Transistor Question

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pacificblue

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Tripmaster

Tripmaster

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Joined 2008
pacificblue said:

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/audio/files/Overture_Design_Guide15.xls
Click to expand...


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 :bawling:

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.

lounge.jpg



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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pacificblue

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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),...
 
Tripmaster

Tripmaster

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Joined 2008
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
 
Tripmaster

Tripmaster

Member
Joined 2008
pacificblue said:
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),...
Click to expand...


You have a good point:)
 
Tripmaster

Tripmaster

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Joined 2008
Arghhhhh...my brain is likely to explode if I look at anymore P2P designs!!!!

I'm a little confused regarding Pedja's amp/buffer schematic.

If I were to opt for the 3886 P2P on your site what value resistor would you recommend for a Pedja's 27v supply?

'Pin 8, the mute pin is connected to the negative supply pin (pin 4) via a resistor. The resistor value depends on the rail voltage and for 35-37 volt rails a resistor value of 18-22K is recommended.'

I am essentially looking to improve upon my Chipamp.com LM3886 if possible.

Thanks

Richard
 
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