I promised a while back to give impressions comparing the Goldwood and the Alpha when I finished the Alpha. Here is what I found on the Alpha. Sounded terrible when I first hooked it up. Muddy midrange and some real boominess. Went back and re-read Martin's article where it says the H-frame needs to roll off at 125 Hz instead of 200 for the OB. So had to scrounge up a 125 Hz cross over.
I didn't quite follow. Does that mean the crossover has to be changed if using the Alpha 15a instead of the Goldwood 18''? Also the baffle dimensions and full range driver height are changed when using the 15a. How much of an effect will that have? Does the crossover need to be adjusted?
Will it require crossover adjustments?
I didn't quite follow. Does that mean the crossover has to be changed if using the Alpha 15a instead of the Goldwood 18''? Also the baffle dimensions and full range driver height are changed when using the 15a. How much of an effect will that have? Does the crossover need to be adjusted?
Will it require crossover adjustments?
Here are some pictures from the get together yesterday. The Goldwood and the Eminence should be obvious. There will be more comments posted as we go along. At this point, I am somewhat convinced the Jordan Mini-monitors may be a few dB low for either H-frame.
AZDIY2009 Detail Photos
Martin's discussion of the Eminence in OB, U, H, only gave values for the crossover for the OB. He did state that the H required something closer to 125Hz, but did not provide values. I am still playing with Full Range height and also do think the Alpair 12 baffle may be too small.
AZDIY2009 Detail Photos
Martin's discussion of the Eminence in OB, U, H, only gave values for the crossover for the OB. He did state that the H required something closer to 125Hz, but did not provide values. I am still playing with Full Range height and also do think the Alpair 12 baffle may be too small.
I'm very curious to hear the impressions of the different open baffle designs at the meet. I have been thinking about building the Goldwood version but the Eminence might be better for my room. I also can't afford the Jordan driver for the top end and would like to see different options for that.🙂
I am waiting on comments from others, since as the one who made them, I might be a bit biased. My Goldwood has many more hours on it than the Eminence, but with that caveat, I find the Goldwood a bit more detailed.
Some will complain when I say it has a better stage as there are differing opinions on staging that low. However, both reproduce Ray Brown quite well with a solid image on the new K2 We Get Requests CD. I don't think you can go wrong with either. And at this point I can't really say that the Eminence is noticeably any more sensitivity or missing going as low as the Goldwood. Have not tried to measure them yet, and in some sense, we are getting into an area where room and placement may make more of a difference.
Some will complain when I say it has a better stage as there are differing opinions on staging that low. However, both reproduce Ray Brown quite well with a solid image on the new K2 We Get Requests CD. I don't think you can go wrong with either. And at this point I can't really say that the Eminence is noticeably any more sensitivity or missing going as low as the Goldwood. Have not tried to measure them yet, and in some sense, we are getting into an area where room and placement may make more of a difference.
Forgot to mention. The Alpair 7 is a steal and seems to work quite well. The lower sensitivity seems to be offset by it being a 4 ohm driver. Neither tube amp, the one at the festival, or my VT-130 had any problems with being on the 8 ohm output.
It looks like in the pics you provided you are using a passive crossover on the two different models you built. Are you biamping them? I would want to run them full range from a single amp (at least for now) with a passive crossover...
My room, which is also my painting studio, is a bit of a problem. It is fairly narrow and long. The dimensions are about 10' x 20'. Placing the speakers out from the rear wall 2' or so isn't a problem (on the short wall) but to create an equilateral triangle with my listening position requires that they be about 7' apart. This of course puts them about 1.5' from the side walls, which might be too close. I'm hoping some of you who have built these and tried them in different rooms could give me some feedback on your experiences before I plunk down the money for drivers.
I know I like the ob sound from the few experiments I have done with some EV coaxials I had
My room, which is also my painting studio, is a bit of a problem. It is fairly narrow and long. The dimensions are about 10' x 20'. Placing the speakers out from the rear wall 2' or so isn't a problem (on the short wall) but to create an equilateral triangle with my listening position requires that they be about 7' apart. This of course puts them about 1.5' from the side walls, which might be too close. I'm hoping some of you who have built these and tried them in different rooms could give me some feedback on your experiences before I plunk down the money for drivers.
I know I like the ob sound from the few experiments I have done with some EV coaxials I had
I am running passive crossover with a single amp. The Goldwood uses the values in Martin's paper. Post #376 has the values I used for the Eminence and the Alpairs. The 2nd order crossover did not work outside the mini-monitor box due to a 3rd order on the tweeter, so I went with a 1st order on the mini-monitor at 147uf because it is what I had handy for now. It still needs some work.
