I want to try the Mod-podge cone-coating treatment. But, the podge has to diluted with water before use and there isn't a set ratio on how much water to add (someone mentioned to get to the consistence of "auto transmission fluid"....) these is a bit of guess work involved, some kind of "feel" needs to be developed I suppose.
So I bought two Quam 8" full-range from a thrift store, will be practicing coating on those before doing more expensive drivers. (Quam's are 8C10FEPAXB industrial/ceiling speaker with whizzer cone, foam surround, supposedly 40Hz to 18k, Fs=50),
How do I know if I have done the coating right? (what kind of change is to be expected when it is done right?) Is it supposed to kill glare/shout or tighten up bass or enhance details? And what is the symptom of too much podge/not enough dilution?
So I bought two Quam 8" full-range from a thrift store, will be practicing coating on those before doing more expensive drivers. (Quam's are 8C10FEPAXB industrial/ceiling speaker with whizzer cone, foam surround, supposedly 40Hz to 18k, Fs=50),
How do I know if I have done the coating right? (what kind of change is to be expected when it is done right?) Is it supposed to kill glare/shout or tighten up bass or enhance details? And what is the symptom of too much podge/not enough dilution?
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You want todilute it so that it is thin enuff toapply easily, but not sothin that it warps the paper. This takes a bitof experimentation.
The treatment seals the surface of the paper, locking the paper fibres in place & supplying some damping. This reduces cone self-noise and increases DDR. It also makes the conemoreopaque to stuff coming back thru the cone from inside the box.
Use too much and you will attenuate HF. Don't thin it enuff and it is hard to get an even coat. Be careful but quick, with a big cone it will start to dry before you are done, slightly (and i mean slight) wetting of the brush after initial application can help stetch the time you have to get things even.
You might want to start with paper cone woofers to get a feel, they are less sensitive to too much or not even enuff.
dave
The treatment seals the surface of the paper, locking the paper fibres in place & supplying some damping. This reduces cone self-noise and increases DDR. It also makes the conemoreopaque to stuff coming back thru the cone from inside the box.
Use too much and you will attenuate HF. Don't thin it enuff and it is hard to get an even coat. Be careful but quick, with a big cone it will start to dry before you are done, slightly (and i mean slight) wetting of the brush after initial application can help stetch the time you have to get things even.
You might want to start with paper cone woofers to get a feel, they are less sensitive to too much or not even enuff.
dave
All well designed drivers do not/should not need any type of coating/treatment (some already have some type of treatment). The way it sounds is the way the designer designed it to be. Use a filter instead or sell the driver and buy something else.
I've ruined two pair of drivers using modgepodge, the result was a dead sound. A thin coat subtly muted the sound and too much turned the driver into a woofer. So, for a hot peaky driver that you cannot give away than this might be the way...
If the compulsion to mod is overwhelming, you may want to try/experiment with dammar or similar type C-37 (natural not poly) "coating." For those small Fostex drivers use only 2 thin applications (about 70/30 thinned) wait at least two days in between applications. The first application should have gone completely into the paper, the second is barely on the surface almost not a "coating." The change was a subtly clearer sound/less papery sounding treble; not more bass or attenuation of shout. I coat most of my cheap Fostex drivers with this type of varnish to protect from mold, mildew, dirt etc. Otherwise, I would just leave it alone.
I've ruined two pair of drivers using modgepodge, the result was a dead sound. A thin coat subtly muted the sound and too much turned the driver into a woofer. So, for a hot peaky driver that you cannot give away than this might be the way...
If the compulsion to mod is overwhelming, you may want to try/experiment with dammar or similar type C-37 (natural not poly) "coating." For those small Fostex drivers use only 2 thin applications (about 70/30 thinned) wait at least two days in between applications. The first application should have gone completely into the paper, the second is barely on the surface almost not a "coating." The change was a subtly clearer sound/less papery sounding treble; not more bass or attenuation of shout. I coat most of my cheap Fostex drivers with this type of varnish to protect from mold, mildew, dirt etc. Otherwise, I would just leave it alone.
Very few of those. And they all already have a coating, so in the strickest sense not a paper cone driver.
Cost is the major driving force behind most driver.
I've killed a few myself, but had WAY more successful ones (literally 1000s of units).
My experience with dammar was that it is useful for some specific applications, but coating an entire cone was not it. It adds too much stiffness and increases unwanted resonances.
