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How to Train Your PM180-8

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  • jbruner
    commented on 's reply
    Sliced paper is definitely the right thing for midrange performance. One reason smooth off-axis is so important, is that when the anomalies are from break-up, the crossover correction on-axis just makes the off-axis even worse because it's at a different frequency. So, I wouldn't really say it's the off-axis as much as the break-up itself. You have to get rid of it. The Scan revelator showed us the way, but modern motors have gotten better since then, which is one reason the modified SB15 won the comparison. My slicing technique seems to be more effective than the rev, due to softer glue and a narrower slit. Kapton formers are audible, too. I wasn't completely happy with the original SB15, but I'm thinking the new version SB15NRX2C30-8 with the straight cone will be a better candidate. I'll update that thread soon, so we can move this conversation over there.

  • tktran
    replied
    Loves the part about

    "The Scan settles right in, making you think you are a good speaker designer. This is why you spent the big bucks, right?"

    LOL!

    So what were your conclusions or progess on that 2 years later. Did you continue to modify any others or move forward with the SB? Or did you go in a different direction?

    I'm convinced smooth off axis matters, way beyond the pass band. It's probably why paper-type cones are preferred to metal cones. Maybe. Or maybe not. I don't have the evidence for that. Apart from the fact that virtually call P/A / pro drivers do NOT use metal cones

    Leave a comment:


  • jbruner
    replied
    Originally posted by tktran View Post
    Yes, what about the SBA paper cone. They are a paper cone with a horrible breakup 5-10KHz.

    What did I miss? Sensei, what's the glue that's used and show me how?
    I did a shootout with the sliced SB15 vs the Revelator.. This thread "Scan-Speek 4" for 49 cents?" started it all and explains everything. All of my modified drivers so far include pole cavity treatments under the dustcap. The glue is DAP Alex plus clear. More discussion in this DIY Audio thread.

    Leave a comment:


  • tktran
    replied
    Yes, what about the SBA paper cone. They are a paper cone with a horrible breakup 5-10KHz.

    What did I miss? Sensei, what's the glue that's used and show me how?

    Leave a comment:


  • scottq
    replied
    Originally posted by Pete Basel View Post
    It would be great if someone could make a 3D printed template with slots to guide the cutting
    of this cone. Then anyone, hopefully, could make the slit cone version with at least some
    confidence.
    I'd be willing to take a stab at it - sounds fun. Send me a PM if you're serious.
    Is the PM180 seems to be NLA. I suppose could do it to the PS180 instead - hack the whizzer off first.

    I don't personally have any of these drivers, so would need some measurements provided.
    This PM180/PS180 cones appear to be quite conic in the pics? Are they as straight in reality as they appear?

    Frankly, I'd be interested in making this mods to a lot of drivers...

    Leave a comment:


  • scottq
    replied
    Originally posted by Pete Schumacher View Post

    They have been Ryan's main speakers since the day we finished them. Still occupy his main listening room today. Your mod is utterly transformative and should be incorporated at the factory.
    That's some impressive feedback and praise!
    Thanks to jbruner for the update

    Leave a comment:


  • Pete Basel
    replied
    It would be great if someone could make a 3D printed template with slots to guide the cutting
    of this cone. Then anyone, hopefully, could make the slit cone version with at least some
    confidence.

    Leave a comment:


  • jbruner
    commented on 's reply
    Glad you enjoyed it. I aim to please.

  • scottvalentin
    replied
    This was a fun read - hadn't seen it before. jbruner thanks for updating this.

    Leave a comment:


  • jbruner
    commented on 's reply
    I would love to see your results!

  • Pete Schumacher
    replied
    Originally posted by jbruner View Post

    Yeah, I'm certain it's a really nice speaker now! Good to see the old people still around! Enjoyed meeting you a few years ago!
    They have been Ryan's main speakers since the day we finished them. Still occupy his main listening room today. Your mod is utterly transformative and should be incorporated at the factory.

    Leave a comment:


  • jbruner
    replied
    Originally posted by Wolf View Post
    I heard the ply-stacked Derecho version on the banner at AXPONA that year, and I really liked them! Smooth, easy, and dynamic; they are a special build.

    Good to see you are still around, Josh!
    Wolf
    Yeah, I'm certain it's a really nice speaker now! Good to see the old people still around! Enjoyed meeting you a few years ago!

    Leave a comment:


  • fatmarley
    replied
    I used the slicing technique on some Eminence alpha 6C drivers that I bought for the car. It worked well and allowed me to run the drivers without a low pass filter. Should have the measurements somewhere...

    Leave a comment:


  • Wolf
    replied
    I heard the ply-stacked Derecho version on the banner at AXPONA that year, and I really liked them! Smooth, easy, and dynamic; they are a special build.

    Good to see you are still around, Josh!
    Wolf

    Leave a comment:


  • jbruner
    replied
    I had hoped that Pete or Ryan would update this thread, but I guess it's up to me to tell what happened. Upon request, I sent the original drivers from this thread to Ryan at Vapor Audio. That was early July, 2015. No response. In January 2016, I attempted to contact him. I got thru to him in February and told him I wanted to pass the sliced pair on to someone else, He said they were in the Derecho, and he wanted to keep them. He said he was planning on a full write-up, which tragically never happened. He did send me replacement drivers.

    In the next few years, I saw sporadic glimpses on the internet of the sliced drivers at some industry shows. Apparently they were very well received. Just this year, I reached Ryan by phone and got permission to post this update.

    The sliced PM180s are still in service in Ryan's Derecho speakers. He likes the improvements and said there is no downside. Without putting words in his mouth, here's a quote from Ryan on the internet. "The Derecho have the same midrange, but with the sliced cone process applied that totally transforms and greatly refines the presentation. It was a DIY'er, Josh Bruner, who created and perfected the process. When we got our hands on a pair, we decided to make them the standard midrange. It's a small improvement on paper that results in a large improvement in the real world." I also noticed that Pete S. praised the modified drivers in another thread, but never came back here to reveal his changed opinion.

    So, I'm back here to say that the process works, and is long-term durable. I have some sliced drivers that have been in service for 6 years. I've already presented the science, so I'll just give my opinion now. The results are MAGICAL. No other driver modification is this effective or this important. This process will transform many drivers into the proper midranges that you always wished they were.

    Here's a pic of the Derecho I cribbed from the web. Click image for larger version

Name:	zzzzzzzAxpona Derecho mod.jpg
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