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Meet Dolly, the Olson clone!

Hi Redboy,

Looks nice, hope you can sort out the hum! In the closeup underside view, I noticed two unsoldered connections. It was probably an in-progress pic, but might be something to look for?

Since you're using a three-wire plug, how are the other two wires connected? The white wire in the AC cord is supposed to be neutral, and black is the hot. The white wire should connect to circuit's ground. The green ground wire should go to the chassis. A 47k resistor and a MOV would connect circuit ground to chassis. Might be easiest to simply disconnect the green wire as suggested and make sure the circuit's "ground" side goes to the white wire.

A DMM set to AC could be used to make sure there's no "hot" voltage on the chassis by metering from there to the ground at your outlet.

I've had amp hum caused by a bad tube. Might not hurt to swap other tubes in if you have spares.

-Ed
 
All right Ed, those are some ideas I'm going to have to investigate. I did lift the green wire as suggested and it made no difference, but I'll check for proper power wiring otherwise. I used an IEC connector in the amp, so I don't know which wires are what color, but the terminals are marked "L," "N" and "E." Huh? "E" must be "Earth," right? That's the center terminal, currently grounded to chassis.

Those unsoldered connections you spotted were indeed from "in progress" pictures, and are now soldered properly.

What's a(n) MOV?
 
Musicalme said:
L=Line N=Neutral E=Earth
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I was off by one letter - I guessed "Live," but that still sounded a little off to me...
saltwater said:
Nothing wrong with dolly, or olson, look good. maybe down the line there will be a mary kate, or ashley!
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They would be Dolly's twins, right? It's a possibility... I'd like to put one in a Hammond extruded aluminum box.
 
Mike Stehr said:
Try a couple 100 ohm resistors to ground off each heater winding. One should even work off one leg.
I've use the common CRC supplies with respect to SE 6BQ5and haven't had many issues with PS noise.

AC heater growl from a open non CT winding has usually been barely acceptable from my experiences, and a 100-300 ohm R to ground off a winding always seems to help quiet it down.

Try it....if it doesn't work, then you know it may other problems such as inadequate PS filtering.
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Mike, I don't know why it took me so long to try this (I think I got distracted by another project or two along the way) but that did the trick!

Question, though: Is a 1/2 W resistor going to be okay or do I need something burlier?

Today's pics:

IMG_7750.jpg

IMG_7748.jpg
 
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I've been using 1/2 watt resistors in my Magnavox 8600 series amp for years, and they haven't burned up yet....you should be good to go....

Nice work as usual. I guess I should order some parts for my latest Magnavox SE 8600 console amp, I can probably swing it. I need to finish it.
Then I'm thinking PP 2A3...I got most he parts to do it.

Here's my old 2A3 SET beast. Still sounds good....
 

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I've been listening to it today in the system. This is a really nice little amp, a great budget alternative to my SE 2A3! :yes: I really think you could build this entire amp for about the price of a decent pair of 2A3s!

Stereo separation is not quite as good, highs are a little less detailed, and the bass is not quite as defined, but all in all, they're not that much different!

In the system:

IMG_7767.jpg
 
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Redboy said:
Can they get any different?! Maybe you want to do an A/B comparison... :lmao:
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Well I can't A/B right now because I packed up the B-2 for shipment to the "spa" last night. Holy crap. Just setting that beast down on top of the bubble wrap popped most of the cells from the pressure alone. I spent over $30 on a new box and a sheet of 2" expanded foam insulation, and scrounged all of the big bubble wrap that I could find from work. About 90 minutes later I was wrestling it into my car, sweat pouring off me.

Dolly does sound nice, I'm pretty surprised for such a simple device. Bass is way better than anticipated, imaging is very good, and the noise floor is undefinable. I could see owning one.

Maybe an A/B can be done when the B-2 returns with fresh caps and a calibration!
 
The Twin Cities AK'ers are about the kindest and most generous group of guys I've met. Nate is right up there, too.

The Karma is strong here.
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I concur....what a hotbed for AK the Minneapolis area is:thmbsp:

I have had this amp for less that 24 hours and have really been putting her through the paces.
Initial impressions are very, very good. I have had success at every turn including phono playback and what ever speaker I have to throw at it. Very detailed, excellent imaging, very distinguished at all levels of the spectrum. It has particularly shined on the Klipsch KG 3.2's which are about big as I can go with my room.....Great work Nate..:yes:
I am a sucker for a 6BQ5/EL84 amp, such sweet tone....




Bill
 
cableguy said:
I concur....what a hotbed for AK the Minneapolis area is:thmbsp:

I have had this amp for less that 24 hours and have really been putting her through the paces.
Initial impressions are very, very good. I have had success at every turn including phono playback and what ever speaker I have to throw at it. Very detailed, excellent imaging, very distinguished at all levels of the spectrum. It has particularly shined on the Klipsch KG 3.2's which are about big as I can go with my room.....Great work Nate..:yes:
I am a sucker for a 6BQ5/EL84 amp, such sweet tone....




Bill
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Hey Bill, I'm glad it's working out for you so far. It was a project that exceeded my expectations in the sound department.

Have fun!
 
beans said:
What's the problem with the power supply wiring? I think it looks great.
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No problem except cosmetically - I think it could have been neater. Someday I hope to be able to build those beautifully laid out amps where everything runs at right angles to everything else. For now, this works.
 
Redboy said:
Some underbelly shots. I know it's a spaghetti mess. I'm not particularly proud of how the power supply wiring turned out...
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Are you kidding? How much old tube gear have you looked at? Yours is certainly much neater than 98% of the old gear. :thmbsp:
 
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