Hi,
I've been toying with the idea of making self powered studio monitors for some time, since I heard of the Gainclone, I've been Wondering how small the amp can be made?
The whole cab could be pretty small. It could have an 8" fostex driver. If you needed a heatsink, you could have the whole amp mounted inside the back panel (like some crossovers are) with the heatsink integrated into it and coming out the other side.
Of course it'd have to be shielded, or use a shielded speaker.
If you're worried about long line level runs picking up noise, you could build a balanced GC and use XLR inputs for a really pro setup.
By the way, has anyone attempted a GC at +4 dBu line level?
Just some musings. I might try it once I have a good homebrew speaker cab. I'm working on that one now.
-Erik.
P.S. I just thought I'd edit this piece and add the idea that this would be the ultimate in keeping with short lead lengths the GC likes in order to sound good. It would only be inches from the speaker driver. Very little signal loss. And there's the benefit of being able to tweak the amp and speaker response together so they are matched well. Some kind of built in eq filters perhaps to account for any dips or peaks in signal response of the driver in that particular enclosure.
Lastly, the use of a Fostex driver like the FE206E or FE207E (shielded) eliminates the need for a crossover as they are relatively cheap good sounding full range drivers. Again, more clutter out of the signal path for the ultimate fidelity.
I've been toying with the idea of making self powered studio monitors for some time, since I heard of the Gainclone, I've been Wondering how small the amp can be made?
The whole cab could be pretty small. It could have an 8" fostex driver. If you needed a heatsink, you could have the whole amp mounted inside the back panel (like some crossovers are) with the heatsink integrated into it and coming out the other side.
Of course it'd have to be shielded, or use a shielded speaker.
If you're worried about long line level runs picking up noise, you could build a balanced GC and use XLR inputs for a really pro setup.
By the way, has anyone attempted a GC at +4 dBu line level?
Just some musings. I might try it once I have a good homebrew speaker cab. I'm working on that one now.
-Erik.
P.S. I just thought I'd edit this piece and add the idea that this would be the ultimate in keeping with short lead lengths the GC likes in order to sound good. It would only be inches from the speaker driver. Very little signal loss. And there's the benefit of being able to tweak the amp and speaker response together so they are matched well. Some kind of built in eq filters perhaps to account for any dips or peaks in signal response of the driver in that particular enclosure.
Lastly, the use of a Fostex driver like the FE206E or FE207E (shielded) eliminates the need for a crossover as they are relatively cheap good sounding full range drivers. Again, more clutter out of the signal path for the ultimate fidelity.
Its been done. In fact you can get Alesis amps from www.apexjr.com for $50 each wit a LM3886 chip driving the woofer and a LM2976 chip for the tweeter.
Attachments
Do they sound as good as the homebrew GC?
Yeah, but are they using the GC circuit? I thought that commercial use of the design would be forbidden since it's so close to the original Gain Card, no?
It's a neat little amp unit. Looking at the pic, I'm really impressed with how small it is.
I can't help but think that a homebrew unit could be made custom to suit the driver and cabinet and thus sound better.
Thanks for the link!
-Erik.
Yeah, but are they using the GC circuit? I thought that commercial use of the design would be forbidden since it's so close to the original Gain Card, no?
It's a neat little amp unit. Looking at the pic, I'm really impressed with how small it is.
I can't help but think that a homebrew unit could be made custom to suit the driver and cabinet and thus sound better.
Thanks for the link!
-Erik.
take in one step further... amps in the speaker boxes, and the powersupply external.. or was that the idea in the first place? lol
EDIT:
actually... thats not such a bad idea... perhaps I should do it for my towers... I was gunna have to make an amp anyway... but if all I have to make a box for is a couple of transformers, it simplifies things quite abit.. and the amp shouldn't displace much space in the boxes at all, cos the heatsink would be external, and the rest would fit in the thinkness of the MDF pretty much... hmm.. it also simplifies Bi or Tri amping quite abit... hmm hmm... worth a try do you guys think? hehe
or was that the idea in the first place? lolEDIT:
actually... thats not such a bad idea... perhaps I should do it for my towers... I was gunna have to make an amp anyway... but if all I have to make a box for is a couple of transformers, it simplifies things quite abit..
and the amp shouldn't displace much space in the boxes at all, cos the heatsink would be external, and the rest would fit in the thinkness of the MDF pretty much... hmm.. it also simplifies Bi or Tri amping quite abit... hmm hmm... worth a try do you guys think? hehe
I tried GC with long cables and the very short ones and didn't notice any difference, really. But, if the drivers and crossovers are not chosen properly, the degradation of sound will be substantial. The way you mount the whole GC module inside the speaker (and possible vibrational influence) will have much bigger impact on the sound than the advanatge achieved with using short speaker cables. Although it may seem weird, the closer the PS to the amp, the better. PS wires influence the sound the same way as speaker wires
>>Yeah, but are they using the GC circuit? I thought that commercial use of the design would be forbidden since it's so close to the original Gain Card, no?<<
This is not a proprietary design, but comes out of National's application notes, so anybody is free to use it, without infringing any copy rights and patents. The only issue may be with a similar case design, but even here, it's still questionable.
