fwater said:
If you are going OB, then I believe that the Eminence Alpha 15A would work better. No matter which driver you use you are not going to get below 40 Hz on an OB. The higher Qts of the Alpha 15A is going to be an advantage over the Goldwood GW-1858 for OB. Later if you decide to build the H frame, the Alpha 15A will go almost as deep.
MJK said:
Good to know. I have a pretty firm understanding of how the low end of an OB is governed by the size of the panel, assuming the driver can get that low. Using the dipole spreadsheet that somebody has furnished here, I can graph the effects of series resistance and see that a small amount applied to the 1858 puts it on par with the Alpha in terms of extension. The side effect is the sensitivity penalty, negating the advantage of the 18". With enough power on tap in a plate amp, this can be overcome. Assuming possible (probable) use in an H-frame in the future, the Alpha would take a smaller overall cab. How much of a cost in extension are we talking about with the 15" vs. the 18" in an H-frame?
Decisions, decisions...
Hi martin,MJK said:
Yes it helps.
I only had a quick read of the paper before I when away for the weekend so I missed that you were now going active, thus some of my rambling. Also, in my haste I neglected the 6dB boost due to the floor. As for the Xmax, I guess that depends on what you listen to. Displacement requirements drop off quickly as frequency increases (1/f^3) so by 32 Hz your probably pretty safe.
As you know, I'm not so miuch a full fange driver fan, but I still think this is a nice effort that many would be please with.
Martin, I cannot find the documentation....
I went to projects, Jordan/Goldwood OB project and all I can get to is the first page with 2 links and a picture.
These seem quite similar to a project I have been developing with my audio partner for the "Spirit of Orion". It is a cosmetically similar Jordan JX92S OB with a 12" sub and plate amp per channel (sealed).
stew
I went to projects, Jordan/Goldwood OB project and all I can get to is the first page with 2 links and a picture.
These seem quite similar to a project I have been developing with my audio partner for the "Spirit of Orion". It is a cosmetically similar Jordan JX92S OB with a 12" sub and plate amp per channel (sealed).
stew
ok, finally got it...
browser wasn't configured to open Adobe (but it did save the files). Nice project Martin. I've resized an image of the "Spirit of Orion" loudspeakers to get on diyAudio.
The upper drivers have been changed to the Jordan JX92S drivers. right now working on developing a PLLXO suitable to reduce the low frequencies to the Jordans' amplifier. Subs are M&K and plate amps are M&K as found in the "1250" active sub. The internal crossover in the plate amps is suitable for adjusting the LF crossover point, but it passes full frequency sound out of the plate amp.
As I do not have any measuring devices, except perhaps an old school RS analog DB meter,any measurements I do will be a little crude.
browser wasn't configured to open Adobe (but it did save the files). Nice project Martin. I've resized an image of the "Spirit of Orion" loudspeakers to get on diyAudio.
The upper drivers have been changed to the Jordan JX92S drivers. right now working on developing a PLLXO suitable to reduce the low frequencies to the Jordans' amplifier. Subs are M&K and plate amps are M&K as found in the "1250" active sub. The internal crossover in the plate amps is suitable for adjusting the LF crossover point, but it passes full frequency sound out of the plate amp.
As I do not have any measuring devices, except perhaps an old school RS analog DB meter,any measurements I do will be a little crude.
Attachments
rear tweeter?
Martin, great work as usual,
Ever think of trying a rear-facing tweeter as Linkwitz used in the Orion++? It seems by his comments that it has more to do with enhancing the soundstage illusion than affecting the frequency response, though it does that to some degree too. Maybe it will give you a little of what you liked in the Lowther, just in a different way?
http://www.linkwitzlab.com/orion++.htm
He gets into his reasons for the rear-facing tweeter a little farther down the page.
Martin, great work as usual,
Ever think of trying a rear-facing tweeter as Linkwitz used in the Orion++? It seems by his comments that it has more to do with enhancing the soundstage illusion than affecting the frequency response, though it does that to some degree too. Maybe it will give you a little of what you liked in the Lowther, just in a different way?
http://www.linkwitzlab.com/orion++.htm
He gets into his reasons for the rear-facing tweeter a little farther down the page.
Hello Martin,
very creative work.
