Thanks for the kind words! I was never dissatisfied with the DBR monitors, except that they were never, ever, going to fit into the globes of my Clairtone Project G! I built them primarily for reference as I progressed in my project.
Someday those Saburos in the basement will be gone and I may fire the DBRs up again. Or a friend may be interested in them, we'll see.
Latest happenings
Okay, got some test tones out and started playing with some new positions:
As I am prefering the imaging and soundstage of wider cabinet separtion (about 6 feet), I was curious to see if pointing the horns away from a corners and into the middle would yeild better bass on the listening couch. See photo #1. I am surprised to report that this made no diference at all!
Ao just for the fun of it, I decided to try the horns facing forward, like a Chang or Mikasa. See Photo #2. At 200 Hz, this appeared to work. I thought, oh no, I did build the wrong cabinet! But at 100 Hz, this front horn acted worse then Avebury at 100 Hz. I was disappointed and relieved at the same time!
For fun I tried this front horn pushed right in the corners! Photo #3. That was the worst of them all! So dispite the directional nature of front horns, it does not solve the bass problem on the listening couch. What this tells me is even if I go with a subwoofer system instead, I will have the same bass issues in these positions. This is not an Avebury acoustical problem, but possibly a couch area acoustical problem. We are narrowing things down atleast. So time to try some room treatments in the back of the room.
More to type in....
Allen
Okay, got some test tones out and started playing with some new positions:
As I am prefering the imaging and soundstage of wider cabinet separtion (about 6 feet), I was curious to see if pointing the horns away from a corners and into the middle would yeild better bass on the listening couch. See photo #1. I am surprised to report that this made no diference at all!
Ao just for the fun of it, I decided to try the horns facing forward, like a Chang or Mikasa. See Photo #2. At 200 Hz, this appeared to work. I thought, oh no, I did build the wrong cabinet! But at 100 Hz, this front horn acted worse then Avebury at 100 Hz. I was disappointed and relieved at the same time!
For fun I tried this front horn pushed right in the corners! Photo #3. That was the worst of them all! So dispite the directional nature of front horns, it does not solve the bass problem on the listening couch. What this tells me is even if I go with a subwoofer system instead, I will have the same bass issues in these positions. This is not an Avebury acoustical problem, but possibly a couch area acoustical problem. We are narrowing things down atleast. So time to try some room treatments in the back of the room.
More to type in....
Allen
Attachments
Amp happenings
I finally got around to testing the amps with test tones and a dummy load. They pretty much tested out as Peter Daniel's tutorial said they should. The power supplies are big enough and so are the heat sinks. These amps put out 40 clean watts per channel, after which they start to clip, regardless of frequency. So some of the "grain" I have mentioned in previous posts are indeed clipping artifacts. Some things clip more gracefully then others. For instance, Internet Radio you can bearly tell as it is already so compressed, but orchestral build-ups are very obvious! I actually put a marker mark (erasable) on my TV where the volume's level meter is displayed, and sure enough something undesirable happens when that point is crossed! I tried removing the bass with the EQ to see if that made a diffence. Of course it did not, when that level is crossed, it is crossed. So even for mid-range use, I would like more powerful amps, mainly for the dynamic headroom. I am not sure how Alpair with Avebury would work with say 80 - 100 watt amp, this I would say, may be more frequency dependent. Thereolgically speaking, we are only looking at a 3dB increase, but I am thinking it would help with bandwidth and dynamics. What are your thoughts! I think AVebury has more, but I am not sure how much more. Some of my recordings push them pretty close at 40 watts/channel. I am getting to this point.
Allen
I finally got around to testing the amps with test tones and a dummy load. They pretty much tested out as Peter Daniel's tutorial said they should. The power supplies are big enough and so are the heat sinks. These amps put out 40 clean watts per channel, after which they start to clip, regardless of frequency. So some of the "grain" I have mentioned in previous posts are indeed clipping artifacts. Some things clip more gracefully then others. For instance, Internet Radio you can bearly tell as it is already so compressed, but orchestral build-ups are very obvious! I actually put a marker mark (erasable) on my TV where the volume's level meter is displayed, and sure enough something undesirable happens when that point is crossed! I tried removing the bass with the EQ to see if that made a diffence. Of course it did not, when that level is crossed, it is crossed. So even for mid-range use, I would like more powerful amps, mainly for the dynamic headroom. I am not sure how Alpair with Avebury would work with say 80 - 100 watt amp, this I would say, may be more frequency dependent. Thereolgically speaking, we are only looking at a 3dB increase, but I am thinking it would help with bandwidth and dynamics. What are your thoughts! I think AVebury has more, but I am not sure how much more. Some of my recordings push them pretty close at 40 watts/channel. I am getting to this point.
