Vintage Australian PA amp AWA?
Hi all,
I bought a vintage Australian PA amp head off e-bay last week. It works and sounds great for harp. I have not found the brand or model yet but I think it is an AWA the classic aussie radio manafacturers. I also think itis early 50's by some of the components in it. It has 2 x 6V6 and one 6A6 (similar to 6V6) power tubes, an 83V full wave rectifier tube, 2 x 6J7 and a VT99 input (preamp) tubes. It also has an added on output transformer with two sets of output wires. I found this transformer specs and it handles 4,8,and 16 Ohms. I just dont know which wires are what impedence. Does any one know how to test? I am not very familiar with amps so I am taking it very slowly and carefully. Lets hope I dont slowly and carefully electrocute myself.
Also looking at a cabinet forit. I have4 vintagePleesey speakers. 2x8' at 4 Ohms and 2x10' at 8 Ohms. I was thinking two cabs. A 2x8' and a 2x10' for bigger gigs. Any suggestions here on series/parrallel setups?
Thanks Chris.
Thanks for the tube info. Thats useful.
This old PA has obviously had an OT added on later. The smaller original is also there wired to an old 5 pin speaker connection. I wonder if this is more likely to be a higher impedence connection for use in an office? The make/model is still unknown although I am still searching. I'm also guessing that I shouldnt try connecting a speaker to this 5 pin connection until I findout what it's specs are? Are 5 pin connectors common in old PAs? Any clues would be greatfully recieved.
Cyclone- There is no "typical" way of hooking up a five-pin connector for speakers, especially if the output transformer has been changed. You would need enough experience to know how to correctly identify the secondary leads. You say it sounds great, so I would stick with the taps you are using for now.... they are likely to be 8 or 16 ohms. I must say that this particular amp is a tough way to learn some good tube amp basics. Something smaller and simpler would be better for a beginner.
Skip Simmons
Yes, I am in over my head. My basic electronics knowledege needs a major refresh (been a long time since I rock'n'rolled). There are bloody wires everywere. At the end of the day all I want is something that sounds great for harp and I think I may have lucked on to a winner here. I need to take it to a tech for advice/service and I will do that. In the mean time I am learning heaps about tube amps while being very mindfull of the dangers. I also found in my searching a cataloge with the wire colors of the add on OT. So now I have options on the output impedence. Thanks for your help. I notice on your very nice PA that you bypassed the two speaker connectors (5 pin as well?) and put in a single speaker plug. I take your point about there being no standard way of connecting these plugs. But just out of curisosity what was yours wired up for? What sort of impedence? Direct to speakers or a 'LIne' of speakers needing Line transformers of their own? Thanks again.
Cyclone- I notice one more thing you said..... You mentioned that there is more than one output transformer! A circuit with two output transformers is very rare except in stereo amps. I would guess that you are mis-identifying some of the components, which again brings up the point that this is a tough amp to learn on. If, at the end of the day, you want something that sounds great for harp, you better get someone with some experience to take a look at this amp.
My PA heads are usually set up with a selector to run 2,4,8, and 16 ohm cabinets.
Skip Simmons
Hello Chris- Sounds like a fun amp! I don't know anything about the AWA brand myself, I've only seen a few amps from Australia and they were "Philips"-branded. You are lucky that a 50-year-old amp works! The 6A6 is not similar to a 6V6, it's a dual triode comparable to the more common 6N7. The VT-99 is a military version of the 6F8.
Skip Simmons