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Part Sourcing Assistance/Advice Thread


n_maher

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I was looking at the Schitt Audio Mjolnir amp and noticed that it has an 4-gang Alps RK27 for volume control.  Does anyone know where I could find these.  I see some motorized ones on ebay but am not sure if they are real.  I don't really want to spend more on a stepped attenuator than the rest of the whole project cost.  

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Thanks guys.

 

Nate and Pars, let me know what you have.  I am working on a Shalco stepped attenuator for my Beta 22 but would like to have some sort of volume control other than my pc.  After that it will be moved to a balanced SSMH amp I have in the works.  One of those dumb things I just want to do for fun.  I know it defeats the whole premiss of the SSMH but I want to do it anyway.

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If I remember correctly the gain is pretty substantial and not adjustable on the SSMH so going balanced would not only defeat the purpose but might render the amp useless.  I checked Pete's article and can't find a gain spec'd but you might want to look into that issue a bit more before sinking more $$ into the project.  One of the more technically inclined here can probably look at the schematic and figure it out for you but I'm not your man for that.

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Gain is a little less than mu of the tube. Might be 15 at the current level used.

 

Tying two SSMHs back to back as a "balanced" amp is a bad idea in terms of, well, everything. If you want to build a balanced amp, build a balanced amp. But don't build two non balanced amps and think that putting them together makes something better.

 

Also, conveniently, the 6J6 tube is built to be used as a differential pair.

 

Edit -- and a shunting pot (Config B below) will allow you to use an off the shelf 2 gang pot, sound better, be better balanced, and will cut the signal by ~6dB.

 

Figure_17.jpg

Edited by dsavitsk
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Thanks for all the info guys.  It was really just a thought I had but with this information I see it would be ridiculous to even try.  

 

I do like the idea of that shunted pot.  It looks pretty simple to do as well.  I have to see if I have any 2-gang pots laying around. 

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  • 2 weeks later...

Just did some biasing to my Parasound 1600 (one channel had a nasty 0.5V DC offset). Turns out that despite using really nice (for that time) opamps Parasound decided to use rather cruddy MOSFETs as current buffers for the IV stage. Therefore I'm thinking to swap them out for a BUF634 buffer that would most likely give better linearity and no danger of DC offset.

 

Have any of you got experience with using this chip as a current buffer in similar applications? I could whip up a smd diamond buffer but I have a hard time seeing practical benefits of this.

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  • 4 weeks later...

Parts help needed - somehow in my last Mouser order I forgot the 2 N-channel MOSFETs that I need for a KGSS power supply.  Anyone have a couple spares kicking around that they could send my way.  They are, predictably, the last two damn parts that I need to fully stuff the boards...

 

@c12 - I do have a one of the 4ch alphas if you are still interested.  Just drop me a line and we'll figure something out.

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Parts help needed - somehow in my last Mouser order I forgot the 2 N-channel MOSFETs that I need for a KGSS power supply.  Anyone have a couple spares kicking around that they could send my way.  They are, predictably, the last two damn parts that I need to fully stuff the boards...

 

@c12 - I do have a one of the 4ch alphas if you are still interested.  Just drop me a line and we'll figure something out.

What part exactly? Might have some kicking around. 

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  • 2 weeks later...

Anybody have any ideas for a panel mountable male 30 pin iPod type connector?

I found a connector that would be perfect but it appears I would have to order it direct from the manufacturer and then design a break out board for it.....

 

 

http://www.wellco.com.tw/PDF/IPODConnectors03.pdf

 

 

Sparkfun has one that would do the job but it's pretty huge...

 

https://www.sparkfun.com/products/8295?

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