Bottlehead Forum
Bottlehead Kits => Legacy Kit Products => Quickie => Topic started by: Bartguy on January 05, 2013, 07:09:59 AM
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Hi, I' built a PJCCS version of the Quickie which worked great except that when connected to a 50W solid state amp, the volume got too loud at around 8'oclock on the volume knob. So I read up on this forum about how to reduce it by replacing the jumpers between the input selector switch and the pot with 100K ohm resistors. The forum thread was http://www.bottlehead.com/smf/index.php/topic,563.msg3575.html#msg3575
Sounded easy enough, so I did it, using some good Dale resistors rated at 100kohm, power rating 100mw, voltage rating 200v. The result was way too much gain reduction. I had to turn the volume to it's max to even hear if there was music playing. So then...
I replaced the 100Kohm resistors with 10Kohm Dale resistors, thinking that the 10Kohms would attenuate the signal less, thus splitting the difference between the 100K resistors and the jumpers. But the result was the same, I had to turn the volume to the max just to hear any music.
I double checked that I'm soldering the resistors to the right inputs on the input selector switch and volume pot. (mid right on selector to bottom left on pot. Mid left on selector to top left on pot.)
I'm just a newb, so maybe I'm misunderstanding what I should be doing. Can anybody tell me what am I doing wrong?
Thanks
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What percentage of the rotation is 8 o'clock for you?
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Maybe 20% of the way from completely off (all the way counterclockwise)
Seems like the usable range is between off and 25% tops.
Are you thinking that it doesn't need to be attenuated at all?
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try this info from goldpt:
www.goldpt.com/mods.html
It can apply to potentiometer.
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Maybe 20% of the way from completely off (all the way counterclockwise)
Seems like the usable range is between off and 25% tops.
Are you 100% sure the 10K resistors are 10K resistors? (I'd measure them to check)
The difference in attenuation between the 100K series resistor and the 10K series resistor is around 5db (in other words, the 10K series resistor should be close to inaudible).
-PB
(25% of the rotation is useable - sure, I'd attenuate that a bit, try 33K or 47K)
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I think there's a problem with the way the resistor is connected. 100K should reduce the sound only 6dB, which is about 45 degrees rotation of the knob - so you should get to 9:30 on the clock before it gets too loud. Somehow, you have gotten huge attenuation. I'd look at the pot connections, which are confusing and hard to see. Get a strong light and reading glasses if necessary; look for bad connections and/or bits of wire that are touching each other but shouldn't.
You should have replaced the wires shown in the right-hand photos on page 23 of the manual - black wire in the top right photo, red in the center right photo. Notice that the top right photo especially is quite dark where the black wire is shown, making it especially easy to mistake the intent. Also, the ground wire (not installed yet, in the manual photos) is bare; make sure it's not touching the resistor leads.
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I'll check all the connections again. Thanks for the timely help everyone.