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The John East preamp club

#861
I have a Uni Pre 5 knob installed in my Lakland 44-02 with Bart pups. Love it. I'm trying to get some direction on how to set the jumper for pre shape.
Technical Details
• VOLUME / BLEND CIRCUITS
5 Knob Type
3 & 4 Knob Type
VOLUME
PLUG-IN TONE CAPS
BLEND
PLUG-IN TONE CAPS
BLEND GAIN TRIMS
POWER & OUTPUT
VOLUME
PICKUP GAIN TRIMS
POWER & OUTPUT
PICKUP
PICKUP INPUTS
PICKUP INPUTS
• EQ CIRCUIT
BASS
TREBLE (Pull for BRIGHT)
BASS - BOOST/CUT or BOOST ONLY
SET TREBLE CONTROL FREQ
SET BASS CONTROL UPPER FREQ
SET BASS CONTROL LOWER FREQ
SET FOR FLAT RESPONSE or PRE-SHAPER
• BASIC RESPONSE, GAIN & EQ SPEC.
• FLAT RESPONSE: Neutral response setting.
• PRE-SHAPE: Gentle lift at the lower and higher frequencies, peaking +4dBs at 40Hz & 10kHz.
• PICKUP GAIN: Internal Trimmers 0-12dBs for each pickup in Active Mode.
• BASS CONTROL: +/- 18dBs Cut/Boost with internally adjustable 'bass window'.
• BASS WINDOW: Lower Frequency Filter 20-80Hz & Higher Frequency Filter 40–200Hz.
• MID CONTROL: +/- 14dBs Cut/Boost with Frequency Sweep 100Hz – 2.5kHz.
• TREBLE CONTROL: +/- 18dBs with internally Shelf Frequency 1kHz – 7.5kHz, Pull for Bright peaking at 10kHz.
 
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#862
Here is the diagram from JE.
IMG_0964.jpeg
 
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#863
Uni-Pre internal Setup

This guide is designed to give you the most control of your tone. Works best for hi fi, modern and scooped slap tones. A mid range heavy tone will require a slightly different approach .

The way the Uni pre ships, there is a lot of overlap in frequencies. The bass goes up into low mid territory and the treble goes down into high mid territory. This guide will give greater separation of the frequency bands and give more control over your midrange.

Start with the pre shape jumper. It's worth checking. With darker sounding pickups, setting the pre shape jumper will instantly raise the bass and treble a little giving a "slightly" scooped mid.
Doing this will allow you to use less eq on the exterior controls.

Next, turn up your bass and treble a lot. I went all the way up for this so I could hear the affect better. If you have brighter pickups, you may not need to crank them up as much. Leave the exterior knob for mid gain centered on the click.

Find the 3 internal rotary dials. Start with the last one (low bass) Set it to center. This is about 40 hz. We will revisit it later.

Move on to the center dial (high bass) Rotate it all the way to the right (clockwise). After moving the dial to the fully clockwise, play and pay attention to the low mids. They should be quite boosted now. Roll back the middle dial counter clockwise a few degrees at a time, while playing between adjustments, until you have removed most of the low mids and tightened up the bass significantly.
Doing this will make your bass knob only boost or cut the actual bass and keep it out of the low mid territory. This is great for adding depth and roundness to the lows without making things muddy.
It also lets you take bass away without cutting the low mids.

Now we move on to the treble adjustment (the first internal or "highs" dial).
Turn it all the way counter clockwise.
While playing, rotate it a few degrees clockwise at a time. We are listening for how much high mid boost we have.
Rotate it listening for harshness, finger noise and clarity. Doing this allows treble boost with sparkle and keeps your treble knob out of high mid territory.

After adjusting the internal treble dial, use your exterior bass and treble knobs to zone in on the tone you are after. Once happy, is either a boosted or cut, go back to the center dial and adjust listening to the low mids. After that fine adjustment is made, revisit the first dial (treble) and make fine adjustment paying attention to the upper mids. Get as close as possible to your desired tone.

Once you are as happy as possible with the results, move back to the the last dial. The one for the low bass adjustment. Turn it all the way counter clockwise to start. Slowly move it a few degrees clockwise, going back and forth between the dial and playing, to tune how much low bass is being let through. You are listening for clarity and removing low, unwanted frequencies that arent useful. At this point your low bass should be getting tighter and tighter.

Check your bass and treble knobs gain once more. Once the bass is tightened up you will be able to use substantially more boost without causing low mid mud, and only remove low bass , not low mids, when cutting.

It may be necessary to revisit all the internal rotary dials and make minor adjustments.
The more fine tuning you do, the closer you will get to your desired tone.

