another new guy warning

[fishboat]

Does anyone know how warm the top plate of the Stereomour gets with normal use? 

Room temp?, 90 degrees?, slightly warm..?

[rlyach]

I just measured my Stereomour after playing it for a while at almost full volume. The hottest part of the plate was about 96 degrees F. The power transformer reached 105 degrees F. I am not sure what you need the number for but the coefficient of expansion for aluminum is 12.3 micro inches / inch / degree F. So a 12 inch plate would expand by .016 inches from zero degrees. Just a guess that this is what you are after. BTW, the ambient temperature in my room was 78 degrees F and if you start there the expansion is only .004 inches.

[Grainger49]

Bottlehead plates and transformers run hot.  So do the tubes, the glass.  Paul Joppa, who designs the transformers, knows what heat will be seen during operation and it is taken into account.  That is to say a hot transformer/plate/tube glass is normal.

[fishboat]

Thx guys..exactly the info I was looking for.  I was just considering more options.  I was thinking about toning the plate to a warmer color with a tinted shellac.   I see where some have painted the plate.  From the pics I've seen the swirl aluminum looks nice. With tinted shellac could turn the plate any color I like to match the wood base.  Shellac is a hard finish, I'll just need to find out what kind of heat it could take before it gets soft. 

[rlyach]

I wouldn't cut it too close with the temperature. Depending on how thick the shellac is it will change the thermal conductivity of the plate, reducing its ability to draw heat out of the system. Your temperature might run hotter than mine, since I have bare aluminum.

BTW Grainger, While my system was playing at full volume I measured the sound pressure at 86db at 10 feet. That is how far my chair is away from the Orcas. This is good correlation with your number. At least I know that I am getting as much out of my "3.5 Watts" as I can.

[Paul Joppa]

For what it's worth, I think the Stereomour power transformer runs cooler than the others.

[fishboat]

I wouldn't cut it too close with the temperature. Depending on how thick the shellac...

The shellac would be a thinner coat than paint(a typical 1 lb cut of shellac is about 12% solids where paint will be in the 35-50-% solids range..higher solids = higher coating thickness) & painting seems fairly common.  I agree that any coating will insulate & raise the temp of the plate a bit.   I looked into the thermal aspects of shellac...it starts to soften at about 100 deg(F) and melts in the 160-ish deg range.  Sooo..while a tinted shellac would be perfect for adding color, it'll be too soft given the heat..oh well   There's other options.  Thanks for the measurements, they really helped.

[drewh1]

Such a helpful discussion - I just cut my wood base and was wondering if I left enough room for expansion. 1/16 should be more than enough. thanks guys - this is a very helpful forum.

[howardnair]

fishboat- here some pics of 2 stereomours with wood chassis and inputs and binding posts on back
https://picasaweb.google.com/100635555508988591604/Mar202013?authkey=Gv1sRgCO2NkufB29GP9QE

[4krow]

Howard,

    Well, looking at such woodworking humbles me. Whether that was furniture or stereo gear, I am speechless. The chosen woods are perfect, as are the finishes. I would say more, but am not willing to risk stumbling all over myself. Well done indeed.

[fishboat]

Howard....very nice  work & thanks for posting the link to them.  Cocobolo? Sapele?  I've considered the all-wood option also..along with the bucket of other options I'm thinking about.  Your pics are a really valuable reference.  Your rear panels are exactly what I was thinking.

Where did you get the drilled washer-trim at the base of each tube(on the darker wood amp)?  I'm guessing you may have made them? 

Beautiful work!

[rockdrummer]

WOW that is beautiful work Howard.

There is another Stereomour that Ebag4 built that has a decorative wood cover behind the tubes.  Great looking amps.

I thank the Bottleneck Gods that I got directions and don't have to know how to build an enclosure from scratch.

What considerations need to be made when adding a cover and avoiding a fire?  I bet that is a lengthy question to answer.  Another day maybe.

Great work and can't wait to hear mine!

Ben

[fishboat]

....don't have to know how to build an enclosure from scratch.

For me, that's the easy part.  In my case the electronics assembly part will break a little new ground..

[howardnair]

the wood is bloodwood--and here is a great site for drilled washer trim and all kinds of other goodies
http://www.vt4c.com/shop/program/main.php?cat_id=1021&group_id=2&hit_cat=

[fishboat]

Howard,

Great resource!  What they haven't got isn't worth having.

thanks..