PA060S Transformer
Is this compatible with the 240v electricity network that we have in Norway?
Because i was about to change the transformer in my 40yr old ST70 an i discovered different colorcoding on the old and new transformer.
My experience with tubes are maintainly with simple modifications. You know, replacing components and so-on.
Andreas
Is this compatible with the 240v electricity network that we have in Norway?
Because i was about to change the transformer in my 40yr old ST70 an i discovered different colorcoding on the old and new transformer.
My experience with tubes are maintainly with simple modifications. You know, replacing components and so-on.
Andreas
One of my weirdest results with a Dynaco 70 (stock PT, SDS board and Triode Electronics input board) was quickly soldering in some plate caps and running Mullard EL38s. The EL38s do bias differently than the EL34 and I could only get 40mA (!) a pair with the stock bias supply. Well I shrugged my shoulders and ran with it - I just wanted to hear what the EL38s sounded like.
Anyways, I'm not sure if it was the lower current through the OTs or the lower power supply requirements - but the sound of the amp became transformed. Big, dynamic... could have been the effect of pushing it hard into Class B?
anyways - never experimented with it further and ended up going back to EL34s before I sold the amp.
Anyways, I'm not sure if it was the lower current through the OTs or the lower power supply requirements - but the sound of the amp became transformed. Big, dynamic... could have been the effect of pushing it hard into Class B?
anyways - never experimented with it further and ended up going back to EL34s before I sold the amp.
317 Regulated
... just read my Morgan Jones. He blesses using 317 voltage regulators on the High Voltage plate supply.
Also a 317 could be used for the screen supply. Now we're talking modern amp !!!
Small problem though is somehow making sure that the screen supply does come up before the plate supply and the screen doesnt have a voltage on it if the plate supply fails.
Any ideas on how to design this part ??
...
... just read my Morgan Jones. He blesses using 317 voltage regulators on the High Voltage plate supply.
Also a 317 could be used for the screen supply. Now we're talking modern amp !!!
Small problem though is somehow making sure that the screen supply does come up before the plate supply and the screen doesnt have a voltage on it if the plate supply fails.
Any ideas on how to design this part ??
...
Yes, I see the question. Normally, if the plate voltage supply doesn't come up, neither will the screens, since they're run off the same raw supply as the plates.
If the plates are regulated and a plate reg fails, it will invariably either blow the fuses very quickly and/or go high (to the unregulated voltage) as the pass device fuses into molten conduction. Failing open-circuit is not common.
The turn-on time of Curcio and Maida regulators, assuming a solid state rectifier in the raw supply (a good idea!) is much faster than the tube warmup time, so any differences in their relative turn-on times is only seen by a cold tube.
If the plates are regulated and a plate reg fails, it will invariably either blow the fuses very quickly and/or go high (to the unregulated voltage) as the pass device fuses into molten conduction. Failing open-circuit is not common.
The turn-on time of Curcio and Maida regulators, assuming a solid state rectifier in the raw supply (a good idea!) is much faster than the tube warmup time, so any differences in their relative turn-on times is only seen by a cold tube.
Which OPt>?
This company is just down the street, so no expensive shipping or duties to pay. Really high Q gear. Which model would you recommend?
http://www.plitron.com/audio_std.asp
PS - The more I work on my '70 the more I realize it not a Dynaco anymore.
This company is just down the street, so no expensive shipping or duties to pay. Really high Q gear. Which model would you recommend?
http://www.plitron.com/audio_std.asp
PS - The more I work on my '70 the more I realize it not a Dynaco anymore.
SY said:
hey-Hey!!!,
The Curcio cascode 6DJ8 circuit is nearly ready. Delete some parts, and re-organize some of the connections and we're OFF! Running a regulator for a LTP/diff amp seems a waste to me. PSRR is already excellent, and a shift in OP due to variations in B+ isn't detrimental.
Since the cascode is a pentode construction, ref'ing the g2/upper tube grid to the cathode is just as important, given that significant signal exists on the cathodes. As drawn it is ref'd to ground.
cheers,
Douglas
wiring on PA521
I've got this older modell of the ST-70 which i'm (still) upgrading..
And i wonder if the colorcoding of the wires have changed?
since i've got problems with finding out where they're supposed to be at?
an example is 2 yellow on the older version an white on the new?
Could the possibly be miscoloured?
I've got this older modell of the ST-70 which i'm (still) upgrading..
And i wonder if the colorcoding of the wires have changed?
since i've got problems with finding out where they're supposed to be at?
an example is 2 yellow on the older version an white on the new?
Could the possibly be miscoloured?
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