Greets!
My electronics designing knowledge is limited also. This chip was recommended to me some years ago for this app, but I haven't gotten around to researching it. I just tossed it out here in the hope that one of the other 'hotshots' would comment/elaborate on using it, but apparently not.
Google is a 'bootiful thang' 😉: http://mysite.verizon.net/tammie_eric/ericindex.html
http://www.speakerworkshop.com/SW/Project/Equipment.htm
Don't know of any correction chart for the latest version of the RS meter. I would compare whatever response is in the owner's manual against what's published for the previous version to see if its applicable.
GM
My electronics designing knowledge is limited also. This chip was recommended to me some years ago for this app, but I haven't gotten around to researching it. I just tossed it out here in the hope that one of the other 'hotshots' would comment/elaborate on using it, but apparently not.
Google is a 'bootiful thang' 😉: http://mysite.verizon.net/tammie_eric/ericindex.html
http://www.speakerworkshop.com/SW/Project/Equipment.htm
Don't know of any correction chart for the latest version of the RS meter. I would compare whatever response is in the owner's manual against what's published for the previous version to see if its applicable.
GM
Thanks for the links. I guess I searched around for RadioShack dB meter and found mention of Eric Wallen's site with the faulty link. Didn't ever search for Eric Wallen 🙄 .
Unfortunately all his mods are for earlier versions of the meter. It does show a mod for replacing the mic element and putting the new element on a "wand". That looks pretty universal so I might try that, probably do some testing with the RS meter as is for now so I can see the difference when the change is made. Sounds like fun😀.
Joe
Unfortunately all his mods are for earlier versions of the meter. It does show a mod for replacing the mic element and putting the new element on a "wand". That looks pretty universal so I might try that, probably do some testing with the RS meter as is for now so I can see the difference when the change is made. Sounds like fun😀.
Joe
Well my girlfriend was kind enough today to pick up the rest of the cables I needed today at the RadioShack in town. So I've got my first set of tests done. Quite exciting. The measurements look good if you take into account Salas' compensation numbers. I don't think there is anyway to get a pretty graph with the compensation so I'll just post the pretty graph, and those of you who really care can take add up all the numbers (ok, probably nobody cares that much, but I just cann't help myself😉 ). As you can see there is a little be of nastiness from the room centered around 70-80Hz, which has been pretty apperant with every speaker I've ever heard in my cabin. Now that I know where it is I might have to look into some way of bringing it down a bit.
Thanks everyone for the help
Joe
Thanks everyone for the help
Joe
Attachments
Yeah, I think it's just the RS dB meter that's rolled off on top, in the manual it only claims to be good to 10kHz. The speakers are two ways with a Fostex 108es on top and an Emenince Delta 12lf on bottom. I'm probably going to build the pre amp and mic that youyoung posted earlier, since it seems pretty simple and econmical to build. That way I can get some more reliable results. I'ld like to expierment some with the crossover, but I'll probably wait on that until I get a more accurate setup. I really like the sound of my speakers now, but I cann't really help myself, I'm a natural born tweaker
.
Joe
Here's a picture of my speakers when I was still working on the crossover.
.Joe
Here's a picture of my speakers when I was still working on the crossover.
Josephjcole said:Yeah, I think it's just the RS dB meter that's rolled off on top, in the manual it only claims to be good to 10kHz. The speakers are two ways with a Fostex 108es on top and an Emenince Delta 12lf on bottom. I'm probably going to build the pre amp and mic that youyoung posted earlier, since it seems pretty simple and econmical to build. That way I can get some more reliable results. I'ld like to expierment some with the crossover, but I'll probably wait on that until I get a more accurate setup. I really like the sound of my speakers now, but I cann't really help myself, I'm a natural born tweaker
Joe
Here's a picture of my speakers when I was still working on the crossover.
I somehow have a feeling that you would get similar results even if you get the new mic setup. But let wait and see what happens.
