EHX - English Muffin  [schematic]

All about modern commercial stompbox circuits from Electro Harmonix over MXR, Boss and Ibanez into the nineties.

Re: EH - English Muffin

Postby Bernardduur » 30 Sep 2009, 08:43

I had one in yesterday; the owner complained that the power LED turned on and off by switching and the status LED didn't come on at all!

I checked. The power LED WAS the status LED (:D) and the power LED was connected the wrong way around on the PCB......... quality check????
'No more....... loud music.......'
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Re: EH - English Muffin

Postby bumblebee » 01 Oct 2009, 01:05

borislavgajic wrote::block: boxing is almost complete........now to electronic....I am making it point to point.......more in a fiew days :thumbsup
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Those tubes are just waiting to be snapped off by some clumsy duffus! :whappen:
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Re: EH - English Muffin

Postby Liquids » 02 Oct 2009, 15:28

Just in case anyone else is interested in this project...

I got mine in used for a very good price and in very good condition yesterday by mail.

The tubes in mine are 12AX7EHs - the website has said they come with 12AY7s though they mention that you can use ax's for more gain or au's for less..not sure if they changed and are shipping with the 12ax7's or were swapped by the previous owner, but either way that works for me, since swapping tubes is not the only mod available for me. :D

Anyhow, I only had about 5 minutes to plug it in, but am impressed. The (assumedly) stock tone isn't as bad as I thought - pretty usable.

My first points of interest in modding are 1) the gain range is pretty high - I ran the gain at or about full counter clockwise and that was plenty for me, though it's pretty touch sensitive and cleans up like an amp in this range. I'd like to be able to dial in less. The gain gets really hot quickly on the knob, so over halfway the differences were negligible with that much saturation going on. I'm going to mod it so it's range is more useful for me. 12AY7s would presumably be cleaner but 12AX7s are more typical in preamps I'm comparing, and I have many, so again, I'll stick with that for now.

The tone quality isn't as bad as I'd imagined from the schematic, which I was expecting to be or scooped sounding and wooly/farty. Still, I preferred running it with the mids on/near 'full' since my amp has a scoop of it's own. Overall the tone is rather 'grainy' to my ears, even with the highs all the way down, so it may need some improved filtering after I get the gain range where I want it (I'm thinking significantly bigger grid resistors and more standard 100k plate resistors, to start), but I'm just being critical and picky - it's got a surprisingly good base tone.

I've not popped it open yet since I just got it and really only had 5 minutes upon delivery, so keep that in mind. But I think this is a great pedal for people like myself who want a 'gateway' into voicing, messing with the sound of tube stuff and Higher Voltage. It seems that to anyone who can get one used, a little know-how about working with higher voltages, namely discharging the voltage safely, plus a few tools and higher voltage parts in a spots where it's needed is all you'd need. There are tons of resources out there to find out about working with tubes, and/or some of the principles of working with other low-voltage things like BJTs, mosfets and Jfets apply. Many hacks (including boutique amp builders) seem to do just fine with less knowledge, but with a little patience and research, the possibilities are vast. With some reference schematics, it's should make a fantastic base for any 3-stage (and potentially 4-stage) preamp you'd like, and a great way to tinker at that!

FYI, the price of them new is low for a tube pedal, but was still a little high, for me, though cheaper (quicker, easier, and safer) than starting from scratch where I was standing. Used they seem to hover around $100-130 us. I found one on the guitar center site used for a steal of price so I grabbed it, but there are quite a few available there in the given price range for anyone else interested.
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Re: EH - English Muffin

Postby tomas.blahos » 11 Nov 2009, 17:38

To: Liquids

Have you made any modifications? I wonder how to remove the grain from the sound. The sound is too fuzzy ...
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Re: EH - English Muffin

Postby Liquids » 11 Nov 2009, 19:03

I've done quite a few mods so far, still have more in mind. I finally got some parts in, and I just finished another project so I may get to it today.

Note that I'm running mine with 12ax7s, since that is what I have most of, what came in my used version, and what I am most familiar with.

Anyhow The EQ is the typical post-OD, passive, scooped marshall-type tonestack (cathode follwer and a mix of fender and marshall values).
A few things here - make the treble cap 470pf, and I make the mid cap something like 6.8n. It's not typically for an amp, but most people amps are scooped enough. So This EQ mod This removed the scoop, or at least makes it narrower (470pf passed more high mids, 6.8n passes more low mids). Unless you like it that way... All that say, I pretty much keep the treble pot all the way down.

Not a big fan of the dual 'treble peaking' either. I snipped C6 (470p). C3 is an odd value - 470pf or 560pf. Moreso, or even 1n, or 5n would be more typical and less grainy. I also find C4 culprit - 6.8n, rather than 22n. Since the voltages on the EQ caps and that both need to be high, I was able to swap C6 And C12.

It has way too much gain for me. I made all the plate resistors 100k (make sure they are 1watt or 1/2 watt) and all the cathode resistors 1.5k, which is a good start. If you want more/less gain, you can change the cathode resistors from there...

C5 is a little small at .47uF, and C1 is unnecessarily large at 200uF. I'd start with those at about 5uF and mod each stage's bass to taste that way. I also increased the grid resistors here and there...it's a lot of gain.

