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Old 30th June 2007, 05:09 PM   #11
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Have added the speaker terminals and wow! There seems to be loads of bass now so disregard the last entry about bridging the 1uf caps. The signal seems to go through the chip between the 1uf cap and the 2.2uf cap so the 1uf cap needs to be there....!
I have just unplugged the original speakers and may fit a switch so they can be used when needed.
I shall listen for a while to see how it sounds.. better than 20 plus speaker terminals though!
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Old 30th June 2007, 06:38 PM   #12
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How does it compare to a modded S.I amp ?
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Old 2nd July 2007, 05:52 PM   #13
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Quote:
Originally posted by Puffin
How does it compare to a modded S.I amp ?

I've had a bit of a listen and seems that the preamp section is having an effect on the sound. The bass is boosted at about 120Hz (I would guess) and treble is a bit shut in.
When the amp is used with a separate preamp and connected at the 2.2uf caps it sounds very similar to the S,I amp. it is not as loud because of the input and feedback resistors give it different gain.
I attached 47k resistors in parallel with the 33k input resistors to give about 20k input and 20k feedback, but still not as loud.
I also don't know if the output coils are big enough to handle full size speakers, they look smaller than the S.I amp coils (I can't measure the inductance or wire gauge) . They've been alright so far (not melted).
Barry...
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Old 3rd July 2007, 08:27 PM   #14
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Just aquired two of these for a play.... stereo mono's should be interesting. I have enough leftovers from previous exploits to completely modify these anyway

Hell... @ 20 quid it makes the SI look positively expensive... speakers and SMPS throw in ...

Might get a few more for birthday and Christmas pressies at that price as well

Nice find Barry.
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Old 3rd July 2007, 08:33 PM   #15
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I wonder if I could use the speaks as tweets in an active fullrange setup...?.... this could be interesting
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Old 7th July 2007, 09:20 AM   #16
Puffin is offline Puffin  United Kingdom
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I have just re-boxed my Kensington. I initially used the input connections under the 3.5mm jack socket and ran wires to the phono sockets. Fired it up, it worked but sounded s*ite. Then I coonected to the 2.2 caps. Thats more like it. The amp is running in at the moment before I hook it up to my main system.

Audio1st. Can you give detaisl of the mod to the feedback resistors you did. What type of resistors did you use, 0.6w metal film or SMD's ?
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Old 7th July 2007, 07:11 PM   #17
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Update. When I went to connect it to my main system, I noticed that on switch on it sucked the cones right in ?!. I switched off immediately. Is this what is known as oscillating ? and if so why and can it be cured ?
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Old 8th July 2007, 08:55 AM   #18
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sounds more like negative DC offset Puffin.
Get your DMM out and measure across the terminals to see how much.
Could be that the input caps are connected in wrong place allowing the input bias voltage to see ground?
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Old 8th July 2007, 10:09 AM   #19
Puffin is offline Puffin  United Kingdom
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I will check the DC. I went in at the bottom two solder pads shown on your photo for the 2.2uf's. I assumed that this was "in" and then the signal passes through the cap and on up to the 2024 chip ?
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Old 8th July 2007, 10:51 AM   #20
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Lostcause. DC on left channel is -0.06 and Right +0.05. I attach a copy of your phot with details of where I connected to.

http://i73.photobucket.com/albums/i2...nsex/S2000.jpg
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