Thanks, and welcome to the slowest thread in town 😀
I actually have a couple of pics showing a test baffle, which I think I forgot to post. I will get those up shortly
Simon
I actually have a couple of pics showing a test baffle, which I think I forgot to post. I will get those up shortly
Simon
Just read thru this thread and think the project looks great Simon! I wish i could cut holes like you have. I was thinking about using the Beta 8A on open baffle too but decided not to futz with a crossover between 2 and 4kHz. I will be watching your thread for your listening impressions when you get around to it. Please keep us posted on your progress.
Godzilla
Godzilla
I will try to talk Gary Pimm into commenting on the use of EnABL'd Beta 8 drivers. He will likely be here this weekend to attend Rene' Jaeger's amp building seminar / club. I am quite sure you can count on the EnABL'd Beta 8 for very smooth and clear performance out to 8 to 10k. They were easily at that point here when I was using them full range, nude on stands to get the EnABL treatment for them completed.
The plastic woofers are always a problem. If they are polypropylene you must "tooth" them with about a 4k grit wet sanding paper. If they are formed mylar then no special pre-treament is needed. Best to apply a set of pattern rings with the acrylic poly S paint and see if they will stick. If they do, then the Gloss will also. Other than that the treatment regimen is the same, though it is unlikely you will need to add more than one 50% coating of Gloss.
Loss of efficiency due to adding the patterns and gloss will be less than the differences between drivers in the same run, with the added mass being in the neighborhood of .005 grams once cured out. I would not use any other materials here, the PVA and Damar are used primarily to stop paper cone fiber noise and are quite useful when your drivers are coherent and audible to 90 db down. Plastic drivers do not have this problem and as Ashok noted, you want to keep from adding uneeded mass.
As for breakup, it ceases to be an issue, once you have found and dispersed the main resonance node of the driver. We use a "tap test" to find these things and with a bit of experimentation, with the thin end of your pen nib holder, you can locate just where the working pattern needs to be applied. With this mid cone pattern and patterns at the periphery, the audible consequences of breakup become inaudible and with the resonance node dispersed, treated drivers sound as you have experienced them to, just like music, rather than like speakers reproducing music.
In any event, plastic drivers are not different in their needs than paper ones, other than fiber noise.
Can you mount a thin plywood cover over your tweeter mounting hole to provide a locating point for your router, for rounding the baffle off? Might be worth a try.
Bud
The plastic woofers are always a problem. If they are polypropylene you must "tooth" them with about a 4k grit wet sanding paper. If they are formed mylar then no special pre-treament is needed. Best to apply a set of pattern rings with the acrylic poly S paint and see if they will stick. If they do, then the Gloss will also. Other than that the treatment regimen is the same, though it is unlikely you will need to add more than one 50% coating of Gloss.
Loss of efficiency due to adding the patterns and gloss will be less than the differences between drivers in the same run, with the added mass being in the neighborhood of .005 grams once cured out. I would not use any other materials here, the PVA and Damar are used primarily to stop paper cone fiber noise and are quite useful when your drivers are coherent and audible to 90 db down. Plastic drivers do not have this problem and as Ashok noted, you want to keep from adding uneeded mass.
As for breakup, it ceases to be an issue, once you have found and dispersed the main resonance node of the driver. We use a "tap test" to find these things and with a bit of experimentation, with the thin end of your pen nib holder, you can locate just where the working pattern needs to be applied. With this mid cone pattern and patterns at the periphery, the audible consequences of breakup become inaudible and with the resonance node dispersed, treated drivers sound as you have experienced them to, just like music, rather than like speakers reproducing music.
In any event, plastic drivers are not different in their needs than paper ones, other than fiber noise.
Can you mount a thin plywood cover over your tweeter mounting hole to provide a locating point for your router, for rounding the baffle off? Might be worth a try.
Bud
Thanks for the kind words. I am very unsure about crossover points but with a Beta 8A and waveguide tweeter I should have a huge range of options from 1khz to 10khz I would think.
Bud,
I hear what you're saying re. smooth and clear sound. Just on a quick dirty test the 8A sounded surprisingly pleasant for a "PA" driver, and very open and detailed.
The woofers are indeed PP so I will attack them with very fine sandpaper before applying any surface treatments.
I hear what you say about added mass and what to add, I will just do the gloss and EnABL.
Nice idea bout the panel over the baffle to locate the circle jig screw. I had sort of thought about that but not worked out exactly how to do it... until now - a piece of wood just neatly bridging the diameter of the recessed portion of the cut-out. I just need to make sure it's strong enough to take the router swinging around it. That would work but then again I do like the way they look!! So it comes down to whether the sonic trade-off is significant leaving the top squared off.
I hear what you're saying re. smooth and clear sound. Just on a quick dirty test the 8A sounded surprisingly pleasant for a "PA" driver, and very open and detailed.
The woofers are indeed PP so I will attack them with very fine sandpaper before applying any surface treatments.
I hear what you say about added mass and what to add, I will just do the gloss and EnABL.
Nice idea bout the panel over the baffle to locate the circle jig screw. I had sort of thought about that but not worked out exactly how to do it... until now - a piece of wood just neatly bridging the diameter of the recessed portion of the cut-out. I just need to make sure it's strong enough to take the router swinging around it. That would work but then again I do like the way they look!! So it comes down to whether the sonic trade-off is significant leaving the top squared off.
