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/11571687@N02/sets/72157603119448350/
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
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/11571687@N02/sets/72157603119448350/
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
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
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
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
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...
If the voltages are too high you could always consider downregulating...
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
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
Thanks Andrew,
I will give up with the big trasnformer but now I have a another possible option.
A friend of mine has two spare Atrim toroidal transformers. They are 240V with 2x12V secondaries. Since 18v is the minimum I am not sure if using one transformer per channel implies that the transformers could be considered as 24v (ie 12x2).
Thanks for your help, all this is new for me.
Regards
Antonio
I will give up with the big trasnformer but now I have a another possible option.
A friend of mine has two spare Atrim toroidal transformers. They are 240V with 2x12V secondaries. Since 18v is the minimum I am not sure if using one transformer per channel implies that the transformers could be considered as 24v (ie 12x2).
Thanks for your help, all this is new for me.
Regards
Antonio
Unfortunately 2x12 is too low, and although you could use them both as 0-24V transformers I wouldn't recommend doing this.
You are probably best getting a 2x25 160VA toroidal transformer. Rapid have them at quite a reasonable price.
The big capacitors should be reusable. The label on them unfortunately doesnt mean much but I am guessing they will be at least rated for 63v. They certainly look hefty enough! There are also plenty of nice parts in that amp that you could use.
If you are sure that the amp is not worth repairing, now would be a good time to strip it down and perhaps take some pictures of all the parts - we can then go from there.
You are probably best getting a 2x25 160VA toroidal transformer. Rapid have them at quite a reasonable price.
The big capacitors should be reusable. The label on them unfortunately doesnt mean much but I am guessing they will be at least rated for 63v. They certainly look hefty enough! There are also plenty of nice parts in that amp that you could use.
If you are sure that the amp is not worth repairing, now would be a good time to strip it down and perhaps take some pictures of all the parts - we can then go from there.
Thanks for the replies.
I have changed my mind. I think it would be a "crime" to get rid of the Sonographe Amp and turn the box into a GC just becasue one channel blew up. So I will store it until I have the time and the money to have it properly fixed in the future. It is a very good amp.
However, I am going to keep going with a GC project and I will get a new toroidal transformer.
So, going back to my original main question, can anyone share experiences or give specific tips to taylor a Gainclone specifically to fit the Jordans JX92s?
Many thanks
Antonio
I have changed my mind. I think it would be a "crime" to get rid of the Sonographe Amp and turn the box into a GC just becasue one channel blew up. So I will store it until I have the time and the money to have it properly fixed in the future. It is a very good amp.
However, I am going to keep going with a GC project and I will get a new toroidal transformer.
So, going back to my original main question, can anyone share experiences or give specific tips to taylor a Gainclone specifically to fit the Jordans JX92s?
Many thanks
Antonio
I'll be using both the LM3875 and LM1875 chips with JX92S's in the near future. The JX92S will dip down to about 5 ohms near DC and above the resonance until the inductance makes the impedance gradually rise to around 20 ohms at 20khz, so it's safe to assume that the minimum impedance the amp will see is around 5 ohms.
BWRX said:
Thanks BWRX,
Please let let us know how it goes when you try the Jordans with the LM3875.
In my case after reading tons of long threads I think I will go for the LM3886 and snubberized PSU using BrianGT kits (the Carlosfm design) and I will see how it goes
I would really like to go for p2p but I would need some time learning how to read schematics...and even how to solder properly (I would love to build in this way http://www.vikash.info/audio/p2plm3886/ but I might get in trouble if I try )
By the way www.chipamp.com has been off for a couple of days. Does anyone know what's going on??
Regards
Antonio
Antonio
If you want some practice soldering buy a big bag of cheap resistors and some stripboard. Its better to burn a track on a practice piece rather than your only PCB. Make sure the stripboard is shiny clean and grease free and off you go.
Scrap video players yield plenty of desoldering practice too and a low budget enclosure if prettiness and time to modify it is not an issue.
Good luck
John
If you want some practice soldering buy a big bag of cheap resistors and some stripboard. Its better to burn a track on a practice piece rather than your only PCB. Make sure the stripboard is shiny clean and grease free and off you go.
