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LJM Audio

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#421
germanach said:
Hi. Can i use this: New DC 50V Power Supply 8 4A 420W Switching Power Supply with CE | eBay
to source the L15D ? Its about $50
http://www.ebay.com/itm/New-DC-50V-...953?pt=LH_DefaultDomain_0&hash=item27fa6b5629
Click to expand...

http://www.diyaudio.com/forums/vendors-bazaar/180625-irs2092-iraudamp7s-irfi4019.html
L15D is suitable for the voltage. Recommend + -50V DC voltage.
If the switch power supply board power and transformer + filter capacitor, equal to the price, so I will choose the transformer and filter capacitor.
 
#423
doctordata said:
I use 5 L15D amps with a decent SMPS from Connexelectronics with a few minor improvements on the L15D as described elsewhere in this forum and the soundstage is far from narrow with a fantastic low end.

Cheers ,

Rens
Click to expand...

Hi Rens, what did you do to get that low end ? My L15D Pro's sounded quite flat when I first ran them. But after a couple of days they seem to have gotten better in the low end although I would like them to be a bit more punchy. Is there an easy tweak to achieve that ? I am using a 45v/300w SMPS from Connex.

Thxs

R
 
#425
r100 said:
Hi Rens, what did you do to get that low end ? My L15D Pro's sounded quite flat when I first ran them. But after a couple of days they seem to have gotten better in the low end although I would like them to be a bit more punchy. Is there an easy tweak to achieve that ? I am using a 45v/300w SMPS from Connex.

Thxs

R
Click to expand...

I changed the standard 220uF/63V rail buffers with 820uF/63V Panasonic Low ESR ones ( RS 571521 ) they fit on the board and this is audible as a tighter Bass .The standard input caps were changed by Elna SilmicII 22uF/63V . At first I was disappointed by this mod , found the sound a bit dull , but after a couple of hours the sound opened up and after a week or so it sounded much better as the originals .I also added 10.000uF/63V capacitors to each rail at the PSU ( that's for 5 amps in my case , so 3300uF or 4700uF will do for 2 amps or you might trip the overcurrent protection on the Connex SMPS )

Cheers ,

Rens
 
#426
r100 said:
Hi LJM, do you supply a upgrade kit with the new components for the L15D Pro ? What difference do the new components make to the sound quality ? Thank's.

Greetings

R
Click to expand...

I'm sorry I have no way to provide a package for the previous products, upgrade.
And once the product does not appear any defects. But now the capacitor after the upgrade, the performance is improved.
To reduce the distortion of capacitor, capacitor temperature decrease, increase the service life of the capacitor.
 
#427
ljm_ljm said:
I'm sorry I have no way to provide a package for the previous products, upgrade.
And once the product does not appear any defects. But now the capacitor after the upgrade, the performance is improved.
To reduce the distortion of capacitor, capacitor temperature decrease, increase the service life of the capacitor.
Click to expand...

LJM,

Are you using these polymer caps on your L20D amps now? I am thinking of getting a pair from you TB store.

Regards,
 
#428
sozkarabacak said:
An externally hosted image should be here but it was not working when we last tested it.


An externally hosted image should be here but it was not working when we last tested it.
Click to expand...

I have never sold a red board products. All red for the fake and shoddy.
I use the circuit board are all military enterprises production, gold plating process.
All the components are the need for strict testing, the selection of the best performance products.
 
#429
ljm_ljm said:
I'm sorry I have no way to provide a package for the previous products, upgrade.
And once the product does not appear any defects. But now the capacitor after the upgrade, the performance is improved.
To reduce the distortion of capacitor, capacitor temperature decrease, increase the service life of the capacitor.
Click to expand...

Ok, I understand, no problem. Do you have a time frame for the new version ? Thank's very much.

PS. I have a L15D Pro. Can I replace the default capacitors with the OSCON ones as in the picture below ?
 