Expect the Beta 8 to behave with the same sort of presence and force you would get from a this driver and a LeCleach horn, once EnABL'd. They are very dynamic and excruciatingly clear and smooth. It took Gary a bit of time to adjust his crossover and divider networks when shifting from UnEnABL'd to EnABL'd versions.
I don't like sharp corners on speaker boxes, but I can work with them. My own open baffle system will not have any however.
I was actually serious about the adhesive backed, clear cabinet shelf plastic. It disappears when applied to wood surfaces and is very effective at making the speaker disappear audibly.
Bud
I don't like sharp corners on speaker boxes, but I can work with them. My own open baffle system will not have any however.
I was actually serious about the adhesive backed, clear cabinet shelf plastic. It disappears when applied to wood surfaces and is very effective at making the speaker disappear audibly.
Bud
Should work very nicely. Do leave enough material for EnABL pattern blocks though....... Actually, you might try the pattern blocks out on the uncut baffle, just to see if the boards will disappear without cutting anything. You might only need to round the corners. I say this because my instincts (all I have left for mentation purposes) tell me you won't have enough surface to blend mids and highs on, with that tight of a coupling to the edges of the shaped baffle. On the other hand it is very close to what I am planning to do, so I don't know why I think these thoughts about your plans.
Look her for a pic and you will see what I am going on about.
http://www.diyaudio.com/forums/multi-way/152893-wild-hair-open-baffle-idea.html#post1988031
Bud
Look her for a pic and you will see what I am going on about.
http://www.diyaudio.com/forums/multi-way/152893-wild-hair-open-baffle-idea.html#post1988031
Bud
Thanks. I have my speakers about 50-60cm from the back wall - as far forward as they can go (it's a bedroom system for the time being).
One is in a corner and does exhibit an issue in the upper bass. The foam corner absorbers behind help, plus they absorb some of the rear output at higher frequencies, which seems to be an ok side-effect.
My CD racks and plants aid diffusion back there - it's all making the most of a terrible listening space. Dipoles seem to be the way to go for getting enjoyable bass from a tiny room, but it's still not easy.
On a quick test one single new baffle (with no t-bass) was able to shake the small room with articulated and deep bass. It was a revelation.
The 2nd pic I've attached is under-exposed due to my bright monitor!
Attachments
You might want to look into Alex from OZ room teatment. He claims bass resonances are severely dispersed and tells me privately that a full height corner treatment is delicious.
Bud
Bud
having them so close to the computer, any specific reason you preferred a passive setup over an active pc based crossover?
Too complex; I don't really want the pc on when I listen; question marks on the final quality; no room for extra amps really; no money for extra amps yet; my pc is very quiet but is built for gaming ie. not silent; no idea where to begin; like to start simple.... enough reasons? 😀
sure 🙂 i was asking just because i don't want to mess up with electronics so i'm looking at heither pc-based, but it will have the cost of at least two dacs... or at something like the minidsp board... so i'd like to know if there are reasons i share against this route... i was not criticizing at all
The idea is a bit complex for me right now but I know a few others have done PC crossovers and got good results. My reasons for not using that route are not universal ones, just about what I feel comfortable doing at present 🙂
Pimm says he has solved all of that, except for the extra amps. He is using an Echo external DSP based sound card with more than enough outputs and does all of the frequency division and compensation in software, riding on the "Console" program. I think he said it was all shareware.
And then there are the Sure tri-path 100 and 200 watt class D amps, really quite fine sounding up to 4 kHz or so. So, you aren't really farther away than a small lap top with 1 terabyte external hard drive.
Gary Koh, CEO of Genisis, published a paper on what you needed to do to windows to get it to cooperate (XP only) and since that is his area of deep knowledge it is worth knowing. The paper is too big to publish here but I can send it to you if you PM me with an edress.
Only reason I am going with a passive volume control preamp / Berringer DCX is because I actually like all of that old time "gear" sitting on shelves, irritating she who must be obeyed.
Have you dropped into WOW yet?
Bud
And then there are the Sure tri-path 100 and 200 watt class D amps, really quite fine sounding up to 4 kHz or so. So, you aren't really farther away than a small lap top with 1 terabyte external hard drive.
Gary Koh, CEO of Genisis, published a paper on what you needed to do to windows to get it to cooperate (XP only) and since that is his area of deep knowledge it is worth knowing. The paper is too big to publish here but I can send it to you if you PM me with an edress.
Only reason I am going with a passive volume control preamp / Berringer DCX is because I actually like all of that old time "gear" sitting on shelves, irritating she who must be obeyed.
Have you dropped into WOW yet?
Bud
what puzzles me about a pc based XO, is that the quality will depend upon the dacs used.
using the berringer (or the miniDSP) the SQ i guess will depend on the dac section of the it anyway, how can it be as good as a dedicated DAC for that price? how is it emerald physic or audio granada are using them? do they sound so good just like a dac?
using the berringer (or the miniDSP) the SQ i guess will depend on the dac section of the it anyway, how can it be as good as a dedicated DAC for that price? how is it emerald physic or audio granada are using them? do they sound so good just like a dac?
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