I'm not expert in speakers but there is one thing that I don't understand:
why you look for a low efficency fullrange to mach the efficency of the woofer,if you use bi-amplification?
Can you compensate efficency with a different regulation of the electronic crossover?
All this questions because I've a Silver Iris15" OB that is about 95db and I'd like to add a OBwoofer like Augie or your more perfomce and economic H frame with Alpha 15 or Goldwoods woofer .
Any suggestion or indication of the better solution?
Thanks a lot for your serious point of view and sorry for my poor english.
Ciao
Guglielmo
Italy
very creative work.
I'm not expert in speakers but there is one thing that I don't understand:
why you look for a low efficency fullrange to mach the efficency of the woofer,if you use bi-amplification?
Can you compensate efficency with a different regulation of the electronic crossover?
All this questions because I've a Silver Iris15" OB that is about 95db and I'd like to add a OBwoofer like Augie or your more perfomce and economic H frame with Alpha 15 or Goldwoods woofer .
Any suggestion or indication of the better solution?
Thanks a lot for your serious point of view and sorry for my poor english.
Ciao
Guglielmo
Italy
Re: rear tweeter?
Thanks for the positive feedback.
I have a Fostex super tweeter on a small baffle that I used with my Lowther OB system. I have tried it with this new system as you describe for a day or two but pulled it out since everything was still too new for me to form a solid opinion. I will reinsert it at some point to see if it improves performance. Right now I want to live with the current set-up for a few more weeks.
berm said:
Thanks for the positive feedback.
I have a Fostex super tweeter on a small baffle that I used with my Lowther OB system. I have tried it with this new system as you describe for a day or two but pulled it out since everything was still too new for me to form a solid opinion. I will reinsert it at some point to see if it improves performance. Right now I want to live with the current set-up for a few more weeks.
guglielmope said:
You are right, I could have used one of my Lowther drivers and added more gain to the H frame so that it matched the higher efficiency. That is one of the big advanyages of an active crossover. The H frame woofer could be paired with a lot of other midrange/tweeters or full range drivers with a wide range of higher or lower efficiencies.
The reason I decided to use a less efficient full range driver is so that I can also offer a passive crossover design as an option. I am already getting questions/requests for a passive alternative. So hopefully in the next few weeks I will update the desing with a passive crossover using 1 - 2 dB of attenuation of the Jordan to match the H frame.
You don't need to apologize for your English, it is just fine.
Hi Tinnitis
I think you get much less treble coming off the rear of a full range driver, but I don't think that is the point of using a rear-facing tweeter in most cases anyway. It seems to add a sense of spaciousness and give more "size" to the soundstage, at least where I've tried it. I remember years ago adding a ribbon working in the supertweeter range, out beyond the range where music lives, and it seemed to expand the sense of space around the musical event. It's just a psychoacoustic effect I know, but, done right, it can add a nice sense of what people often call "air".
Godzilla and several others have mounted tweeters on the rear of some of the speakers they build, and I assume it's this effect that they like in rear-mounting them.
The Wharfedale SFB3 open-baffle speaker used a rear-mounted upward-firing tweeter also.
- I'm still amazed by the quality and quantity of Martin's work. The man must be part machine.
I think you get much less treble coming off the rear of a full range driver, but I don't think that is the point of using a rear-facing tweeter in most cases anyway. It seems to add a sense of spaciousness and give more "size" to the soundstage, at least where I've tried it. I remember years ago adding a ribbon working in the supertweeter range, out beyond the range where music lives, and it seemed to expand the sense of space around the musical event. It's just a psychoacoustic effect I know, but, done right, it can add a nice sense of what people often call "air".
Godzilla and several others have mounted tweeters on the rear of some of the speakers they build, and I assume it's this effect that they like in rear-mounting them.
The Wharfedale SFB3 open-baffle speaker used a rear-mounted upward-firing tweeter also.
- I'm still amazed by the quality and quantity of Martin's work. The man must be part machine.
berm said:
Sure, it does that, but maybe exactly because it turns the upper frequencies into dipole or bipole...and an omni supertweeter would most likely do that too
I have a pair of very cheap horntweeters...I once tried to place them on top of my speakers with only a small series cap
In my world it ought to work but sound completely awful...but it didnt...just fore the record, I dont do that
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