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#430
doctordata said:
I changed the standard 220uF/63V rail buffers with 820uF/63V Panasonic Low ESR ones ( RS 571521 ) they fit on the board and this is audible as a tighter Bass .The standard input caps were changed by Elna SilmicII 22uF/63V . At first I was disappointed by this mod , found the sound a bit dull , but after a couple of hours the sound opened up and after a week or so it sounded much better as the originals .I also added 10.000uF/63V capacitors to each rail at the PSU ( that's for 5 amps in my case , so 3300uF or 4700uF will do for 2 amps or you might trip the overcurrent protection on the Connex SMPS )

Cheers ,

Rens
Click to expand...

Thank's Rens. I'm glad you have also experienced the "opening up" over time of the this amp. I thought I was hearing things but the SQ definitely did change (to the better ). So, I am really happy with the sound at the moment even without any mods. But am looking forward to doing some anyways 😀
 
#432
ljm_ljm said:
May have to tell you a good news. I spent a lot of time to order a OSCON capacitor.
The specification is 25V22UF it is for L15D, L20D, L25D customized products.
Its parameters is very good, about 20-50 times of ordinary electrolytic capacitor. The value of loss of about 0.016% 1KHZ.
Its price is very high, about 5 times that of ordinary capacitor. I was ordered to it but. Will appear in future products.
Click to expand...

Hi LJM,

Sorry for being such a noob but I cannot find the exact blue version of this capacitor, can I use an alternative OS-CON capacitor like this one ?

Thank's
 
#435
I have spent couple of hours to read this thread but haven't found the answer for my question. Here it is: I have a transformer and a PS board from an old amp supplying +-50V and am thinking about using 2xL15D bridged to build an instrument amplifier for my bass.
Can anyone tell me is it something I can do using the boards of ljm_ljm? I mean without external parts for reverse phase input of the 2nd half of the bridge.
THX
 
#436
nqmad said:
I have spent couple of hours to read this thread but haven't found the answer for my question. Here it is: I have a transformer and a PS board from an old amp supplying +-50V and am thinking about using 2xL15D bridged to build an instrument amplifier for my bass.
Can anyone tell me is it something I can do using the boards of ljm_ljm? I mean without external parts for reverse phase input of the 2nd half of the bridge.
THX
Click to expand...

You need a phase inverter for one of the amps .
see my post : http://www.diyaudio.com/forums/clas...-irs2092-irfi4020h-200w8r-38.html#post2951879

Cheers ,

Rens
 
#437
Many thanks Rens, very useful post.
Any experience using such amp for bass? I am hoping the sound quality (especially for the low end) is good enough.
I would put the amp and ps in my 1x15 cabinet to avoid carrying the amp as an another "box" and would feed it from an external preamp on my pedal board.
Should I go for the Pro version with the speaker protection or the v3 is good enough for this?
Thanks
 
#438
nqmad said:
Many thanks Rens, very useful post.
Any experience using such amp for bass? I am hoping the sound quality (especially for the low end) is good enough.
I would put the amp and ps in my 1x15 cabinet to avoid carrying the amp as an another "box" and would feed it from an external preamp on my pedal board.
Should I go for the Pro version with the speaker protection or the v3 is good enough for this?
Thanks
Click to expand...

No experience for bass only , I use them full range with 15" Tannoy's and the bass is impressive !
I would go for the Pro version because the build in DC protection and the 2 separate FET's. vs one dual FET in the L15D. The L15D has no protection
Make sure you use at least 10.000uF capacitors per rail .

Cheers ,

Rens
 
#439
doctordata said:
No experience for bass only , I use them full range with 15" Tannoy's and the bass is impressive !
I would go for the Pro version because the build in DC protection and the 2 separate FET's. vs one dual FET in the L15D. The L15D has no protection
Make sure you use at least 10.000uF capacitors per rail .

Cheers ,

Rens
Click to expand...
Thanks Rens. I've just ordered an assembled pair (pro) on ebay from china. 🙂
Hope I got it soon and if everything goes well with the installation I am going to report my impressions.

Cheers
 
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