C37 works well on some drivers, but it turned out judicial use of mod-podge was as effective at 100th or so the cost.
It is not really possible to give an exact ratio of thinning because how much is needed is dependent on how "stiff" the mod-podge starts out at. Fresh stuff does not need anywhere that much, and stuff that does is probably paste it use-by date and suitable only for cheap woofers.
When i 1st started out with FRs i was coming from 25+ years of doing woofers, and used 2 coats, i now use only 1.
If you are getting it to soak in it is too thin. It should sit on the surface and hardly penetrate at all. I prefer the glossy stuff and you end up with a sheen with 1 coat, and with the white Fostex clones a change in colour towards a parchment colour.
If this is how you are doing it, it could explain the deadness.
Yes, yes, no. I have found it quite helpful in taming shout (ie suppressing resonances). In the case of the FE127 some measures to back that up (treatment more complex than just mod-podge thou)
dave
thanks for the inputs.
since the chance of messing up at the beginning seems quite high, I bought 4 more Quam's as back up genie pigs (the "50% off Saturday" deal helped triggered the impulse buy as well.....I suppose I can't lose at $3 per).
since the chance of messing up at the beginning seems quite high, I bought 4 more Quam's as back up genie pigs (the "50% off Saturday" deal helped triggered the impulse buy as well.....I suppose I can't lose at $3 per).
The first coat is done. I only added a little water to the podge before it felt like transmission fluid (less than 90:10) between my fingers.
Could not get an even coat. I did the whizzer first, the entire front surface plus a 1/4" line on the underside along the lip. Then the main cone.....got tiny white foam came out of the sponge, probably should have use a bristle brush instead. Anyway, the stuff was "sitting on the surface hardly penetrating", and it dried pretty quick, about 5 minutes I got a glassy surface, but it is uneven, I can see my "brush strokes", especially on the main cone.
Does the "brush strokes" suggest I didn't put in enough water?
Could not get an even coat. I did the whizzer first, the entire front surface plus a 1/4" line on the underside along the lip. Then the main cone.....got tiny white foam came out of the sponge, probably should have use a bristle brush instead. Anyway, the stuff was "sitting on the surface hardly penetrating", and it dried pretty quick, about 5 minutes I got a glassy surface, but it is uneven, I can see my "brush strokes", especially on the main cone.
Does the "brush strokes" suggest I didn't put in enough water?
I use a regular artist stranded brush, sounds like the foam brush is generating bubbles
I buy the cheap starter packs of artists brushes at Michaels and give the foam and natural fibre ones to the school.
dave
I buy the cheap starter packs of artists brushes at Michaels and give the foam and natural fibre ones to the school.
dave
Thanks Dave, are brush strokes visible when done right?
After one hour the coat appears to be completely dry. So I put the driver into the test rig (cardboard open baffle..... 16x21.5" 😱).
the sound seems
--a little softer, a little less bite,
--a bit less glare,
-- bass might have tightened up a little (can't really tell, since the boom is still there, probably from the cardboard baffle 😱. )
-- no change in detail reproduction.
I guess the coat has smooth out the mid range peaks and reduced the top end. The sound is now boarder line too soft (the Quam is a little soft to start with). I will run the driver a little more, then add another coat tomorrow.(turning it into a woofer is not a problem for me. If I ever have to use it I can glue a tweeter to the pole piece and cross over at 4~5k using a film cap).
After one hour the coat appears to be completely dry. So I put the driver into the test rig (cardboard open baffle..... 16x21.5" 😱).
the sound seems
--a little softer, a little less bite,
--a bit less glare,
-- bass might have tightened up a little (can't really tell, since the boom is still there, probably from the cardboard baffle 😱. )
-- no change in detail reproduction.
I guess the coat has smooth out the mid range peaks and reduced the top end. The sound is now boarder line too soft (the Quam is a little soft to start with). I will run the driver a little more, then add another coat tomorrow.(turning it into a woofer is not a problem for me. If I ever have to use it I can glue a tweeter to the pole piece and cross over at 4~5k using a film cap).
Brushed on the second coat late last night, let dry over night...
The difference is more noticeable this time.
The second coat didn't kill more highs. The bit is still about the same as one coat, but the sound is somehow more clear and more "detailed" (even the bass has some details now, instead of the old one-note boom), perhaps because it is a little brighter.
I will run it for a few hours to see if the brightness becomes tiring, then I will add the third coat
The difference is more noticeable this time.
