Orange AD200B Mk II Bass Amp

[TDS]

A few questions if it is possible for you to answer:

MK1 Amp

1. What are the V4, V3, V2 and V1 voltages.

2. What are the AC output voltages from the two HT windings to the bridge rectifiers?

MKIII Amp

1. What are the V4, V3, V2 and V1 voltages.

2. What are the AC output voltages from the two HT windings to the bridge rectifiers?

3. The secondary winding of the OPT shows only one winding for both 4 and 8 ohm speakers. Is this correct?

4. What type of diodes are D3 and D4 in the poweramp. Is it possible that they are LED's as was used in the Trace Elliot V8 Bass Amp to indicate blown fuses?

Any answers will be appreciated.

[Bernardduur]

I have both of em rigth in front of me so if persons have questions I would love to answer em!

[TDS]

Thanks, I've been looking for this info for quite a while. I'll comment further when I've looked over them in detail.

[Bernardduur]

Here are the schematics!

LINK

Please, comment on them. The owner of the Mark I finds it pretty sub-bassy and needs more treble. As you can see it also lacks a NFB.........

[TDS]

I would be very grateful for copies of both schematics if possible.

[Bernardduur]

I have the schematics of the Mark I and the Mark III when people are interested!

[Enzo]

Well, you could contact Orange. Worst outcome is they tell you "no."

[TDS]

Enzo, The information I have found so far indicates that the 12AX7 preamp tube, the 12AT7 PI tube and the quad of 6550's are the correct tubes for this amp. Apart from some pictures and brief information I found there don't seem to be any schematics around anywhere where I can confirm the PI resistor values. I'm hoping that somebody has been close enough to one of these amps to know what the resistor values should be.

Heres Hoping

[Enzo]

I don't know the amp, but maybe they converted from 12AX7? Look at the schemo for the Orange Hustler at Schematic Heaven for an example.

[TDS]

I have one of these bass amps on the bench. I suspect that the resistor values have been changed around the 12AT7 LTP PI area.

The values currently appear to be Fender AB763 values:

Plates - 47K
Cathodes - 470R
Tail - 22k
bottom - 100R
feedback - 1K2
Input cap 0.022uF
Output caps 0.1uF

Can anybody confirm what the correct PI and feedback resistor values should be?

TIA