surfguy13
Member
Hi guys
Greetings from the UK!
Just acquired my second PA20 head and have a couple of questions.
This head is a '72 and has never been messed with.....pretty much mint and it sounds great. The quietest head I've ever used. It's just been serviced by Marshall and the only work carried out was 4 new vol/tone pots. It's currently wired to 8 ohms.
Anyway to my ears the 2 'channels' sound identical which I'm guessing would be the case for a PA amp. Can anyone confirm this? I never jumpered my last PA20 ('70) for this reason.....couldn't see the point of mixing two channels that sound identical. However, be good to know if the two channles are the same and whether anyone has a view on the benefits (or lack) of jumpering with these amps.
The second question is re biasing.....I seem to remember asking this question when I had my last PA20 and got some great advice but I honestly can't remember what the consensus was.
This head is fitted with two Boogie EL84s and a pair of Boogie ECC83s. Sound excellent but have no way of testing them. I believe that I was advised that if the valves test within the parameters of the fixed bias it's OK but......if they don't?!!
Any advice and/or links would be gratefully received.
Finally (yes, this is a bit of a loaded post!! ).....the previous owner asked Marshall to change it to 8 ohms from 16. They warned him that this would cause a drop in volume. Is this the case? I would prefer to run it at 16 ohms as my cabs are 16 but can obviously re-wire to 8 in a flash. Happy to change it back to 16 but not sure what the pros and cons are?
Few photos:
Greetings from the UK!
Just acquired my second PA20 head and have a couple of questions.
This head is a '72 and has never been messed with.....pretty much mint and it sounds great. The quietest head I've ever used. It's just been serviced by Marshall and the only work carried out was 4 new vol/tone pots. It's currently wired to 8 ohms.
Anyway to my ears the 2 'channels' sound identical which I'm guessing would be the case for a PA amp. Can anyone confirm this? I never jumpered my last PA20 ('70) for this reason.....couldn't see the point of mixing two channels that sound identical. However, be good to know if the two channles are the same and whether anyone has a view on the benefits (or lack) of jumpering with these amps.
The second question is re biasing.....I seem to remember asking this question when I had my last PA20 and got some great advice but I honestly can't remember what the consensus was.
This head is fitted with two Boogie EL84s and a pair of Boogie ECC83s. Sound excellent but have no way of testing them. I believe that I was advised that if the valves test within the parameters of the fixed bias it's OK but......if they don't?!!
Any advice and/or links would be gratefully received.
Finally (yes, this is a bit of a loaded post!! ).....the previous owner asked Marshall to change it to 8 ohms from 16. They warned him that this would cause a drop in volume. Is this the case? I would prefer to run it at 16 ohms as my cabs are 16 but can obviously re-wire to 8 in a flash. Happy to change it back to 16 but not sure what the pros and cons are?
Few photos: