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Old 21st December 2012, 12:48 PM   #591
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Originally Posted by Stammheim View Post
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
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Old 21st December 2012, 03:34 PM   #592
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Quote:
Originally Posted by Stammheim View Post
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.
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Old 22nd December 2012, 02:06 PM   #593
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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
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Old 22nd December 2012, 03:26 PM   #594
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Originally Posted by Stammheim View Post
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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Last edited by doctordata; 22nd December 2012 at 03:41 PM.
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Old 23rd December 2012, 02:57 PM   #595
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Originally Posted by doctordata View Post
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

Last edited by Stammheim; 23rd December 2012 at 03:08 PM.
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Old 23rd December 2012, 04:20 PM   #596
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Originally Posted by Stammheim View Post
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,Many thanks,

Stammheim
Its normal, my 2092 amps put out even more carrier on the output.
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Old 23rd December 2012, 05:27 PM   #597
luka is offline luka  Slovenia
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Originally Posted by nigelwright7557 View Post
Its normal, my 2092 amps put out even more carrier on the output.
all oscillating amps do that, some less, some more, depends on the design
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Old 23rd December 2012, 09:22 PM   #598
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Originally Posted by luka View Post
all oscillating amps do that, some less, some more, depends on the design
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?
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Old 24th December 2012, 05:37 PM   #599
exflaco is offline exflaco  Armenia
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Luka could eliminate complete these carrier? like crest lt series?
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Old 24th December 2012, 05:49 PM   #600
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Originally Posted by Stammheim View Post
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

Cheers ,

Rens
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