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Class D Switching Power Amplifiers and Power D/A conversion

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Old 28th October 2011, 08:06 PM   #51
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Location: Mountain View, CA
Quote:
Originally Posted by ljm_ljm View Post
I'll in my products indicate the LJM letters.
OK, thanks.

I'm still very interested in the answer to these questions:

1. Is it correct that with +/-60V the L15D gives 150w/8R and the L20D gives 200W?

Perhaps the numbers approximate, or at different distortion?

2. At the same +/-60V, what are their idle power dissipations?

Thanks
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Old 29th October 2011, 12:30 AM   #52
Bernie7 is offline Bernie7  Singapore
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Default New boards are updated

My later purchases of the L20D boards all come with 80v power caps and changeover to the bigger 2W resistors (3 per board).

My dc-coupled L20D approaches 200 hrs run in and seem to be still improving in sonics. Iirc ARC recommends 400 hrs or so on their Class D line which is IRS2092 based
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Old 29th October 2011, 12:43 AM   #53
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Quote:
Originally Posted by ljm_ljm View Post
I'll in my products indicate the LJM letters.
How can we buy your products?

Thank you.

Rod
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Old 29th October 2011, 03:18 AM   #54
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Originally Posted by nwboater View Post
How can we buy your products?
eBay - New & used electronics, cars, apparel, collectibles, sporting goods & more at low prices

L15D Digital Audio amplifier board IRS2092 IRFI4019H | eBay

their stores also have the L20D
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Old 29th October 2011, 03:38 PM   #55
ljm_ljm is offline ljm_ljm  China
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Quote:
Originally Posted by noah katz View Post
OK, thanks.

I'm still very interested in the answer to these questions:

1. Is it correct that with +/-60V the L15D gives 150w/8R and the L20D gives 200W?

Perhaps the numbers approximate, or at different distortion?

2. At the same +/-60V, what are their idle power dissipations?

Thanks
In theory, the same voltage +-60 V.
Their output power will be the same.

But in +-60 V voltage and L20D will be more security. Not quite a higher voltage of the transistor and capacitors.
Also includes the resistance of the current size and power control.
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Old 2nd November 2011, 05:52 PM   #56
ranger3 is offline ranger3  United States
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Quote:
Originally Posted by trevmar View Post
True, the widerange speakers I stuck to my ear are 84dB/W, Peerless 830983, But they cover from 40Hz to 20K, as long as you don't want a lot of volume... and as long as you use a MiniDSP to equalize them

These days I myself would select a higher power, highly efficient amp (like the L20D) and a wider range, very low distortion, speaker

Still, 113dB/W is a pretty impressive achievement
.

Trevmar,

Can you point me to a thread that has the specs. on those PVC speakers you have in the photo.

I'd be interested in build a pair.

Thanks,

Allen ...
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Old 4th August 2012, 08:00 PM   #57
redjr is offline redjr  United States
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Join Date: May 2011
Location: Danbury, CT
Quote:
Originally Posted by ljm_ljm View Post
In free time I draw a picture, may help.

By the way, power and voltage is connected.

L15D work 40 to 60 V DC (+-)125-150 W8R
L20D work DC 60-80 V (+-)200-250 W8R

According to from already the need to choose the better.
You have any free time?
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Old 4th August 2012, 08:09 PM   #58
redjr is offline redjr  United States
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Join Date: May 2011
Location: Danbury, CT
trevmar - Thanks so much for your testing and insight with the L20D amp and furthering this discussion and knowledge along. I'm just now reading this thread and others on the ljm class D design. As has been requested by a few other readers, it would be nice for someone to summarize what hacks/mods are essential, and what ones are so esoteric as to not make much of a difference in a typical listening environment.
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Old 6th August 2012, 01:46 PM   #59
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Location: Lisboa
Yesterday I assembled a double L20D in substitution of a T2.
The difference is audible, from my first impression beeing the TK2050 more "analytic"
or colder in the mid-highs than the IRS2092, the IRS2092 more "solid" or warmer in the mid-basses than the T2.

In the meantime I've put in place my old and faithful Denon SS amp and no, no comapraison, muddy bass and foggy stage.

My perfect setup would be a biamped system: a T2 for the tweeters (maybe with a waveguide), a couple of L20D to drive the woofers, all over an active Xover.
I think I've found my next project. Stay tuned.
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Old 14th August 2012, 05:17 PM   #60
dgta is offline dgta  United States
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Trevmar or any others who have used the LJM boards:

It appears that the LJM does not have any of the protections included on the original IRAUDAMP7S board. So why choose this board? It seems a bit odd to me, when the IR board is widely available:
L15DX2 IRS2092 CLASS D AMPLIFIER IRAUDAMP7S 125-500W | eBay

LJM, why no protection?
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