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PPSL build?


Rudy81

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1 hour ago, zobsky said:

Probably not an option for your current prototype but have you considered a removable  slot manifold sub-assembly?

Or possibly a drop in slot that reduces the area of the opening.  This could be just for experimental purposes.  You could clamp a plate on the front of the box with a reduced slot size just to see what it does to the frequency response.

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1 hour ago, zobsky said:

Probably not an option for your current prototype but have you considered a removable  slot manifold sub-assembly?

 

Exactly what I am working on now. As CECAA850 suggests, I am also looking at some method to reduce the opening once the drivers are in there. That would be the simplest and quickest.  Fortunately, I made the bottom removable in case I needed to adjust the port size.  That should allow me to remove the current slot if needed.

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12 minutes ago, windashine said:

… o O (PPSL = Push Pull Slot Loading ?) … I had to finally look up what this mean's

Yes....that's it.

Years ago when I was trying various open baffle designs, I built a Ripole.  The bass output was very impressive.  Particularly, the impact, or slam, the little box could produce.  This is a somewhat similar design, although a ported box concept.

 

 

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Summary:

In case anyone stumbles on this thread in the future....

I continued my experiments by creating a wooden ring that I could slide under one driver so as to get the drivers as close as possible and leaving enough room for Xmax displacement.  Sweeps on that configuration yielded absolutely no improvement in the upper frequency range.  Clearly, this PPSL design is not usable much above 200hz with the Dayton DCS380-4.  The driver is advertised as 20hz-500hz. 

 

Since I had so much success with my Full Size Marty builds, I though I would convert my test box into a single driver, vented, box.  Roughly 10 cu. ft. with the vent I had made should give me a 20hz tuning and plenty of range betwen 20hz and 400hz.  The glue wasn't even dry when I ran the attached sweep and this leads me to try a more conventional approach for this project.  I'm calling this box a Mid Marty since it approximates the volume of the Mid sized Marty.

 

I will let the glue dry today and will hook it up to my system to listen to actual music using the new prototype from 20hz-350hz or so.  I realize this is a very inexpensive driver and may not fill the 'quality' standard, but it will give me an idea of what can be done.  I am considering using the Dayton RSS390HF-4, which more than twice the price, but should be a more capable driver for this purpose.

Mid Marty DCS380-4 v PPSL.jpg

Mid_Marty_DCS380_4.png

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16 hours ago, Rudy81 said:

Summary:

In case anyone stumbles on this thread in the future....

I continued my experiments by creating a wooden ring that I could slide under one driver so as to get the drivers as close as possible and leaving enough room for Xmax displacement.  Sweeps on that configuration yielded absolutely no improvement in the upper frequency range.  Clearly, this PPSL design is not usable much above 200hz with the Dayton DCS380-4.  The driver is advertised as 20hz-500hz. 

 

Since I had so much success with my Full Size Marty builds, I though I would convert my test box into a single driver, vented, box.  Roughly 10 cu. ft. with the vent I had made should give me a 20hz tuning and plenty of range betwen 20hz and 400hz.  The glue wasn't even dry when I ran the attached sweep and this leads me to try a more conventional approach for this project.  I'm calling this box a Mid Marty since it approximates the volume of the Mid sized Marty.

 

I will let the glue dry today and will hook it up to my system to listen to actual music using the new prototype from 20hz-350hz or so.  I realize this is a very inexpensive driver and may not fill the 'quality' standard, but it will give me an idea of what can be done.  I am considering using the Dayton RSS390HF-4, which more than twice the price, but should be a more capable driver for this purpose.

Mid Marty DCS380-4 v PPSL.jpg

Mid_Marty_DCS380_4.png

Pictures?  

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4 hours ago, zobsky said:

Any updates?

 

I spent quite a bit of time trying everything imaginable and gave up on the PPSL.

The standard ported enclosure works just fine, but I was not pleased with the driver when compared to the performance of my Kappalite 3015LF drivers, currently in my OB.

 

After much discussion with a very knowledgeable cabinet designer, I have been convinced that the Kappalite drivers I have will be great for my ported enclosure.  Plan is to build three double driver ported boxes.  Boxes will be around 15cu.ft.net, with a tune in the low to mid 20hz. With a little EQ, the Kappalite 3015's should do well.  

 

Funny thing is that I am returning to where I started years ago with my DBB build, found on a build thread here. Problem with that build is that the cabs were not tuned to get me much below 70hz or so.

 

I still find that the mid bass in an OB is the best I have heard, but the trade off is very poor low bass performance.  Hence, the need for a subwoofer to take up the slack.

