freestompboxes.org

I'm a bit confused about the mid caps.
The 12kHz treble might correspond to the 1k treble resistor.

The mid frequency specs for the Xotic Basses are the same as the EWS Trilogic II pedal.
The treble is different.
Bass XJ-1 (upto 2009 with switches on back)
Bass XJ-1T (2009/2010 and beyond, switches on front)
SW1: "Mid switch", +/-12dB @ 400Hz/800Hz
SW2: "Bright switch", +/-18dB @ 6kHz/12kHz

However Nikifena mentioned the basses had mid caps 47n and 100n.
I have this feeling the mid frequencies might have got moved on the EWS pedal but the printed specs were not?
I have no specs for the original Xotic Tri-logic pedal.

Anyway From what I can work out the models around are:
1) Xotic "Tri-logic Bass Preamp". (From <= 2006 upto 2011?)
Wide box pedal. Black.
2) Early model Xotic Bass XJ-1: sames specs as XJ-1T except switches on the back. trimpot on back. (From ???? to about 2009)
3) Later model XJ-1T. Toggle switches on front. Trimpot? (From 2009/2010 and beyond)
4) EWS Tri-logic II. Black (From 2011 to 2015).
5) EWS Tri-logic III. Grey/Silver Hammertone (2015 to now).
Bass freq switch. Treble Freq Switch. Mid freq Control.

EWS Trilogic II
Update V1.0 2018_12_02 to V1.1 2018_12_03

The other Xotic products do tend to use 50kB pots.
So I suspect this is correct.

Issues:
1) Not happy about 1nF cap. It has a black dot like a value small cap.
2) What to do about the 1k0 vs 1k8 treble cap issue.
3) Not happy about mid caps
4) The NE5532 opamp current draw looks too high for the current
consumption spec. Possibly RC4557D
--------------------------------------------------------
Bass: +/- 13.5dB @ 90Hz (Mid switch HI)
--------------------------------------------------------
1) 1n treble cap. I can see a black top on the cap
which would imply NPO/COG and small value.
It is quite possible it is 100pF like the 100pF NPO/COG input cap.

*** Chicago Mike (p1), Image 015, we can see this cap in 100pF

Also,OrionManMatt (p3) Handdrawn overlay shows 100pF

So clearly it *is* 100pF

2) Treble Resistor
After changing the 1nF cap to a 100pF cap we can revisit the
esponse specs and the 1k8 vs 1k0 treble treble resistor issue.

1k8: Treble: +/- 13dB @ 10kHz ; This now agrees with the Tri-logic II specs.

1k0: Treble: +/- 16.9dB @ 10kHz

The response is *very* close to the Xotic BB Tone control
when the Treble caps are doubled. Which *might*
be what is done in the Bass version Xotic BB.

3) Mid caps:

OrionManMatt (p4), it fairly clear on the mid cap
high-mid side: 473k
low-mid side: 154k

These are clearly correct, at least for his version of the
board, with the 1k0 treble cap.

Chicago Mike (p1) remembered on of the mid caps was 47nF.
The other cap is unknown.

Nikifena p6. On the Xotic Bass.
Mids 47n and 100n; maybe no 2.4k on mids(?)

Conclusion:
The hi mid-cap is probably 47nF.
The low mid-cap is probably 150n on the version with the 1.0k treble resistor.
The low mid-cap might could be 100n or 150n on the version with the 1.8k treble resistor.

The mid frequencies don't match-up with the published mid frequencies.

47nF: +/- 8dB @ 1.3kHz
100nF: +/- 9.3dB @ 520Hz
150nF: +/- 10.2dB @ 360Hz

4) The Opamp might be an RC4559.
Other's have speculated this part for Xotic Pedals.

I've been looking at thing too long.

I just came back to check it and I realized the 100pF I mentioned is actually across the other part of the opamp!!! What a dilweed

Ignore the thing about 1nF cap and the treble control spec update.

I'm surprised the specs line-up better with the smaller feedback cap on the tone control.

So how do we know the 1nF cap is 1nF?

EDIT
OK I can see where it came from, OrionManMatt's (p3) Handdrawn overlay.
So it must be correct?

OK I've fix up the mistakes and regenerated the performance specs.

Can't go any further without more pics or info.

One thing I can add is the Xotic XJ-1T bass looks like it uses the same PCB as the EWS pedal.
The switches and mid-caps are mounted on a second board which is wired to the main board.

I found a pic of an Xotic bass which had a large square PCB but still had the switches on the back (not the two toggle switches on the front). It had 100kB pots for the BMT controls! It also had two 8-pin opamps. I could not see a MOSFET.

So this thing is a big mess in terms of versions!

That bass had the same board as the original Xotic-tri-logic(1) pedal.

Maybe the square board with the two opamps is an old version and the smaller rectangular board with the MOSFET is a new version. That might explain "Tri-logic" preamp vs. "Tri-logic 2"/"Tri-logic II".

HI George!

The larger Tri-Logic is the older version. The II version is the same used in the Xotic Basses , but now with the III version out they may have updated the preamp more.

I have a Tri-Logic II again but it's in storage. I may take it apart fully and take full on gut pics later this month

Hi Mike, long time no see! In the past few years I've been going over a lot of your old posts and gut shots.

