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Post subject: Blue Deluxe Reissue volume pot question
Posted: Wed Apr 21, 2010 11:49 am
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Hello, everyone, I am looking for some advice. I have a Blues Deluxe Reissue and have noticed the volume pot is very sensitive. A little movement on the knob goes a long way. In other posts, I have read about others having the same issue. The culprit seems to be the pot taper characteristics. My observation is that there is a quick jump in loudness and then the increase flattens at about 5. There is little left after that point. I would like to have the range start slower and level out about 8 or 9 on the knob.

Has anyone retrofitted the pot(s) with a quality aftermarket pot that changes the taper to reduce the sensitivity, but still allow the amp to operate to full capacity? I really don't know how to calculate what I want it to do. This question applies to both the channels.

I have done amp mods before and I am pretty handy with a soldering iron so I am cool with making the change if I know what the pot characteristics need to be. I prefer to not use trial and error if possible.

Is there any help out there?


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Posted: Wed Apr 21, 2010 1:58 pm
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yeh there is an audio taper pot to retro fit the amp from antique electric supply but you have to basicly disassemble the amp but i hear its worth it.


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Posted: Wed Apr 21, 2010 3:01 pm
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The volume pot on the clean channel is audio taper, the volume pot on the drive channels is linear taper, both channels suffer from the same problem. The only real fix is a volume box or attenuator.

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Posted: Wed Apr 21, 2010 4:07 pm
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I havent tried the volume box ,but its cheap and supposedly gets good results.


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Posted: Thu Apr 22, 2010 4:17 am
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budglo wrote:
I havent tried the volume box ,but its cheap and supposedly gets good results.


I used one with my HRDx and thought it was great. You can build one or buy one for $20.

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Posted: Thu Apr 22, 2010 7:30 am
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Put a good quality 12au tube instead of the 12ax7 in V3 phase inverter preamp position and the volume problem goes away.


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Posted: Thu Apr 22, 2010 7:38 am
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FXA wrote:
Put a good quality 12au tube instead of the 12ax7 in V3 phase inverter preamp position and the volume problem goes away.


Interesting. Have you tried this?

I just happen to have received a bunch of late 50's 12AU7's a couple of years ago that I haven't been able to use. I thought V3 was simply a phase inverter. It also controls the volume "boost" (for lack of a better word)?


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Posted: Thu Apr 22, 2010 7:44 am
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It's my current setup. I like what it does but you may not. Let me know.


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Posted: Thu Apr 22, 2010 7:46 am
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Thanks. The tubes are interchangeable, so I 'll give it a try.


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Posted: Fri Apr 23, 2010 6:24 am
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Good advice! That definitely works and well. I didn't get to crank it up too much yet as it was late when I got to the swap out, so we'll see how the 12AU7 performs this weekend at louder volumes. If the overall volume remains close and it still has enough crunch, it is a great change.

I will say it sounds great at normal inside volumes while played clean.


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Posted: Fri Apr 23, 2010 6:47 am
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I have cranked it and the crunch is there. I would like your thoughts when you get a chance. My impression is that it breaks up earlier but I really never could get the thing loud enough to breakup the way I would like it with the 12ax7.


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Posted: Fri Apr 23, 2010 3:57 pm
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higher gain tubes have to be pushed harder to get good breakup. remember the lower the gain the earlier they breakup. the 12au7 in the pi position is causing your power tubes to achieve more compression and head room. a lower gain tube in this position also basicly regulates the power section to not breakup too soon. some realy like a power tube to distort early like a 12ax7 in pi will cause some dont its all personal preferance


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Posted: Fri Apr 23, 2010 4:39 pm
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I use a 12AT7 as the P/I in mine. More gain than the 12AU7, but I like it.


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Posted: Sat Apr 24, 2010 8:36 am
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Based on what blackstrat 71 says then the main crunch I would be getting early would be preamp breakup. Power tubes would then breakup latter. If 12ax7 is in p1 power tubes and preamp might be breaking up closer together.


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Posted: Sat Apr 24, 2010 9:21 am
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With the 250K drive control, the amp was definitely designed to get some power tube distortion or at least some P/I distortion. I've actually switched the drive and master pots to get more preamp distortion because of the volume level needed to power tube distort.


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