Another ChipAmp running

12 Cents · 20th August 2005, 08:21 PM

Hello,

since I found this forum I wanted post some "Hello post" with a project worth showing. So please take this as a kind of introduction post from me, ok

?

The amplifier is a LM3886 in a datasheet-like fashion like proposed by Mr. SL. I left out Ci, 17mV DC offset at the outputs with a source attached. Without, ~70mV. It worked (almost) from the start and sounds just good.

My thanks go to the designers and manufacturers of these great little chips.

theduke

12 Cents · 20th August 2005, 09:08 PM

Also my true thanks go out to the makers and all the contributors of this forum. This is great.

Mick_F · 21st August 2005, 07:33 PM

It looks as if you have some quite big caps in the PS. Do you have some snubbers close to the supply bypassing caps of the amp to account for this? If not, there might be some serious improvement possible here.

Mick

12 Cents · 21st August 2005, 08:15 PM

Yes, I cloned Carlos' snubbered filter section with 2x10mF per rail. Slight problem: I measure 100mV less voltage on the negative rail (after the filter R's)

Regards,
theduke

Mick, I like your photography

Mick_F · 22nd August 2005, 09:41 AM

Quote:

I measure 100mV less voltage on the negative rail (after the filter R's)

Did you check the values of all capacitors and resistors involved? A difference of 100mV is less than one percent of the rail voltages and might be explained within the parts' tolerances.

Quote:

Mick, I like your photography

Thanks

12 Cents · 22nd August 2005, 05:15 PM

It must be the bleeders, which act as virtual ground creators in my case too. Should the circuit ground be earthed?

12 Cents · 24th August 2005, 05:21 AM

Feedback resistor, Mute resistor

Mick_F · 24th August 2005, 08:37 AM

Thats a good idea to put the mute resistor directly onto the pins.

Btw. Where do you buy your parts in Germany?

Mick

12 Cents · 24th August 2005, 11:07 AM

Bei Reichelt

The LM's are from a forum guy, brunoravera...

slackman · 24th August 2005, 01:26 PM

Hi Mick,
drop me a line if you're interested in LM-chips. I still have some samples stocked.

If you pay the transport fee, National will also send samples to you (I think). The only point is you must create an account and you should have a credit card...

My first sets (LM4780) i bought from Peter Daniel , really nice work and price is ok.

Heho Elektronik also has the LM3886 in T and TF for about 9,- Euros and some other LMs too (no 4780...

).

Michael

PS: Great photos, I like this style...

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20th August 2005, 09:08 PM	#2
12 Cents diyAudio Member Join Date: Nov 2004	Also my true thanks go out to the makers and all the contributors of this forum. This is great.

21st August 2005, 07:33 PM	#3
Mick_F diyAudio Member Join Date: Jun 2005 Location: Cologne	It looks as if you have some quite big caps in the PS. Do you have some snubbers close to the supply bypassing caps of the amp to account for this? If not, there might be some serious improvement possible here. Mick

21st August 2005, 08:15 PM	#4
12 Cents diyAudio Member Join Date: Nov 2004	Yes, I cloned Carlos' snubbered filter section with 2x10mF per rail. Slight problem: I measure 100mV less voltage on the negative rail (after the filter R's) Regards, theduke Mick, I like your photography

22nd August 2005, 05:15 PM	#6
12 Cents diyAudio Member Join Date: Nov 2004	It must be the bleeders, which act as virtual ground creators in my case too. Should the circuit ground be earthed?

24th August 2005, 08:37 AM	#8
Mick_F diyAudio Member Join Date: Jun 2005 Location: Cologne	Thats a good idea to put the mute resistor directly onto the pins. Btw. Where do you buy your parts in Germany? Mick

24th August 2005, 11:07 AM	#9
12 Cents diyAudio Member Join Date: Nov 2004	Bei Reichelt The LM's are from a forum guy, brunoravera...

24th August 2005, 01:26 PM	#10
slackman diyAudio Member Join Date: Mar 2005 Location: Germany, lower saxonny (Bremervörde)	Hi Mick, drop me a line if you're interested in LM-chips. I still have some samples stocked. If you pay the transport fee, National will also send samples to you (I think). The only point is you must create an account and you should have a credit card... My first sets (LM4780) i bought from Peter Daniel , really nice work and price is ok. Heho Elektronik also has the LM3886 in T and TF for about 9,- Euros and some other LMs too (no 4780... ). Michael PS: Great photos, I like this style...

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