Bingo. Forgot about that one. Thanks for the link.
Don't tempt me.
Right. I remember you mentioning Bell / WE favoured aluminium back in the day. Seems to me with widebanders there's too much interest being thrown at the (semi) myth of piston operation of late & not enough on their resonant behaviour, despite that being the way they generate most of their BW. Then again, I couldn't design a drive unit's components to save my life, so I'm not exactly in the best position to pass much comment.
Bingo. Forgot about that one. Thanks for the link.
Don't tempt me.
Right. I remember you mentioning Bell / WE favoured aluminium back in the day. Seems to me with widebanders there's too much interest being thrown at the (semi) myth of piston operation of late & not enough on their resonant behaviour, despite that being the way they generate most of their BW. Then again, I couldn't design a drive unit's components to save my life, so I'm not exactly in the best position to pass much comment.
now for a different tenor we could migrate this conversation to Mark's commercial forum - on second thought let's not
There is no "best" material / design / approach for anything - all is compromise
The fact is that a truly competent designer / engineer can achieve satisfactory result with virtually any combination of readily available / affordable materials. Not all do of course, and for many of us it's exposure to those results that will bias our anticipation - good or bad- of other products using similar materials / design features. Gizmo ( Harvey Rosenberg) talked about our "aural matrix" at any given point in time being the culmination of all past listening experiences - individually unique, and for most of us, continually evolving
I'll candidly admit that after hearing more than a couple of DIY builds of the Bottlehead Straight 8 line array with all MCM aluminum cone mid-bass and I think metal dome tweeter, well over 10yrs ago, and which had me leaving the room quickly, I was quite prepared to find fault with the Jordan JX92s that I heard a few years later. The fact that the first pair of those I heard had sustained some abuse damage, and the second pair were from the (in)famous / suspect group buy of a couple of years ago did little to dissuade me of that opinion. The Alpair metals were a revelation.
I had a similar experience with the Hammer Dynamics Super12 (built a pair for a buddy, and heard several at shows in the early 2000s), and the Hawthorne Silver Iris OB. Both based on large Eminence woofers with popsicle stick mounted dome ( Super12) or horn loaded coaxial compression tweeter (Hawthorne) . Some folks apparently just love these, but in both cases the results were, for whatever reasons, too bloated and colored for my taste.
OTOH, for me a no-name brand small (Korean?) wide driver in an OB just blew the SI away in all aspects except bass extension/ weight, and of course, sensitivity and max SPL. Definitely a case of less is more.
O.K. I'm back in. The second box was a bit easier to do as I used a couple squares to keep thing at 90 degrees where the internals meet.
There is one side to side brace that will attach to the plywood plates on the outside. One small dowel that connects both top plates and the more stable bottom of the chamber. I didn't brace the back with wood but put a small thin FC wing for a short distance.
I'm ready to close it up but am open to any suggestions. The stuffing represents the amount I put in the first section last time - More....Less?
There is one side to side brace that will attach to the plywood plates on the outside. One small dowel that connects both top plates and the more stable bottom of the chamber. I didn't brace the back with wood but put a small thin FC wing for a short distance.
I'm ready to close it up but am open to any suggestions. The stuffing represents the amount I put in the first section last time - More....Less?
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The results are very impressive. Stereo fills in a lot. I'm doing some testing now and will have some pictures/charts to show either late this evening, in the morning or just when I figure out what I'm doing.
With two DNAs there is a good amount of room shaking near 30hz. SPL is decent and I believe somewhat better than the cornu. Still not happy with the top end of these drivers but always thought they would need help.
Using this app (iPad version) and a video camera. Be back soon............
With two DNAs there is a good amount of room shaking near 30hz. SPL is decent and I believe somewhat better than the cornu. Still not happy with the top end of these drivers but always thought they would need help.
Using this app (iPad version) and a video camera. Be back soon............
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Bob,
Congratulations on achieving STEREO! It must make a huge difference. Did that extra bracing help with the second box? Is that the water cooled F5 amp in the middle? Are you driving the DNA's with the ACA? Seems like it would be a good match given the DNA's supposedly higher sensitivity.
