I have just been offered a pair of JBL LSR25P monitor speakers at a very good price, and doing some research I found the schema on the JBL website. They use 1 amp for the tweeter and 2 bridged for the woofer with active crossovers.
So, I'm posting the link to the pdf in the hope it might help some people out trying to do a similar thing
http://www.jblproservice.com/pdf/LSR Series/LSR25P.pdf
So, I'm posting the link to the pdf in the hope it might help some people out trying to do a similar thing
http://www.jblproservice.com/pdf/LSR Series/LSR25P.pdf
A lot of the complication comes from the various switchable options for the built in sub hp xover, baffle step compensation if used next to a big monitor, and 3 different slopes on the high end to compensate for room response etc.
If I get them, (which is looking likely), then I will post some pics and give some details on the other op amps used.
If I get them, (which is looking likely), then I will post some pics and give some details on the other op amps used.
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Joined 2002
Well I am getting them for a specific task, as I need to knock together a little playout video for a conference I'm doing next week. I was planning on building some monitors, but this job came in at short notice, and is paying well enough just to go out and buy them.
So I'm sure I will be doing some tweeking when that job is wrapped, swapping out op amps looks like it might be a good start, as well as some decent Schottky diodes in the PSU.
Strangely, however, I was doing some serious listening to them this morning, before I handed over the cash, and I noticed none of the slight "compression" type sound I noticed when I built an inverted GC with the same chip. So I wonder if the 3886 is a chip that needs a litttle more support circuitry to get it to sound at it's best.
And yes, they are not quite Genelecs, but then again, it would be a close run thing to buy the parts to build them for the price I am paying
So I'm sure I will be doing some tweeking when that job is wrapped, swapping out op amps looks like it might be a good start, as well as some decent Schottky diodes in the PSU.
Strangely, however, I was doing some serious listening to them this morning, before I handed over the cash, and I noticed none of the slight "compression" type sound I noticed when I built an inverted GC with the same chip. So I wonder if the 3886 is a chip that needs a litttle more support circuitry to get it to sound at it's best.
And yes, they are not quite Genelecs, but then again, it would be a close run thing to buy the parts to build them for the price I am paying
Re: But then again...
You would be suprised at the high production values used in some conferences, one we did for HP had the set designed by a world famous artist, very high quality surround sound, and all the video inserts were filmed on 35mm, and then transferred to HD video for playout.
Yeah, I posted my impressions of all the chips in four or five posts somewhere in the NJAGC thread, feel free to look
I know where there are two more SH, but at about £350 each new I don't think I will be buying the fifth. Besides, it's much more fun to build them
p.s. Pics will be coming soon, I just had the phone call to say they will be dropped off tonight...
Da5id4Vz said:
You would be suprised at the high production values used in some conferences, one we did for HP had the set designed by a world famous artist, very high quality surround sound, and all the video inserts were filmed on 35mm, and then transferred to HD video for playout.
Yeah, I posted my impressions of all the chips in four or five posts somewhere in the NJAGC thread, feel free to look
I know where there are two more SH, but at about £350 each new I don't think I will be buying the fifth. Besides, it's much more fun to build them
p.s. Pics will be coming soon, I just had the phone call to say they will be dropped off tonight...
Over the years Ive worked around quite a few corporate staging people. They often seem to have the best budgets, most interesting projects, and highest level of satisfaction compared to their theater, broadcast, and documentary counterparts.
Another neat aspect about the niche is that it is (oops was) fairly unknown to the usual "characters" that can make those other worlds such a joy to work in.
I dissected a Genelec 1031A late one night about a decade ago. I was floored to see a 2 channel chip amp with a bunch of surface mount op amps for the x-over. I cant remember what the genre of the chip was (STK?) but do remember that they had put some effort into mechanically decoupling the amps from the speakers vibration.
Another neat aspect about the niche is that it is (oops was) fairly unknown to the usual "characters" that can make those other worlds such a joy to work in.
I dissected a Genelec 1031A late one night about a decade ago. I was floored to see a 2 channel chip amp with a bunch of surface mount op amps for the x-over. I cant remember what the genre of the chip was (STK?) but do remember that they had put some effort into mechanically decoupling the amps from the speakers vibration.
Attachments
moamps , moinfo please
Wow, I'm impressed,
Do you just take better notes than I do or do you have documentation on these things? Its not on a web site like the JBL is it?
Perhaps you’ve tweaked a set, I'm sure you didn’t learn all this from doing repairs, Ive never seen a set fail.
I think it would be very interesting to compare the JBL and Genelec approaches.
Thanks, I'll try to retain it this time.
-Dave
Wow, I'm impressed,
Do you just take better notes than I do or do you have documentation on these things? Its not on a web site like the JBL is it?
Perhaps you’ve tweaked a set, I'm sure you didn’t learn all this from doing repairs, Ive never seen a set fail.
I think it would be very interesting to compare the JBL and Genelec approaches.
Thanks, I'll try to retain it this time.
-Dave
Re: But then again...
My shop replaced our JBL LSR28P's (which are currently on permanent backorder due to shortages in Kevlar) in our Pro-Tools surround set-up with five of these recently, and they do a great job. They're pretty flat and work great as near-field reference monitors. I'm also a certified JBL tech here, and I've only had to fix two of these in the past year. So, they are also fairly reliable.
I was fairly surprised to find those LM3886 chips when I opened my first one up. One interesting note.....JBL also used these same chips in the HF section of the LSR28P, and EON15G2 (first version). I've also found these chips in some powered KRK speakers I worked on recently with the same configuration as the JBL. i.e. one for the HF, and two bridged for the LF.
You would be amazed how many powered speakers are using the LM3886 for their power sections. We may just all be on the right track with the Gainclone stuff eh?
