Carvin DCM 1500/2000/4000

Hi there!

I am repairing a Carvin DCM 4000, this is the 4 channels version of DCM 1500 and the DCM 2000 is the same that DCM 1500 but more powerful version. All are the same design I suppose but in my repair process I can't to decipher how the output section works?, this look like an AB amp class but I can't find the output path.

http://carvinimages.com/schematics/DCM2000%20REV.%20H.pdf

I read this amp have a very rare output section arrangement!!. look like the amplifier output is at the center of the main power supply capacitors but I would like yo get more information about. Do someone could explain this rare output path please?

Thanks anticipated
Opacheco

not very rare, called "driven rail"....

JR

...or grounded half-bridge.
The output is the junction of the PT's center-tap and reservoirs.

The similar concept Crown used in CT  series of amps, IIRC.  I saw it for first time about 30 years ago.
http://www.academia.edu/16243142/Crowns_Grounded_Bridge_Output_Topology

moamps said:

The similar concept Crown used in CT  series of amps, IIRC.  I saw it for first time about 30 years ago.
http://www.academia.edu/16243142/Crowns_Grounded_Bridge_Output_Topology

Click to expand...

Yes, Crown extended the concept of "driven rails" or "grounded half-bridge" to "grounded (full) bridge", claiming better use of transformer copper/iron and smoothing cap. IMO the most significant advantage was that it allowed using lower Vce transistors and improved second-breakdown resilience.
Unfortunately, the first generation (Microtech 1000) was plagued with improper manufacturing process of transistors.

abbey road d enfer said:

Yes, Crown extended the concept of "driven rails" or "grounded half-bridge" to "grounded (full) bridge", claiming better use of transformer copper/iron and smoothing cap. IMO the most significant advantage was that it allowed using lower Vce transistors and improved second-breakdown resilience.
Unfortunately, the first generation (Microtech 1000) was plagued with improper manufacturing process of transistors.

Click to expand...

Another (cost) advantage is that the amplifier front end can all be entirely low voltage technology. Only the power transistors (used common-emitter) need to handle full rail voltage. At Peavey we made truckloads of these for inexpensive instal and top box amps. I even investigated reducing the amplifier front end to a full custom IC but the junior engineer assigned by the IC company didn't even know how OTAs work (our front end design included an OTA for clip limiter).

JR

I will need to study more about the "driven rails" or "grounded half-bridge" to "grounded (full) bridge" topology amps!!.....if anyone can provide me some info about (the "http://www.academia.edu/16243142/Crowns_Grounded_Bridge_Output_Topology" id excellent start!!)

Thanks to all for your comments!!

Opacheco

opacheco said:

I will need to study more about the "driven rails" or "grounded half-bridge" to "grounded (full) bridge" topology amps!!.....if anyone can provide me some info about (the "http://www.academia.edu/16243142/Crowns_Grounded_Bridge_Output_Topology" id excellent start!!)

Thanks to all for your comments!!

Opacheco

Click to expand...

Try to find the original Crown paper (I believe it was in the owner's manual) of the MT1000.

abbey road d enfer said:

Try to find the original Crown paper (I believe it was in the owner's manual) of the MT1000.

Click to expand...

Sure!.....I got it and I read it already and its very interesting configuration!!.

Thanks a lot to all for the recommendations
Opacheco.