Allen
Have you tried toed in such that the axis cross in front of you. This might also allow you to try pulling them out so that the rear is clear of the cavity (a couple big windows in the side walls of the cavity (or a whole bunch of little ones) might do something similar basswize). I have something similar designed into my room.
dave
A run around, Dave, I need your help!
During all these test tone type of tests, I noticed at 100 Hz, just before clipping, the right Avebury would make a nasty vibrating sound! A physical, something is loose kind of sound. I checked the screws, they where tight. I switched channels, Amp and wires, still same cabinet. I took the speaker out, looked it over, no cracks, no sawdust, wood chips or glue. The sound come more from the right side of the driver, so a tried putting a cork pad, thinking maybe it was the wood protruding in on the driver cutout. See photo #1...
Nope is was not that!
Next I cut all the driver cutout frame notches, thinking maybe the frame was rubbing agaist them, being such a good fit.
Nope not that either! What could it be? It sounds like it is coming form the speaker itself, but when it is unmounted, it does not did it!
Next I removed the denim stuffing behind the driver, and sure enough I found a 1/32" gap between the side wall and diffusion blocks. See photo 2. So I cut some fillers. Photo #3. After about 1 solid hour of cusing, I got what I could in. One side was 1/32, tapering down to nothing on the other side. And the pieces that went in only went down an inch at most. Wow, could this really cause this? I put the denim back in, and left the cabinet to dry.
Off to church I want, I needed it after all of that! Then night job...
I got home, put the speaker in, and sure enough, it still did it!
Aaaaagggghhhh!
I set the cabinet on the ground, and it stopped! huh, I turned the cabinet top to bottom, it come back! I put the cabinet on its side, still there, but it disappears when Alpair is laying flat. I took it out, and that is when I heard a tiny plastic click... Oh no! It did not crack! Thankfully not. But that is when I noticed that this driver has a bezel cover, apparently, it has come partically loose.
So, Dave, how do I take the rest of it off without braking it? What kind of tool would you use to do that? What kind of glue do you use to reglue it? how do you clamp it? Am I even qualified to do this? Plastics are not my thing, but I will give it a go if it is not too plasticy breakable!
Believe me, it was far easier for me to believe that it was my very mindfully built cabinet, then a flaw with Alpair 12! It was quite a mind trip downer, that is for sure. I am relieved it was not the cabinet I built.
The one cool thing I got out of all of this was feeling the significant breeze at the horn mouths playing these low test tones. I have a few air leaks to fill around some of the tenions that where on the loose side.
That is something I can do, I have the pieces cut already!
Your prayers at this point will be greatly appreciated!
Allen
During all these test tone type of tests, I noticed at 100 Hz, just before clipping, the right Avebury would make a nasty vibrating sound! A physical, something is loose kind of sound. I checked the screws, they where tight. I switched channels, Amp and wires, still same cabinet. I took the speaker out, looked it over, no cracks, no sawdust, wood chips or glue. The sound come more from the right side of the driver, so a tried putting a cork pad, thinking maybe it was the wood protruding in on the driver cutout. See photo #1...
Nope is was not that!
Next I cut all the driver cutout frame notches, thinking maybe the frame was rubbing agaist them, being such a good fit.
Nope not that either! What could it be? It sounds like it is coming form the speaker itself, but when it is unmounted, it does not did it!
Next I removed the denim stuffing behind the driver, and sure enough I found a 1/32" gap between the side wall and diffusion blocks. See photo 2. So I cut some fillers. Photo #3. After about 1 solid hour of cusing, I got what I could in. One side was 1/32, tapering down to nothing on the other side. And the pieces that went in only went down an inch at most. Wow, could this really cause this? I put the denim back in, and left the cabinet to dry.
Off to church I want, I needed it after all of that! Then night job...
I got home, put the speaker in, and sure enough, it still did it!
Aaaaagggghhhh!
I set the cabinet on the ground, and it stopped! huh, I turned the cabinet top to bottom, it come back! I put the cabinet on its side, still there, but it disappears when Alpair is laying flat. I took it out, and that is when I heard a tiny plastic click... Oh no! It did not crack! Thankfully not. But that is when I noticed that this driver has a bezel cover, apparently, it has come partically loose.
