Bottlehead Forum

Bottlehead Kits => Crack => Topic started by: mSummers on February 12, 2014, 01:30:29 PM

Title: Top Plate Question
Post by: mSummers on February 12, 2014, 01:30:29 PM

I decided to have a new top plate cut from mirror finish stainless.  Since I wanted to add holes to facilitate future capacitor upgrades, a choke, etc, I drew up a new plate in CAD after carefully measuring the original.  But, I forgot to draw the vent slots before having the plate cut. 

So my question is, do I need to have another cut with the vent holes added, or are they not that important? 

Title: Re: Top Plate Question
Post by: Paul Joppa on February 12, 2014, 02:09:48 PM

Because of the cathode follower loads (resistors or Speedball) a lot of power (heat) is dissipated under the chassis. Most components are heat sensitive - lifetime halves for every 10 degrees C increase.

That's the background. Anybody has temperature measurements?

Title: Re: Top Plate Question
Post by: galyons on February 12, 2014, 02:11:19 PM

Based on how hot my plate get around vents....Yes!  The 2 3k resistors are creating much  heat, if no Speedball.  The Speedball big board heat sinks need plenty of ventilation.  Either case these are the components directly under the vent. 

 If you already have the plate cut, you could carefully drill a grid of vent holes.  But I would do so only if you have access to a drill press and are comfortable using one.  Not likely to get an esthetically pleasing result by hand drilling.

Cheers,
Geary

Title: Re: Top Plate Question
Post by: mSummers on February 12, 2014, 02:20:26 PM

Thanks guys.  I'll just have another one cut.  I figured they were important or they wouldn't be there.

At least this one won't be a total waste since I can mount all the parts to the plate to make sure everything fits.

Title: Re: Top Plate Question
Post by: Mike B on February 12, 2014, 03:33:52 PM

Good idea.

Crack runs hotter than Stereomour, I have both.

I would make them larger while you are at it.

Title: Re: Top Plate Question
Post by: Evan on February 13, 2014, 07:19:24 AM

Mike has a good suggestion about making the top plate larger. If you really want to experiment with caps and chokes an 8"x10" top plate would work great. I can attest to the fact that shoehorning big caps in the stock Crack can be tough, especially if you want to have room for the Speedball kit.

Title: Re: Top Plate Question
Post by: Paul Birkeland on February 13, 2014, 07:23:50 AM

The bigger plate also means more air space under the chassis, so all those parts have to work a lot harder to effect the same temperature rise.  (Provided those cooling slots are there ;) )

We are happy to sell you an 8" x 10" base too if that's helpful. 

Title: Re: Top Plate Question
Post by: Mike B on February 13, 2014, 07:59:30 AM

I was suggesting he make the cooling slots bigger.