• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

You can't get the iron, you know

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haiqu

haiqu

Member
Joined 2005
#1
I have a quad of 807s purchased some years ago, but the previously common interstage and output transformers that seemed to be available at every corner store are no longer around.

The OP trannie needs to be somewhere between 6600-8000 ohms CT and with a 25W rating. What do you guys use for this application?

I can't see the value in having bespoke transformers manufactured, even cheap ones. These valves were OK but not world-beating, and I'm doing it mostly for nostalgia reasons rather than how the result will turn out.

Ebay and Gumtree have turned up nothing and I've been monitoring it for weeks. Ideas?
 
#2
I see 2 choices:
- get something from AliExpress that suits PP 807. Or another Asian transformer maker like Silk.
- use valves that suit whatever OPT you can get for a good price in Australia. Valves are cheap, OPTs are more of an investment.

If you abandon the 807s or sell them or whatever, then you can start from the beginning and even consider a SE amp.
 
#4
AFAIK 6K6 OPT's are as common as drunk English men on a Friday night.


Edcor CXPP60-MS-6.6K Transformer, 132,34 €


25W 6600 Ohms Ultra Linear Push Pull Output transformer – Primary Windings


ClassicTone # 40-18080, HiFi Style, 35W Ultra Linear, 4.3K / 6.6K to 4 / 8 / 16 Ohm, Output Transformer


That's three I found in 1 minute. I've bought primary windings OPT's, they're well made but there is a lead time as there might be on quite a lot of iron what with the global situation , EG shortage of components and materials. If it were me I'd buy a higher power rated OPT if I had the dosh.


Andy.
 
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#5
andyjevans said:
I see 2 choices:
- get something from AliExpress that suits PP 807. Or another Asian transformer maker like Silk.
- use valves that suit whatever OPT you can get for a good price in Australia. Valves are cheap, OPTs are more of an investment.

If you abandon the 807s or sell them or whatever, then you can start from the beginning and even consider a SE amp.
Click to expand...

No, I specifically wanted to build a pair of 807 pp monoblocks. Personal reasons.
 
#6
I think we should factor in that the OP is in Australia and import duties and shipping from Europe and the USA are going to add considerably to the overall cost. It's easy to find OPTs that are "available" but they need to be available in Australia. There are Hammond dealers in Australia for sure, but I don't know if they stock tube transformers.

Maybe the OP can tell us what countries are cheap to ship from and which are expensive? I imagine Asia is cheaper than Europe or the USA.

I'm in Europe and the same thing applies - I get products recommended to me that are in the USA but shipping and import charges mean I'm never going to buy them. In fact, after Brexit even Europe means added charges. My suggestion in threads like this is to start with the OP's country of origin and proceed on that basis.
 
#8
Diabolical Artificer said:
AFAIK 6K6 OPT's are as common as drunk English men on a Friday night.

Edcor CXPP60-MS-6.6K Transformer, 132,34 €

25W 6600 Ohms Ultra Linear Push Pull Output transformer – Primary Windings

ClassicTone # 40-18080, HiFi Style, 35W Ultra Linear, 4.3K / 6.6K to 4 / 8 / 16 Ohm, Output Transformer

That's three I found in 1 minute. I've bought primary windings OPT's, they're well made but there is a lead time as there might be on quite a lot of iron what with the global situation , EG shortage of components and materials. If it were me I'd buy a higher power rated OPT if I had the dosh.

Andy.
Click to expand...

Thanks Andy, but I live in Australia. Those already outrageous prices would need to be doubled to get them here.
 
#9
andyjevans said:
I think we should factor in that the OP is in Australia and import duties and shipping from Europe and the USA are going to add considerably to the overall cost. It's easy to find OPTs that are "available" but they need to be available in Australia. There are Hammond dealers in Australia for sure, but I don't know if they stock tube transformers.

Maybe the OP can tell us what countries are cheap to ship from and which are expensive? I imagine Asia is cheaper than Europe or the USA.

I'm in Europe and the same thing applies - I get products recommended to me that are in the USA but shipping and import charges mean I'm never going to buy them. In fact, after Brexit even Europe means added charges. My suggestion in threads like this is to start with the OP's country of origin and proceed on that basis.
Click to expand...

+1
 
#13
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