Scrap video players yield plenty of desoldering practice too and a low budget enclosure if prettiness and time to modify it is not an issue.
Good luck
John
Re: you got to be nuts!!!!!
Sakis,
Indeed I have no idea about amps but I am not nuts and as I said few messages above I have realized that I should not destroy the Sonographe and will try to have it fixed.
Actually, the idea of considering the possibility of using the case and parts of the Sonographe for another project actually came from another DIYer who evidently knows about this business and who kindly gave some guidelines here:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=121293
There are some problems to consider:
1-This model is sold from time to time for around 250 dollars on ebay and internet sites (that is 125 pounds) and I cannot see paying anything less than that to have it repaired in the UK and I do not have the knowldege to repair it myself.
2- I live in the most expensive city (and one of the most expensive countries) in the world where everything becomes disposable as fixing costs are ridiculous. I do not know any good and reliable person to repair it here and to send it somewhere else I would need to pay shipping costs and the amp is really heavy (Or could I send just the board??)
5- The parts that might have been damaged (the ones at the output stage but there could be more) are discontinued Mosfet transistors: numbers J115/Y7J and K405/YTG. Please let me know where to get them if you know. I have not found them anywhere. I have already asked Conrad Johnson for the schematic and I am waiting for it.
6- If new equivalent transistors have to be used I might have to change the ones on the other channel as well (cost??). Will equivalent transistors work the same or better but no worse? How can I know this without the knowledge or the equipment?
My fear is to end up paying few hundred $$$ and end up with a piece if equipment which delivers a sound not as good as before, which will be very likely the case if I end up in the hands of a dodgy repairer. I would not mind paying some good money if I trusted that the reapir will work perfect.
This is what I though putting the Sonographe in a closet , wait until I find the right person to repair it (or I learn to do it) and build a Gainclone provisionally (just for fun and to start learning).
If some one was ready to guide me remotely to make the diagnosis and help me to find where to get the parts (originals or substitutes), I will equip myself with a multimeter and soldering iron and will try to repair the Sonographe myself
. And I would learn in the process 
.
Regards
Antonio.
sakis said:
Sakis,
Indeed I have no idea about amps but I am not nuts and as I said few messages above I have realized that I should not destroy the Sonographe and will try to have it fixed.
Actually, the idea of considering the possibility of using the case and parts of the Sonographe for another project actually came from another DIYer who evidently knows about this business and who kindly gave some guidelines here:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=121293
There are some problems to consider:
1-This model is sold from time to time for around 250 dollars on ebay and internet sites (that is 125 pounds) and I cannot see paying anything less than that to have it repaired in the UK and I do not have the knowldege to repair it myself.
2- I live in the most expensive city (and one of the most expensive countries) in the world where everything becomes disposable as fixing costs are ridiculous. I do not know any good and reliable person to repair it here and to send it somewhere else I would need to pay shipping costs and the amp is really heavy (Or could I send just the board??)
5- The parts that might have been damaged (the ones at the output stage but there could be more) are discontinued Mosfet transistors: numbers J115/Y7J and K405/YTG. Please let me know where to get them if you know. I have not found them anywhere. I have already asked Conrad Johnson for the schematic and I am waiting for it.
6- If new equivalent transistors have to be used I might have to change the ones on the other channel as well (cost??). Will equivalent transistors work the same or better but no worse? How can I know this without the knowledge or the equipment?
My fear is to end up paying few hundred $$$ and end up with a piece if equipment which delivers a sound not as good as before, which will be very likely the case if I end up in the hands of a dodgy repairer. I would not mind paying some good money if I trusted that the reapir will work perfect.
This is what I though putting the Sonographe in a closet , wait until I find the right person to repair it (or I learn to do it) and build a Gainclone provisionally (just for fun and to start learning).
If some one was ready to guide me remotely to make the diagnosis and help me to find where to get the parts (originals or substitutes), I will equip myself with a multimeter and soldering iron and will try to repair the Sonographe myself
. And I would learn in the process .Regards
Antonio.
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