"The Wire AMP" Class A/AB Power Amplifier based on the LME49830 with Lateral Mosfets - Page 90 - diyAudio
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Old 13th March 2012, 12:43 AM   #891
AP2 is offline AP2  Italy
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Originally Posted by IanAS View Post
Bias is related to number of devices. From what Owen measured I'm guessing it would be 720mA bias for 4 pairs of devices. Though we use less, only 400mA for 4 pairs and about 90V rails for the MOSFETs and my Meridian 605 amps use only 240mA for three pairs and are 63V so one of your SMPS would go OK in those M605 or if I 'cloned' them.

I'm not sure how to suggest an output current requirement. My pals Tanoy D7's apparently drop to 2 Ohms at places but are generally higher and about 93dB. A 6 or 8 MOSFET 300W/Channel Perreax amplifier gripped those adequately, mine also. It's not about the wattage, just low volume the benefit of that hulking brute is obvious. My larger speakers are about 6 Ohms and about 87dB. The lower the impedance the amp's PSU, output stage, mains supply, the more 'grip and wallop' the speakers deliver.
has already used a DPS-500 / S for this type of mosAmp (8 mosfets). up to 800mA bias,limited at + /-68V 20Amp repetitive peak. yes just brute fast..but one per amp.
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Old 13th March 2012, 01:07 AM   #892
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Quote:
Originally Posted by IanAS View Post
Bias is related to number of devices. From what Owen measured I'm guessing it would be 720mA bias for 4 pairs of devices.
i am confused.

didn`t owen measure 360ma with one pair?

i am just not sure if it`s for the pair or the single mosfet.
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Old 13th March 2012, 01:14 AM   #893
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Anyone feeling a bit like the attached picture?

Source - http://xkcd.com/386/
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File Type: png duty_calls.png (13.8 KB, 335 views)
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Old 13th March 2012, 01:17 AM   #894
IanAS is offline IanAS  England
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The current flows from one rail, through a N channel, through a P channel, to the other rail. That's one pair.

These double die Alfets have two dies in parallel in each. So two Alfets is two pairs.

One Alfet on it's own is no pairs, just two half's.

Each pair needs at least 80mA. Each die in each Alfet needs that minimum of 80mA.

I don't really recall, but I think Owen said 360mA for the working amplifier. That would be 180mA per pair, ie, 180mA for one die in each Alfet 'pair' and 180mA for the other die in each 'pair'.

That's as clear as mud! But the best I can do

Last edited by IanAS; 13th March 2012 at 01:19 AM.
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Old 13th March 2012, 01:23 AM   #895
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Originally Posted by IanAS View Post
The current flows from one rail, through a N channel, through a P channel, to the other rail. That's one pair.

These double die Alfets have two dies in parallel in each. So two Alfets is two pairs.

One Alfet on it's own is no pairs, just two half's.

Each pair needs at least 80mA. Each die in each Alfet needs that minimum of 80mA.

I don't really recall, but I think Owen said 360mA for the working amplifier. That would be 180mA per pair, ie, 180mA for one die in each Alfet 'pair' and 180mA for the other die in each 'pair'.

That's as clear as mud! But the best I can do
it`s ok.

i understand now but i didn`t know those are double.
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Old 13th March 2012, 01:31 AM   #896
IanAS is offline IanAS  England
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has already used a DPS-500 / S for this type of mosAmp (8 mosfets). up to 800mA bias,limited at + /-68V 20Amp repetitive peak. yes just brute fast..but one per amp.


With 68 we might run into clipping with friends with bigger low efficiency speakers in their soundproofed listening rooms but for my other pals and myself that might do (in a mono block driving a passive crossover) as these days I have keep the volume down a bit. If I get the active cross over sorted then I'd have to get another pair of SMPS I guess.

85 would be better though. Is that too much?

Last edited by IanAS; 13th March 2012 at 01:34 AM.
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Old 13th March 2012, 01:57 AM   #897
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With 68 we might run into clipping with friends with bigger low efficiency speakers in their soundproofed listening rooms but for my other pals and myself that might do (in a mono block driving a passive crossover) as these days I have keep the volume down a bit. If I get the active cross over sorted then I'd have to get another pair of SMPS I guess.

85 would be better though. Is that too much?
at 85volt you will run out of current at lower loads.

do you plan to add extra alfets?
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Old 13th March 2012, 02:02 AM   #898
IanAS is offline IanAS  England
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Quote:
do you plan to add extra alfets?
Yes. Actually 3 pairs and 4 pairs of single die devices.
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Old 13th March 2012, 02:06 AM   #899
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I think is better that you know well this smps,or ask table of voltage/power output
dps-500/S decrease 3V @750w(burst). not 15V
at 80V (3R) repetitive peak is 2kw.
at 68V (8R nominal) you have 750w (just when you up volume and is clean. (i suppose load decrease 3,2R with audio enveelope) tannoy or B&W or sonus faber..think other good full-range.
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Old 13th March 2012, 02:56 AM   #900
qusp is offline qusp  Australia
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uh oh, IanAS has started talking like the borg again, enlisting the weight of so many audiophiles behind his voice. me, i just have this one and this experience rather than many in parallel

also rather happy at this point to be noob

reads like we are all of a sudden talking about a different amp in this thread

Last edited by qusp; 13th March 2012 at 03:10 AM.
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