Mike, a horn subwoomper? I envy you. You have a square miles big flat and no neighbours. (email me - I have the blueprint of the Shearer somewhere)
Parts Express is running a sale this month with the Goldwood 20% off. Still a bit higher than I paid a while back, but seems to be about the best price around.
sale my ***. forget what they say reg. price is. they have taken $.63 off
this driver for their "sale" compared to their regular catalog for the 18" 1858 model.
this driver for their "sale" compared to their regular catalog for the 18" 1858 model.
When Aegnus posted about using a tube instead of a box in post 243 I had similiar thoughts in the past.
http://www.diyaudio.com/forums/full...ood-gw-1858-woofer-h-frame-5.html#post1757261
After further discussion with Aegnus he drew up a couple of ideas that can be seen in post 265 -272.
http://www.diyaudio.com/forums/full...ood-gw-1858-woofer-h-frame-6.html#post1762602
The internal volume of a 20" x 20" x16" cube is 107.77 liters and a 22.5" x 16" tube is 104.25 liters. The exact tube equilvilant would be 22.877 id x 16". I found a piece of 24" schedule 40 PVC that has an OD of 24" and an average ID of 22.544".
http://www.usplastic.com/pdfdatafiles/drawings/pipespecs.pdf
Now that I have all the parts to build except the PVC which is on it way I put together a drawing. With the drawing I now see I should have should have thougt of this more before acquiring a piece of pipe.
Note in the drawing the center of the Goldwood would be 1.5" above Martin's design on the left. I don't see a problem there but now with the 24" tube the Jordan may be facing some problems by being higher up and not having a flat surface at the bottom.
I normally don't like to vere from speaker plans but thought the tube was good idea outside the norm.
Martin in you article you made original measurements with the Jordan and Goldwood independently and merged the graphs since you software wouldn't allow a flat panel and h frame to work together. Should I revert back to original plans or do you think I can make this work OK without dramatic changes in measurements from the original?
Brad
http://www.diyaudio.com/forums/full...ood-gw-1858-woofer-h-frame-5.html#post1757261
After further discussion with Aegnus he drew up a couple of ideas that can be seen in post 265 -272.
http://www.diyaudio.com/forums/full...ood-gw-1858-woofer-h-frame-6.html#post1762602
The internal volume of a 20" x 20" x16" cube is 107.77 liters and a 22.5" x 16" tube is 104.25 liters. The exact tube equilvilant would be 22.877 id x 16". I found a piece of 24" schedule 40 PVC that has an OD of 24" and an average ID of 22.544".
http://www.usplastic.com/pdfdatafiles/drawings/pipespecs.pdf
Now that I have all the parts to build except the PVC which is on it way I put together a drawing. With the drawing I now see I should have should have thougt of this more before acquiring a piece of pipe.
Note in the drawing the center of the Goldwood would be 1.5" above Martin's design on the left. I don't see a problem there but now with the 24" tube the Jordan may be facing some problems by being higher up and not having a flat surface at the bottom.
I normally don't like to vere from speaker plans but thought the tube was good idea outside the norm.
Martin in you article you made original measurements with the Jordan and Goldwood independently and merged the graphs since you software wouldn't allow a flat panel and h frame to work together. Should I revert back to original plans or do you think I can make this work OK without dramatic changes in measurements from the original?
Brad
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Hey, Brad - glad to hear you're working on this one; I'm still interested but still about 7 projects behind. 🙁
I hope Martin sees and answers your question, since that would be definitive. But in the interim, I can't see that presenting a rounded surface at the top of the h-frame would make any real difference to Jordan; and I don't see why you couldn't set the Jordan at the original height as well - it would still be about the same _average_ distance above the h-frame baffle as in the original design.
I'd say it's worth a try (of course I'd say that, it's not me doing the work 😀), since you already have the tube all you can lose is the piece of plywood for the baffle...
Anyway, please keep us posted. Who knows, maybe you'll goad me into action.
Regards.
Aengus
I hope Martin sees and answers your question, since that would be definitive. But in the interim, I can't see that presenting a rounded surface at the top of the h-frame would make any real difference to Jordan; and I don't see why you couldn't set the Jordan at the original height as well - it would still be about the same _average_ distance above the h-frame baffle as in the original design.
I'd say it's worth a try (of course I'd say that, it's not me doing the work 😀), since you already have the tube all you can lose is the piece of plywood for the baffle...
Anyway, please keep us posted. Who knows, maybe you'll goad me into action.
Regards.
Aengus
At the crossover frequency, about 200 Hz, the wavelength of sound is approximately 67.5 inches. So my guess is that a few inches of difference in the design dimensions will not be an issue.
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