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Dirty-South Blues Harp forum: wail on! >
Pre-amp tubes for 59 Bassman & Blues Jr
Pre-amp tubes for 59 Bassman & Blues Jr
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Georgia Blues
137 posts
Dec 03, 2014
6:40 PM
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In my Blues Jr I run 12ay7s in slot one and two, 12dw7 in slot 3 and el84 Mullard's in the power slots. This was a big improvement over stock.
I dropped in the billm basic mods and TO 20 output transformer. THAT helped a lot. The cherry on top is a BK Butler BlueTube overdrive with an 12au7. Now all I need is bigger amp! Asking Santa for a bassman. Aren't we all?
Last Edited by Georgia Blues on Dec 03, 2014 6:41 PM
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hvyj
2602 posts
Dec 04, 2014
6:17 PM
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FWIW, I have had good luck using 12DW7 variants in the phase inverter slot to control feedback without eroding tone. A DW7 is half AX7 and half AU7.
In my Super Reverb Reissue I have the amp biased somewhat cool with an ECC832 (the equivalent of a DW7) in the PI slot and no other tube substitutions in the reverb channel. Tone is great and no feedback problems.
My Princeton Reverb Reissue is modified with a Mercury Magnetics Fat Stack Axiom output transformer and a Weber 10F150H 50 watt hemp cone speaker. This amp is also biased a little cool but feedback was an issue. Putting a 5751 in VI didn’t let the amp drive the hemp cone speaker hard enough for good tone and response. So, I put an ECC823 (a backwards DW7) in V4 and the feedback problem became a lot more controllable. V4 is half vibrato driver and half PI. The 823 puts the AU7 triode in the PI position. Now, after the speaker got very broken in, I was eventually able to put a ECC81 (12AT7) in VI with no adverse effect on tone or response and it actually smoothed everything out nicely.
YMMV, but in my experience, tubing down the PI or half of the PI (depending on the design of the circuit) can be an effective alternative to swapping out other preamp tubes to make an amp more harp friendly.
Last Edited by hvyj on Dec 04, 2014 6:19 PM
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bikerpvc
1 post
Mar 03, 2015
5:30 PM
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Settings on the Fender Hot Rod Deluxe.
Hey folks, I have a FHRD amp and I changed out the pre-amp tubes to the Y7s in the 1 and 3 slots. I notice a marked difference in tone already however I'm wondering if you all could tell me where you are setting the controls such as bass, middle, presence, master, treble etc. in order to get that Chicago sound.
I've been playing with the controls and getting some good sound but would like to know if someone could give me a good starting point.
Many thanks.
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Littoral
1214 posts
Mar 03, 2015
7:03 PM
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"...but would like to know if someone could give me a good starting point."
Short answer is the woodshed.
If the answer was in the EQ or tube swaps this thread wouldn't get to 2 pages much less the endless other threads in the archives. A lot of VERY experienced players in this thread and there's a slightly different take from each of them on tube choices, much less eq controls. For example, I've been running rap thump crap through 4 new speakers in my 60 Concert to get at least 100 hours to break them in. Then I will spend an entire weekend on pre-amp tube options until I can't stand it, and that's without messing too much with EQ.
James Cotton, to reference pure Chicago, played through the house PA and a SM 58.
Last Edited by Littoral on Mar 03, 2015 7:05 PM
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SuperBee
2436 posts
Mar 03, 2015
10:35 PM
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bikerpvc that is a very amusing handle.
i have a Hot rod deluxe which i don't use for harp, and a hot rod deville which i modified for harp. the deville runs stock tubes, but has reduced gain and cool bias among other things. the amps are actually very similiar circuits except the deville is 60 watt and the deluxe 40
my settings are something like Bass around 6 - 8, middle maybe 4 or 5, treble maybe as high as 4. your ears will tell you. prescence i think i start around 4.
Master? just use the clean channel. i think that is very important. don't mess with those drive channels, they are bad news. even guitarists don't go there if they are sensible. the joy of the amp is in the clean channel. (the unjoy is in the construction; treat it nice and it should be ok)
and you might want to use input number 2. i have of course plugged a mic lead into the hot rod deluxe and from memory it was a feedback zone somewhere between 2 and 3 on the volume, and closer to 2 than 3
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