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Old 7th March 2002, 08:35 PM   #1
km is offline km
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Default lc audio the end and thd

hi.

did any of you measure thd data on this amp? or do you know of such measured specs (website , magazine,...)

we have a bit of discussion (in denmark) about this, partly because of the claim form this site;
http://www.geocities.com/ResearchTriangle/Node/2356/

it seems that simulation on a model of the amplifier gives thd results 200 times worse than those published by lc audio.

a bit of facts would be helpfull for sure (enough bs and crap allready ,,,,)

thanks - k madsen - cad audio dk
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Old 7th March 2002, 08:55 PM   #2
sonnya is offline sonnya  Denmark
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The harmonics needs to be 100dB down... No way possible with a load but with no load a 1Vrms out.. could be possible.

They do not tell what level and load the have test this distortion level. I have been asking it myself.

Have you tried a sim without a load?

Sonny
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Old 7th March 2002, 09:14 PM   #3
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Default Who says?

km,

You represent a competitor of LC Audio in the same (very small) country. You have posted some opinions on LC Audio. Perhaps you should leave others to comment on your competitors?


BTW: I do not own any LC Audio products other than their soft start circuit.

Petter
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Old 7th March 2002, 09:24 PM   #4
km is offline km
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hi.

what opinions petter?

i did not write the site i refer to, just asked a few questions and got a bit curious.

my opinion about lc audio and their products is not the issue here and i dont think i have said anything about that , we do not sell hifi amplifiers and such and we are not directly competitors but anyway , ,,,(and i agree for sure)....

i still think i have a valid question and i actually ask here to see if anybody can help with a bit of facts opposed to the rubbish you can see around.

i also think that a comparison of simulated specs and measured specs would be helpfull, just noticed a recent thread about this and mentioning the amp in question.

k madsen - cad audio dk
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Old 7th March 2002, 10:12 PM   #5
sonnya is offline sonnya  Denmark
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Have you compared the Schematic the site you have linked to with the one from LC Audio.

If you question is made from comparing the measurement from there site with the russian sim.

Maybe you should do a sim yourself (Not to be hard on you), before making any comments.
They do not use the same transistors like the ones in the sim.

So it cannot be compared before the sim is equal to the real world.

Sonny
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Old 7th March 2002, 10:25 PM   #6
km is offline km
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hi.

i did read that the driver transistors is possibly different (the original ones could not be identified).

apart from that i think the schematic is the same.

i do not wish to make a sim , the reason for my posting (if thats unclear in any way) is to ask if anybody here did in fact make thd measurement on actual amplifier.

i think it would be interesting to compare the measured specs with the simulated ones (and if you like to the specs published by lc audio).

if a small difference was detected i dont think that would be interesting , but the claimed 200x is what caused my curiousity.

thd figures is simulated and published for -3 db level , so they do in fact tell what levels are used.

regards k madsen - cad audio dk

ps. i/we could measure thd on an amp we borrowed but i would prefer an (or several) "outsiders".
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Old 7th March 2002, 10:37 PM   #7
sonnya is offline sonnya  Denmark
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I didn't find level spec. as you did but okay then i looks strange.

You wrote :

I do not wish to make a sim , the reason for my posting (if thats unclear in any way) is to ask if anybody here did in fact make thd measurement on actual amplifier.

It is clear .. sorry for the reply.

You wrote :
ps. i/we could measure thd on an amp we borrowed but i would prefer an (or several) "outsiders".

I really do not understand you.. I think You do have all the equipment to do this. Why not satisfy your couriosity!?

Sonny
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Old 8th March 2002, 01:46 AM   #8
grataku is offline grataku  United States
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SonnyA and Petter,
km asked a simple, legitimate question. If you don't know the answer or have nothing useful to contribute other than strirring the sand in the water please move on to the next thread. Thank you!
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Old 8th March 2002, 06:57 AM   #9
ergo is offline ergo  Estonia
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Hey guys.

I hadn't seen the thread til now.....

Anyway, I own The End Millennium kit based amp. I will try to make the measurements this weekend. I can do it with 4 and 6 ohm load and I quess I will make them at 1W and then at max power (if my dummy load can take it) or as high of a power as possible.

Do you have any special requests of the types of tests. My setup is limited to audio band, but I can make THD and IMD measurements with FFT analyses and visible spectral content (SpectraLab)

Ergo
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Old 8th March 2002, 08:46 AM   #10
km is offline km
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hi.

for best comparisons with simulated specs it would be great if you can measure at -3 db (related to full output).

i think specs for 4 ohm and 8 ohm would be just fine.

additional specs would of course be most welcome.

on the site i referred to you can find specs for different power levels (see under power amplifiers without negative feedback).

i shall look forward to see what you come up with.

k madsen - cad audio dk

ps. grataku i think you would be amazed to see the crap i got from asking same question locally
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