Cheers,
Zach
P.S. If anyone needs any JBL, Infinity, or Harmon Kardon schematics, just drop me an e-mail and I will get them for you.
Cheers,
Zach
Da5id4Vz said:
My shop replaced our JBL LSR28P's (which are currently on permanent backorder due to shortages in Kevlar) in our Pro-Tools surround set-up with five of these recently, and they do a great job. They're pretty flat and work great as near-field reference monitors. I'm also a certified JBL tech here, and I've only had to fix two of these in the past year. So, they are also fairly reliable.
I was fairly surprised to find those LM3886 chips when I opened my first one up. One interesting note.....JBL also used these same chips in the HF section of the LSR28P, and EON15G2 (first version). I've also found these chips in some powered KRK speakers I worked on recently with the same configuration as the JBL. i.e. one for the HF, and two bridged for the LF.
You would be amazed how many powered speakers are using the LM3886 for their power sections. We may just all be on the right track with the Gainclone stuff eh?
Cheers,
Zach
P.S. If anyone needs any JBL, Infinity, or Harmon Kardon schematics, just drop me an e-mail and I will get them for you.
Cheers,
Zach
Listening Impressions
Well, I have to say, after two days glued to my computer, getting this video sorted, I am very impressed with these speakers. Very good, clear tops, a crisp midrange, and excellent soundstaging, even when less than a metre from the speakers. I have a little bass boom, but I suspect that is due to placement, my setup being in the corner of a room due to space constraints. Even when listening to streaming audio, from the BBC whilst Photoshopping, quality was excellent, with absolutely no trace of the earlier mentioned compression type artifacts I noticed previously with this chip. I may have to try the LM3886 again, but with a more conventional layout, rather than the GC style.
Zach
Are you using the matching sub, (LS12 I believe)? I was just wondering if it was worth cloning to get a full system. I have access to JBL pro drivers so that aspect should not be a problem. It would be interesting to hear your opinions if you have heard it as to if it is worth copying, or weather I should just design my own.
/waiting for the sign-off from the client...
Well, I have to say, after two days glued to my computer, getting this video sorted, I am very impressed with these speakers. Very good, clear tops, a crisp midrange, and excellent soundstaging, even when less than a metre from the speakers. I have a little bass boom, but I suspect that is due to placement, my setup being in the corner of a room due to space constraints. Even when listening to streaming audio, from the BBC whilst Photoshopping, quality was excellent, with absolutely no trace of the earlier mentioned compression type artifacts I noticed previously with this chip. I may have to try the LM3886 again, but with a more conventional layout, rather than the GC style.
Zach
Are you using the matching sub, (LS12 I believe)? I was just wondering if it was worth cloning to get a full system. I have access to JBL pro drivers so that aspect should not be a problem. It would be interesting to hear your opinions if you have heard it as to if it is worth copying, or weather I should just design my own.
/waiting for the sign-off from the client...
Re: moamps , moinfo please
Hi,
I am a freelance AV engineer working on design/installation/servicing for the general distributor of Genelec and JBL for this part of Europe. I have installed several active systems, from small nearfield monitors to big main theater systems. When it comes to servicing these monitors, so far I've had experience with only one failure on an S30 monitor (hard drop in OB-van caused several cold junctions) and that was all.
Of course, I have some datasheets for 1030/31/s30 (unfortunately, not for 1029A). If you are interested in any of these schematics, I can send them to you (but don't be too greedy as I have to scan them first).
Regards
Da5id4Vz said:
Hi,
I am a freelance AV engineer working on design/installation/servicing for the general distributor of Genelec and JBL for this part of Europe. I have installed several active systems, from small nearfield monitors to big main theater systems. When it comes to servicing these monitors, so far I've had experience with only one failure on an S30 monitor (hard drop in OB-van caused several cold junctions) and that was all.
Of course, I have some datasheets for 1030/31/s30 (unfortunately, not for 1029A). If you are interested in any of these schematics, I can send them to you (but don't be too greedy as I have to scan them first).
Regards
Re: Listening Impressions
We are using the matching sub. It's called the LSR12P. I like this sub a lot, but you can DIY one for less money. The nice thing about the sub is the input electronics. It allows you to fullfill a wide variety of set-up options without having to buy any accessories. Also, the cabinet is literally bulletproof with it's graphite and kevlar woven front baffle. If you do try to copy this one, good luck duplicating the front baffle. Thanks to the recent war, kevlar has become a little hard to get a hold of. (i.e. that's what they make bulletproof flack jackets out of) I think a great sub could be built using other, more readily available components. But, if you want a matching sub to go with your LSR25's, you won't go wrong with the LSR12P. Unfortunately, they are not being made by JBL at this time. JBL is currently re-designing the sub, and they are on indefinate back order. If you are thinking of copying the LSR12P, I can get you all of the electronic parts, but not the front baffle or the cabinet. Let me know.
Cheers,
Zach
pinkmouse said:
We are using the matching sub. It's called the LSR12P. I like this sub a lot, but you can DIY one for less money. The nice thing about the sub is the input electronics. It allows you to fullfill a wide variety of set-up options without having to buy any accessories. Also, the cabinet is literally bulletproof with it's graphite and kevlar woven front baffle. If you do try to copy this one, good luck duplicating the front baffle. Thanks to the recent war, kevlar has become a little hard to get a hold of. (i.e. that's what they make bulletproof flack jackets out of) I think a great sub could be built using other, more readily available components. But, if you want a matching sub to go with your LSR25's, you won't go wrong with the LSR12P. Unfortunately, they are not being made by JBL at this time. JBL is currently re-designing the sub, and they are on indefinate back order. If you are thinking of copying the LSR12P, I can get you all of the electronic parts, but not the front baffle or the cabinet. Let me know.
Cheers,
Zach
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