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unquitting

Posted 18th August 2011 at 12:10 AM by Erik F

I am back
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LM3886 x 3 First Test

Posted 16th August 2011 at 06:29 AM by panson_hk

I briefly measured the LM3886 x 3 parallel board this morning. THD vs freq for one, two in parallel and three in parallel are measured.

Load of 4 Ohm was also tested. When using one 3886, the on-chip protection activates periodically when doing low frequency (~ < 500 Hz) test. No such protection operation happens for the same output level for higher frequencies (>1kHz). The problem goes away when using 3886s in parallel.

More systematic tests will follow.
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LM3886 x 3 continue

Posted 15th August 2011 at 06:14 AM by panson_hk
Updated 15th August 2011 at 06:58 AM by panson_hk

The DC offset of the three 3886 are interrelated. Hence, adjusting them all 0.0 mV is tough if not impossible. I now made them all 8.9 mV to achieve DC balance. Next will adjust the AC gain. DC offset may need readjust again. This is a game for $ (cost foe DC servo) vs time.

The three 3886 have identical batch number.
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JE Sugden C51

Posted 13th August 2011 at 10:19 PM by Terry Barker

I have a sugden C51 control unit non operational. The unit has been tampered with. Can anyone help me with a cicuit diagram or where I may obtain one?
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LM3886 three in parallel board

Posted 12th August 2011 at 09:14 AM by panson_hk
Updated 12th August 2011 at 09:28 AM by panson_hk

Here is assembled LM3886 x 3 (inverting) board. I think you may see similar/identical board before. Who is the original? Copycats are everywhere. The kit comes with a Solen like film cap. Most likely a fake one. The measured data is not too bad though. The three LM3886 are samples from NS. Original!

The kit provides 0.2R 5% instead of 1% for paralleling the three 3886. Gain setting is by 200k and 10 k 1% metal film. Three 50 k trim pot are provided for DC offset adjustment. I do not solder the three 0.2R first in order to see the gain of the three 3886s.

One of the 3886 DC offset can't be adjusted to 0.0 mV. It has ~25 mV. The other two can be turned to 0.0 mV. This may cause a problem among them. Let see.
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Amp kits from TaoBao

Posted 12th August 2011 at 07:50 AM by panson_hk

I can resist the low price from TaoBao. An LME49810 300W amp kit (w/o heatsink) is just RMB 200.00, ~$32.00. Similar "identical" kit is available from ebay for similar to higher price. So, it is time to buy some and evaluate. I just ordered such an amp kit and one 3886 x 3 amp kit.
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Headphone amp from TaoBao

Posted 12th August 2011 at 07:11 AM by panson_hk
Updated 12th August 2011 at 07:16 AM by panson_hk

I recently purchased a headamp from TaoBao. It is very inexpensive, less than US 30.00. The built quality is good though the outlook is so common. You can find my other sellers selling "identical" item under different brands e.g. 发烧级HIFI LS-100耳机放大器,耳放,耳机监听放大器@ PK千元耳放-淘宝网. My one is cheaper!

I will share my test results in the forum.
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CLASS D AMPLIFIER LINE OUPUT OPTIONS

Posted 11th August 2011 at 08:29 PM by radams23j6

I have a class d amplifier where all three ouputs are used ie both stereo chnls & sub-woofer channel. I want to add a line out connection to drive my external active speakers which are not very sensitive. Can i safely take a line out connection from each speaker crossover board, any advice would be "very much appreciated".

From. Radams23j6.
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VSPS Kit

Posted 3rd August 2011 at 01:21 AM by rjm

My notes tell me the first VSPS Kit was shipped on July 24th 2009. Two years later, there are just over 15 of the 100 kits left unsold. This was a limited edition, once gone they are gone and at the current rate that will happen before the end of the year.

So if you had it in mind to get one...

ordering page
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Philips CDM9 industrial production version bald turntable

Posted 31st July 2011 at 05:28 AM by junya

Click the image to open in full size.Three years ago, repaired a ALTIS the turntable, the sound sense in it, and therefore would like engraved it, after three years of efforts to: copy board, spare parts, commissioning. Trial finally came out.
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