Yeah, I think it's just the RS dB meter that's rolled off on top, in the manual it only claims to be good to 10kHz. The speakers are two ways with a Fostex 108es on top and an Emenince Delta 12lf on bottom. I'm probably going to build the pre amp and mic that youyoung posted earlier, since it seems pretty simple and econmical to build. That way I can get some more reliable results. I'ld like to expierment some with the crossover, but I'll probably wait on that until I get a more accurate setup. I really like the sound of my speakers now, but I cann't seem to leave them well enough alone .
Joe
Here's a picture of my speakers when I was still working on the crossover.
Joe
Here's a picture of my speakers when I was still working on the crossover.
Attachments
Sorry, I forgot to straighten out my picture, and I double posted... I'm not always with it in the mornings🙄 . Anyways, I would certainly hope that getting a new mic/preamp would change things, I'm quite sure my speakers don't start to roll off at 8kHz. It might be a little while till I get all the parts ordered and assembled for a new mic/preamp, but I'll let you know what I find.
Joe
Joe
Josephjcole said:
They would roll off if compensation is not considered in the design. The larger the surface area the more significant.
I'm sorry, I'm not sure I understand. Do you mean that my fostex driver will roll off if not compensated for or that my mic will roll off if not compensated for? Which surface area are you talking about?
Joe
Joe
Josephjcole said:
The driver! Normally there need to be some sort of compensation to balance the mids and the highs so that you don't see that kind of roll-off. If you already have compensation, then it might just be the mic that's rolling the highs off.
Greets!
Can't comment on the lastest version, but older models vary 'all over the map' WRT HF accuracy, from -1dB to -12dB/20 kHz being the measured extremes that I'm aware of. FWIW, my 1st gen. unit (40-3019) was -11.2dB/20 kHz when it was measured back in the late '60s at GE's Atlanta calibration lab, which BTW is considerably better than its published response.
Unfortunately the same can't be said for its LF response, so with no correction curve it's accurate BW is limited to ~50-5 kHz +/- ~1 dB or ~32-8 kHz if +/- ~3 dB is acceptable. Who knows what it is now though. Regardless, it's useful for making relative comparisons.
GM
Can't comment on the lastest version, but older models vary 'all over the map' WRT HF accuracy, from -1dB to -12dB/20 kHz being the measured extremes that I'm aware of. FWIW, my 1st gen. unit (40-3019) was -11.2dB/20 kHz when it was measured back in the late '60s at GE's Atlanta calibration lab, which BTW is considerably better than its published response.
Unfortunately the same can't be said for its LF response, so with no correction curve it's accurate BW is limited to ~50-5 kHz +/- ~1 dB or ~32-8 kHz if +/- ~3 dB is acceptable. Who knows what it is now though. Regardless, it's useful for making relative comparisons.
GM
soongsc,
There is no compensation on my fostex drivers, just a cap to cross it over to the emenince. I could be wrong, but I really doubt my speakers are acctually rolling off at the 8kHz that is on the graph. I've used these drivers in other designs which I have had measured by other people, I think they have a slighty rising response all the way up to 20kHz. If my memory serves me.
Salas,
What model number is the correction graph that you posted for? I've seen quite a few for the earlier models, but none for the 33-4050 model.
GM,
I was under the impression that within a certain run of RS dB meters that the variances from flat were fairly consistant. That would be too bad if they weren't. I guess I should have done more research before runnnig out and buying one.🙄
thanks
Joe
There is no compensation on my fostex drivers, just a cap to cross it over to the emenince. I could be wrong, but I really doubt my speakers are acctually rolling off at the 8kHz that is on the graph. I've used these drivers in other designs which I have had measured by other people, I think they have a slighty rising response all the way up to 20kHz. If my memory serves me.
Salas,
What model number is the correction graph that you posted for? I've seen quite a few for the earlier models, but none for the 33-4050 model.
GM,
I was under the impression that within a certain run of RS dB meters that the variances from flat were fairly consistant. That would be too bad if they weren't. I guess I should have done more research before runnnig out and buying one.🙄
thanks
Joe
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