I have H100 RCF horn can you show me(picture please)the type of fume filters you use.
I rolled up the reticulated foam and stuffed it into the throat as far back as it goes without hitting the diaphragm.
Then I taped on another half inch layer. (This whole experiment is held together with tape!) More might be better but I have no more.
I have no idea if this foam is the 30ppi that Gedlee uses or not. Lots of aquarium supplies and other places sell this foam.
I've used the foam in 2 other horn/waveguides and this is the first time it made a big difference in the sound quality.
The purpose of the foam was not to absorb sound. It is a cheap, easy to work with material that would be a roundover to reduce diffraction.
I'll be getting the DDS waveguide and need the roundover to be flexible.
Ideally a shiney black, smooth surface, flexible pipe, hose or tube that can be cut lengthways and glued to the DDS edge almost seemlessly is my goal.
Any better ideas would be appreciated.
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The DDS ENG 1-90 from US Speaker $120 ea
The throat is not round but wobbles a bit. I'll sand it down or ream it out later.
All other aspects seem very good. Back is rough. Solid fiberglass.
I also doubt it has a 6.5 degree throat flare to match the B&C driver flare. Probably straight as to be more universal. Maybe not.
Fill the throat gap with Mortite to smooth the transition.
Put some swim foam around it to reduce diffraction, tossed in the reticulated foam I have for backwave and echo reduction.
Left the same xover as the RCF WG/horn. Sounds a lot better even unEQed. A lot more potential right off.
The B&C 10" driver tube or box is next. Need about a 30-35 Liters enclosure for about 100hz.
The throat is not round but wobbles a bit. I'll sand it down or ream it out later.
All other aspects seem very good. Back is rough. Solid fiberglass.
I also doubt it has a 6.5 degree throat flare to match the B&C driver flare. Probably straight as to be more universal. Maybe not.
Fill the throat gap with Mortite to smooth the transition.
Put some swim foam around it to reduce diffraction, tossed in the reticulated foam I have for backwave and echo reduction.
Left the same xover as the RCF WG/horn. Sounds a lot better even unEQed. A lot more potential right off.
The B&C 10" driver tube or box is next. Need about a 30-35 Liters enclosure for about 100hz.
I rolled up the reticulated foam and stuffed it into the throat as far back as it goes without hitting the diaphragm.
Then I taped on another half inch layer. (This whole experiment is held together with tape!) More might be better but I have no more.
I have no idea if this foam is the 30ppi that Gedlee uses or not. Lots of aquarium supplies and other places sell this foam.
I've used the foam in 2 other horn/waveguides and this is the first time it made a big difference in the sound quality.
If you're in a hurry, plain ol' polyester fiberfill will work in a similar fashion as the foam. The advantage of the foam is that it's consistent, and you can cut it into a shape that extends beyond the edge of the waveguide, to soak up HOMs near the mouth. (A lot of HOMs are generated at the mouth and the throat.)
Ordered them on Monday this week received Tuesday.
Seems like good quality. The back is still rough as you can see in the photo.
Can you please give us more detail about the throat of this horn? On the one picture it looks like it is either conical or it flares out very rapidly, but not close to OS?
Looks a little like the drawing I did at the start of this thread.
Sakrete tube is 3 layers, no air space. About 27 liters.
The 10" B&C driver is a lot better in this app than the 12" Volt driver.
Not even close to having the Xovers dialed in. Rough with warts sounds goods.
Later I'll get one of the software programs and a mic to measure this stuff and see were I am.
Having some fun with DIY!
Um....the tape on the foam inside the horn is a significant problem. You're significantly obstructing the wavefront at HFs... and generating whole new HOM sets....
I put in 2 notch filters.
One knocked down a peak pretty good for a guess using spare parts.
The other kinda hit and kinda missed.
Played with the xover point up and down, sounds better closer to 1,100hz.
Subjectively it sounds much better. Better than I expected at this point.
I wish the 10" was waveguide loaded in some way so it could be as dynamic as the tweeter. It's not a deal breaker just a minor thing.
Downloaded HOLMinpulse and am studying it and reading the DIY thread about it.Getting Mic and cables/PS soon.
Is a CD with a sine wave sweep from 10hz to 50khz or so the best way to generate a test signal for the speakers?
One knocked down a peak pretty good for a guess using spare parts.
The other kinda hit and kinda missed.
Played with the xover point up and down, sounds better closer to 1,100hz.
Subjectively it sounds much better. Better than I expected at this point.
I wish the 10" was waveguide loaded in some way so it could be as dynamic as the tweeter. It's not a deal breaker just a minor thing.
Downloaded HOLMinpulse and am studying it and reading the DIY thread about it.Getting Mic and cables/PS soon.
Is a CD with a sine wave sweep from 10hz to 50khz or so the best way to generate a test signal for the speakers?
