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Old 8th February 2009, 12:31 PM   #21
AndrewT is offline AndrewT  Scotland
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Quote:
Originally posted by Tripmaster
What is the formula to calculate the LM3886 power output?
read the datasheet and the application note and download National's spreadsheet.
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Old 9th February 2009, 07:34 PM   #22
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Quote:
Originally posted by Tripmaster
I am wondering if there will be enough power to drive my 8ohm 88db speakers.
A 1 W amplifier will be able to drive your speakers to 88 dB at 1 m listening distance. How many dB do you want to achieve at what distance from the speakers? And will the speakers be up to that task?

http://www.national.com/appinfo/audi...gn_Guide15.xls
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Old 9th February 2009, 08:22 PM   #23
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Quote:
Originally posted by pacificblue

A 1 W amplifier will be able to drive your speakers to 88 dB at 1 m listening distance. How many dB do you want to achieve at what distance from the speakers? And will the speakers be up to that task?

http://www.national.com/appinfo/audi...gn_Guide15.xls

Hi

I had a look at this spreadsheet last night, thanks for sending it anyway

I don't really get the chance to play my music loud for long...well not if the wife's at home

As you can see by the picture below the speakers are quite close. I intend to make some full range speakers soon so it wont be much of an issue.

Click the image to open in full size.


I am also planning to build a P2P LM3886 dual mono amp. Is there a preferred configuration bearing in mind I wish to use these inefficient speakers and Pedja's discrete power supply?

I am currently looking at designs on the following sites.

http://dogbreath.de/Chipamps/CopperAmp/CopperAmp.html and

http://myweb.tiscali.co.uk/nuukspot/decdun/

Richard
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Old 9th February 2009, 09:27 PM   #24
Nuuk is offline Nuuk  United Kingdom
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GC's will drive speakers with less efficiency but the consensus of opinion is that a GC really comes into its own (ie sounds very good) when it had an easy load.
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Old 9th February 2009, 09:42 PM   #25
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Nick

Would I run into any problems operating this amp with my speakers due to its lack of Zobel network.

http://dogbreath.de/Chipamps/ThreeRe...reeResAmp.html

Richard
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Old 9th February 2009, 09:48 PM   #26
Nuuk is offline Nuuk  United Kingdom
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Quote:
Originally posted by Tripmaster
Nick

Would I run into any problems operating this amp with my speakers due to its lack of Zobel network.

http://dogbreath.de/Chipamps/ThreeRe...reeResAmp.html

Richard
Try it and see. If you do, add a Zobel.
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Old 10th February 2009, 05:01 AM   #27
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One part of engineering is to provide protection against all possible imaginable faults. That does not mean those faults will ever happen, but Murphy's law tells us that they will happen, if you don't take precautions.

The three resistor amp (with four resistors according to the schematic) does not provide protection for a bunch of possible faults. Spikes from the source or attenuator (Rb missing), DC from the source (Cin missing), excessive DC offset (Ci or DC servo missing), oscillations (Zobel missing), RF interference (Cn missing),...
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Old 10th February 2009, 01:17 PM   #28
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Good afternoon Nick

I am currently using the SOAP pre-amp with my LM3886 and I also have a pair of Pedja’s discrete buffers from Justblair’s group buy a few months back (Built but currently unused)

Is there a schematic/parts list of Pedja’s chipamp circuit on your website?

Thanks

Richard
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Old 10th February 2009, 01:18 PM   #29
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Quote:
Originally posted by pacificblue
One part of engineering is to provide protection against all possible imaginable faults. That does not mean those faults will ever happen, but Murphy's law tells us that they will happen, if you don't take precautions.

The three resistor amp (with four resistors according to the schematic) does not provide protection for a bunch of possible faults. Spikes from the source or attenuator (Rb missing), DC from the source (Cin missing), excessive DC offset (Ci or DC servo missing), oscillations (Zobel missing), RF interference (Cn missing),...

You have a good point
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Old 10th February 2009, 01:22 PM   #30
Nuuk is offline Nuuk  United Kingdom
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Quote:
Originally posted by Tripmaster
Good afternoon Nick

I am currently using the SOAP pre-amp with my LM3886 and I also have a pair of Pedja’s discrete buffers from Justblair’s group buy a few months back (Built but currently unused)

Is there a schematic/parts list of Pedja’s chipamp circuit on your website?

Thanks

Richard
Yes there is Richard.
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