 

I am really looking to go true 2-way with the Oris horns, then I can get rid of the 2 RSW-15s currently picking up the bottom end. 

 

Looks like I'll get started on that build when work permits.

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Here are some suggestions. 

 

  • Why chase 20 Hz ? ... why not aim for 30 Hz (that is plenty for music and it looks like you you have subs for LFE anyway)
  • PPSL are bandpass designs - hence your difficulties trying to expand their bandwidth.
    • one way out to cheat would be to use multiples of smaller woofers - will allow you to use a smaller slot . DJK used this approach with a quad of 8" drivers retrofit to a lascala via a PP manifold
  • Why not just build a quarter pi or a straight midbass horn - something like a 80 to 100 Hz wouldn't be too large (relatively speaking)
  • If you do build dual channel reflex boxes, consider flipping one woofer so you can still get harmonic cancellation advantages of PP (but not the bandwidth limiting qualities of the slot). If you had the drivers on opposite side of the enclosure i.e. BiPole,  you would achieve  vibration cancellation advantages but this may / may not be what you want if you are aiming for extended bandwidth because of the direct/reflected sound.
  • Lastly, there is always the option of building , ... Dare I say the word ... Karlson k15 type cabs as long as you can cross over about 300 Hz . Should be good till 50 Hz with a VERY punchy sound if your woofers are low enough qts
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Chasing 20Hz for various reasons.  Trying to build a true 2-way that won't require subs. I have subs supporting the mains now and want to get rid of them. I also use the same mains for movies in HT and am guessing they have much more 20-30hz content than music.

 

I was trying to duplicate what others have done with a PPSL getting closer to 400hz.  Different drivers of course.

 

I'll be looking into the flipped driver concept.  Aesthetically, not the best option. I have not researched the harmonic cancellation theories.

 

I looked at the Karlson and have read about it's performance. 

 

I should begin some sort of build next week. I'll see what the options are.  I have problems with a well designed ported cabinet.  Lot's of flexibility and power if designed properly.  Just a little large, but I have a large room.

 

 

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2 hours ago, moray james said:

you won't get much bass below 40 Hz out of a Karlson. You will however get astounding dynamics.

Unless ported and boosted (might get to 30 Hz that way). FWIW, I never tried this while I had my K15  because I didn't have suitable woofers  at the time. https://www.diyaudio.com/forums/multi-way/3995-karlson-enclosure-16.html

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3 hours ago, zobsky said:

Unless ported and boosted (might get to 30 Hz that way). FWIW, I never tried this while I had my K15  because I didn't have suitable woofers  at the time. https://www.diyaudio.com/forums/multi-way/3995-karlson-enclosure-16.html

Thanks very much for the link Zobsky! I had not forgotten about the Exemplar but not being a crossover savvy guy I tend to ignore designs which require special networks with compensation. I forget that today you can buy pro amps with digital EQ included (memory too for multiple settings) for not a lot of money. One thing I know is that the Karlson K15 I built with with a selenium woofer which only have about a 3mm p-p linear had the most impressive dynamic impact and played louder than anything I have ever built while at the same time with seemingly zero cone motion. It would play so loud on a thirty watt per channel SS integrated you could not talk beside it no matter how loud you yelled and most of the time you could not see the woofer so much as move. Superb impedance match between the woofer and the air in the room. The exact opposite of those massive subs we so often see in videos where the woofer looks like a giant bowl full of jelly exhibiting massive excursion but you hardly hear any bass from them. I did have dual vents (plastic fittings of some sort) on those think they were about a 4" OD but they were only about 3" long. Hard to remember exactly now as it was a long time ago.

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  • 2 months later...
On 2/18/2019 at 10:02 PM, Rudy81 said:

I really do like the sound of the OB.  As we all know. the issue with any OB is that is just can't get below 40 or 50hz very well.  At least now with a very specialized driver.  Even then, 20hz is out of the question.  I have thus far used two RSW-15's to go down to 20hz.  But, I would like to be able to build a true 2-way system with my Oris horns.  I am hoping this might work.  I should have the drivers installed tomorrow afternoon and will take some performance measurements as soon as I can.  

 

 

My friend took second place at the Midwest Audio Contest 2 years ago with his OB speakers called AlphaSaurus! He used Eight 15" Eminence Alphas per channel. Those tall babies get down to 24 Hz. with no trouble and almost zero cone motion. Most impressive bass from OB i've ever heard. Near Horn performance but it's about $1,000 for all 16 of those drivers!! LOL.

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