Lastly adjust your mids gain and center frequency to taste.

If done correctly this will give you the most clarity and control of your tone. It will allow you to really zone in on narrower frequency ranges and target low or high mids more independently without a lot of overlap. This allows separate targeting of the bass, low mids, high mids and treble with the use of only 3 knobs. The mid frequency select knob gives even more control and has a far more usable range once the bass and treble dials are set to taste.
Settings are very pickup dependent so, follow the method above if you change pickups or if you have a Uni-Pre in multiple basses.
 
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#864
YES! That is the kind of information I was looking for! Thank you so much @ptidwell for all your help! Just moving the jumper from flat response to pre shape, got me closer to where I wanted to go!
Your explanation of the internal EQ adjustments was done very well, thank you again!
Some have mentioned John not getting back to them, I emailed him with a brief but detailed question and he responded in less than 8 hours!
IMG_0954.jpeg
 
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#866
ptidwell said:
Uni-Pre internal Setup

This guide is designed to give you the most control of your tone. Works best for hi fi, modern and scooped slap tones. A mid range heavy tone will require a slightly different approach .

The way the Uni pre ships, there is a lot of overlap in frequencies. The bass goes up into low mid territory and the treble goes down into high mid territory. This guide will give greater separation of the frequency bands and give more control over your midrange.

Start with the pre shape jumper. It's worth checking. With darker sounding pickups, setting the pre shape jumper will instantly raise the bass and treble a little giving a "slightly" scooped mid.
Doing this will allow you to use less eq on the exterior controls.

Next, turn up your bass and treble a lot. I went all the way up for this so I could hear the affect better. If you have brighter pickups, you may not need to crank them up as much. Leave the exterior knob for mid gain centered on the click.

Find the 3 internal rotary dials. Start with the last one (low bass) Set it to center. This is about 40 hz. We will revisit it later.

Move on to the center dial (high bass) Rotate it all the way to the right (clockwise). After moving the dial to the fully clockwise, play and pay attention to the low mids. They should be quite boosted now. Roll back the middle dial counter clockwise a few degrees at a time, while playing between adjustments, until you have removed most of the low mids and tightened up the bass significantly.
Doing this will make your bass knob only boost or cut the actual bass and keep it out of the low mid territory. This is great for adding depth and roundness to the lows without making things muddy.
It also lets you take bass away without cutting the low mids.

Now we move on to the treble adjustment (the first internal or "highs" dial).
Turn it all the way counter clockwise.
While playing, rotate it a few degrees clockwise at a time. We are listening for how much high mid boost we have.
Rotate it listening for harshness, finger noise and clarity. Doing this allows treble boost with sparkle and keeps your treble knob out of high mid territory.

After adjusting the internal treble dial, use your exterior bass and treble knobs to zone in on the tone you are after. Once happy, is either a boosted or cut, go back to the center dial and adjust listening to the low mids. After that fine adjustment is made, revisit the first dial (treble) and make fine adjustment paying attention to the upper mids. Get as close as possible to your desired tone.

Once you are as happy as possible with the results, move back to the the last dial. The one for the low bass adjustment. Turn it all the way counter clockwise to start. Slowly move it a few degrees clockwise, going back and forth between the dial and playing, to tune how much low bass is being let through. You are listening for clarity and removing low, unwanted frequencies that arent useful. At this point your low bass should be getting tighter and tighter.

Check your bass and treble knobs gain once more. Once the bass is tightened up you will be able to use substantially more boost without causing low mid mud, and only remove low bass , not low mids, when cutting.

It may be necessary to revisit all the internal rotary dials and make minor adjustments.
The more fine tuning you do, the closer you will get to your desired tone.

Lastly adjust your mids gain and center frequency to taste.

If done correctly this will give you the most clarity and control of your tone. It will allow you to really zone in on narrower frequency ranges and target low or high mids more independently without a lot of overlap. This allows separate targeting of the bass, low mids, high mids and treble with the use of only 3 knobs. The mid frequency select knob gives even more control and has a far more usable range once the bass and treble dials are set to taste.
Settings are very pickup dependent so, follow the method above if you change pickups or if you have a Uni-Pre in multiple basses.
Click to expand...
Did a deeper dive into the internal control of frequencies. This circuit system is so very flexible! Takes some experimental tweaking but is so worth it as mentioned by Paul, once set the variable mids is what really brings so much to this pre. Very happy with mine. Have owned other brands of pre's but this is my favorite so far.
 
#867
ptidwell said:
Uni-Pre internal Setup

This guide is designed to give you the most control of your tone. Works best for hi fi, modern and scooped slap tones. A mid range heavy tone will require a slightly different approach .

