Is my Ming Da..........

[Paul Dimaline]

........a power amp with a volume pot fitted or has it got a active pre amp stage?

I have always asumed the former but then I read a thread on AudioKarma that said...

.....I have bypassed the selector switch and removed the pre amp circuit so it is virtuley a power amp now and it sounds great.....

.

He has the "A" version, the same as lordsummits amp whereas I have the "B", but it still has 2 pre-amp tubes as well as 2 driver tubes.

I am toying with the idea of getting a pre amp and using my Ming Da as a power amp but then I came acros the above....


Paul.

 

[lordsummit]

I've got a switch on mine that turns it into a pre, but I don't think it's passive. I could be barking completely up the wrong tree, but I thought (think?) that the little tubes are part of the active pre-amp system

 

[Paul Dimaline]

I've got a switch on mine that turns it into a pre, but I don't think it's passive. I could be barking completely up the wrong tree, but I thought (think?) that the little tubes are part of the active pre-amp system

Mmmm, didnt realise there was a switch on your amp. As I understand it the driver tubes are part of the power amp section.....but the signal runs from the volume pot to the pre amp tubes (the 6N2's in the center) so is this the (active) pre amp section? It is quite dificult to trace the wiring by eye as there are quite alot of wires in there, many of them twisted together and of the same colour.

 

[zanash]

Arn't they more a buffer stage than a pre amp ?

 

[Paul Dimaline]

Arn't they more a buffer stage than a pre amp ?

Dont know, I was hoping you could tell me

If the "A" has a switch to turn it into a pre amp it would surely have a gain stage wouldnt it? How many components are needed for a simple active tube pre amp? A Croft Micro certainly didnt have many.

 

[zanash]

my dynovox had a simple vol pot feeding the 'normal' first stage of a power amp. This was just passive [and very poor!] The jump in sound quality once removed was jaw dropping !

Every valve power amp has a pair of small 'line drivers' and a number of pairs power valves. But without seeing a schematic I'd not like to be quoted !

 

[Paul Dimaline]

Not a very good photo, but you can just see the black signal cables going to the 2 (center front) pre amp valves, these then go to the driver tubes (the 2 outer front). Other than a few resisters and a couple of caps that seems to be it for the pre amp.