nice combination. I just sold a set of each to another forum member.

Zilch
11-07-2007, 01:01 PM
Thus far, Rob, it seems you and I are the primary fans of PT waveguides on the forum. I find the compact "F" versions more easily integrated (mechanically) into systems. The directivity control is supposedly not as good, but they have lower distortion, according to the white paper.

Of late, it's PT-F95HF I favor, using 2452H-SL with Aquaplas'd titanium diaphragm. Compensation is the familiar series resonant filter from N3134, tweaked a bit. I'm not using them with 2435s because of the anomalous reponse notch I documented elsewhere in these forums.

I haven't tried them in combination with the 2251J-1s yet, but that's on the agenda, to move the XO frequency up from 1 kHz 2-way to 1.2 kHz 3-way. From what work I have done with those, they'd be my contemporary 10" midbass of choice, primarily because I have them. I have no experience with the drivers more conventionally used for the purpose.

Robh3606
11-07-2007, 07:04 PM
Hello Zilch

Well what I like is how well some of these older drivers have held up. They can still make an impressive sounding system even when paired with more modern drivers. As a matter of fact I think they are enhanced buy it as the current high frequency and compression drivers are better sounding than their predecessors.

Just goes to show you that a good driver is just that and they can stand the test of time and hold there own 25 years or more down the road. Not to say that they cannot be surpassed by more modern offerings just that I find it remarkable how well they were originally engineered.

Rob:)

4313B
11-07-2007, 07:35 PM
Just goes to show you that a good driver is just that and they can stand the test of time and hold there own 25 years or more down the road.Yep.

Of late, it's PT-F95HF I favor, using 2452H-SL with Aquaplas'd titanium diaphragm.PT-F95HF (338650-001) HORN,WAVEGUIDE, VP7212MDP $98.00
2452H-SL (352328-003X) TRANSDUCER $1,315.00

reference

VP7212MDP Powered 12" 2-Way Integrated Stage Monitor Loudspeaker System (http://www.jblpro.com/installedsound/vpseries/specsheets/JBL_VP7212MDP.v5.pdf)


I'm not using them with 2435s because of the anomalous reponse notch I documented elsewhere in these forums.What does it sound like?

Zilch
11-07-2007, 10:38 PM
What does it sound like?Sounds fine to me; I can't say I have a particularly discriminating ear at 14 kHz, though:

http://audioheritage.org/vbulletin/showthread.php?t=17069

I should send Rob a pair of these PTs to try and maybe he can figure out what's going on, or at least, confirm my findings.... :dont-know

Product reference for 2251J-1 10" midrange driver is 4-way 4348:

http://manuals.harman.com/JBL/HOM/Technical%20Sheet/4348%20ts.pdf

Robh3606
12-15-2008, 10:47 PM
Damn it only took me a year to get back to this thread:banghead:. I decide to try a couple of passive crossovers for the top so it will be a biamp only proposition. I am going to build both starting with the 12db network and then give the 18db a try. Already have the 2435 networks done. So the 2108 should be real quick.

I am curious to see how they will actually measure and sound. So here are the schematics and simulated response based on measurements on the baffle board. The 18db definatley looks better on paper. Had a hard time trying to minimize of that pesky notch around 2K. I have 1/3 smoothing on the 2108's none on the 2435's.

Rob:)

Robh3606
12-28-2008, 01:22 PM
I ended up getting one of the 12db networks up and running. Took some measurements and it looks good as is. The predicted 1.8K notch is not there. Still trying to figure that one out?? I must have goofed on a measurement or the error can maybe go your way?? Never thought about that before. Hope to get the pair up sometime tonight, in mono it sounds good. The black is the actual 1/3 averaged measurement.

Rob:)

Mr. Widget
12-28-2008, 01:26 PM
Looks pretty good... is the measured response on HF axis at 1 meter?


Widget

Zilch
12-28-2008, 01:37 PM
Which waveguide, Rob?

I do not get a 13 kHz notch using 2435HPL on PT-H1010HF or PT-F1010HF, just with PT-F95HF.

Also, where are they crossing, acoustically?

Robh3606
12-28-2008, 01:55 PM
Hello Widget

Yes that's on the waveguide axis at 1 meter. I had some problems trying to use Sine ended up with Gated Sine and MLS. Gated Sine and MLS agreed Sine was all over the place every time I moved the microphone things changed radically.

