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PostPosted: February 28th, 2023, 4:27 pm 
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Joined: July 25th, 2013, 9:41 am
Posts: 78
Thought I post some pics of Jim's Joseph Crowe speaker we worked on together.

The baffles were CNC'd by Joseph Crowe.
The rear enclosures were built by me.
The finish work was done by Jim.
The crossovers were designed/built by me.
Some polar measurements are included below (at 1M distance - 3.5ms gating). The speaker has even smoother integration a little bit further out, as the crossover was designed with a typical listening distance in mind.

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PostPosted: February 28th, 2023, 4:39 pm 
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Location: Parkville, Maryland
They are beautiful and the workmanship is superb!! BRAVO!! :handgestures-thumbupleft:

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PostPosted: February 28th, 2023, 5:10 pm 
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Those look GREAT!

David


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PostPosted: February 28th, 2023, 6:47 pm 
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Incredibly well constructed and finished. Kudos to you both. I can also say that of all the tweeters I have ever used including Sequerra T1 ribbons, Heil AMTs, Janzen electrostats, and BG planars, the Satori beryllium tweeter is by far the best. I have a friend that has used the Purfi midbass driver you have and it is great. Should be a real winner.


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PostPosted: March 2nd, 2023, 11:32 am 
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Many thanks to Dhar for helping to bring this project together. He put in far more hours than he should have, including time fixing my mistakes. I have to say right here that many members of this group have given a lot of their time over the past few years to help me with various projects, and/or shared their knowledge with me. I'd just like to say how much I appreciate it. Thank you very much, Dhar, Dave M.,Dave B.,Tom, and Charlie.

These speakers are available in a kit form, or just as CNCed baffles from Joseph Crowe. He's very flexible and will make slightly different variations like a longer baffle for a floorstanding speaker if requested. His original design was using the Satori 29mm softdome and 5" midwoofer. I asked if he'd modify it for the BE tweeter and Purifi woofer, and he did so at no extra expense. He has a YouTube video of this model comparing it to using the same drivers in the same volume box but with a faceted baffle for more typical wide dispersion.
https://youtu.be/f6S2V9D9_08

Everyone seems to like small 2 way speakers that have deep bass but I am not a fan of trying to make small woofers play deep bass. There is an issue with the Purifi woofers having so much excursion that it demands extremely long ports or multiple passive radiators to play deep. The engineer at Purifi recommended a sealed enclosure. The box size is 16 liters and is crossing over to subwoofers at about 60hz without a high pass on the monitors. Opted for this route as opposed to a 3 way as music in this room is generally played at very low levels and I wanted flexibility to still have deep bass response without adding subs under a 3 way, as well as the extra expense of building larger more complicated speakers.

I lost my listening room during a recent remodel of our home and now have a more modest system in our livingroom under dreadful listening conditions. Wide dispersion loudspeakers were not working there. These speakers sound lovely and with their excellent off axis performance and controlled dispersion there is a stable image in almost any seat in the livingroom. The midrange and treble are just natural and engaging, even with generic electronics in the chain ahead of them. I'm looking forward to trying them with some better gear soon.

I'm not sure if Dhar has distortion measurements but they are extremely low. Here's the step response and null.


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PostPosted: March 3rd, 2023, 8:59 am 
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Congratulations Jim! This looks like the best of all worlds: you picked a speaker well designed that would fit your listening space; then had the designer modify it to use your preferred (and, no doubt, superb) components; then had Dhar help you by building and testing a great assembly; then you worked your own magic by doing a superb job of finishing the speakers. I'm not sure which looks better, the speakers themselves or the measurements!

And, best of all, they are truly DIY!

Stuart


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PostPosted: March 3rd, 2023, 10:36 am 
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Stuart Polansky wrote:
I'm not sure which looks better, the speakers themselves or the measurements!


Definitely the speakers! The pictures don't do them justice. Jim definitely did an outstanding job with the finish.

In regards to measurements - the speaker components are such high quality that designing the crossover was relatively simple (minimal crossover parts).

I must say though, as amazing as Joseph Crowe is with CAD modeling + CNC + Horn Design, I think he is absolutely terrible with xover design. The crossover he recommended Jim was, in my opinion, unusable. The crossover he recommended to me for his Sabourin speaker was also terrible.

I honestly think that he just rushes through the crossover design stage, and maybe his time is better spent elsewhere. For me, it takes me several weeks and sometimes several months (and 100s of measurements) to design/finalize a crossover - and I honestly think that time investment is worth it.


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PostPosted: March 3rd, 2023, 1:17 pm 
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It is truly hard to build a good passive crossover. A long time ago, I switched to active not only for the flexibility, but to eliminate anything between the amp and driver.


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PostPosted: March 3rd, 2023, 1:19 pm 
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tomp wrote:
It is truly hard to build a good passive crossover. A long time ago, I switched to active not only for the flexibility, but to eliminate anything between the amp and driver.


Does this mean you no longer have protection circuitry between the amps and drivers?

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PostPosted: March 3rd, 2023, 2:17 pm 
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I do but it contains no in line resistors, inductors, or capacitors. Only one very low resistance relay contact, and that is because I am perhaps overly cautious.


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