So, Dave, how do I take the rest of it off without braking it? What kind of tool would you use to do that? What kind of glue do you use to reglue it? how do you clamp it? Am I even qualified to do this? Plastics are not my thing, but I will give it a go if it is not too plasticy breakable!
Believe me, it was far easier for me to believe that it was my very mindfully built cabinet, then a flaw with Alpair 12! It was quite a mind trip downer, that is for sure. I am relieved it was not the cabinet I built.
The one cool thing I got out of all of this was feeling the significant breeze at the horn mouths playing these low test tones. I have a few air leaks to fill around some of the tenions that where on the loose side.
That is something I can do, I have the pieces cut already!
Your prayers at this point will be greatly appreciated!
Allen
Attachments
It is likely it was always like that. And difficult to detect.
I discard the bezel covers when i can, but all the 12s i got came with them attached.
It is very unlikely that the bezel can be removed without destroying the driver.
I'm going to take a stab, but i'm also going to ping Mark for his advice, so hang tite till he chimes in.
Ideally you figure out how to inject some 2 part epoxy in between the frame and the bezel where it is loose. Then simply pressing the 2 parts together and letting cure should do the job.
If that won't work ... maybe some super glue?
dave
Toe in impresions
Yes, I have. It sounds more jumbled up on the listening couch, but one thing I liked about this set-up is that it did make the whole couch the sweet spot. Infact I liked the sound better in the off axis positions better then the middle with this set-up.
I could do that on the right wall, but the left wall and back wall are outside walls. If I had the $$$$, I would put footings in and build this room and the room next to it out thru the back wall and extend the bay window area thru the side wall. Half of this addition would be a passive solar green house.
Always dreaming Big!
Allen
Yes, I have. It sounds more jumbled up on the listening couch, but one thing I liked about this set-up is that it did make the whole couch the sweet spot. Infact I liked the sound better in the off axis positions better then the middle with this set-up.
I could do that on the right wall, but the left wall and back wall are outside walls. If I had the $$$$, I would put footings in and build this room and the room next to it out thru the back wall and extend the bay window area thru the side wall. Half of this addition would be a passive solar green house.
Always dreaming Big!
Allen
Me too... i have a 14' tall south facing wall. I would like to build a 24' x 12' green house to enclose this, paint the wall flat-black, cover it in an arrar of black PVC pipe and use it for heating purposes.
dave
2 other comments... the leaks will definitly affect performance at least a little bit, and don't tighten the screws too much.
dave
dave
I am not lazy when it comes to sound!
Did placing your cabinets close to the back wall give you the mid-bass you were seeking? I tell you, Zia, if I had another pair of finished boxes laying around like that to listen to, you could not hold me back from trying them!
I looked for information on Tubelab PP. I could not find a kit, but supposidly there is a PCB for it - somewhere? Thanks for the information, I am really thinking Alpair would enjoy a reasonably powerful amp! I am curious to know what they sound like thru a tube amp!
Allen
Did placing your cabinets close to the back wall give you the mid-bass you were seeking? I tell you, Zia, if I had another pair of finished boxes laying around like that to listen to, you could not hold me back from trying them!
I looked for information on Tubelab PP. I could not find a kit, but supposidly there is a PCB for it - somewhere? Thanks for the information, I am really thinking Alpair would enjoy a reasonably powerful amp! I am curious to know what they sound like thru a tube amp!
Allen
Chris has one of those. A nice amp. We do prefer the sonics of the Class A triode El Cheapo (within its limitations -- 3.2W), but having the power on the less efficient speakers is nice.
dave
You are helping more then you believe
I am collecting all the information I can to help me decide what direction I am going to go with my Alpair 12s in my given room, which is almost half the area of yours. I am amazed the Deathstars fill that space and you have that wide of a sweet spot. My sweet spot is not that big, eventhough my speaker separation is about the same. Maybe the octokens work better then Avebury in that way. But, as you say, we are dealing from two diferent reference points.
I am not sure yet if the bass is overwhelming my mid-range becuase of the room acoustics, not enough amp power, Alpair 12, or all of the above. I can say that Alpair 12 does well in its ability to play mid-range and bass at the same time! Better then any other speakers I have owned. I would say most of my problems are room acoustics, then too samll of an amp, then Alpair 12. The first two will be nothing more then time and (augh) $$$ to fix, but when Alpair 12 does indeed become the weak link, what then? That is why Avebury hangs in the balance, becuase if Alpair 12 does not meet my demands as an all out full-range system, I am sure it can as a two-way system with sub-woofer. I have always wanted to try a spherical cabinet. But the big question in my mind now, is will Avebury cut it when I have the right amp and some of the acoustical stuff figured out?