The way the Uni pre ships, there is a lot of overlap in frequencies. The bass goes up into low mid territory and the treble goes down into high mid territory. This guide will give greater separation of the frequency bands and give more control over your midrange.

Start with the pre shape jumper. It's worth checking. With darker sounding pickups, setting the pre shape jumper will instantly raise the bass and treble a little giving a "slightly" scooped mid.
Doing this will allow you to use less eq on the exterior controls.
Click to expand...

Hey @ptidwell, this is a nice guide, thanks for that!
I am having trouble figuring out whether I am in flat or preshape mode.

When the jumpers look like the picture attached below, it sounds like preshape mode, but going to passive has a drop in volume so it's a bit hard to tell.

When I move the front jumper one pin to the right (when looking at the picture) the active signal is now softer than the passive so it's hard to tell whether I am now in flat mode.

Can anybody help me with this? I want to retain the passive sound when in active mode, no scoop.

Should I move the jumper and then adjust the pickup gain trim pots?

eq.jpg
 
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#869
XLunacy said:
Both jumpers must be moved together to switch from "flat" to "preshape".

View attachment 5196331

If you've got both jumpers like the picture, you should be in "flat" mode :) the difference in volume should be achieved by lowering the gain trimpots (near the pickup inputs) to minimum (CCW).
Active will always sound slightly brighter due to the buffering provided by the preamp.
Click to expand...
Exactly!
 
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#870
I just finished installing my J-Tone into my Squire CV70's Jazz. I had some trouble with the cavity itself, which was a bit non-standard and had to chisel the rounded cavity at the front end of it square to help it fit, nothing anyone will see under the copper shielding so my workmanship is safe! Otherwise the only difficulty I had is due to my ocular disability and post-cataract modification: it turns out fiddling with wires is tricky and needs more light and several angles and magnification :D

I've chosen the .33 tone cap and a bass boost/cut configuration, toning back the treble a bit so I can have more of a '60ish sound in passive mode and all the treble boost and bass in active, and this works well with the original pickups. I'll revisit this when I upgrade them. I'm happy with the preamp, it's not messed with the sound or the quality and it's given me more options on a bass that was already pretty flexible!
 
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#872
redname said:
Hi, not sure if it's me or my unit tht has problem

I can't seem to get a gd tone out of it when I switch to active but passive sounds beautiful

Using the j-retro

Any advice?
Click to expand...
Hmm...
I'd start with it set as close to flat as you can get: treble and middle at the center detents and the bass control all the way CCW. I also set mine so active mode (with these "flat" settings) is pretty much the same level as passive mode, which was with the internal gain trimpots all the way CCW.
If it still sound off, perhaps there is something bigger going on.
 
#873
bigtone23 said:
Hmm...
I'd start with it set as close to flat as you can get: treble and middle at the center detents and the bass control all the way CCW. I also set mine so active mode (with these "flat" settings) is pretty much the same level as passive mode, which was with the internal gain trimpots all the way CCW.
If it still sound off, perhaps there is something bigger going on.
Click to expand...
For me it all depends on the amp. With Mesa or Eden I have everything flat except the treble, it's cranked all the way. The Fender Rumble sounded way thin with the treble up.
 
#874
juancaminos said:
For me it all depends on the amp. With Mesa or Eden I have everything flat except the treble, it's cranked all the way. The Fender Rumble sounded way thin with the treble up.
Click to expand...
...but you say passive mode sounds good. Passive tonality is roughly equivalent to having the active EQ set to the 'flat' settings and no gain boost, mentioned above. If that active setting is not tonally working with the amps, maybe contact East?
 
#875
bigtone23 said:
...but you say passive mode sounds good. Passive tonality is roughly equivalent to having the active EQ set to the 'flat' settings and no gain boost, mentioned above. If that active setting is not tonally working with the amps, maybe contact East?
Click to expand...
??? I am not the OP. Just stating my J Retro setting in active mod. I have six J retros and have never used the passive setting
 
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#876
I'm hoping to be able to fit the Uni-pre 4 knob into an Fender Deluxe Precision (2004 model)(the bass in my avatar).
Any hope of making this fit?
When I decided to upgrade I got a little too excited and didn't research how much space this needs. Maybe I can add a picture soon. Thx.
 
#878
Illbass said:
I'm hoping to be able to fit the Uni-pre 4 knob into an Fender Deluxe Precision (2004 model)(the bass in my avatar).
Any hope of making this fit?
When I decided to upgrade I got a little too excited and didn't research how much space this needs. Maybe I can add a picture soon. Thx.
Click to expand...

upload_2023-11-18_10-1-58.png
 

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