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The John East preamp club

#1,061
bigtone23 said:
I have a Jazz with Bart Classics and the J Retro. I set mine pretty much the same to sort of offset the contour: bass off, sometimes a little cut to the treble (though the Barts are smooth up top), maybe a small boost to mids.
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Thanks to both replies. That is is 100% my experience, a little boost to the upper mids seems to help. About 1/8 of turn from max on the mid frequency Knob and about 1/8 of a turn up from center on the level. Treble flat and a bit of tone roll off.

I read it somewhere before …maybe here: Do we know what frequency the bass boost in the contour is? I can always adjust my amp by ear but curious what I might do outboard the bass to counteract the contour. Overthinking it I know.

Overall I can tell it is a quality preamp and that is why I am not looking to replace it. I just love having B M(+ freq) T + passive tone at my finger tips. If I had a magic wand I would erase the contour, lose the bright switch and have blend work in passive. But I understand that's not the way it was designed and I can accept that…. Sorta :)
 
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#1,062
I'm glad I finally made the leap to install one of the J Retro 01s in my Torzal jazz, (vol/bl). It really opened up the SD Apollo set that's in there.

East Preamp.jpg
 
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#1,065
Hey guys, huge fan of John East's circuit designs (IMO heads above the other aftermarket bass pre-circuit designs)!! I have a super old J-Retro deluxe in a J-bass deluxe w/Nordstrand VJ4's that's unparalleled in versatility but crazy wide sonic "sweet spot" even at potentiometer extremes!

**Quick question for folks who've replaced a Lakland 55-02 or other instrument with serial/parallel/single coil pickup toggle switches;
I've got Delano MM/J (MM5 FE + JMC5 FE) and I really love having the ability to solo the MM bridge single coil in tandem with the J-style neck, plus have the big loud serial HB bridge or classic parallel "Ray" HB tone w/Bridge solo'd.. I really don't wish to give this up!

-Are there any concerns with mixing an active blend design in the uni-pre in combination with a switching ground lead connection going between serial/parallel??
It's not an issue for a Hum/N.Single/B.Single ala Lakland's switch configuration. But I suspect this may be why they do it this way. IMHO a MM's bridge & neck coil's aren't worth the 10 cents in hookup-wire (sound close to identical)
There ARE preamps I've owned (Audere etc) that have a discrete FET input/signal blend that can't work with this switching.. Thoughts??
 
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#1,066
JfetPre775 said:
Hey guys, huge fan of John East's circuit designs (IMO heads above the other aftermarket bass pre-circuit designs)!! I have a super old J-Retro deluxe in a J-bass deluxe w/Nordstrand VJ4's that's unparalleled in versatility but crazy wide sonic "sweet spot" even at potentiometer extremes!

**Quick question for folks who've replaced a Lakland 55-02 or other instrument with serial/parallel/single coil pickup toggle switches;
I've got Delano MM/J (MM5 FE + JMC5 FE) and I really love having the ability to solo the MM bridge single coil in tandem with the J-style neck, plus have the big loud serial HB bridge or classic parallel "Ray" HB tone w/Bridge solo'd.. I really don't wish to give this up!

-Are there any concerns with mixing an active blend design in the uni-pre in combination with a switching ground lead connection going between serial/parallel??
It's not an issue for a Hum/N.Single/B.Single ala Lakland's switch configuration. But I suspect this may be why they do it this way. IMHO a MM's bridge & neck coil's aren't worth the 10 cents in hookup-wire (sound close to identical)
There ARE preamps I've owned (Audere etc) that have a discrete FET input/signal blend that can't work with this switching.. Thoughts??
Click to expand...
I installed mine in combination with 2 Delano MM with serie/parallel/sigle mode switchs for both pikups and zero issue.
 
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#1,067
Zeom said:
I installed mine in combination with 2 Delano MM with serie/parallel/sigle mode switchs for both pikups and zero issue.
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@Zeom Fantastic!! I honestly figured as much, John seems to consider every possible factor to the install process (and far far beyond!!) I'm literally going over to the Best Bass site right now to get me a 4 knob Uni-Pre!!! Off I go! :)
 
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#1,070
I recently put a John east 4 knob into my warmoth custom fretless. Sounds great and the tone control is nice to have since I was missing it before.