Hello Zich

Thats on a PTH1010. Where are you seeing a 13K notch?? There is a drop in the raw 2435 measurement but that's out at about 16K. Averaged you don't really see it. More importantly it's not all that easy to hear. Comparing the top end to the 4344 with the 2405 things are a bit muted in a direct comparison but it's sounds balanced so I am OK with it. No worse than a 2344.

The crossover is at 1.4K

Here's what they look like. Still on a temp baffle.

Rob:)

Zilch
12-28-2008, 02:02 PM
Where are you seeing a 13K notch?? There is a drop in the raw 2435 measurement but that's out at about 16K. Averaged you don't really see it. More importantly it's not all that easy to hear.What notch are YOU talking about, then, in the sim @ 1.8 kHz? :dont-know

Robh3606
12-28-2008, 02:21 PM
What notch are YOU talking about, then, in the sim @ 1.8 kHz? :dont-know

Hello Zilch

Don't you just love the internet clear as mud!

OK now I get it, would be nice if I put what notch I was talking about.

Originally I was concerned with that 1.8k notch. In the sims it was a PITA to minmize which is why I tried the 18db network as well. It' looks much better but moves up a bit in frequency in that network. I expected a hole there that didn't show up.

Rob:)

Mr. Widget
12-28-2008, 03:23 PM
Comparing the top end to the 4344 with the 2405 things are a bit muted in a direct comparison but it's sounds balanced so I am OK with it. No worse than a 2344.


.. is the measured response on HF axis at 1 meter?That's why I asked about the measurement set up... assuming you are listening with the HF at your ear's height, I'd have guessed that it sounds a little dull up top.

I like your curve up to about 5KHz, but I try to voice a speaker to be pretty much flat above 1KHz.... yours is looking to be about 3-5dB down depending on frequency.


Widget

Robh3606
12-30-2008, 10:58 AM
OMG I want to rip my hair out. Wow I made the same mistake twice. I ended up using the wrong measurement again. It screwed everything up. I actually had a wiring error, found it, reshot the measurements and it was total chaos.

Nothing was making sense as far as the measurement agreeing with the simulation. The sims are very accurate and once I substituted the correct curve it all became clear. Operator error on my part. It messed up my crossover values and attenuation. But it's working now.

Valuable lesson if it looks different than sim start looking over everything to look for mistakes.

Rob:)

Mr. Widget
12-30-2008, 04:58 PM
Valuable lesson if it looks different than sim start looking over everything to look for mistakes. :yes:

As you know, there have been numerous debates on the forum about the utility of measurements... I find that when I assemble a new system, if the plots don't agree with my expectations, I can usually use them to track down where I cross wired something. :o:


Widget

Robh3606
01-01-2009, 12:13 PM
Well I finally have a working pair to listen too. Have them on now listening to some Randy Newman. Have to listen too them for a week or two to see if they are going to stay the way they are. They matched up pretty well except for a rise with one of the midrange drivers. Want see it that's "real" or not and how noticeable it is.

Here's a smoothed 1/3 octave relative measurement of the pair using MLS. They are bi-amped through the DX-1 at 300hz.

Rob:)

Robh3606
01-04-2009, 12:32 PM
I am reposting the corrected Schematic. When I removed the resistive pads I got an impedance spike so I dropped in a 25ohm shunt resistor to help smooth things out a bit. I ended up with the 18db network instead of the 12, it ended up working better.

I have to still spend some time to see if there are any changes needed but so far after a couple of days they sound good.

Rob:)

Robh3606
01-06-2009, 05:32 PM
Just adding some time domain data. I will do some polars and listening window averaging on them once I get the shells built for the top of the system. They look pretty naked and raw right now without them.

Rob:)

Robh3606
01-06-2009, 05:35 PM
Here are the Impulse Black and Step Response Red and well as the CSD Plots for the system.

Rob:)

4313B
09-04-2009, 05:56 AM
I do not get a 13 kHz notch using 2435HPL on PT-H1010HF or PT-F1010HF, just with PT-F95HF.#1 (http://audioheritage.org/vbulletin/showpost.php?p=147356&postcount=1)