X
Congratulations on achieving STEREO! It must make a huge difference. Did that extra bracing help with the second box? Is that the water cooled F5 amp in the middle? Are you driving the DNA's with the ACA? Seems like it would be a good match given the DNA's supposedly higher sensitivity.
X
Yes, it's good to have the second one done. These take much longer to build than the cornu - matching angles. Still not that bad, around two hours for the FC and another two for driver/bracing/final gluing.
The bracing did a lot for stability. Still have to do the mouth but much more energy is coming through. That's a Honey Badger clone (6 power transistors per channel) in the liquid cooled case. Extremely nice sound, no leaks and temperature stays just above room temps. F5 being reworked with new design. Haven't hooked up the ACAs yet but will tomorrow.
More info in the morning.
The bracing did a lot for stability. Still have to do the mouth but much more energy is coming through. That's a Honey Badger clone (6 power transistors per channel) in the liquid cooled case. Extremely nice sound, no leaks and temperature stays just above room temps. F5 being reworked with new design. Haven't hooked up the ACAs yet but will tomorrow.
More info in the morning.
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Just to let you know .... Not getting usable results from the equipment and software I'm using. I've been trying to pass some sine waves through three sets of speakers to display freq. and db comparisons. Both the iPad and Android apps track quite well till I get below 80Hz and then all kinds of overtones take over. Looks like I'll have to find an inexpensive calibrated (calabratable) external mic... I needed an excuse I have some more professional programs and hardware but won't try that route till a get a better mic.
The little music I've listened to mostly confirms what I've already reported. The Cornu/Vifa combination has the best presentation across the spectrum. The DNA has a cleaner/tighter bass - a lot more physical vibration but less body in the low notes. It's like amps, each unit has it's own character... I'm having a hard time with the top end of the DNAs cause they are sitting next to the Sunflowers which have exemplary highs. Hopefully I'll have time to plug in those tweeters tomorrow.
I just finished rebuilding the DIY power supply for the ACAs so that will be my next audition. I'm getting 20.5 VDC so I should probably re-bias/check DC offset before I proceed.
I have some more professional programs and hardware but won't try that route till a get a better mic.The little music I've listened to mostly confirms what I've already reported. The Cornu/Vifa combination has the best presentation across the spectrum. The DNA has a cleaner/tighter bass - a lot more physical vibration but less body in the low notes. It's like amps, each unit has it's own character... I'm having a hard time with the top end of the DNAs cause they are sitting next to the Sunflowers which have exemplary highs. Hopefully I'll have time to plug in those tweeters tomorrow.
I just finished rebuilding the DIY power supply for the ACAs so that will be my next audition. I'm getting 20.5 VDC so I should probably re-bias/check DC offset before I proceed.
Thanks for the update Bob. I am surprised the Vifa Cornu's still sound so good in comparison. It is a very flat response driver. For measurements buy a $2 Panasonic wm61a mic capsule. Doesn't need calibration as itnis naturally flat from 20 hz to 20 khz. If you use Holmimpulse, it comes with a cal file for that mic to get extra accuracy.
You may be addressing the DNA problem with the different mouth sizes you are talking about on the other thread. The bottom of the Cornu sounds fuller - weightier which gives the impression of more bass. The DNA will shake the room and rattle the windows more at the same SPL/Hz, but it's more physical than audible. That's what I was describing in my first impression when I said "flutter/vibrate the legs on my pants". The second mouth size might fill in what's missing.
I hope someone else has purchased some Aurasound NS525 drivers so I can get some other reports/impressions about the quality of the high end.
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Tweeterdom Rules ! Now I can hear cymbal shimmer and stick hits. There is audible air in reed instruments and voice/instrument placement is better defined. I'll call it a definite and needed improvement.
However,,,, more still needs to be done. I simply placed a 2.2 uF cap on the positive of the tweeter. A full 12dB highpass ( add a .46 mH coil) has no determinable effect. The added tweeter seems to bring out some honkiness at the top of the midrange that I hadn't noticed before. I have several larger tweeters (inc. PE RS28AS-4, Vifa DX25TG09-04) and trying to get more of the mids on those might be a possibility.