The second coat didn't kill more highs. The bit is still about the same as one coat, but the sound is somehow more clear and more "detailed" (even the bass has some details now, instead of the old one-note boom), perhaps because it is a little brighter.
I will run it for a few hours to see if the brightness becomes tiring, then I will add the third coat
Added the 3nd coat, let dry for two hours...
The sound got a little sharper still. no change to glare/bite. There is more "presence", more up front. Bass detail is more obvious, the quantity of low bass is less, more punchy, less boom. Top end about the same, maybe a little less, the overall sound is more "mid-rangy" though, I suspect the 2nd and 3rd coat both bumped up the mids, which give the sense of improved details.
At this point it is still good for guitar use. I think I will stop here, before turning the Quam (a mediocre elevator background music speaker) into an aggressive mid-bass woofer.
The sound got a little sharper still. no change to glare/bite. There is more "presence", more up front. Bass detail is more obvious, the quantity of low bass is less, more punchy, less boom. Top end about the same, maybe a little less, the overall sound is more "mid-rangy" though, I suspect the 2nd and 3rd coat both bumped up the mids, which give the sense of improved details.
At this point it is still good for guitar use. I think I will stop here, before turning the Quam (a mediocre elevator background music speaker) into an aggressive mid-bass woofer.
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couldn't help myself, added the 4th coat...
bass definition continues to improve, tighter bass with more visible texture; top end softer still; voice still good though, realistic but soft and dark.
At this point there is no glare (top end got knocked down enough) and no bite. Maybe this is where a super tweeter becomes necessary.
bass definition continues to improve, tighter bass with more visible texture; top end softer still; voice still good though, realistic but soft and dark.
At this point there is no glare (top end got knocked down enough) and no bite. Maybe this is where a super tweeter becomes necessary.
Hi audiocats. I am interested in your experiments. Thank you. Just a question re: methodology. How are you checking the differences (progress) between coats? Have you two speakers and only altering one at a time and doing "before and after" or are you comparing each change with an "base", unmodified "standard" that you are doing comparisons with? Or given the four or more you bought do you have the advantage of 3 or 4 different unit to compare?
I guess I am most interested in "clarity". Your best result for that so far?
Cheers, Jonathan
I guess I am most interested in "clarity". Your best result for that so far?
Cheers, Jonathan
I am only using two right now, one is always "one coat ahead" of the other, so I can do "back and forth" comparison. However, these are ceiling/industrial PA speakers and they don't exactly match, the two I am using right now didn't sound exactly the same before modification, one was more flavorful (peaky I guess) and the other more "bland" (maybe flatter), though the basic sound signature was the same (boomy, lacks detail, has glare & bite around the same frequency).
For clarity, 4-coats yielded the best result so far. There was still some boomy-ness with 3 coat, the 4th coat turned it into (more or less) visible bass texture. with the 4th coat also came a little mid-range honkey-ness, it is still clear though.
Again, these Quam's are cheap ceiling speakers, with weak magnet and likely high Qts, the kind of trend I am getting in this experiment might not apply to speakers with lighter cones or stronger motors.
I will put on the 5th coat later tonight.
For clarity, 4-coats yielded the best result so far. There was still some boomy-ness with 3 coat, the 4th coat turned it into (more or less) visible bass texture. with the 4th coat also came a little mid-range honkey-ness, it is still clear though.
Again, these Quam's are cheap ceiling speakers, with weak magnet and likely high Qts, the kind of trend I am getting in this experiment might not apply to speakers with lighter cones or stronger motors.
I will put on the 5th coat later tonight.
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added the 5th coat....
sound is clear and attention grabbing, no longer "background". But the Quam, being a cheap ceiling speaker, has noticeable distortions at times, making it unsuitable fore critical listening.
Hot mids with clean bass, good for guitar use.
sound is clear and attention grabbing, no longer "background". But the Quam, being a cheap ceiling speaker, has noticeable distortions at times, making it unsuitable fore critical listening.
Hot mids with clean bass, good for guitar use.
~~how many for a Nirvana Super10? - that speaker sounds pretty good stock in a classic Karlson K15 but rough as a direct radiator. Does unopened Modpodge vary much in viscosity?
have no idea.
Somebody will have to get a Super10 to experiment on, then report back..... Not me.
Somebody will have to get a Super10 to experiment on, then report back..... Not me.
Certainly my experience is that one container tothenext it can have, but at the size i buy, the time between containers can be measured in over a year.
dave
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