>>Yeah, but are they using the GC circuit? I thought that commercial use of the design would be forbidden since it's so close to the original Gain Card, no?<<
This is not a proprietary design, but comes out of National's application notes, so anybody is free to use it, without infringing any copy rights and patents. The only issue may be with a similar case design, but even here, it's still questionable.
And you thought you had vibration problems before?
I am trying to see the advantages to this set up. It will regardless still take long leads from a pre or some sort of controlling unit.I believe any advantages would be lost in the greater vibration unless some sort of super isolaton method could be developed.
OK lets look at some methods.
Either an IR or RF controller.RF would be better.It would take a dual P/S.Or make the whole thing RF controlled with a central transmitter with the sources going into it and have the output of the central transmitting to 2 recievers(each channel) that way no wires.But then you would be subject to stray RF signals.
ron
OK as an after thought an optical cable?I have used them in the past but strictly as a low state/high state controller, i have no idea as to how well they would transmit an analog signal.
I am trying to see the advantages to this set up. It will regardless still take long leads from a pre or some sort of controlling unit.I believe any advantages would be lost in the greater vibration unless some sort of super isolaton method could be developed.
OK lets look at some methods.
Either an IR or RF controller.RF would be better.It would take a dual P/S.Or make the whole thing RF controlled with a central transmitter with the sources going into it and have the output of the central transmitting to 2 recievers(each channel) that way no wires.But then you would be subject to stray RF signals.
ron
OK as an after thought an optical cable?I have used them in the past but strictly as a low state/high state controller, i have no idea as to how well they would transmit an analog signal.
It must work or it wouldn't've been done before, right?
Wow.
That's some pretty hardcore engineering. None of that was necessary for the Alesis.
Is all the isolation necessary because of the Gainclone's sensitivity to vibration in particular? Or is any amp going to be this way?
It begs the question how did Alesis achieve a working amplifier as depicted in JCoffey's post -second from the top?
I had envisioned a high output current balanced preamp or a distribution amplifier as the device which would drive the line to the powered monitor. That would be consistent with a pro studio setup.
ron clarke said:
Wow.
That's some pretty hardcore engineering. None of that was necessary for the Alesis.
Is all the isolation necessary because of the Gainclone's sensitivity to vibration in particular? Or is any amp going to be this way?
It begs the question how did Alesis achieve a working amplifier as depicted in JCoffey's post -second from the top?
I had envisioned a high output current balanced preamp or a distribution amplifier as the device which would drive the line to the powered monitor. That would be consistent with a pro studio setup.
The Alesis M1 amp boards really don't sound that great. They don't have much punch, and the sound stage and depth of field is lacking. If you want to check out a better implementation of the "chip amp in a monitor," check out the JBL JSR25P's. They use a single LM3886 for the tweeter, and two LM3886's for the woofer. They sound much better than the Alesis amps and the circuitry is much simpler. here is a link to the schematics:
http://www.jblproservice.com/pdf/LSR%20Series/LSR25P.pdf
I hope this helps.
Cheers,
Zach
http://www.jblproservice.com/pdf/LSR%20Series/LSR25P.pdf
I hope this helps.
Cheers,
Zach
JBL/Alesis: What isolation?
OK, so I've looked at the JBL and the Alesis Schematics, now, and I don't see any super duper isolation techniques implemented, and no optical cable interface or the like. Just your standard fare: solidly mounted, XLR connected goodness.
So, why all the concerns with vibration etc...?
Am I missing something? These are chip amps just like the GC circuit.
-Erik.
OK, so I've looked at the JBL and the Alesis Schematics, now, and I don't see any super duper isolation techniques implemented, and no optical cable interface or the like. Just your standard fare: solidly mounted, XLR connected goodness.
So, why all the concerns with vibration etc...?
Am I missing something? These are chip amps just like the GC circuit.
-Erik.
