Quickie preamp

[earwaxxer]

Here's the choke link
http://angela.com/hammondchoke156c.aspx

 

[galyons]

Batteries from radio shack industrial grade.

Now there is an oxymoron if I have ever seen one!! 

Quickies are fun and perform to an amazing level!  Radio Shack...not so much!  ;D

Cheers,
Geary

 

[underdawg]

I was just trying to find reasonable batteries is all, and at least the shack changes the stock frequently.

 

[Paul Birkeland]

FYI - a 47uF-100uF at 6+V will work for the cathode bypass capacitors.

 

[underdawg]

why such a high value capacitor, normally I bypass power supply caps with .1 to 1 uf caps?

 

[Paul Birkeland]

A bypass capacitor implies that it's bypassing a larger capacitor. 

The capacitor across the cathode resistor is there to act as a short for AC on the filament, removing degenerative feedback that would otherwise be there.

The cathode bypass cap also stabilizes the bias point, though this becomes unnecessary with the PJCSS upgrade IMO.

The size of the cathode bypass cap must be sufficient to offer the same "short" across all audio frequencies and then some.  The 1000uF cap we put in the last Quickie was used because we already had it, the new Quickie uses a 150uF capacitor that we added to our inventory for the BeePre.

-PB

 

[Grainger49]

The above post is an example of Bottlehead's business acumen.  Stocking a new part costs money.  Until it is necessary you don't do it. 

 

[underdawg]

so based on 1000 uf and 150 uf, I assume since I just ordered one its coming with 150 uf caps, so I have some nice mundorf 390 electrolytics that should work ok?

 

[underdawg]

so based on 1000 uf and 150 uf, I assume since I just ordered one its coming with 150 uf caps, so I have some nice mundorf 390 electrolytics that should work ok?

The caps I have are bipolar 390ufd 63 volt, but I am not sure what side is the negative either, I feel stupid being in electronics 25 years and cant tell, tried to google but mundorfs site couldnt tell me.Anyone know if they will work and which side is the negative?

 

[Grainger49]

You mean there is no stripe on the Mundorf?

 

[Paul Joppa]

Bipolar electrolytics are just that - no polarity, either end can be negative. They do have a reputation of sounding better than polarized electrolytics.

 

[Paul Birkeland]

A 390uF/63V cap will work well, and the new layout has more room for such adventures.

A bipolar cap doesn't technically have a positive and negative side, just hook them up as you like (but be consistent if there happens to be two different lead lengths).

-PB

 

[underdawg]

Thank you paul and cauc I rememebered finally, hence then name , bi, both ways. I did find nos nobles volume controls and they are stereo but each side has 4 posts instead of 3. Any idea's?

 

[underdawg]

You mean there is no stripe on the Mundorf?

on these no there isnt, but we figured it out.the leads are the same size also. but since these are bi polar, bi, both ways.

 

[Paul Birkeland]

Thank you paul and cauc I rememebered finally, hence then name , bi, both ways. I did find nos nobles volume controls and they are stereo but each side has 4 posts instead of 3. Any idea's?

I think a pot with 4 posts may have a tap for loudness, you'll probably have to use some clip leads and test it out and see how it should be hooked up.

 

[underdawg]

Thank you paul and cauc I rememebered finally, hence then name , bi, both ways. I did find nos nobles volume controls and they are stereo but each side has 4 posts instead of 3. Any idea's?

I think a pot with 4 posts may have a tap for loudness, you'll probably have to use some clip leads and test it out and see how it should be hooked up.

ok when it comes in ill meesage you with measurements