Something Stirs in the Workshop

Dedicated to those large boxes at one end of the room
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vinylnvalves
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#91 Re: Something Stirs in the Workshop

Post by vinylnvalves »

Finally got some time to do some proper back to back measurements on the acoustic filter/lens for the Beyma TPL. The acoustic filter basically removes the sharp edges off the steel comb plate.
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Which to be honest is something they should have done In the first place. It fits behind the mounting plate.
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The responses are with (pink) and without (black) it does remove the 8k nasties which it was designed to do. No smoothing of the response just as gated (500hz). It’s interesting how the additional 6mm of thickness of the filter, which adds to the length of the horn, gives a little LF extension.
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Not shown but the harmonic distortion is down around the 8k peak by around 10db.
iansr
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#92 Re: Something Stirs in the Workshop

Post by iansr »

Useful bit of taming Steve. Looks like you don’t need anything above it. Where do you crossover the Beyma at the lower end?
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vinylnvalves
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#93 Re: Something Stirs in the Workshop

Post by vinylnvalves »

I am hopeful of getting them to cross with the Beyma 12p80nds around a 1000Hz. Need to find a bigger protection cap to test lower.
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ed
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#94 Re: Something Stirs in the Workshop

Post by ed »

interesting plots...I just had a look through the notes and I got peaks at 4k and 9k, exactly where you get troughs
beyma hi1.jpg
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beyma both2.jpg
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ed
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#95 Re: Something Stirs in the Workshop

Post by ed »

I think I should have tried a bit harder at the time
bayma all2.jpg
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vinylnvalves
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#96 Re: Something Stirs in the Workshop

Post by vinylnvalves »

Those plots look familiar for the standard Beyma horn. Not sure what’s causing the 4K dip. I have considered using it without the horn, however I need to lower x-over point to be able to use the 12” Beyma. If I go smaller than it will need to be a 3 way which I am trying to avoid. Aiming for a 2 way with a sub for LF.

Talking about the sub, I have had a day of listening to one frequency band only....( starting to get like Mark :wink: ). The favourite currently configuration from listening upto 100hz.( yes real low end) is this.
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Comparing with the same drivers in sealed and H frames, this has the edge on low end detail, it’s not one note. Not very efficient though, pushing 200w into each driver and it’s not enough for Owston, enough to shake my windows so probably enough in reality.
I do wonder if I end up going sealed for the main speakers and this configuration for the LF , then maybe it will be a modern take on the following...
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I said I wouldn’t look at Ripoles again ... maybe I need to reconsider :(
iansr
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#97 Re: Something Stirs in the Workshop

Post by iansr »

i don’t believe this; are you hacking my computer Steve!? In the the last few days I’ve been reading a lot about baffle-less designs including the journey that Vic of Trans-fi has been on and also the Circles of Doom thread on DIYA. Both have used this clam shell approach on baffle-less woofers. Just 5 minutes ago I messaged someone about 4 x 18” woofers they are selling, and the next thing I do is click on this thread! Very spooky!
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Ali Tait
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#98 Re: Something Stirs in the Workshop

Post by Ali Tait »

I’ve been to Vic’s to have a listen. Best domestic bass I’ve heard by a long way. Never heard a live recording sound more like the venue.
vinylnvalves
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#99 Re: Something Stirs in the Workshop

Post by vinylnvalves »

Yes I have been reading the same threads to.. I am not sure about the circles of doom, I think you need the surface area to make them work properly. I am not sure what the polar plots will look like.
I have been trying to understand these better... to see if the downsides of the ripole can be designed out. https://6moons.com/audioreviews2/ecobox/2.html
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iansr
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#100 Re: Something Stirs in the Workshop

Post by iansr »

Ali, More synchronicity, I actually spoke to him this afternoon! Your comment is tipping me over the edge, think I’m going to have to do it.
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iansr
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#101 Re: Something Stirs in the Workshop

Post by iansr »

Steve, those speakers are referenced on the DIYA thread. I think the consensus was that the clamshell is orientated the wrong way because the dipole nulls will be at the front and rear. Or am I missing something?
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Paul Barker
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#102 Re: Something Stirs in the Workshop

Post by Paul Barker »

Im lost from you three of four’s including Ali or five’s if Mark joins in.

But two of you arriving similar places is to do with search engine predictions and tracking.
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#103 Re: Something Stirs in the Workshop

Post by steve s »

vinylnvalves wrote: Thu Dec 30, 2021 9:05 pm Yes I have been reading the same threads to.. I am not sure about the circles of doom, I think you need the surface area to make them work properly. I am not sure what the polar plots will look like.
I have been trying to understand these better... to see if the downsides of the ripole can be designed out. https://6moons.com/audioreviews2/ecobox/2.html
1950A5F8-59A3-4BD3-80EC-E5145E2F4A67.jpeg
F2164ABC-614C-4D44-BEDA-34AE1231D834.jpeg
From that link
Team less echo (and no box!) refine that recipe. Facing their woofers at each other does some useful things. It lowers their resonant frequency to increase bandwidth and output. It raises radiation resistance for higher pressurization and superior cone breaking power over lossier standard OB woofers which face an entire room's cubic air volume.
In my view thats how my speakers work. The lower resonant is nothing new
The drawback is that increasing cone pressure decreases the drivers ability to follow the signal, probably enhancing low notes with a little distortion .. but most ported speakers cause some change, its about how audible it is, and if you hear it.
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Ali Tait
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#104 Re: Something Stirs in the Workshop

Post by Ali Tait »

iansr wrote: Thu Dec 30, 2021 9:09 pm Ali, More synchronicity, I actually spoke to him this afternoon! Your comment is tipping me over the edge, think I’m going to have to do it.
It’s still on the to do list for me. The drivers are not cheap though. I do like his idea of the mini scaffold and hanging the drivers from cables. Seems like a bad idea but I couldn’t detect any movement of the baskets, they are heavy drivers.
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#105 Re: Something Stirs in the Workshop

Post by iansr »

Ali, yes the cable suspension idea seems to have been done by quite a few people and all report positive results from what I can see. Industrial chic 😎
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