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Chip Amps Amplifiers based on integrated circuits

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Old 13th June 2003, 12:45 AM   #1
Previously: Kuei Yang Wang
 
Join Date: Nov 2002
Default Bridgeclone - Rowland Concentraclone

Koinichiwa,

I just came across some hi-rez internal shots from the new Cncentra. It may be of interest to those seeking to "clown around" with "Bridges over the River Kwai" and the like....

First the overview:

Click the image to open in full size.

As can be seen, unlike the other Rowland Amps that use switch mode supplies, the concentra still does it the oldfashioned way...

The inputs are switched by little, very familiar looking relais, goldflash over copper contact IIRC and then you get a nice Jensen Input Transformer:

Click the image to open in full size.

There is a lot of jiggery pokery and to those who already know, the Concentra uses the CS3310 as volume control.

The following picture shows parts of the PSU, pretty basic, single bridge with ceramic snubber caps, 4 pcs Nichicon PSU Cap's, I'd guess from the looks 10,000uF/63V each:

Click the image to open in full size.

Now onwards to one of the six Nat Semi LM38XX (we know they are 3886) output chips in bridge/parallel:

Click the image to open in full size.

No sign of a servo. Dale 0.2R 1% Output Resistor. All else SMD, including the two local decoupling caps which are by the looks X7R or possibly even Z/Y5U Multilayer Ceramics. All the other SMD resistors appear to be tight tolerance (guess) and there is no manual offset correction either. The paucity of passive components suggests BTW inverting mode....

Sayonara
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Old 13th June 2003, 10:59 AM   #2
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Default Nice!

Nice pictures! Where did you find them?

Cheers,

Mark
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Old 13th June 2003, 11:03 AM   #3
Previously: Kuei Yang Wang
 
Join Date: Nov 2002
Default Re: Nice!

Koinichiwa,

Quote:
Originally posted by mhennessy
Nice pictures! Where did you find them?
www.image-hifi.com

Sprechen sie deutsch?

Sayonara
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Old 13th June 2003, 11:29 AM   #4
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Default Re: Re: Nice!

Quote:
Originally posted by Kuei Yang Wang
Koinichiwa,

www.image-hifi.com

Sprechen sie deutsch?

Sayonara
No, but Google does
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Old 13th June 2003, 12:34 PM   #5
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Very nice clamping bar holding the IC's onto the heatsink. It puts the pressure right on the part of the tab that has the most heat. Way better than using the bolt hole that pulls the IC down unevenly. Good method for TO-220's and TO-247's too, especially if you are working them hard.
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Old 13th June 2003, 01:17 PM   #6
grataku is offline grataku  United States
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Quote:
Originally posted by Circlotron
Very nice clamping bar holding the IC's onto the heatsink. It puts the pressure right on the part of the tab that has the most heat. Way better than using the bolt hole that pulls the IC down unevenly. Good method for TO-220's and TO-247's too, especially if you are working them hard.
Don't forget the nice SS fasteners, the only screws I use.
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Old 13th June 2003, 01:30 PM   #7
cm961 is offline cm961  Canada
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It looks like a very nice amp, I hope mine turns out like that

As soon as I get a mill machine and start making two sided PCBs, the possibilities will be endless.

Pete
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Old 14th June 2003, 03:20 PM   #8
miguel2 is offline miguel2  Portugal
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The signal goes directly from the jensens to the vol control and then to the output chips? No other gain/buffer ICs in between?

Miguel
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Old 15th June 2003, 12:32 AM   #9
mothman is offline mothman  United States
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A beautiful amp indeed and if I had the extra $7000 I'd buy one!
I'd settle for a dozen of the chip insulator pads though at this point.
Anybody know where a fit pad like those can be had?
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Old 15th June 2003, 07:08 AM   #10
MWP is offline MWP  Australia
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Quote:
Originally posted by mothman
I'd settle for a dozen of the chip insulator pads though at this point. Anybody know where a fit pad like those can be had?
TO-3 silicon rubber insulators cut in half work well on the LM3876/3886.
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