I tried several different speaker to rear wall distances using a Radio Shack meter and the NCH tone generator:
@ 68 Hz
2.5' = 74 dB
8" = 63 dB
@ 40 hZ
2.5' = 72 dB
8' = 74 dB
@ 30 Hz
2.5' = 71 dB
8" = 72 db
30 Hz is really solid if the volume is increased. Fills the room completely.
@ 20 Hz sound is inaudible.
I'll be glad to do some white or pink noise (or other) readings at full spectrum if that will be helpful. I do have an Audix OM2 mic that I can use with a Mackie Satellite Pre till the Panisonic modules arrive. I'll take any suggestions on which software to use.
Overall - from the 30 Hz results there is no doubt the horn is working and working well. Just have to find a better solution for mid and upper response. Please don't get me wrong. As is, this combination sounds OK to good. It's usable and enjoyable - specially considering the total cost is under $16 and most of that is the FC. I just think there is room for improvement to make it something really special.
However,,,, more still needs to be done. I simply placed a 2.2 uF cap on the positive of the tweeter. A full 12dB highpass ( add a .46 mH coil) has no determinable effect. The added tweeter seems to bring out some honkiness at the top of the midrange that I hadn't noticed before. I have several larger tweeters (inc. PE RS28AS-4, Vifa DX25TG09-04) and trying to get more of the mids on those might be a possibility.
I tried several different speaker to rear wall distances using a Radio Shack meter and the NCH tone generator:
@ 68 Hz
2.5' = 74 dB
8" = 63 dB
@ 40 hZ
2.5' = 72 dB
8' = 74 dB
@ 30 Hz
2.5' = 71 dB
8" = 72 db
30 Hz is really solid if the volume is increased. Fills the room completely.
@ 20 Hz sound is inaudible.
I'll be glad to do some white or pink noise (or other) readings at full spectrum if that will be helpful. I do have an Audix OM2 mic that I can use with a Mackie Satellite Pre till the Panisonic modules arrive. I'll take any suggestions on which software to use.
Overall - from the 30 Hz results there is no doubt the horn is working and working well. Just have to find a better solution for mid and upper response. Please don't get me wrong. As is, this combination sounds OK to good. It's usable and enjoyable - specially considering the total cost is under $16 and most of that is the FC. I just think there is room for improvement to make it something really special.
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Thanks. That's a single but if I can find my cut sheet program and input the data, we might get just barely get two speakers from one 4' x 8' sheet.
I didn't include my Murphy's law cost. I put my new glue gun where I wouldn't loose it which naturally means it was nowhere to be found when starting the DNA. Off to the dollar store for a $3 special. Several hours after finishing the second box.......you guessed it. Now I have one for each holster.... Might make a short Indy-Film "The Hot Glue Kid from FC Valley"
Cal or Chris, if you are still around, got any suggestions for a preferred software for getting good measurement data without taking out a mortgage to pay for it? I have a bunch of programs but haven't perfected the use of any of them.
I didn't include my Murphy's law cost. I put my new glue gun where I wouldn't loose it which naturally means it was nowhere to be found when starting the DNA. Off to the dollar store for a $3 special. Several hours after finishing the second box.......you guessed it.
Now I have one for each holster.... Might make a short Indy-Film "The Hot Glue Kid from FC Valley" Cal or Chris, if you are still around, got any suggestions for a preferred software for getting good measurement data without taking out a mortgage to pay for it? I have a bunch of programs but haven't perfected the use of any of them.
if that's directed at chrisb, he doesn't do acoustic measuring or modeling, and I'm not so sure about Cal, either
Dave uses Fuzzmeasure (Mac) and I believe, Smith & Larsen Woofer Tester? - both of which have their issues.
Bob Brines might have some suggestions
This could be a case, like glue guns, trim routers and Bessey F-clamps, where you can't have too many tools in your kit?