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:

http://www.image-hifi.com/51/bilder/15110-4.jpg

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:

http://www.image-hifi.com/51/bilder/15110-2.jpg

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:

http://www.image-hifi.com/51/bilder/15110-1.jpg

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

http://www.image-hifi.com/51/bilder/15110-3.jpg

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

Nice!
 

Nice pictures! Where did you find them?

Cheers,

Mark ;)

Re: Nice!
 

Koinichiwa,

www.image-hifi.com

Sprechen sie deutsch?

Sayonara

Re: Re: Nice!
 

No, but Google does ;)

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. ;)

It looks like a very nice amp, I hope mine turns out like that :clown:

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

Pete

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

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?

TO-3 silicon rubber insulators cut in half work well on the LM3876/3886.