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PostPosted: 16 May 2009, 17:37 
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Location: Chillicothe, Ohio
Another pic of my build in progress. I received my Rifa 100uf/450V and Nichicon Muse electrolytics today. The Rifas are snap-in, which makes the soldering so easy. That is if the terminals aren't bent out of shape. I had to tweek a couple, but when I got them right the caps stayed fully in place and snug against the board when I flipped it to solder. Also received my 2W 100K R23 from Antique Electronic Supply.

BTW, I am using one of the Rifa 100uf in place of the 47uf.

I'm lovin' this build.

Later, Greg

Image

NOTE: When looking at the side of the board marked "TOP" at C2 position, you are actually looking at the side that will be facing down in your chassis. The capacitors, etc., will be mounted to this side and be hanging upside down. The sockets and tubes will be mounted to the side labeled "BOTTOM", that is if you want them to protrude through the top plate of your chassis.


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PostPosted: 16 May 2009, 17:56 
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Location: Australia
Neat. Who's resistors? I have seen them before but can't remember who makes them.

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PostPosted: 16 May 2009, 18:30 
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The red resistors are 1% metal film PRPs(Precision Resistive Products) I got from Sonic Craft. I measured about 25 1K 1/2W and they were all between 998R and 1006R. I don't know if it's a bunch of hooey or not, but they are hyped to be quality control checked for noise and made specifically for audio applications. And Sonic Craft had every value in stock for the 1/2W and 1W, so that was nice. They are about twice as much as a 1% Vishay at Digi-Key, but that added a cost of only $10 or so to what I needed for two pcbs. If I needed a million or so, I'd have to rethink that.

There's a link to Sonic Craft in the first post of this thread.

Later, Greg


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PostPosted: 17 May 2009, 02:36 
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Thank for the info. I've book marked the page. I have some ccts. for inverse high precision RIAA comp. which need very accurate and quiet components. I'm thinking "Future Project Oh Insane One".

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PostPosted: 17 May 2009, 10:59 
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Hi Greg, Looking real good. What were you planning on using for the larger power resistors, R14 and R22?

From the photo angle, C8 looks pretty close to VT3, the rectifier tube. Do you think high temperature from the tube could cause problems?

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PostPosted: 17 May 2009, 16:25 
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Hi Guys,

Just to confirm the Heater connections for the signal tubes does not have to be connected if you do not have a heater winding on your power transformer, One alternative is use two 5 - 10 W 100 Ohm Resistors each connected from one side of the heater winding to ground to "balance the ac" and reduce the hum.

Hope this helps

-Dan

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PostPosted: 17 May 2009, 20:51 
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Dan wrote:
Just to confirm the Heater connections for the signal tubes does not have to be connected if you do not have a heater winding on your power transformer, One alternative is use two 5 - 10 W 100 Ohm Resistors each connected from one side of the heater winding to ground to "balance the ac" and reduce the hum.

Thanks, Dan!


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PostPosted: 17 May 2009, 21:06 
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Gio wrote:
Hi Greg, Looking real good. What were you planning on using for the larger power resistors, R14 and R22?

From the photo angle, C8 looks pretty close to VT3, the rectifier tube. Do you think high temperature from the tube could cause problems?

Gio,

The sockets and tubes will be mounted on the opposite side of the board, so that won't be an issue. That's something everyone will have to keep in mind when doing their build. When looking at the side of the board marked "TOP" at C2 position, you are actually looking at the side that will be facing down in your chassis. The capacitors, etc., will be mounted to this side and be hanging upside down. The sockets and tubes will be mounted to the side labeled "BOTTOM", that is if you want them to protrude through the top plate of your chassis. Of course there are other ways to skin a cat, and depending on the type of chassis, one could mount things differently. For example, if someone wanted to use a chassis with the tubes fully enclosed, the pcbs could be mounted to the chassis bottom and chassis mount tube sockets used and hardwired to the pcb. When doing that one would have to be extra careful to be sure to wire in the correct order around the tube socket.

For R14 and R22 I'm paralleling some Clarostat 5W 1Ks that I have already. I ended up with 501, 502, 502, and 503 at those four positions on two boards. Those are 1% resistors and seem to be very consistent, like the PRPs.

Cheers, Greg


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PostPosted: 18 May 2009, 10:26 
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Gee, thanks for pointing that out as I had not looked at the boards too closely and assumed the opposite. I marked the note in bold and also copied it to the front page under the first photo so no one misses that point.
Cheers

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PostPosted: 18 May 2009, 11:20 
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Thanks, and great idea!


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