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Old 18th January 2011, 12:23 PM   #61
magma is offline magma  India
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Quote:
Originally Posted by Cristi View Post
I recommend LM4702 SAP15 amplifier, and power supply A350SMPS. for moderate output power levels ~ 100W this is a great combination.
hi cristi
thank you very much for your help
i would like to go for the SAP 15 as recommended and a speaker protection ckt

on the power supply part, i was leaning towards linear supplies because its easy to replace components where i live if a fault occurs
SMPS is difficult
 
Old 23rd January 2011, 03:34 PM   #62
tcpip is offline tcpip  India
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I was curious about using SMPS with high-quality Class B power amps.

AFAIK SMPS introduces high-frequency noise to the output rails, which then affect the sound quality of the power amp (I'm assuming ordinary Class B topologies which don't have extremely high PSRR specially at high frequencies). Is this correct?

If yes, can we take care of this by replacing the normal C with a C-R-C "pi" filter on each rail between the SMPS and the power amp's supply rails, where the value of each C will be equal to what one would normally use in a traditional PSU (e.g. 10,000uF/rail for a 100W Class B channel) and the R would be something like 0.5 Ohm 10-20Watt. Basically, I'm suggesting that for a 100W mono power amp, I'll put a 10,000uF capacitor block, then a resistor of 0.5 Ohm or so, then another 10,000uF capacitor block, on each rail.

Will this allow pretty much any SMPS, (e.g. you A350SMPS) to be used with any Class B amp?

Last edited by tcpip; 23rd January 2011 at 03:36 PM.
 
Old 23rd January 2011, 03:55 PM   #63
sangram is offline sangram  India
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Since Class B does not have a constant input current, I'm assuming a CRC will not be particularly effective and will either waste power at high outputs or be too low in resistance to have any effect.

I've used 0.1 ohm resistors in a similar configuration and there is extremely little difference.

Using good decoupling will help avoid some of the issues caused by spurious switching noise, though it may be possible to get a switching supply with lower than 10mV of ripple and noise - which is difficult for even a good linear supply to achieve. As always, the devil is in the details.
 
Old 23rd January 2011, 05:35 PM   #64
AndrewT is offline AndrewT  Scotland
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is the output from the smps already fitted with an LC filter?
A second LC filter will help, but I have no idea what performance to expect.
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Old 25th January 2011, 06:46 AM   #65
tcpip is offline tcpip  India
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Quote:
Originally Posted by sangram View Post
Since Class B does not have a constant input current, I'm assuming a CRC will not be particularly effective and will either waste power at high outputs or be too low in resistance to have any effect.
In realistic domestic use, Class B amps play at 1-5W RMS, and have a fairly high supply-line Zin, I would think. At very power levels, the PSU will see the amp as being almost straight-wire and will see the speaker impedance almost directly -- but at those power levels, who cares about small high-freq hash on the supply rails?

Quote:
I've used 0.1 ohm resistors in a similar configuration and there is extremely little difference.
I would expect this too. I guess the difference will be more audible with more back-to-basics topologies which have worse PSRR. For instance, I remember a very good 55WPC DIY amp from Australia which recommends a dual-mono PSU, and apparently it's been confirmed in listening tests that this makes a difference. I suspect the amp has PSRR on the lower side. So I guess the C-R-C pi-filters will make audible differences only in the very high-end cases or with low-PSRR amps.

Quote:
Using good decoupling will help avoid some of the issues caused by spurious switching noise, though it may be possible to get a switching supply with lower than 10mV of ripple and noise....
I was not hoping to reduce the magnitude of the ripple -- I just wanted to filter out the HF component from the ripple. Most Class B amps are quite immune to low-freq ripple of 10-20mV on the rails, I think.
 
Old 2nd June 2011, 04:15 AM   #66
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Cristi,

From photo of your website:
300W LME49810 is at output power of 170W/8Ω with 3pairs of BJT
500W LME49810 is at output power of 320W/8Ω with 5pairs of BJT

1) What is the BJT used?
2) For stereo power amplifier, 2 pcs are required. Do you provide a pair of Left & Right mirror symmetry PCB?
3) Do plan to make LME49830 + Mosfet?
 
Old 31st January 2012, 02:15 PM   #67
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Hi cristi,

Havnt spoken for some time, how are you?

Im looking for an amplifier for a pair of compression drivers that are 115db/1w.

I cannot use my ta3020v3d units I got from you a couple of years back, as the noise floor is too high for this extreme application- can you recommend an amp from your designs that would have the lowest noise floor at 0.1w??

Amp needs 20w+ output.
 
Old 1st February 2012, 03:09 PM   #68
Cristi is offline Cristi  Europe
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The lowest noise floor class AB amplifiers are the LME49810 based amps, 300W and 500W versions and the LM4702 based amps, SAP1x, followed by MOS-FET and Bipolar versions.
I remember that your TA3020 boards were v2, not v3d, at that time only v2 was available, TA3020v3d is one of the newest version, with improved performances and noise ratio.
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Old 6th September 2012, 07:30 AM   #69
back is offline back  Greece
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hello.

looking for amps to drive woofers in active system.

20-400hz.

is the 500watt lme 49810 "fast sounding" at this range?

i know "fast" is the wrong term for bass but i think you guys know what i mean.

i want really dry bass and not soft drum kicks.
 
Old 6th September 2012, 08:56 AM   #70
AndrewT is offline AndrewT  Scotland
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500W lme49810 !!!!!
What voltages are you planning to run at?
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