[Paladin79]

As one gets older, I read that it is fairly normal to lose a one octave range, high frequencies. I can no longer hear 15,750 hertz or above so I try to remain objective about sound and garner other opinions. There are obviously tubes I like more than others but I often wonder if specific used tubes might be at their best when received.

 

[Allanmarcus]

can anyone post what parts are needed for the rectifier cree/Schottky diodes needs for the mod? The board, I think is this one:
http://www.partsconnexion.com/product26996.html

but what about the diodes?

 

[bloodhawk]

can anyone post what parts are needed for the rectifier cree/Schottky diodes needs for the mod? The board, I think is this one:
http://www.partsconnexion.com/product26996.html

but what about the diodes?

https://www.mouser.com/ProductDetail/941-CSD01060A

 

[Allanmarcus]

https://www.mouser.com/ProductDetail/941-CSD01060A

Thanks! Any idea about the Schottky?

 

[bloodhawk]

Thanks! Any idea about the Schottky?

That is a Schottky Diode. Which is a type and not a brand

 

[Paladin79]

Cree brand. I have several in my shop but not Cree. Barrier diode.

 

[Allanmarcus]

That is a Schottky Diode. Which is a type and not a brand

Doh! I though Schottky was a brand, not a type. Research time.

Thanks.

 

[Paladin79]

Walter Schottky was the inventor. Names like Volta, Faraday, Galvani, were attached to invention.

For some fun research look up Giovanni Aldini, nephew of Galvani. His experiments with electricity on frogs are thought to be the basis of the first science fiction novel, Frankenstein by Mary Shelley.

 

[Dababy]

I have found that the Crack is very sensitive to microphonic, almost not matter what tube you put in. Anyone have any ideas on chassis modifications to make it more stable and isolate more vibrations?

 

[Allanmarcus]

I have found that the Crack is very sensitive to microphonic, almost not matter what tube you put in. Anyone have any ideas on chassis modifications to make it more stable and isolate more vibrations?

Yep. I had the same issue. Here's how I solved it.

First, I get a few of these any vibration pads:
https://www.supplyhouse.com/sh/control/search/~SEARCH_STRING=anti vibration

I got the some of the blue ones and some of the cork ones. They are so darned cheap, I got a nice variety for different purposes. Some times I use them under speakers to protect the surface. Sometimes I use them to increase ventilation under a component.

For the crack I did this. I use four 2" square pads under a 5 pound granite cutting board ($11), then 4 more under the crack. The heavier surface between the crack and the table seems to help stabilize the crack.

I would start with the anti-vibration pads, and if you need more isolation, add a heavy surf between the crack and the table, with anti vibration pads in between. it's a very inexpensive solution.

 

[Dababy]

This does look like a very neat solution! I found that my EC ZDS with triangular rubber feet isolates vibration very well. I wonder how rubber spike would work under the granite....

 

[Allanmarcus]

I wonder how rubber spike would work under the granite....

There are some examples of that on Esty. There are also lots of spikes and feet on Amazon (probably on AliExpress too). This would not be hard to make:

https://www.etsy.com/listing/268521224/audiophile-walnut-isolation-platform

Just some nicely stained, thick hard wood and some feet like these: https://smile.amazon.com/gp/product/B077SVS33N
Add more weight with the granite cutting board.

If you google search for "The Tube Anti-Vibration/isolation Discussion" you will find a thread I started on a another site on this topic. There are some good ideas there too.

Also, herbies makes some good stuff that isn't too expensive
http://herbiesaudiolab.net/compfeet.htm and http://herbiesaudiolab.net/misc.htm and http://herbiesaudiolab.net/softdots.htm
They also have some well regard anti-vibration stuff for the tubes too. http://herbiesaudiolab.net/tube.htm
Might even be helpful, though I have not tried it, to put weight on the crack itself. Any herbies has some "stabilizers" specifically for that, but they are pricey http://herbiesaudiolab.net/stable.htm
.
The trick is to get some weight to stabilize it.

I would try the anti vibration pads first.

 

[Maxhawk]

In my opinion, a properly functioning tube should not be microphonic. The 12AU7 input tube contains all the gain so it will be more susceptible, but there's nothing about the Cracks's topology that makes it more sensitive to microphonics. I have probably a dozen input tubes and maybe 1-2 of them are microphonic.

 

[Paladin79]

I happened to notice dampers for various sized tubes the other day in the event a tube is slightly microphonic.

https://www.ebay.com/itm/10Pcs-19mm...12AU7-12AT7-EL84-ECC88-6F2-/263366770809pers-

I have no idea if these work on tubes.

Personally I have no problems with this issue, the three plates I incorporated in my crack weigh in at three pounds and I used one inch thick oak for an enlarged cabinet. Weight alone probably helps mine a bit.

To quote Allan...
The trick is to get some weight to stabilize it.

Mine is very stable, but not your normal Crack build.

 

[Paladin79]

In my opinion, a properly functioning tube should not be microphonic. The 12AU7 input tube contains all the gain so it will be more susceptible, but there's nothing about the Cracks's topology that makes it more sensitive to microphonics. I have probably a dozen input tubes and maybe 1-2 of them are microphonic.

I do agree with this statement, if you look at the other components used, the wire etc., there is very little in the design that can cause issues. There is some thing called a flag pole effect, if you have a tube that is slightly microphonic sitting on the cabinet I can imagine the microphonics being made evident with a slight cabinet shake.

I had not even purchased a crack, I glanced at a photo of the parts in the kit and I knew immediately I did not want to use the top plate. I went so far as to ask the dimensions and order an 1/8 inch copper plate before I even received the kit. I also incorporated other changes, a larger cabinet to allow for more expansion, dual volume controls, etc. I believe Allan was kind enough to tell me it was a 6x10 inch top plate and I went from that.

I did use the aluminum plate on another build but only after I added a layer of carbon fiber and double the basic cabinet size, two more plates and 16 layers of laquer so it has some extra weight as well, and little vibration.

I should also mention, and this is more of a personal thing, but I did not like the idea of reaching around the tubes on the top plate to turn the amp on or plug in a cable, or plug in the quarter inch headphone connector. All inputs on mine are on the back, controls are on the front, and my headphone jack is on the side in one inch oak. I do little to add any vibration even if it is just adjusting the separate left and right volume controls.