The larger Tri-Logic is the older version. The II version is the same used in the Xotic Basses , but now with the III version out they may have updated the preamp more.
I have a Tri-Logic II again but it's in storage. I may take it apart fully and take full on gut pics later this month

Thanks for the confirmation. By the time I got to my last post I found a few pics that more or less confirmed the Tri-Logic II was a different beast. After that it made sense. I also notice the Xotic bass docs started quoting Tri-Logic II as well.

If you want to check over it that would be great. From what I can remember the hanging items were:
the caps on the mid switch, the values of the pots, the value of the resistor that goes to the wiper on the treble pot (some units seem like 1k0 and others 1k8), and maybe the zener markings.

I have one of these again since I liked it too much! LOL!
It's in storage but I dont mind taking it out and getting good piccies

I have a few toys I will get good piccies of for the forum.

Just need to get my self organized...LOL!!

Im happy to check over anything too!

Thanks a lot Mike. You certainty have put up a lot of pic over the years.
(FYI, some time back posted a schem for the Lakland Hanson LH-3 you posted. It's in the Electric Guitar Rewiring forum.)

Im getting a "small" collection of pedals and will get real good pics. I want to make sure I get stuff we dont already have on the forum or if its already on the forum, maybe better pics might help for some pedals.

I used to work at a repair shop and maybe I can use my "contacts" to get official schematics too.

Here to help out if I'm able

hi guys,

I wonder what the situation is...?

I hope you are doing fine

guess what, I've just bumped into this... dated of February 2019

this could be it, right?
http://effectslayouts.blogspot.com/2019 ... mp-ii.html


_

jeepe wrote: this could be it, right?
http://effectslayouts.blogspot.com/2019 ... mp-ii.html
_

Source for that was probably viewtopic.php?f=7&t=16263&p=273119#p273119
December 2018

modman wrote: ↑19 Jan 2020, 22:53
Source for that was probably viewtopic.php?f=7&t=16263&p=273119#p273119
December 2018

you're absolutely right -- I didn't by any means want to suggest that it was before this one...

instead, I wanted to point out that activity ended here, and continued there...
last post here: January, first post there: February

hi, I saw this comment of mine today (Dec 29. 2020) and was terrified by the length...
sorry!
I removed it -- since it didn't turn out to be a helpful contribution -- and added it, for the record's sake,
as an attachment... and now it doesn't hurt the topic in either way (I hope)
Peter

I don't have any doubts the schematic I posted on 03 Dec 2018, 23:54 will *work* and even sound OK.
I guess the question is what are the actual values.

08 Jan 2019, 23:46
If you want to check over it that would be great. From what I can remember the hanging items were:
the caps on the mid switch, the values of the pots, the value of the resistor that goes to the wiper on the treble pot (some units seem like 1k0 and others 1k8), and maybe the zener markings.

No photos in the thread resolve these hanging items.
- 50kB pots, relatively high level of confidence.
- 1k8 vs 1k0, perhaps slight bias towards the 1k8
- Mid cap of 100n vs 150n, probably the most uncertain part value

I was curious about how different are the two versions:

I attached the Eagle schematics used for drawing, maybe they of some use for someone. Hopefully, there are not too many mistakes in them. Also, in the Eagle schematics I used my custom libraries, so some components might need replacing.


Regarding the final/not final versions, there were two different circuits traced and analysed. How can the second be the completion of the first? Both have their place, so one solution could be to have multiple "traced" links. The current implementation is a phpBB extension for making a topic "solved", which allows for only one "solver" post. It's a definitely a good suggestion and we'll put it on the list. But, since it requires creating a phpBB extension, it might take a while.

Regarding the final/not final versions, there were two different circuits traced and analysed. How can the second be the completion of the first?

The non-parametric is definitely the one analysed in this thread.

I am quite certain John K's parametric version is his own spin on the EWS trilogic III. He basically took the circuit in this thread then appended the parametric equalizer on RG's (Geofex) page, see circuit about half way down,
http://www.geofex.com/Article_Folders/EQs/paramet.htm

The EWS trilogic III has a parametric but it is a semi-parametric (ie. without a Q-control). My feeling is the actual EWS parametric is probably based on a circuit like,
http://i476.photobucket.com/albums/rr13 ... metric.png
or,
viewtopic.php?f=3&t=27398
or perhaps the similar circuit which has an extra opamp.

george giblet wrote: ↑24 Aug 2020, 06:26 [...] My feeling is the actual EWS parametric is probably based on a circuit like,
http://i476.photobucket.com/albums/rr13 ... metric.png [...]

I hope you don't mind me putting the image here. Hosting sites tend to dissapear ¯\_(ツ)_/¯

I couldn't see the pic. Here's a screenshot
FWIW, the parametric on the EWS Tri-logic III Bass Preamp is +/-10dB with a frequency range of 250Hz to 3kHz.
The closest match parts are,
C1 = 5n6
C2 = 5n6
which gives +/- 9.5dB and a frequency range of 260Hz to 2.8kHz.

The cap formula on my schematic only holds for +/-15dB.
For the +/- 9.5dB case it is much simpler C1 = C2 = 1/(2*pi*R*f0); where R= pot + series resistance

Remember, we don't know this is the circuit used in the EWS.

Thank you.

george giblet wrote: ↑26 Aug 2020, 01:54 I couldn't see the pic. [...]

Oh, right, Safari does not yet support the webp image format.