The easy way out is just a good pre amp. I am using a TDA1524a kit with 12 batt supply which is intergrated into the amp case but it will help with the added distance of a pre to the amps (being mounted on or in,not reccomended,of the speakers).The difference with my pre is i install trim pots on the balance,bass ,trebel and taylor the countour slope with another trim pot(my horns need a little help at low volumes).The only knobs on the amp face is the volume and the selector knobs, i leave it on 24/7.The reason i chose the TDA1524a chip is the fact that the pots are not in the signal path.With battery power on the pre and the amps ,IGC LM3875T,the sound is exceptional driving my fostex FE103e horns.
ron
ron
Re: It must work or it wouldn't've been done before, right?
It all depends on what you are expecting from the amp. You can attach the chip to woofer's magnet or basket (pretty smart as heatsinging problems are gone), and it would work, but performance wouldn't be probably nothing to wright home about.
Now, I'm talking about kind of performance that rivals most any amp on the market (in it's class) and this would be hardly achieved if amp is integrated in a speaker. Whatever Alesis did, doesn't even come close to what can be achieved.
e.lectronick said:
It all depends on what you are expecting from the amp. You can attach the chip to woofer's magnet or basket (pretty smart as heatsinging problems are gone), and it would work, but performance wouldn't be probably nothing to wright home about.
Now, I'm talking about kind of performance that rivals most any amp on the market (in it's class) and this would be hardly achieved if amp is integrated in a speaker. Whatever Alesis did, doesn't even come close to what can be achieved.
If you want to see clutter in a signal path , just look at most commercial amps.
At first i was very doubtful about the "buffered" GC, but i have to admit that the active pre chip sounds better than my inactive pre which was a shunted 50K alps pot.
I am really waiting for a report on a batt powered tube buffer before i try that avenue.
ron
At first i was very doubtful about the "buffered" GC, but i have to admit that the active pre chip sounds better than my inactive pre which was a shunted 50K alps pot.
I am really waiting for a report on a batt powered tube buffer before i try that avenue.
ron
correct me if i am wrong but:
i think that it would be better to have the amplifer as close to the course as possable, as a low power, low voltage signal sould degrade more then an amplifed signal going to the speakers
therefore it would be better to try and get the signal path BEFORE it is amplfied as short as possable for a better quality of signal - this would require all the amplifers to be in one box attached very closly to the source
i think that it would be better to have the amplifer as close to the course as possable, as a low power, low voltage signal sould degrade more then an amplifed signal going to the speakers
therefore it would be better to try and get the signal path BEFORE it is amplfied as short as possable for a better quality of signal - this would require all the amplifers to be in one box attached very closly to the source
I use a somewhat GC to power my "active" speakers. I couldn't do it any other way, for my girlfriend always complained that all my amps and preamps were to ugly (I found them nice, she just thinks stereos are stupid) so I moved the amps into the speakers. Also the amps have built in filters that account for the dipole rolloff and there is motion feedback from the woofer which I would have rather not run all the way to the amp in a chasis far away. For me it worked out very well, when building an amp in a speaker you have lots of room to layout things exactly how you want it, can omit any insulation between the transistors and the heatsink (I use dipoles, with wings, so it doesn't heat up a box, and I have material over the open sides to keep out cats and fingers, so there's no zapping), there are advantages and disadvantages, weigh which are important to you. I very much like my active speakers now, yet they're constantly improving...
JBL built some kind of cool and often imitated PA cabinets that weren’t too far off the mark from this. To optimize construction efficiency, the LF spider, heat sinks, and large portions of the cabinet were cast out of a large piece of aluminum alloy. They had the casting on display at some trade show a few years back. It was quite impressive. I had to stare at it a long time to completely comprehend what I was looking at. These were for PA cabinets, I haven’t heard of anyone using a set in the living room.
e.lectronick,
Have you looked at (or listened to) the Genelec 1031A and Meyer HD-1's?
Da5id4Vz said:
I have listened to the Genelecs. They had them at Sear Sound in NYC where I interned many years ago. Very nice sound. Loud, punchy, tight and clear. They had incredible detail. I haven't heard the Meyers however.
With successful active nearfields like the Genelec and others, I know there are ways to make the idea work as a homebrew project. It might even be worthwhile to build them and sell them on Ebay or something as custom alternatives to the super expensive high end monitors being sold by those companies.
-Erik.
The HD-1's sound a lot like the Genelec's, very good. They do however sound different. I found that material mastered on one doesn’t necessarily find the sweet spot of the other.
I remember exploring the insides of both. The Genelec has defiantly got a bunch of chip amps in it. It must have been too early in the morning, too long ago when I explored the HD-1. I can’t remember anything about the insides.
I do remember that I loved them both, and dream of having some for my home.
-Dave
I remember exploring the insides of both. The Genelec has defiantly got a bunch of chip amps in it. It must have been too early in the morning, too long ago when I explored the HD-1. I can’t remember anything about the insides.
I do remember that I loved them both, and dream of having some for my home.
-Dave
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