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Old 28th February 2005, 02:38 AM   #1
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Default JP2.0 project continued

Thanks for all the suggestions on my frist post guys. Alot of people threw out some ideas that got me thinking about a 3-way active design. So here's my idea so far, please let me know what you guys think.

Fountek JP2.0 Tweeter
PR170m0 Midrange
PR380m0 15" Bass

Playing around with SpeakerWorkshop it looks like a 15L sealed cabinet for the PR170m0 and Fountek JP2.0 sitting on top of a 150L bass cabinet.

The PR170m0 has a rise at around 2K which really made the FR look terrible without an asymetric cross over between the mid and tweeter. It looked pretty good with a 4th order LR 2.5K HighPass on the tweeter and a 4th Order LR 2K Lowpass filter on the midrange. The bass driver has a first order Lowpass filter at 100hz and I ran the midrange without a highpass filter. I atached the plots from SW below.

How does this sound? Anyone built something like this before? Comments, suggestions, criticism welcome

--Chris
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File Type: jpg 3-way.jpg (41.1 KB, 577 views)
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Old 28th February 2005, 03:32 AM   #2
AJ is offline AJ  United States
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hey Chris

I have something similar in mind, but I probably won't get to it till summer. I played around with the PR170M0 and a JP2 last year in a narrow open baffle (active XO) and was pretty impressed - it's a great combination. I like the idea of them sitting on top of a 15.

Click the image to open in full size.

So anyway, why does SW recommend a 15L sealed box? I'm just curious, and I haven't done any real looking into it, but WinISd and Unibox show a much smaller enclosure for a ~.7 Qtc. Again, just curious.

Keep the reports coming - I'd really like to hear about your final results.
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Old 28th February 2005, 01:09 PM   #3
gary f is offline gary f  Canada
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Very interresting choice. I am interrested in something like this myself.

The Audax PR170M0 has good reputation and high sensitivity. Anyone know about the PR170Z0, the aerogel version? Almost same thing, but the freq resp seems better.

F
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Old 28th February 2005, 05:27 PM   #4
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Here's what I have now:

Click the image to open in full size.

Fountek JP-3.0, Audax PR170M0 (both on an open baffle), Eminence Beta 12CX (in a sealed enclosure). The XO between the midrange and tweeter is roughly 2500Hz. I think it's a 2nd order on the midrange and 3rd order on the tweeter, set up to get me roughly 4th order L-R slopes on both drivers. The Fountek also needs an R||L network on it to tame its rising top end. I found a lot of good information here, a link that someone on a different forum showed me:

http://home1.stofanet.dk/troels.gravesen/
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Old 28th February 2005, 05:59 PM   #5
tiroth is offline tiroth  United States
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Are those actual plots? I did not see a 2K rise, but I did indeed end up using asymmetric xovers.

Click the image to open in full size.

Probably, there is no limit to how big the PR170M0 box could be, it just impacts your xover point a little. I used about 12L+aperiodic. All things equal, the deeper the better to absorb the back wave and/or delay reradiation through the cone.

Maybe we should start a "PR170M0 + ribbons" fan club. There appear to be a number of members.

About PR170Z0: I have heard from one person that it sounds better, and one or two people that it sounds worse. Either way, it is probably quite similar. I am quite happy with my aerogel HM170Z0 so it could be worth a shot.
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Old 28th February 2005, 06:12 PM   #6
gary f is offline gary f  Canada
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The Audax mids are popular/interresting because they have high efficiency and can be used in open baffle. I think it's frustrating to see Vifa/Seas/scanspeak etc. releasing low efficiency woofers and dome tweeters all the time. There is few high efficiency (93dB+) drivers that are affordable and good (versus tons of low efficiency mid-woofers). The Audax seems one of them.

F
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Old 28th February 2005, 06:35 PM   #7
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Quote:
Maybe we should start a "PR170M0 + ribbons" fan club. There appear to be a number of members.
Yup
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Old 1st March 2005, 08:24 PM   #8
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Hey guys, thanks for all the responses so far. I've been pretty busy so I have not had a chance to respond as quickly as I would like. I apologize ahead of time for the length of my reply

AJ:

SW did not specify 15L, I used Unibox and I think the recommended enclosure size was 8L. However PartsExpress has 15L (.5 cu ft) prefinished cabinets for a good price so I was hoping to use them. Worst case I'll just add a large sandbag to take up some of the room. the 15L enclosure leads to a Q of ~.63.

Saurav:

I'm interested to hear your impressions of the Fountek JP3.0 and PR170m0. How well do they integrate together? Is there a noticable tonal difference between the two drivers? Also, where is this R|L circuit that you spoke about, I looked at the website kind of quickyl but I could not find it.. I am also considering the PHL1120 for a midrange, I would like to hear people's impression of the PHl1120 vs PR170m0. Someone mentioned that the PR is what Nelson used in his Cost-Is-No-Object speaker so that speaks rather highly of it.

Tiroth:

Those where not measured responses. They were modeled using FRD consortium tools to capture the SPL/imp curves and then using the Frequency Response Combiner I subtracted off the measurement baffle and anded my sealed/vented box responses.

Gary F:

I agree with you on the low efficiency woofers. This is actually the one part of this current design that I'm not really satisfied with. The PR380m0 does not go deep enough for me I looked at the PHL5010 but it does not do much better so I decided to go with the PR380 hoping that the signature of it and the PR170 would be similar.

Speaking of the danish manufacturers, has anyone worked with the new scanspeak HDS Exclusive drivers? Looking at the curves they look like exceptionally flat, wideband woofers. I think I've made the decsion to go with the DCX active crossover so I'm not as worried about matching sensativity with the 98db fountek. Maybe use one of the 106mm as a pure midrange (http://www.d-s-t.com/peerless/data/830881.htm) ??? or one of the larger 180mm woofers as a midbass driver (http://www.d-s-t.com/peerless/data/830883.htm) ??
Heck even the largest 208 mm can play almost up to 2K, maybe a pair of these in bass cabinet tuned to around 30hz to round out the system? The side cuts would allow these guys to snuggle up pretty nicely against the Fountek Ribbon..

So many choices its hard to even get started on a project Please help me decide!!!

--Chris

106mm freq response:
Click the image to open in full size.

180mm freq response
Click the image to open in full size.

205 mm freq response
Click the image to open in full size.
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Old 1st March 2005, 08:56 PM   #9
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Quote:
I'm interested to hear your impressions of the Fountek JP3.0 and PR170m0. How well do they integrate together? Is there a noticable tonal difference between the two drivers?
Well, it sounds pretty good to me, but I don't really have the experience to be able to tell you how well it works compared to other possibilities.

Quote:
Also, where is this R|L circuit that you spoke about, I looked at the website kind of quickyl but I could not find it..
Scroll down to the bottom and there's a section on ribbon tweeters. Also, see the crossover for any of the speakers that use this tweeter, and you'll see a 0.1mH || 10R on all of them. In one of them he discusses how he arrived at those values. I'm using something slightly different (0.1mH || 6.7R at the moment), still playing with it to see what sounds best in my room.
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