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Nobis Cantabile / Dynaco Stereo 70 EL34 Based USA Made Tube Amplifier For Sale Madison, WI Area


tidmack

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Hey guys, some of you may remember this ad from about a year ago.

 

I listed this amp on eBay and it sold to a gentleman in Texas. After it arrived, the buyer complained of a hum and said the main power supply capacitor was bad. We agreed on a price to replace the capacitor with one of his choice and he did so. The buyer reported back with a million tests he ran on the amp and said everything else was good and the tubes tested strong. Then, he said the bias adjustments were not present. I'll be totally honest, I don't even know what that does, except that I think the adjustment helps dial the tubes in. I had no idea these were missing (although after the fact, and once I knew what I was looking at, the photos clearly showed there were no bias adjustments present). I used the amp for years without adjusting the bias, apparently. This is why I stick to solid state equipment.

 

At any rate, this transaction didn't end well and I ended up with the amp back at my house. The photos show the old capacitor in place. If a buyer is serious, I can email you updated photos showing the new capacitor installed.

 

I'm not interested in shipping this amp, but if someone within driving distance of Cross Plains, WI wants a fun project during quarantine,  please let me know. Below is some information from a Stereophile review from years ago. This amp is an EL34 based amp, like the Marantz 8 and Dynaco Stereo 70. 

 

The glowing Stereophile review below sums up what a beautiful sounding amp this is. I've owned this wonderful piece for about 15 years and purchased it from a former employee of Nobis, which was located here in Wisconsin.

 
 
 

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16 hours ago, joessportster said:

If you decide you will ship Im you huckleberry.......Joe

 

Hi Joe, thanks for reaching out. I don't want to ship this amp again...I thought I'd price it at a level that would make it worth someone's time in the WI, IL, IA, MN, IN to come get it. With that said, I wonder if we could possibly use the buddy system on this? I don't keep track of when members are meeting up and things like that, but assuming COVID restrictions ease a bit in the next month or so, maybe we could somehow get the amp to you in Carolina? 

 

Jeff

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On 4/8/2020 at 9:58 AM, tidmack said:

Then, he said the bias adjustments were not present. I'll be totally honest, I don't even know what that does, except that I think the adjustment helps dial the tubes in. I had no idea these were missing (although after the fact, and once I knew what I was looking at, the photos clearly showed there were no bias adjustments present).

 

The is a screwdriver adjustment potentiometer, right behind each power tube, clearly visible in the pics. You would need to have the bottom off and use a meter to read the correct values. You measure between the ground and one of the pins (can't remember at the moment). The is no indicator present, as you can see on the under chassis pic.

 

Nice looking amp.

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2 hours ago, Marvel said:

 

The is a screwdriver adjustment potentiometer, right behind each power tube, clearly visible in the pics. You would need to have the bottom off and use a meter to read the correct values. You measure between the ground and one of the pins (can't remember at the moment). The is no indicator present, as you can see on the under chassis pic.

 

Nice looking amp.

Thank you for taking time to explain, Marvel. I sincerely appreciate your time, I understand exactly what you're saying. So the bias CAN be adjusted, just the LED's are missing. Have a terrific evening.

 

Jeff

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1 hour ago, mojomc said:

Aren't the "bias indicators" located in front of the tubes used to take measurements without removing the bottom cover? 

I believe Marvel did a nice job explaining what's going on...the indicator LED lamps are missing, but the bias adjustments can be made from under the amp.

 

Jeff

 

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Stock just went up?
Lol, I just really appreciate Marvel shedding some light on this. The deal just got a little better I guess! I'm hoping someone can find some enjoyment from this unit during these crazy times.

Jeff

Sent from my SM-G960U using Tapatalk

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The original St-70 had a resistor between pin 8 and ground. Measuring the voltage across it gave you the same numeric value as the bias setting.

 

Maybe Maynard could help you figure it out with a couple good pics of an output tube socket and pot area.

 

@tube fanatic

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9 hours ago, Marvel said:

The original St-70 had a resistor between pin 8 and ground. Measuring the voltage across it gave you the same numeric value as the bias setting.

 

Maybe Maynard could help you figure it out with a couple good pics of an output tube socket and pot area.

 

@tube fanatic


 

Yes, this is a very easy adjustment.  However, the possible exposure to lethal voltages makes doing it unsafe for inexperienced users.  
 

 

Maynard

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On 4/10/2020 at 6:45 AM, tube fanatic said:


 

Yes, this is a very easy adjustment.  However, the possible exposure to lethal voltages makes doing it unsafe for inexperienced users.  
 

 

Maynard

Thank you, Maynard. Your disclaimer is a wise one, we don't need anyone getting a jolt !

 

This amp is still available. Lots of interest, but no cash in hand yet. I AM practicing social distancing and have no problem wearing my HEPA mask and gloves while meeting with someone. Heck, I think a nice drive to the driftless area of WI would be good for the soul right now...

 

Jeff

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3 minutes ago, Randyh said:

-quick question , what preamp and klipsch speakers were these used with - tx

I used the amp off and on for a few years throughout my ownership. My main workhorse is a Mac MC2105 I've had for about 23 years now, I guess. When I subbed in the Nobis, I used it with a McIntosh MX113 and a pair of Klipschorns from the early '90s. Thank you for asking.

 

Jeff

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