THAT preamp experiments......

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3nity

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Joined
Dec 30, 2005
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I'm just playing with THAT chips and sound just awesome.

I just followed the datasheet schems no DC-servo unbalanced....but i added a 4.4uF at pin 3 to ground and well i don't know i tried a few values from 1.1uF to 4.4uF, various brands and well each has a unique sound...has anyone played with that??

1.1uF sounded very tight and the 4.4uf sounded big with huges lows.....Is there anything i should experiment aside caps to ground??

I'm using +/- 15V, should +/- 18V make it sound different?

I should record those variations...
 
These are nice chips, aren't they? Clear and quiet.

+/- 18 should just give you more headroom. No real effect on sound (unless you are close to clipping.
 
[quote author="3nity"]I'm just playing with THAT chips and sound just awesome.

I just followed the datasheet schems no DC-servo unbalanced....but i added a 4.4uF at pin 3 to ground and well i don't know i tried a few values from 1.1uF to 4.4uF, various brands and well each has a unique sound...has anyone played with that??[/quote]
Pin 3, which IC-type and package version ? Must be the SO14 then, but that can't be correct either, too small value for high gains. So let's be :roll:

http://www.thatcorp.com/datashts/1500data.pdf
 
Perhaps he's referring to XLR Pin 3, i.e. he's trying to create an impedance balanced output (which however would have to include a resistor equal to the circuit's output impedance and a same size output cap in front of XLR 2 and 3)?
 
[quote author="Rossi"]Perhaps he's referring to XLR Pin 3, i.e. he's trying to create an impedance balanced output (which however would have to include a resistor equal to the circuit's output impedance and a same size output cap in front of XLR 2 and 3)?[/quote]
That's a good suggestion, would male sense like that :thumb:
Let's also get some confirmation from the OP, which type of That stuff are we actually talking about ? The 1510/1512 micpreamp ICs, right ? '3' an IC-pin number or of the XLR like Rossi suggested ?
 
Clint...sorry I was referring to XLR pin 3!

I'm using the 1510 8-DIP.

Rossi i used the resistor but didn;t hear any difference without...??
 
[quote author="3nity"]Clint...sorry I was referring to XLR pin 3!

I'm using the 1510 8-DIP.

Rossi i used the resistor but didn;t hear any difference without...??[/quote]
You shouldn't notice differences in sound indeed, but it'll help for better suppression of eventual disturbances: it makes the impedance of the non-ground-lines (wouldn't call them both 'signal'-lines) equal, hence better suppression because of the comparable amount of developed disturbance-signal on both.

See for instance the unavoidable Jensen AS004.pdf (R4, C3):

http://www.jensen-transformers.com/as/as004.pdf



Regards,

Peter
 
[quote author="clintrubber"]You shouldn't notice differences in sound[/quote]

..Unless you're feeding the output into a transformer-coupled input, in which case it effectively moves to being in-series with the primary winding... in which case it CAN most definately have a sonic effect...

But that's a particular case, and I agree... into a typical transformerless load/destination, it will essentially have NO effect on sound, and only an effect on the sound of residual (uncanceled) noise.

Keith
 
[quote author="SSLtech"][quote author="clintrubber"]You shouldn't notice differences in sound[/quote]

..Unless you're feeding the output into a transformer-coupled input, in which case it effectively moves to being in-series with the primary winding... in which case it CAN most definately have a sonic effect...

But that's a particular case, and I agree... into a typical transformerless load/destination, it will essentially have NO effect on sound, and only an effect on the sound of residual (uncanceled) noise.

Keith[/quote]
True indeed, in case of that case in case your listening carefully :thumb:
 
Keith i'm not using transformers at all.This balanced output was inspired by my NYD1-B build. but in that case i could not hear anything...in capacitors...what's more strange is that when i use the 4.4uF i hear more noise that when i used the 1.1uf!

Here;s a schem of how i did the hook up..
1510.GIF
 
Nah! Don't use +/- 18 V ... they accept it, but not for a very long time :)
+/- 17.5 V is my personal maximum.

THAT Corp., their chips and the nice support simply ROCK.
The chips are easy to get, they're sending much samples and they give free checking of circuits, even for commercial productions.
 
[quote author="3nity"]Here;s a schem of how i did the hook up..
http://www.twin-x.com/groupdiy/albums/userpics/1510.GIF[/quote]
If you add only one cap I'd insert it in the actual signal line. Or better, use two... and a small series resistor, like in the Jensen-circuit above. It'll all work fine though, we're talking details that won't really play a role for most applications in friendly environments.
 
It seems not that difficult to me to actually grab the datasheet and check the absolute maximum ratings for the power supply..? What do my tired eyes see: +/- 20 V. So +/- 18 V is fine.

That cap-grounded XLR pin 3 doesn't make any sense, and you should include a series-isolation resistor in series with the output of the IC. So what we need (as noted before by clintrubber/Jensen): ~47 ohm from IC out to XLR pin 2 and an equal valued resistor from ground to pin 3.

It'll all work fine though, we're talking details that won't really play a role for most applications in friendly environments.
Without series resistor it will pretty quickly go into oscillator mode when it sees more than a few feet cable.

Samuel
 
But do you actually need that output cap? There should be just a few mV at the output, not enough to upset most line inputs.

Personally I feel that anything below 100 uF is too small for an output coupling cap--or you'll get some serious high-pass filtering if once in a while it sees less than the usual 10k load. Or is that an application where the load is known (and high)?

Samuel
 
Nop i 'm just trying to understand why it affects the sound....from dark/warm to thick and present if testig some values....one more thing.

at the moment i'm not using the 10K load resistor.
 
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