i have a wonderful set of NSB line arrays that i have set up in a bi-amped configuration.
i have been looking into building some chip amps for some time. the only problem is that i have read that chip amps dont like dificult loads. my line arrays are running around 98-100db so power isnt really a problem, but i have read that they will be a very high inductance load. is that a problem?
the chip i am planning on using is the lm3887 and i am planning to get a SMPS to drive them. and as i am biamped, i will need to build 4 of them.
if you know of anyone who has done a set up like this before, please point me in their direction.
As always, thanks for your advice in advance
Zhar
i have been looking into building some chip amps for some time. the only problem is that i have read that chip amps dont like dificult loads. my line arrays are running around 98-100db so power isnt really a problem, but i have read that they will be a very high inductance load. is that a problem?
the chip i am planning on using is the lm3887 and i am planning to get a SMPS to drive them. and as i am biamped, i will need to build 4 of them.
if you know of anyone who has done a set up like this before, please point me in their direction.
As always, thanks for your advice in advance
Zhar
zhar said:i have a wonderful set of NSB line arrays that i have set up in a bi-amped configuration.
i have been looking into building some chip amps for some time. the only problem is that i have read that chip amps dont like dificult loads. my line arrays are running around 98-100db so power isnt really a problem, but i have read that they will be a very high inductance load. is that a problem?
the chip i am planning on using is the lm3887 and i am planning to get a SMPS to drive them. and as i am biamped, i will need to build 4 of them.
if you know of anyone who has done a set up like this before, please point me in their direction.
As always, thanks for your advice in advance
Zhar
There's the absolute overlill solution.
Use one side of a LM4780 for every four or so drivers. This would also make EQing them a bit easier.
Alternately, you could sell me a few drivers off of each side .
Actually, it might not be as hard as you might think. LM4780's are cheap, and when both halves are run in parallel (they're essentially dual LM3886s), they can drive 2 ohms.
The more drivers you have in paralell, the lower the inductance. (It goes up when you run them in series, of course.)
If the NSBs are 8 ohms, I'd put them into paralell sets of four, each run by a 4780. Alternately, do a series-parallel array; I'm pretty sure (if I remember my math right) that a 2-series by 4-parallel group would actually have half the normal inductance overall, while still being drivable by a single LM3886.
If you have 16 per side, you could use 2 LM4780's, with one half of each LM4780 for the top 8 drivers per channel, and the other half for the bottom. Inductance should be roughly 1/2 that of a normal driver, I think, and 4 ohms is ideal for a LM3886/LM4780 - plus, you can adjust the top and bottom halves seperately.
For the power supply, I'd reccomend a humongous transformer. If 2 LM4780s are used, 330va is an absolute minimum, with 400va being a bit safer and 500 + VA being ideal if you want to run 'em hot.
The more drivers you have in paralell, the lower the inductance. (It goes up when you run them in series, of course.)
If the NSBs are 8 ohms, I'd put them into paralell sets of four, each run by a 4780. Alternately, do a series-parallel array; I'm pretty sure (if I remember my math right) that a 2-series by 4-parallel group would actually have half the normal inductance overall, while still being drivable by a single LM3886.
If you have 16 per side, you could use 2 LM4780's, with one half of each LM4780 for the top 8 drivers per channel, and the other half for the bottom. Inductance should be roughly 1/2 that of a normal driver, I think, and 4 ohms is ideal for a LM3886/LM4780 - plus, you can adjust the top and bottom halves seperately.
For the power supply, I'd reccomend a humongous transformer. If 2 LM4780s are used, 330va is an absolute minimum, with 400va being a bit safer and 500 + VA being ideal if you want to run 'em hot.
I'm working on a similar arrangement right now. 16 NSBs in a 4 x 4 series/parallel open baffle arrangement, 7 Dayton planars in a 3/4 power taper and two Peerles 8" DVC woofers with a Linkwitz transform. Actively crossed at 125 and 3000 Hz, IIRC. It uses 8 3886 boards from BrianGT and four power supplies. The 4 x 4 NSB arrangement means that you have the same resistance and inductance overall as a single NSB - not a particularly difficult load to drive. Make sure your 3886 has a zobel and you should be fine.
I haven't touched my amp in about 5 months. I've finished the case, inputs, volume controls (master, tweeter, and woofer), crossovers, Linkwitz transform, PSUs, amps, and speaker terminals. I only have to sort out the 120 VAC stuff - soft start and Bulgin power switch. But that has to wait since I'm overseas for the next month.
Here's a picture of the line array:
http://img.photobucket.com/albums/v399/jimtanis/line.jpg
and the back:
http://img.photobucket.com/albums/v399/jimtanis/line3.jpg
and the side:
http://img.photobucket.com/albums/v399/jimtanis/line5.jpg
I haven't touched my amp in about 5 months. I've finished the case, inputs, volume controls (master, tweeter, and woofer), crossovers, Linkwitz transform, PSUs, amps, and speaker terminals. I only have to sort out the 120 VAC stuff - soft start and Bulgin power switch. But that has to wait since I'm overseas for the next month.
Here's a picture of the line array:
http://img.photobucket.com/albums/v399/jimtanis/line.jpg
and the back:
http://img.photobucket.com/albums/v399/jimtanis/line3.jpg
and the side:
http://img.photobucket.com/albums/v399/jimtanis/line5.jpg
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