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biellis  
#1 Posted : Sunday, January 27, 2008 3:14:24 PM(UTC)
biellis

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I plan to use the Ballsie with my Pumpkin preamp that has extra gain for my F4 amps. I would like to reduce the gain of the single ended output of the Ballsie, is there a better way other than resisters at the output?

Bill
Russ White  
#2 Posted : Sunday, January 27, 2008 3:19:12 PM(UTC)
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There is not much gain, its only about 3db. the SE output of the ballsie is right at rebook levels(2VRMS) with full scale output from the opus. :) So I would not even touch it.

Edited by user Sunday, January 27, 2008 3:19:57 PM(UTC)  | Reason: Not specified

biellis  
#3 Posted : Sunday, January 27, 2008 3:36:47 PM(UTC)
biellis

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I am not using the Ballsie with Opus. I plan to drive it from the Pumpkins balanced outputs. The Pumpkin puts out to much voltage, I would like to drive other single-ended devices off of the Ballsie with less voltage output.

Edited by user Sunday, January 27, 2008 3:38:27 PM(UTC)  | Reason: Not specified

Russ White  
#4 Posted : Sunday, January 27, 2008 3:42:42 PM(UTC)
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Interesting... well I would probably just put a voltage divider at the input of the ballsie, since without it the input voltage swing may well be too much even for unity gain.
biellis  
#5 Posted : Sunday, January 27, 2008 3:53:42 PM(UTC)
biellis

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I was worried about overdriving it, The Pumpkin is capable of outputting 30v, If I use a voltage divider on Ballsie input will that affect the other parallel balanced output on preamp?
Russ White  
#6 Posted : Sunday, January 27, 2008 4:29:22 PM(UTC)
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I am not sure exactly what you are asking...

Do you mean loading the output of the pumpkin? That should be in a feedback loop, and a load should not bother it at all, as long as it is not to heavy.

I would use a series resistor around 10K and then try 2.21K as shunt to ground or so until you find the attenuation you want.

30V would seriously overdrive the ballsie, even unity gain.
biellis  
#7 Posted : Tuesday, January 29, 2008 8:07:05 PM(UTC)
biellis

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OK , so put a 10K in series on the + side and - and then a 2.21k from each of them to the ground wire? I am currently driving it from my Twisted X Bosoz with the F4 I run my gain up 3/4 the Balsie is running off my second output and goes to my subwoofer amp. It has way to much gain but is not distorting.

Edited by user Tuesday, January 29, 2008 8:11:06 PM(UTC)  | Reason: Not specified

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Russ White  
#8 Posted : Tuesday, January 29, 2008 8:12:20 PM(UTC)
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Sure that will reduce the voltage in to < 1/4 of what it was. Its a good starting point, see if the ballsie seems to be over driven or under driven. Adjust the resistor to GND accordingly.

Cheers!
Russ
biellis  
#9 Posted : Tuesday, January 29, 2008 8:18:07 PM(UTC)
biellis

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Its nice to have a single ended output again, I have a 300b set amp, kt88 push pull, and a M3 headphone amp that have been idle all this time.
Russ White  
#10 Posted : Tuesday, January 29, 2008 8:22:04 PM(UTC)
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Totally understand. You may also want to adjust the 10K resistor a bit lower, Just don't go much lower than say 2.21K or you will load up your pumpkin. Just figure out the ratio that seems right. The reason I say this is the lower value resistors will have slightly less noise, but even 10K should not be significant.

Let me know how it works out. :)

Edited by user Tuesday, January 29, 2008 8:24:21 PM(UTC)  | Reason: Not specified

biellis  
#11 Posted : Tuesday, January 29, 2008 8:59:48 PM(UTC)
biellis

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It will be a while before pumpkin will be built, so I will change the feedback resisters in Xbosoz for more gain. I am actually putting a little 2 position dip switch on top of a 100k and the original 39k so I can easily switch it back. I will be waiting for Pogo and new version of Joshua and Darwin with display for Pumpkin, may Evan try to incorporate Balsie with multiple output switching.
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