so i've gotten around to removing the dustcap on my guinea pig drivers.
there's still a few rough bits on the edges, is this a problem or should i smooth it off?
there's a very slight lip between the main cone and the whizzer, is this a problem or should i try and get it plush?
a bottle of vits makes the perfect fit into the voice coil thinger, does anything need to be changed to make the phase plug fit closer to the whizzer cone, there's a lot of messy cone area.
thanks for your help
p.s sorry for the picture size.
there's still a few rough bits on the edges, is this a problem or should i smooth it off?
there's a very slight lip between the main cone and the whizzer, is this a problem or should i try and get it plush?
a bottle of vits makes the perfect fit into the voice coil thinger, does anything need to be changed to make the phase plug fit closer to the whizzer cone, there's a lot of messy cone area.
thanks for your help
p.s sorry for the picture size.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
same material as the cone, looked to be pressed paper - listed as paper on the spec sheets.
trying to blow air through it now, i can't.
would i need to make some kind of hollow phase plug?
Hold the driver such that the opening is facing downwards and take a bit of 150-200 grit sandpaper to clean up the rough edges. Don't be fanatical about getting the ridge flat -- your whizzer could come off.
The gap should be small, but not so small that there is contact as the driver moves...
dave
The gap should be small, but not so small that there is contact as the driver moves...
dave
You might want to leave a bit larger gap for cooling, but i feel covering up the pole piece vent will give a sonic improvement.
If the vitamin bottle is to be used, it should get filled with something... the other issue is how it willbe attached?
dave
i will carve a phase plug from wood, this is just playing around with the size etc, comparison with the vanilla driver.
the next question was going to be about the best shape? teardrop? also the overall height of the phase plug, equal to the whizzer? or is the bullet shape the best way to go?
attachment is usually just magnetic no? if not i'm open to wisdom.
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just given it a little play, they seem to sound better with no dustcap. not sure how to describe the change in sound. they seem less fatiguing, smother i guess. at the same time vocals and other things seem to have been brought forward in the sound. i don't think any of the highend has been lost, just moved behind other parts of the sound which gives a more pleasing sound. lowered the SPL of the upper regions?
using the make shift phase-plug doesn't seem to immediately make any change in sound. typically what does a phase plug tend to do?
how long does it usually take to sand down the nub from the dustcap? i'm being fairly careful but the paper cone seems surprisingly tough for such a thin thing. so there's still a fairly pronounced bump and lip which could be interfering with sound?
using the make shift phase-plug doesn't seem to immediately make any change in sound. typically what does a phase plug tend to do?
how long does it usually take to sand down the nub from the dustcap? i'm being fairly careful but the paper cone seems surprisingly tough for such a thin thing. so there's still a fairly pronounced bump and lip which could be interfering with sound?
A couple minutes... very often with a whizzer there will be a discontinuity where the whizzer attaches... just make it smooth.
dave
is there a problem with the gap between where the phase plug sits on the pole piece(?) and the beginning of the cone?
in its present guise the sonic difference is incredible compared to the shorter phase plug i was playing with, which wasn't so much different to the the dustcap free, and a bit better than the standard driver. this one towers out of the whizzer cone but its brought so much brightness to the driver now its quite strange but ultimately very appealing, and far greater change than i had expected from a cheap driver of this size.
the next problem is it is rather heavy and i will try and drill out some of the internals, but it cannot be secured by magnets alone. what would be a reasonable way to secure it without causing all kinds of mayhem? lightly adhesive double sided tape?
upon removing the dustcap, have i reduced the moving weight of the cone and thus changed some of the properties of the driver? higher Fs etc? it seems to have lost some low end response. i'm not immediately concerned about this as i do plan on using the EnABL process on the driver which will probably add the weight back on once i've finished bodging it?
in its present guise the sonic difference is incredible compared to the shorter phase plug i was playing with, which wasn't so much different to the the dustcap free, and a bit better than the standard driver. this one towers out of the whizzer cone but its brought so much brightness to the driver now its quite strange but ultimately very appealing, and far greater change than i had expected from a cheap driver of this size.
the next problem is it is rather heavy and i will try and drill out some of the internals, but it cannot be secured by magnets alone. what would be a reasonable way to secure it without causing all kinds of mayhem? lightly adhesive double sided tape?
upon removing the dustcap, have i reduced the moving weight of the cone and thus changed some of the properties of the driver? higher Fs etc? it seems to have lost some low end response. i'm not immediately concerned about this as i do plan on using the EnABL process on the driver which will probably add the weight back on once i've finished bodging it?
