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Old 25th October 2008, 08:08 AM   #1
packman is offline packman  Italy
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Lightbulb HELP tweaking my tripath based amp!

Hi guys this week i've receive a Laney CA1500 PA final amp
based on the famous tripath TA0104A.
I bought it beacause have an old pair of B&W 801 matrix s2 that needs current (a lot!), the sound is massive but it's a bit harsh
in the highs and not very "detailed", i think need mods!
This is the link of the schemes:

http://tremolo.elektroda.net/Firmowe/LANEY/CA1500.pdf

i don't want to make too much tweaks but i'm sure that the path of signal is too long and need some advises.
Thanks!
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Old 25th October 2008, 01:28 PM   #2
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What type of source are you using? Is it balanced or single ended.

If your source is single ended, you might want to try just bypassing the whole preamp section. You can connect the source outputs directly to pin 5 (SIGNAL B) and pin 6 (SIGNAL A) of header HD4. If the gain is too high or too low you can change the values of R9 and R10 accordingly.

You could also try replacing C10 and C9 with larger >2uF quality film caps.

The power supply filtering on this amp seems a little low at 10,000uF. My Audiosource AMP7T amps have 20,000uF per rail.

A 1uF film cap directly across pins 1 and 3 of the Tripath module can help clean up the +5v supply.

Other than that, it seems like a fairly straight forward implementation of the TA0104A.
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Old 25th October 2008, 03:22 PM   #3
packman is offline packman  Italy
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Hi theAnonymous! My source is a Naim NACD3, my preamp is an Acoustic Reality EAR pre, all unbalanced.
I have to use the preamp because i will use a phono preamp
in the near future.
I have had the same idea of bypassing the preamp but was unsure if can connect directly to HD4 points.
I'm sure that C9 and C10 must be very good, what do you think of 2 polipropilene caps? Or
The 2 rail caps are generic SAMWHA caps.
There is a bit of ripple in the speakers when internal preamp is at max volume.
Thanks
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Old 25th October 2008, 05:04 PM   #4
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You shouldn't have any problems connecting directly to the input header.

Is it possible for you to post any pics of the inside?
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Old 25th October 2008, 07:36 PM   #5
packman is offline packman  Italy
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sure i can, now have my batteries in recharge so i think tomorrow
thanks!
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Old 26th October 2008, 05:46 AM   #6
packman is offline packman  Italy
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Default photos!

This is 2 photos of the Laney:

http://farm4.static.flickr.com/3284/...67e14f64_b.jpg

http://farm4.static.flickr.com/3040/...32c2e75a_b.jpg

i need a RCA input, this amp have jack 6,3 mm for unbalanced and classic XLR for balanced, do you think using a good RCAtoJACK adapter can affect the sound?
I've asked at a shop about the 2 input caps (C10-C11, are the 2 electrolitycs from the HD4 to the TA0104) and they advise me to buy this model for his excellent audio quality:

Mundorf tin foil ZN 250 caps, with 2,2µf and 250V

it's not simple to reach the solder-side of the main circuit because it has aluminium all around and power transistors are fixed on the aluminium and chassis so i have to operate with the solder on the component-side
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Old 1st November 2008, 05:28 PM   #7
packman is offline packman  Italy
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Default caps & more

Hi guys, in this extremely interesting presentation of class D
found in the hypex site:

http://www.hypex.nl/docs/AES124_Masterclass_Putzeys.pdf

at page 86 of 103 the great Bruno Putzeys says that is not necessary to use audiophile “Low Inductance Capacitor”
but a modern film cap because of EMI.
In my amp board , because "the smaller are the better" i have to change small 1uF electrolytics with 2.2uF as suggested, what type of small film vertical caps (around 5mm pin-to-pin) do the job better?
Thanks
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