Only trouble is the difference between passive mode and active mode (with all active controls to center) is something like 6-10db. According to the instructions the pots inside allow for gain adjustment so I went in there but they were all at lowest setting. Only thing I could do was add more. Oh well, I guess passive mode is only for emergencies.

I have a feeling that nordstrands and a JE preamp is the last mod (12 years of messing with this one).
IMG_2104.jpeg
 
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#1,071
ProbablyTooLoud said:
Hey peeps,
I have a j-tone and am curious where other j-tone users set the internal gain trim.
Full on or dialed back a bit?
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I try to set gain so the passive (with tone knob on 10) and active modes (with the EQ at the center detents) are as close in volume as possible.
If the active mode is just a hair louder, that's fine, too.
 
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#1,076
klattman said:
I recently put a John east 4 knob into my warmoth custom fretless. Sounds great and the tone control is nice to have since I was missing it before.

Only trouble is the difference between passive mode and active mode (with all active controls to center) is something like 6-10db. According to the instructions the pots inside allow for gain adjustment so I went in there but they were all at lowest setting. Only thing I could do was add more. Oh well, I guess passive mode is only for emergencies.

I have a feeling that nordstrands and a JE preamp is the last mod (12 years of messing with this one).
View attachment 7036579
Click to expand...
My 2 cents;
#1. Nordstrand Pickups + J. East Preamp's=The two greatest electronic engineers & innovators in bass guitar electronics design.. By a mile!! So yes, I believe it will absolutely be your last mod!

#2. John East's circuit's really aren't designed to be used a ton active bypassed.
I believe East's own (paraphrased) words were; "Its there to keep your sound from going dead.. A basic save your ass during a gig should your battery die switch"Obviously they can be.. But really shouldn't be, for a couple reasons;
The first most & obvious imho is WHY would you want to?!? ;)
The thing is active there's a great deal more going on electronically which's sonically beneficial, beyond simply being a tone control.. From decoupling your pickups' & routing each signal independently through 2 isolated active (and passive!) channels. To removing the load on your pickups, providing a fully buffered low impedance/very low noise output to your amp/D.I./Interference whatever.. Driving long cable runs/true bypass fx etc.. Preserving & improving the true sound of your (awesome Nordy) pickups. And so much more!!

P.S.; Have you experimented with the internal gain trimpot's or rotary wheels (I believe they're using thumb-wheel's now)?? Also the Bass, It could be boost only even if it has a center detent. Which at center detent can account for at least a 5-9db gain increase!
 
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#1,078
JfetPre775 said:
…
P.S.; Have you experimented with the internal gain trimpot's or rotary wheels (I believe they're using thumb-wheel's now)?? Also the Bass, It could be boost only even if it has a center detent. Which at center detent can account for at least a 5-9db gain increase!
Click to expand...
Yes my results are with the internal gain pots minimized. I can only make the active circuit louder.

Passive at same level preserves the often complicated gain staging I use for edge of breakup. Since this bass is hotter than others I need to tweak each tim I use my rig/interface/etc.

Also would be nice to switch between sounds on the fly.

Not a deal breaker…
 
#1,079
Hey all. I have a grounding question I have the 5 knob uni pre. I have some grounding noise and was wondering if I did the grounding correctly. I took the loose green wire from the jack labeled "to main ground point" and soldered it to a point in the control cavity. My cavity has copper tape with conductive adhesive.

I grounded the bridge with a loose wire and soldered it about 1/2" away from that green wire. Should I be doing this another way? Can I take the loose green wire from the jack and put it in the same terminal lug screw as the other green wire that is already under that lug screw in the power and output block? See the attached photo that I doctored up to resemble what I am saying. Both green wires are soldered to the same terminal on the jack, so I don't know why it would be a problem to do what I am saying.

As a test, I removed the entire preamp and replaced it with a basic passive VVT harness. I grounded the jack and bridge to the back of the same tone pot and there is zero noise now. I am wondering what is the equivalent way of doing this grounding in the East preamp.

IMG_5086.jpeg
 

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