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just thought i'd post the best results from my experiments with these for anyone interested. these plots are only accurate as far as comparing the changes made, the actual SPL levels will be wildly off real world results as its an uncalibrated mic and there was obvious sounds of room resonances taking place. however all readings should have roughly the same test conditions.
the wooden phase plug is the same as pictured above, however its starting position has been raised so the start of the flare is level with the start of the cone.
stock (foreground) vs wood (background)
stock (foreground) vs glass (conical flask stuffed with sock[background])
glass (foreground) vs wood
the wooden phase plug is the same as pictured above, however its starting position has been raised so the start of the flare is level with the start of the cone.
stock (foreground) vs wood (background)
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stock (foreground) vs glass (conical flask stuffed with sock[background])
An externally hosted image should be here but it was not working when we last tested it.
glass (foreground) vs wood
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and what if any sonic differences do you detect between the different materials/shapes?
I'd think you'd want to avoid any type of adhesive to attach the plugs - if a few (3-4) flat head wood screws mounted flush aren't sufficient, try for a lighter material
It'd be nice if all pole pieces came tapped for machine screws to allow for such dabbling, coaxial tweeters, etc, but as they say "DIY experimentation is a mother of invention"
well, I know I mumbled the word "mother" a few times myself
I'd think you'd want to avoid any type of adhesive to attach the plugs - if a few (3-4) flat head wood screws mounted flush aren't sufficient, try for a lighter material
It'd be nice if all pole pieces came tapped for machine screws to allow for such dabbling, coaxial tweeters, etc, but as they say "DIY experimentation is a mother of invention"
well, I know I mumbled the word "mother" a few times myself
less fatiguing, smoother and brighter in a good way. i want to say more detail, but very slightly which is probably just a result of the lighter cone? its a sound i wouldn't associate with a cheap PA driver. the glass i think i hit some kind of resonance during the sweep, so i'd like to try the shape again with wood.
stock by comparison is harsher/fatiguing and the peaks at 1500+2500hz were very noticeable. stock sounds very much like the PA driver it is.
i was quite taken back by the difference made if i'm honest. i want to try one more shape that i have a hunch on, and thats a wooden conical shape that is a lot thicker than the glass flask creating more of a plug type shape with the whizzer (see below).
weight is a problem i'm experiencing. from my experiments, the longer the plug is, the better the results. a standard low profile bullet shape didn't produce very favourable results by comparison. because the plugs are so big magnetism alone isn't really doing the job. the pole(?) piece is vented so i was thinking of using a rubber bung attached to the bottom of the plug and then corked into the hole. i tried using balsa wood to make a plug and it didn't sound the best in the world. i may revisit the design but coat it with some epoxy resin to see if that helps.
i also look forward to seeing what the modpodge part of the EnABL process will do to the driver, as the cone is completely untreated, so i expect some acoustic improvements again. by the end of it, i might have an ok extended range driver for use with a super tweeter. the 12" cone certainly has a large presence which is a very appealing sound.
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6 1/2" FR
My A201s were the same as you've posted. I have seen felt dots (lots of vintage drivers went thru here)
dave
like this?
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not sure if i'm doing this right but took some readings anyway.
not sure the actual volume is exactly the same between them all so its best to just look at the pretty wiggles.
the 'short plug' has a few less pieces of foam around the driver, so i will redo these again in the morning this time using 3 pieces of foam only VS the 10 gazillion i had these tests, i will also ensure that my variables are more constant.
the foam does seem to smooth the whole drama out a bit by my eyes. the 500 - 2000 range still looks like a car crash, but this could very well be resonance between the driver and the floor etc, as it was just sitting on a piece of carpet pointing at the roof.
not sure the actual volume is exactly the same between them all so its best to just look at the pretty wiggles.
the 'short plug' has a few less pieces of foam around the driver, so i will redo these again in the morning this time using 3 pieces of foam only VS the 10 gazillion i had these tests, i will also ensure that my variables are more constant.
the foam does seem to smooth the whole drama out a bit by my eyes. the 500 - 2000 range still looks like a car crash, but this could very well be resonance between the driver and the floor etc, as it was just sitting on a piece of carpet pointing at the roof.
An externally hosted image should be here but it was not working when we last tested it.
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here's the plots done properly
lightly wedging 3 pieces of 1-2mm thick foam between the main cone and the whizzer doesn't seem to do all that much, especially when compared to the phase plug.
am i actually doing that whizzer trick properly? any other ideas to try?
lightly wedging 3 pieces of 1-2mm thick foam between the main cone and the whizzer doesn't seem to do all that much, especially when compared to the phase plug.
am i actually doing that whizzer trick properly? any other ideas to try?
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i splodge bodged the front and back surface of the main and whizzer cone and refined my foaming technique. i also tried lightly stuffing some cotton wool to fill the entire gap behind the whizzer but that wasn't a favourable outcome. its definitely killed some efficiency but seems overall much less peaky?
on an aesthetic note, the cone looks far less scruffy and cheap now.
on an aesthetic note, the cone looks far less scruffy and cheap now.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
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