Green pres almost done.

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Ptownkid

Well-known member
Joined
Feb 1, 2005
Messages
4,256
Location
Ajax, Ontario, Canada
So, i got two of the 3 channels i've built so far working fantastically, awesome.

However; one of them is acting a litle funny, it passes sound, but iwth a lot of hiss and the pin voltages are off.

Leftmost to rightmost

0
15.3
12.5
- 15.2
12.5
6 (this one goes up and down one second to the next)
7.5
15.3

7 (fluctuates like above)
7.4
0
- 15.2
- 0.08
- 0.2
- 0.2
15.2

0
0
0
- 15.2
0
0
0
15.2

Anyone that can lead me in the right direction here is the best person ever.

Thanks
 
Well, since you've got two that work, take one of them and do point by by point comparisons through the circuit till you see things get off-then you'll be close.

Joel
 
I just realised that I'm pretty sure I used spdt switches on my green pres, where the bom says spst, do i have the wrong ones? It seems to work fine, but maybe not...

What is the difference between the two, in laymens terms.

I'm assuming dt means on-on and st means on-off.

Does that mean my HPF and +48 won't work right?

Also, what is HPF, haha?
 
Nobody?

Thanks for the reply on the HPF, but i really need the answer to what the diff is between a spst and spdt switch, will my +48 and HPF not work with a spdt switch?
 
Yeah, i stated above that I was fairly certain that i understood the difference, what i really need to know is if I should have used spst switches for my phantom power and high pas on the green pre...

Thanks for the link though, learned some other stuff of interest from it
 
[quote author="Ptownkid"]what i really need to know is if I should have used spst switches[/quote]

Think about it... What difference does it make? As far as the circuit is concerned the connection is being made just the same. Just leave the unused end of each switch floating.

Peace,
Al.
 
Sorry, I should have been a bit more helpful like Alk! You 'should' have used SPST as it is what the BOM called for, but there is no harm using the others, just make sure you wire it in right, do a continuity test with your multimenter and check which pole is thrown where and leave the others floating as Al pointed out. Sorry again for being not so helpful.

Cheers

Matt
 
Thank you both.

Please keep in mind that I'm learning as I go, and though most things are fairly simple for me to understand, there is quite a bit of information that may seem simple and obvious to you, but I don't want to screw shit up.

Thanks again.
 
[quote author="Ptownkid"]there is quite a bit of information that may seem simple and obvious to you, but I don't want to screw shit up.[/quote]

None of this stuff is simple and obvious, so ask away! :thumb:

Peace,
Al.
 
If you look at the circuit, you'll see the following:

HPF is a SPDT.

The phantom is a SPST. However, the PCB is laid out for a SPDT which acts as a SPST. The reason for a SPDT is for better achoring to the PCB.

Not on the circuit:

Phase switch is a DPDT.

Peter
 
Hey Ptown,

I am also a Newbie ;-) A month and half ago I had not even wielded a soldering iron. I am also learning, my head feels like sponge trying to absorb as much as I can. My wife has to pull me away from the PC as I spend far too much time here, but then I remind her how much money I saved on building my own pres and she is satisfied ;-)

Cheers

Matt
 
[quote author="peterc"]If you look at the circuit, you'll see the following:

HPF is a SPDT.

The phantom is a SPST. However, the PCB is laid out for a SPDT which acts as a SPST. The reason for a SPDT is for better achoring to the PCB.

Not on the circuit:

Phase switch is a DPDT.

Peter[/quote]

See, that's what confused me, the ones on the board in the picture are spdt

Cheers
 
the ones on the board in the picture are spdt

You'll see that even in the picture, the phase spdt doesn't connect to anything on one end essentially making it a spst.

Joel
 
Hope you don't mind sneaking in this question here: the discretes, what current gain should they be ? Assuming BC550C, but the schematic mentions BC550B.. (perhaps that was just the kinbd of component available in the drawing-program ?)

Thanks,

Peter
 
Sorry for this, do you mean it's the case that a BC550B should be used OR that it was only a B because of the drawing program ? I thought somewhere else C was mentioned.

One additional keystroke ( B / C ) would clarify it all perfectly :thumb:

Thanks,

Peter
 

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