I exchanged some WW sand cast type resistors with Mills resistors of the same value I had on hand. Didn't expect much change.
I don't think it's measurable, but the music definitely sounds less grainy, less gritty. I didn't think there was any grain or grit before!
Of course it might all be the placebo effect. Or not.
Anyway playing some more with the xover it sounds better and better no matter what resistors are used.
I don't think it's measurable, but the music definitely sounds less grainy, less gritty. I didn't think there was any grain or grit before!
Of course it might all be the placebo effect. Or not.
Anyway playing some more with the xover it sounds better and better no matter what resistors are used.
How I'm reducing the HOM's in my room!
I was thinking about how to tame my room echoes a bit. Why not start at the source?
So I took off some of the yellow foam roundovers and put a folded wool blanket over to reduce the sound from the speakers bouncing around the room.
And it works to a degree. More diffuse and reduced echoing resulting in more focussed, clearer sound from the speakers.
Later on, stick drivers/WG in a wood box and bring out foam/blankets/ugliness for "serious" listening.
Have you ever tried something like this? What were your results?
How I'm reducing the HOM's in my room!
I was thinking about how to tame my room echoes a bit. Why not start at the source?
So I took off some of the yellow foam roundovers and put a folded wool blanket over to reduce the sound from the speakers bouncing around the room.
And it works to a degree. More diffuse and reduced echoing resulting in more focussed, clearer sound from the speakers.
Later on, stick drivers/WG in a wood box and bring out foam/blankets/ugliness for "serious" listening.
Have you ever tried something like this? What were your results?
It's very similar to what I do with foam on horn terminations. It smooths the region below the horn cutoff, which can be the source of a fairly large peak in some instances. I got as much as 2dB of ripple smoothing, as well as extending the directivity of the horn downward, albeit without the sensitivity boost of a horn proper.
Attachments
As the project is now.
B&C 10" is in a PE 1 cu ft sub MDF box that was on sale for $87. 14x14x14 approx. Dayton SWC-1 1.0 ft³ Subwoofer Cabinet | Parts-Express.com
The WG is rebated flush with the baffle. The 10" is mounted on the baffle. This time alignment sounded the best in my listening tests, totally subjective.
The front baffle has 1/2" roundover I routed on it.
Yellow foam works well.
The white ring around the 10" is a 1/2"x1/2" quarter round made of vinyl from Home Depot. Put it in the oven for 10 min at 250 degrees to make it soft and pliable to bend around the speaker frame. The vinyl shrinks.
Supposed to be a roundover, but it only works a little. So I am looking for another solution.
Xover is now at around 1400hz 2nd order LR with one notch filter in the tweeter that works well.
This fall I'll get a mic and cables to test this contraption.
Now it sounds better than it did in the sonotube, cleaner, clearer.
This thread has a lot of good info and test results for many types of WG and mid/woofers:
Flex Your PCD Mettle: - Techtalk at Parts-Express.com
1/6 oct FR using HolmImpulse from listening position about 2.75 M from both speakers.
I don't have an outside to use for measurements (anechoic chamber either). Up close measurements 1M or 0.5M didn't change much from this graph.
I used notch filters at 2.2Khz and 4.4khz and it measured better than this graph. Holm crashed and took the reading off to measurement never never land.
After a week I decided to take off the notches to do a listening comparison. Thinking the notches would better any sound without them, I was slightly surprised that subjectively the overall sound became much more "alive", less constrained sounding. I know, maybe the peaks added fake excitement. Maybe. But I found the overall sound more open, enjoyable. So I left them off.
On another subjective note, I changed the 1uf EQ cap from a Solen to a 1uf teflon I had on hand. Sound for the WG got cleaner, clearer sounding.
Measurements showed no difference. Even the raw data was the same. I was disappointed, I thought at least I could measure the difference I heard.
I have a lot of Mills resistors laying around unused from previous amp and speaker projects. When I switched out the concrete (cheap white blocky rectangles we all know and use) and in with the Mills another level of noise disappeared. Again, I measured no difference.
Why do I have auditory hallucinations only when I switch out parts?
I wish I could hallucinate that the cheapo speakers that came with the TV were fantastic!
Has anybody measured a difference? Is Holm not precise enough?
I use the PE mic Dayton EMM 6 and a Xenyx pre.
I also tried 2 different kinds of reticulated foam in varying amounts. I hear it improving the top end but softening, blurring, the sound from say 1.5khz to 5khz. Measurements showed no diff. Measurements showed a shelved top end of about 1-2 dB. Changing the EQ resistor to match made a slight improvement. I keep putting them in and out.
Anyway, this is my first experience with measurements and it was very educational and fun once I got the hang of it. Made my speaker the best sounding one I've ever built.
Also thanks to Gedlee for all the posts he has done on the CD/WG speakers. And thanks to zilch on PE econowave PCD forum.
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