Hi Lars
Yes, I just wait for the icebears to leave my garage port, or att least for the temperature to go below -10 degrees (Brrrrrr), then I will try to remove the tar from the cover.
However it would be interesting if someone could confirm that the QII power transformer has the oportunity to be reconnected for 220V before open it up
Brgds
Pix
Sweden
Yes, I just wait for the icebears to leave my garage port, or att least for the temperature to go below -10 degrees (Brrrrrr), then I will try to remove the tar from the cover.
However it would be interesting if someone could confirm that the QII power transformer has the oportunity to be reconnected for 220V before open it up
Brgds
Pix
Sweden
. Otherwise one could maybe let another transformer drown in the tar. Just checked one of my QIIs and a 100W Antek lying around and it might be a drop in....
If you wish to series tie your transformers, you need to make sure they are "identical" or else the voltages may not distribute equally between the two. This by itself may not be harmful, but the imbalance may lead to blown components in the one with the higher voltage and reduced power in the lower voltage one.
Just a thought.
Just a thought.
Things to consider are:
I do not know how the mains are configured in your country
Do the mains have the return at Ground potential if it does-
The amp chassis should be grounded.
The impedance of each primary needs to be the same. Easy way to check is remove HT rectifier and check centre of power Tx’s primaries to see if voltage is approx half of supply. Then check heater supply voltage.
It would probably be a good idea to use one power switch on the live side of supply (on one amp), this would mean that the switch on one amp would power the two via series connection. You only want to switch the live side of supply not the return!
The amp without the switch would be connected to the return side of supply.
Just a few thoughts you may have better ideas!
Regards
M. Gregg
I do not know how the mains are configured in your country
Do the mains have the return at Ground potential if it does-
The amp chassis should be grounded.
The impedance of each primary needs to be the same. Easy way to check is remove HT rectifier and check centre of power Tx’s primaries to see if voltage is approx half of supply. Then check heater supply voltage.
It would probably be a good idea to use one power switch on the live side of supply (on one amp), this would mean that the switch on one amp would power the two via series connection. You only want to switch the live side of supply not the return!
The amp without the switch would be connected to the return side of supply.
Just a few thoughts you may have better ideas!
Regards
M. Gregg
I'd be worried about running two power amps in series like that, unless you hide a nice centre-tapped autotransformer holding the centre stable (in which case I'd suggest just getting a big enough one to do the entire job, and eliminate the problem)
After all, except in a straight class A configuration ( which the Quad wasn't) driving one half of the stereo pulls more power, which means that amp becomes a lower impedance, so has fewer volts across it, so cools down…
Not nice.
And it seems clear that the transformers were different from the two sides of the Atlantic.
Also, I seem to remember that changing the tube rectifiers (which were always the first thing that wore out on them ) for semiconductor almost always required a change of smoothing capacitors, so getting extra volts into the one that isn't working would seem unwise. I suppose you could upgrade all the electrolytics; there are really only the two 18µF, and if the main rail's intended to be 350 volts putting in 450s should leave a reasonable safety margin.
After all, except in a straight class A configuration ( which the Quad wasn't) driving one half of the stereo pulls more power, which means that amp becomes a lower impedance, so has fewer volts across it, so cools down…
Not nice.
And it seems clear that the transformers were different from the two sides of the Atlantic.
Also, I seem to remember that changing the tube rectifiers (which were always the first thing that wore out on them ) for semiconductor almost always required a change of smoothing capacitors, so getting extra volts into the one that isn't working would seem unwise. I suppose you could upgrade all the electrolytics; there are really only the two 18µF, and if the main rail's intended to be 350 volts putting in 450s should leave a reasonable safety margin.
Well, first I think I avoid primarys in serie as long as posible
I´ve seen the schematics, but had a small hope, it was a principle schematic. And that the irl power x-former has taps for 110 / 220 Volt.
P walker is told to be a clever man, and I was hoping he used one re-configurable article instead of two
I think I will remove the cover and fint out.
I have som spare x-formers laying around, but I am not sure they fit in the cover.
Brgds
Pix
Sweden
I´ve seen the schematics, but had a small hope, it was a principle schematic. And that the irl power x-former has taps for 110 / 220 Volt.
P walker is told to be a clever man, and I was hoping he used one re-configurable article instead of two
I think I will remove the cover and fint out.
I have som spare x-formers laying around, but I am not sure they fit in the cover.
Brgds
Pix
Sweden
Just for interest,
Have you thought about connecting the two primaries in series?
If the power Tx's are the same then you have 110V + 110V. You could make a connection box and plug the two amps into that with a 220V input.
Just a thought!
Regards
M. Gregg
Unfortunately this is not a very good idea, unless the amplifiers use exactly the same amount of power at all times the voltage will not divide equally across them. (And tolerances in components, tube operating points, and the power transformers assure this mostly won't be the case, factor in differing signal levels at times and the situation becomes more complex.)
I'm pretty sure the north american version of the Quad 2 had a 117V transformer primary ONLY.
Your best and safest recourse is to use an auto-transformer with these amps or replace the transformers.
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