• 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.

ecc82/83 questions

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Stuartarm

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Joined 2011
kevinkr said:
Not really sure why this is a big surprise, it was fairly commonly done. Practically speaking leakage (cross-talk) in the source selector switch and other places probably does more to degrade stereo separation than a shared tube provided some care in construction was used.
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I would think that if there was four tubes in the pre that two would be for phono (one per channel) and two for line stage (one per channel) but I not as knowledgeable as you when it comes to this kind of thing...crosstalk or channel induction through a stereo volume control as well might be an issue?...which brings in another question...to swap the balance control for a mono volume and swap the existing stereo volume for a mono like the Audible Illusions...only if I didn't care about this units originality and it might be best to leave it as is
 
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Stuartarm

Member
Joined 2011
rojoknox said:
Noticed this item on that page:
"...Amplier [sic] was manufactured for Japan so its AC electric volt is 100-110V 50/60Hz, you need step down transformer if you want to use it in 220V area."

You're in Calgary AB Canada; power there is same as here in the US, no? 117VAC nominal, perhaps as high as 125VAC. You would need a Variac, a bucking transformer, or a power-transformer replacement.

Take care,
—
J. E. Knox "The Victor Freak"
Click to expand...
Yes its 115v out of the receptacle and hidden under a resistor welded to the the tranny input is 100v so yes I will look for a bucking tranny that will give me 100v
 
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Stuartarm

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Joined 2011
The 24v transformer I used to buck the voltage to this preamp was 5v shy of the 100v I was hoping to get...would a 20v tranny be the correct choice though?...I had overlooked the fact that the primary was rated at 115v not the 123.5v metered from the outlet therefore the output will be higher than 24v rated...this math should be easy?...the turns ratio is not given but if a % of volts reduced is used this should sort this out?...24/115=20.8% so 20.8% x 123.5=25.6...123.5v - 25.6 = 97.9v...hmm thats only 2v shy of 100v why am i only getting 95?...if I used a 20v tranny 20v/115v=17.4% so 17.4% x 123.5v = 21.5v...123.5 -21.5 = 102v...this should be the better choice?...however considering this preamp is 47 years old and completely point to point wired I was expecting a little disappointment...this pre surprised me...first impression was it has heaps of depth even more than the A.I. modulus 2c...gain seemed enormous like that of a live venue...makes me wonder if this pre would work with a moving coil without the step up transformer I presently use a high output MC ...vocals and symbols also seemed to soar more than the A.I. giving it a sense of presence I had not heard before...this preamp is another shining example of why a preamp is so important in a stereo...don't get me wrong I still think the A.I still has its place and it would be tough to let it go...it has a home still and has attributes that set it apart from the norm...
 
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