Those echoplex preamp pedals, which u like??

[bmf5150]

I tried a popular brand on the forum here last year and was not impressed,sounded ok but not as good as pluging into an echoplex!!has anyone tried the stiff amplification echoplex ep3 booster or his repeat offender(has delay as well)I guess I have higher hopes for these pedals since the guy does so many repairs on echoplex!!anyone try either???

[jnew]

I'd recommend building your own since it is such a simple little circuit. I've ended up with one that is nearly 100% true to the original and can even go between the TIS 58 and TIS 98 as used by the compressor board models. The only difference, which I'd challenge any set of ears on the planet, is the original EP-3 pre amp circuits were fed by 22VDC. Mine has a steady 24 VDC but when biased properly, like I say, this is hardly something that makes any appreciable audio difference.

It's a fun build too.

[axeman]

I would like to build my own, Were do I start ?

[jnew]

Here's what I used:

Improved EPos-3.jpg (49.11 KiB) Viewed 10131 times

The only difference is where it says "18 V", I used a constant 24 VDC supply. Your choice though. You can either do tow 9 Volt batteries for an 18 volt supply or you can use a steady source. I went with a steady source because the pedal is never turned off and the voltage stays constant which means the bias will stay that way too.

Oh, and Q5 is a TIS 58 Transistor as the originals used. These parts are cheap and easy to source. Finding a TIS 58 may prove a little tricky but they're to be had.

[rgorke]

here is what I used and it is dead on to both of my Echoplexs.

[jnew]

I remember yours Roger. I think you had the .047 at the input first for a little while and then ended up changing to the .022. Made it a little brighter for you if I remember.

[rgorke]

I remember yours Roger. I think you had the .047 at the input first for a little while and then ended up changing to the .022. Made it a little brighter for you if I remember.

Yeah, that's right. If you look at some of the different schematics, of the EP3, that value changes.

[vanhalen5150]

I remember yours Roger. I think you had the .047 at the input first for a little while and then ended up changing to the .022. Made it a little brighter for you if I remember.

Yeah, that's right. If you look at some of the different schematics, of the EP3, that value changes.

Did anyone ever draw a layout for that one? I got the parts from Valvestorm but never soldered it up.

[rgorke]

I remember yours Roger. I think you had the .047 at the input first for a little while and then ended up changing to the .022. Made it a little brighter for you if I remember.

Yeah, that's right. If you look at some of the different schematics, of the EP3, that value changes.

Did anyone ever draw a layout for that one? I got the parts from Valvestorm but never soldered it up.

yep,

http://valvestorm.com/Project%20Parts/EP3%20Pedal" onclick="window.open(this.href);return false;

[axeman]

It would realty help me if some one who has build one of these post there build to get an idea how to go about it.


Thanks

[N3m0 7h3 Fi5h]

I dont have any experience to build any EP preamp.. but I get impression that.. it is very similar to other clean booster:

1. Madbean Fatpants, originally designed for EP preamp with additional input buffer.. on board voltage muliplier circuit from 9dcv source, so circuit is working with adjustable 18dcv.. It is using J201 instead of TIS-58.

http://www.madbeanpedals.com/projects/F ... tPants.pdf" onclick="window.open(this.href);return false;

2. Paul Gagon, designed a Jackson JE1000 booster.. a Peak select preamp circuit... Alexi-COB fans loves it so much, until EMG re-issue this booster with SMD parts for lower noise ratio.. EMG ABQ..

In front of preamp input, it has variable mid freq. selection to boost, in small switch configuration. Using 2SK30 Jfet as input buffer. Yes.. it is not using TIS-58.. but...

It is closer to EP schematic above, you may start from its PCB layout ..or to adapt it in any perfboards, then put neccesary PCB mod.. maybe also to remove its 2nd transistor .. so you may get exact EP preamp in the end...

I think .. most of the preamp booster circut, are prone to be noisy.. avoid unnesesarry cable on pot, shorter component legs if posible, then to dip in wax the circuit, after succesfull final testing..

Scroll until in the bottom of this website, you may find schematic & PCB layout...

http://wormwoodprophecymetal.com/2012/0 ... -pictures/" onclick="window.open(this.href);return false;

3. Most "Onboard" JFET guitar/bass preamp/booster (preamp placed in gtr/bass carvity) are good platform to mod, since it is just basic single JFET preamp circuit with small mod... many online resources sells its PCB in reasonable price..

[rgorke]

It would realty help me if some one who has build one of these post there build to get an idea how to go about it.


Thanks

Just use the schematic and layout at Valvestorm. It is actually a pretty easy build. The pedal I built sounds exactly like each of my real '70s EP3s.

[N3m0 7h3 Fi5h]

Just a reference for start point..

1. Bellow is another example of Don Tillman Preamp Circuit


http://www.till.com/articles/GuitarPreamp/" onclick="window.open(this.href);return false;

2. Its layout using Veroboard:

http://www.aronnelson.com/gallery/main. ... alNumber=2" onclick="window.open(this.href);return false;



3. Perfboard layout



4. PCB layout

http://www.diystompboxes.com/smfforum/i ... _next=next" onclick="window.open(this.href);return false;

5. Simply changed & adapt Layout/parts value according to Roger - Rgorke Schematic as posted above.. add 500K pot/trimmer in the end output .... powered with 2x 9v battery.. Voiila... an EP Preamp...!

[rgorke]

Do you have any clips of that Tillman unit? Seems like it uses a different FET. Could sound similar or totally different.

[N3m0 7h3 Fi5h]

I notice :
1. "Mid Select Freq. to Boost" circuit (22nF, R100K, 100pF, R1M) in input of EP Preamp circuit, while "none of it" in Tillman circuit. Jackson JE1000 and EMG ABQ provide better selection of which freq. to boost, in preamp input circuit.



Schematic:
http://static.flickr.com/80/231963271_1515bdfd6a_o.jpg" onclick="window.open(this.href);return false;

2. Different Pin-out legs (G-D-S) between J201 & TIS-58.

J201 Pinout


TIS-58 Pinout


3. Different Transistor character, gain & noise ratio.
4. Different power source, 18-22dcv produce more gain & headroom, compare to 9dcv that only boost flat max. 3db all existing freq.
5. The only concern usage of J201 beside lower noise ratio, is lowest power consumption, so longer usage of 9dcv battery..
6. Not my clip, but at least gives you idea..

[youtube]http://www.youtube.com/watch?v=RDeJXaxguqU[/youtube]