My design L20D IRS2092+IRFI4020H 200W8R

To be honest it's hard for me to compare... I'm currently powering 2 subwoofers in 2 different setups with the L25D's... They're obviously very powerful but I haven't had the opportunity to listen to them in full-range, nor have I had the need to really push them. I'm having a house party in a couple weeks so that should be a good test :).

Both of my systems are tri-amp'd and bi-amp'd so I've never had the opportunity to really listen to the amps in full-range... My next project will be some simple single, full-range driver speakers specifically for that purpose.
 
I am running 2 l25d boards. They are ocp'ing long before I expect them to. Checking the board against the reference schematic shows that it has the same resistors defining the current limiting as does the amp7s. Checking the transistor specs show that they have almost the same voltage consumption, so even though the board has twice as much transistor, the overcurrent limiting seems to be set to the same value. Of course, I assume the 20d and the 25d use the same heat sink. Maybe the heat sink is the limiting factor for the power output on this board. Maybe with a larger heat sink, the overcurrent limits can be set higher.
 
I recently completed an amp build centered around the LJM L25D class D modules. Pictures can be found over here in the class D photo thread. For the short period that I have listening so far I can say it sounds very good. I'm presently using it to drive a couple of very inexpensive bookshelf speakers (Insignia NS-B2111), so please factor that in. While it no match up against my Pioneer SC-05 HT amp with ICEpower modules, it holds its own very nicely.

While I personally like a somewhat 'brighter' high-end, the amp delivers. In addition, I think the mid-range is spot-on, and the soundstage seems a tad fuller than my class AB amp. The base also seems slightly tighter - at least with the Insignia's. A sub-woofer added to the lineup would obviously provide much fuller bass. The Insignia's have a surprising range and sound good with a range of music. With some well recorded country music, the amp sounds full of life, with a slight 'edgy-ness' to the sound. The 'twang' comes through loud and clear. Country music is a good test for the dynamic range of an amp and speakers. Plus the LJM modules seem to be dead quiet as I can't hear any noise at with my ear up to the speaker, and definitely not from my listening distance.

Overall, I'm very happy with how the amp turned out and the sound it delivers for a rather inexpensive solution.

Rick
 
How does something not match up at the same time that it holds its own?

Is that with the same speakers?

I'd expect the IRS2092's to sound every bit as good as the ICE amps.
Hi noah, Yes, using the same speakers. I can't say for sure, but I suspect there's much more circuitry involved in the SC-05 - even in DIRECT mode that Pioneer engineered in to optimize the B&O ICE amps. After all, you can't expect a $45 set of amp modules to compete at the same level sonically with a $2000 receiver. Don't get wrong, the L25D sounds very good indeed, but doesn't have the silky smooth and effortless sound characteristics of the ICE amps. I continue to be amazed at the sound of the ICE amps in my HT.

Rick
 
Hi Rick,

Just to be clear, you used the Pioneer's pre-outs feeding the L25's and compared the same source material and number of speakers?

Was your comparison sighted or blind?

Re the price, I wouldn't be surprised if Pioneer doesn't spend much more for ICE modules.

Anyway, I'll just have to see what I think when I get mine built, using Cristi's IRS2092-based CxD250's for L/C/R and CxD300's for surrounds.
 
2 questions (post box of ljm is sadly full)

I just have 2 questions to the community:
1) in one forum they change (reasonably) the first cheap input cap CP1 with 2 parallel 22uF Wima MKPs. I think the value could be too high because of limiting bass in signal. Can I take instead CP1 a MKT 6 uF ? I think it should work.

2) I have one 450 W torroidal with 2 x 42 VAC out and measured after power supply board about 61,5 VDC+. Is this eventually optimum because I read shortly ago that at higher supply voltages the L25D has some problems to handle 4 ohms speaker impedances.

Thanks

While it no match up against my Pioneer SC-05 HT amp with ICEpower modules, it holds its own very nicely.

Woww ! Did'nt know that Pioneer produced an amp with ICE Power boards. Strictly I am a pure Stereo Fan but despite that 90 % of it's channels are useless are outside my purposes it seems to rock ! One critical point overal about the ICE Power amps is: it's sounds slightly clinical but maybe a listener's adjustment issue.
 
Hi Rick,

Just to be clear, you used the Pioneer's pre-outs feeding the L25's and compared the same source material and number of speakers?

Was your comparison sighted or blind?

No. I did not use the SC-05 pre-out, driving the LJM. That was not my intention. If anything, I would have used the SC-05 amp-in connection, to remove the SC-05 pre front-end circuitry. My testing was not that scientific. This has only been sighted casual listening. I just hooked up the speakers to both and listened - not extensively either - yet - I might add. I've been using my newly finished Doug Self's 2012 preamp to drive the LJM. Same source and same number of speakers.
 
Hi guys,

I run the fresh built amps for few hours now. What I don't like is the heat from the resistors, although I run tthe L25D's with 60V only. Is there a better way by replacing these guys? Did anybody have problems with burnt resistors?

Thanks,

Stammheim

Yes, this is a known issue. Due to the higher rail voltages the resistors do run hotter. LJM chimed in and said it was all good, but others did not like it.

There has been previous discussion about this, somewhere in this monster thread. The end game is larger wattage ratings to lower the resistor heat. A post looked at the temps before and after, with real temp numbers
 
Hi guys,

I run the fresh built amps for few hours now. What I don't like is the heat from the resistors, although I run tthe L25D's with 60V only. Is there a better way by replacing these guys? Did anybody have problems with burnt resistors?

Thanks,

Stammheim

I'm running my L25D's @ 75v. I swapped the 2Watt resistors to 3W's. They still get pretty hot but I haven't had any problems.
 
Yeah, I've also read about the recomendation, but - as you write - the monster thread... I couldn't find it anymore...
I remember, somebody wrote about Mills resistors, but unfortunatelly it's not possible to get them in Germany...
So just replacing the 2W with 3W is OK?
Are there any bigger ones which are the optimum for this?
Many thanks, guys ;)
 
Yeah, I've also read about the recomendation, but - as you write - the monster thread... I couldn't find it anymore...
I remember, somebody wrote about Mills resistors, but unfortunatelly it's not possible to get them in Germany...
So just replacing the 2W with 3W is OK?
Are there any bigger ones which are the optimum for this?
Many thanks, guys ;)

3 Watts are OK , hot is hot for us , but for a resistor , 75 degrees is winter , most resistors have a max operating temp of 150 degrees C so if your PCB can cope with that , there's no problem .

Cheers ,

Rens
 
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3 Watts are OK , hot is hot for us , but for a resistor , 75 degrees is winter , most resistors have a max operating temp of 150 degrees C so if your PCB can cope with that , there's no problem .

Cheers ,

Rens

That's "cool" ;)
Thanks!!!

I got another issue. After I heared hum from the speakers (8x L25D's), I measeured the amps with my oscilloscope. The scope showed me a sine of 2,5V and 400kHz without having signal-in. It's funny, that any amp has the same sine, so it might be normal using the L25D's, or I might have an issue with my SMPS's (both SMPS800RE from Connexelectronics, both with the same result).
Did anybody measure the amps and can help me with comparing?

Many thanks,

Stammheim
 
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Do I get you right? Your speakers produce hum, too? I'll try to measure the SMPS's hum with some resistors, so without the hum from the amps. Doesn't anybody have similar experiences or some measurements?

Are threre any mods so solve it?

Your speakers are not able to produce any output at 400 khz and if they could you would not hear it anyway :D

Cheers ,

Rens