Best Gainclone configuration for Jordan JX92S Drivers - diyAudio
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Old 15th April 2008, 03:31 PM   #1
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Default Best Gainclone configuration for Jordan JX92S Drivers

Hi,

I blew up one channel of my Solid Sate amp and I'm thinking about building a Gainclone using the same case and power supply and other bits

http://www.flickr.com/photos/1157168...7603119448350/

I have made several searches trying to find recomendations in terms of best configuration for Jordan jx92s drivers and did not fiind anything concrete.

I am asuming that the GC works well with the jordans since 47 Laboratories main speakers (the Konus essence) use the Jordans.

As a reference, I'll use the amp exclsively for music (acoustic, jazz, etc), I do not mind very high volumes, but I DO LIKE a good and clear sound at LOW volumes.

Also, I am more for tight clean bass than low extenssion

I might be using a 3db BSC which affect the drivers response and efficencisy whiah are already on the low side (6 ohms 88db).

Any suggestion on chip type, configuration, transformer, caps etc or expereinces with Jordans and gainclones would be appreciated.

Thanks

Antonio

Ah! if someone knows the specs of the magnet shown in the photograph , please let me know (again I searched extensively and could not find anything about it).

Thanks again
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Old 15th April 2008, 04:29 PM   #2
gfiandy is offline gfiandy  United Kingdom
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You need to find out what the DC voltage on the PSU in your existing Amp is as this will help determine which chip amplifer is going to work with your existing PSU.

So long as you don't need high volumes you won't have much trouble with any of the National Chip amps. So it would be better to match to your PSU than to your speakers.

Regards,
Andrew
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Old 15th April 2008, 05:16 PM   #3
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Default Re: Best Gainclone configuration for Jordan JX92S Drivers

Quote:

Ah! if someone knows the specs of the magnet .... [/B]
Sorry I meant Transformer.

Thanks Andrew,

I am trying to get the schematic of the amp to see the transformer's specs. If I cannot get it I'll have it measured.

However, if adapting to the PSU becomes an issue/limitation, I will just buy the most appropriate one for the right configuration for my drivers since the best possible sound is the aim at the end.

Regards

Antonio
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Old 15th April 2008, 05:38 PM   #4
gfiandy is offline gfiandy  United Kingdom
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Hi,

Do you know what the origonal power specification of the amplifer was as we can approximate the transformer output from that.

Regards,
Andrew
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Old 15th April 2008, 06:06 PM   #5
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I'm not sure actually. I know it is 120 watts but I am not sure if it is per channel and cannot find anything on the internet.

Perhaps someone can help. It is a Conrad Johnson Sonographe SA 120 .

Regards

Antonio
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Old 15th April 2008, 07:18 PM   #6
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Andrew:

I found the amp's specs:
Power: 120 watts per channel RMS both channels driven into 8 ohms

Regards

Antonio
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Old 15th April 2008, 08:11 PM   #7
jaycee is offline jaycee  United Kingdom
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I noticed there are two sets of secondaries on the transformer. I'm guessing the red ones run the main outputs and i'll bet theyre 35-0-35VAC which is too much for a gainclone.

What's the specs of the big blue capacitors ?
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Old 15th April 2008, 08:25 PM   #8
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I'd definitely recommend getting yourself a multimeter or you'll be in real trouble if anything doesn't go perfectly smoothly. If you think you'll use it again, fluke seems to be the brand everyone knows and trusts but they are expensive. Maplin are currently doing one for 6 and its on BOGOF so 3 each! I got them and they work fine. Don't expect ultimate accuracy from it obviously but I have used it to measure plenty of voltages and resistances as I built my gainclone and the readings were where I was expecting them.

If the voltages are too high you could always consider downregulating...
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Old 15th April 2008, 08:50 PM   #9
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Thanks for your comments.

The capacitors say: 36 DE / 21000-600 C / 874L 4301

Maybe I should buy a new transformer anyway. That would be cheaper and safer.

Thanks for the tip about the multimeter. I'll go to maplin tomorrow.
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Old 16th April 2008, 01:12 PM   #10
gfiandy is offline gfiandy  United Kingdom
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Hi,

For a chip amp design more than about 50W is quite complex to achive. So if your amp was in the region of 120W the rails will be far to high. You could regulate but you would be dissipating huge amounts of power in the regulators making them difficult to design and very hot.

So I would recomend a new transformer you can keep the existing smoothing caps and rectifier (assuming they are still ok) as they willl be quite happy on the lower voltage.

Regards,
Andrew
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