Radford ZD 50 and ZD 100 schematic anyone ?

[phase_accurate]

Does anyone have the schematic of either one or both of these amps ?

Regards

Charles

 

[gaetan8888]

Hello

The amp section of HD250 integrate amp are same than the ZD100, here is the HD250 schematic.

http://www.audio-circuit.dk/Schematics/radford HD250-ZD22.pdf

Bye

Gaetan

 

[phase_accurate]

Hi Gaetan

This is indeed supercooooooool !

Thanks

Charles

 

[phase_accurate]

There seem to be large differences regarding layout etc between these three, so I would be grateful if someone had the ZD 50 and ZD 100 manuals since this would make servicing easier.

Regards

Charles

 

[gaetan8888]

Hello

Here is a link to a simplified schematic of the Radford ZD amp

It is quite different than my HD250 amp.

http://d.yimg.com/kq/groups/7875825/or/208386291/name/ZD+instructions0006.JPG

Bye

Gaetan

 

[homemodder]

I bet these amps sound pretty good, gaetan8888 ???

 

[gaetan8888]

Hello

I also found this ZD50 output section schematic.

Bye

Gaetan

 

[gaetan8888]

Hello

I also found this ZD50 power supply regulator section schematic.

Bye

Gaetan

 

[gaetan8888]

I bet these amps sound pretty good, gaetan8888 ???

Hello

I have the HD250 integrated amp, it sound very good, but the amp section topology was less good than the ZD50 and ZD100 but the HD250 preamp section are same than the ZD22.

The ZD50 and ZD100 ad a novel type of VAS and bias. The VAS section was isolated from the output by the Penultimate bias section.

As you can see in this simplified schematic.

Anyone seen this type of bias circuit before (the Penultimate bias) ?

I may seen that before but I don't remember where.

Bye

Gaetan

An externally hosted image should be here but it was not working when we last tested it.

 

[jaycee]

it's what we would now refer to as a diamond buffer. See Steve Dunlap's KRILL amplifier on this board for use of one.