Are we having fun yet?
Allen
I am collecting all the information I can to help me decide what direction I am going to go with my Alpair 12s in my given room, which is almost half the area of yours. I am amazed the Deathstars fill that space and you have that wide of a sweet spot. My sweet spot is not that big, eventhough my speaker separation is about the same. Maybe the octokens work better then Avebury in that way. But, as you say, we are dealing from two diferent reference points.
I am not sure yet if the bass is overwhelming my mid-range becuase of the room acoustics, not enough amp power, Alpair 12, or all of the above. I can say that Alpair 12 does well in its ability to play mid-range and bass at the same time! Better then any other speakers I have owned. I would say most of my problems are room acoustics, then too samll of an amp, then Alpair 12. The first two will be nothing more then time and (augh) $$$ to fix, but when Alpair 12 does indeed become the weak link, what then? That is why Avebury hangs in the balance, becuase if Alpair 12 does not meet my demands as an all out full-range system, I am sure it can as a two-way system with sub-woofer. I have always wanted to try a spherical cabinet. But the big question in my mind now, is will Avebury cut it when I have the right amp and some of the acoustical stuff figured out?
Are we having fun yet?
Allen
One last one before bed...
I agree, the leaks almost sound like "static". (Could that be some of the grain I was hearing?) Of course we are talking using all 40 watts of power for one bass tone!
I find screwing in Alpair 12 very stressful, I need to get a "T" style metric allen wrench. One pet peeve I allow others to make towards the USA. Why are we still using an inferior measuring system?
How much power and headroom does Chris's TubeLab PP have?
I appreciate tonights dialog, thanks Dave, lots of emotion today.
God Bless
Allen
I agree, the leaks almost sound like "static". (Could that be some of the grain I was hearing?) Of course we are talking using all 40 watts of power for one bass tone!
I find screwing in Alpair 12 very stressful, I need to get a "T" style metric allen wrench. One pet peeve I allow others to make towards the USA. Why are we still using an inferior measuring system?
How much power and headroom does Chris's TubeLab PP have?
I appreciate tonights dialog, thanks Dave, lots of emotion today.
God Bless
Allen
Why indeed.
Can't you just get one at the local hardware store?
Sorry, can't help you with all of your questions. As far as my listening experience with the Deathstars is concnerened, either they're good enough or I'm not picky enough. Can't say more than that right now.
Well, Allen, it's a puzzle to me that by this time you don't have a rather complete set of metric tools. All you need is available at Lowe's and HD. BTW, I got a set of bits at WalMart (Black&Decker) the fit a 1/4" hex drive. Includes such novelties as #1 and #2 Robertson, metric hex drive 1.5mm-6mm, four small torx bits, etc. I drive the screws for Alpairs and anything else with a 12v power driver with the clutch set at 1 or2 (with pilot holes, of course).
And BTW #2, while you are at HD, get a Stanley 5m/16' tape measure.
Bob
And BTW #2, while you are at HD, get a Stanley 5m/16' tape measure.
Bob
Hi Allen,
Dave has pointed me to your posts. From what I've read so far, there's an easy fix.
Assuming most of the cover is still firm, run a small beed of glue into the frame - cover gap. You won't need much glue.
Mix a small amount of glue on some paper. Dip the tip of a cocktail stick or similar into the mix then push the glue inside the frame- cover gap. Gradually work you way around the driver, mix fresh glue as you go, immediately wiping any excess off . You could gently partly insert a small pin (or similar) to open the gap slightly between frame and cover. Don't force the pin far in, just enough to aid the process.
Make the beed a minimum of 2 screws holes (see pic).
Here's the recommend thread for glues: http://www.diyaudio.com/forums/markaudio/197071-glueing-alpair-front-trim-rings.html
Make sure the front baffle is flat, no bumps in the wood. Use a straight edge steel ruler and eye-ball the mounting area around the baffle. Don't over-tighten the mounting screws. A gentle nip-up is all that's required
If you need more advice and want me to further check the remedy with you before gluing, feel free to email me: support@markaudio.com
Cheers
Mark.
Attachments
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Novelties? More like necessities. I buy 20 packs of the red Robertson (#2). I use the green (#3) much more often than the black (#1) or the yellow (#4)
If Chris isn't looking i use brass robertson, instead of the ones Mark supplies ... you know you tightened it too much if the head snaps off.
dave
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