That's a good start at least...but it's still a bit high gain. 3 stages is a lot for classic 'marshall' type if you ask me. And If it's too bright, you might want to experiment with some high voltage pf-value caps (as a starting point) across the plate resistors.
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Re: EH - English Muffin

Postby tomas.blahos » 11 Nov 2009, 23:20

Thank you very much, Liquids !
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Re: EH - English Muffin

Postby tip142 » 15 Nov 2009, 16:03

Hi to all this great community ,i'm also very interested and here my question :
the schematics from talk bass at the beginning of the post is wright??

I see that pin 9 of 12ax7 (V2C on schematic) go to the 220 omhs ,why only on one valves ;is wright??
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Re: EH - English Muffin

Postby borislavgajic » 15 Nov 2009, 19:55

tip142 wrote:Hi to all this great community ,i'm also very interested and here my question :
the schematics from talk bass at the beginning of the post is wright??

I see that pin 9 of 12ax7 (V2C on schematic) go to the 220 omhs ,why only on one valves ;is wright??


I build it based on that schem(audio part), but heating part I made normaly without that resistor....and with DC 12.6V regulated ........ :block:

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Re: EH - English Muffin

Postby tip142 » 15 Nov 2009, 20:51

Well thank you Boris for reply,you connect only pin number 4 and 5 on each valves?

Why that schema show that connection(filament) for balancing noise reduction?

On how many PCB you building the effect?
Oh how many answer .....
:blackeye
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Re: EH - English Muffin

Postby borislavgajic » 15 Nov 2009, 21:21

tip142 wrote:Well thank you Boris for reply,you connect only pin number 4 and 5 on each valves?

Why that schema show that connection(filament) for balancing noise reduction?

On how many PCB you building the effect?
Oh how many answer .....
:blackeye


yes ......pins 4 and 5
no PCB ...I did it oldfashion way Point to point............works great :thumbsup
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Re: EH - English Muffin

Postby tip142 » 15 Nov 2009, 22:48

Ok in Vintage style...but the number on drawing 2-4-6 ,8-10-12,14-16 ,15-13 what mean?
I am a fan of Riblja Corba ,i think that you know they Or don't?
Have you some pics of your pedal inside?
Does you put two led (high blue)at the bottm of the 12ax7 or i'm wrong...
Pobeci negde..daleko sto dalje- gde ne trebaju
:)
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Re: EH - English Muffin

Postby himister » 16 Nov 2009, 02:21

tip142 wrote:Have you some pics of your pedal inside?


Hey Boris I would like to see some guts too. :wink:

Oooo jos jedan komsija....pozdrav i dobrodosaoi! :thumbsup
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Re: EH - English Muffin

Postby borislavgajic » 16 Nov 2009, 09:46

.but the number on drawing 2-4-6 ,8-10-12,14-16 ,15-13 what mean?....they are pin numbers of connector..........? you do not need them just make wire connection instead

Have you some pics of your pedal inside?....sorry did not make photos....was in hurry to deliver it for a custommer :cry: :oops: ...I can post hand drawing of how I connected parts inside.....if you want?

Does you put two led (high blue)at the bottm of the 12ax7 .....Yes I does...doesn't I....... :thumbsup ....when you engage pedal...tubes glow blue......when it is in bypass mode tubes glow on their own :block: and they are glowing nice

Pobeci negde..daleko sto dalje......where are you from?.......I like AZRA more and Vlatko Stefanovski.... :thumbsup
cheers

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Re: EH - English Muffin

Postby tip142 » 16 Nov 2009, 16:44

For himister ,thank to thank to thank you for welcome [smilie=orange.gif]

Well , Borislav thank you very much for precious informations you done

Yes, hand drawing is superwelcome i think not only for me i think....

I'm living in Italy and my half is ......(Dalmatinka :mrgreen: )
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Re: EH - English Muffin

Postby borislavgajic » 17 Nov 2009, 13:59

I'll post all I have in fiew days.... :thumbsup
............pozdrav Dalmaciji :block:
...near Sombor is a little place called Ridjica.....they are all from Dalmacija :block:

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Re: EH - English Muffin

Postby tip142 » 17 Nov 2009, 18:58

[smilie=a_sunflower.gif]
we also love D.Balasevic
Thank you Borislav
Stoj mi dobro stari
:D
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Re: EH - English Muffin

Postby borislavgajic » 18 Nov 2009, 11:35

here it is........be carefull with high voltages........no power supply shown........ :block:

boris :thumbsup
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atreidesheir (22 Jul 2016, 17:28)
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Re: EH - English Muffin

Postby tip142 » 18 Nov 2009, 14:27

Thank you :thumbsup
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Re: EH - English Muffin

Postby uncleboko » 18 Nov 2009, 15:36

tip142 wrote:For himister ,thank to thank to thank you for welcome [smilie=orange.gif]

Well , Borislav thank you very much for precious informations you done

Yes, hand drawing is superwelcome i think not only for me i think....

I'm living in Italy and my half is ......(Dalmatinka :mrgreen: )


Qué - Meester Fawlty :scratch: :scratch: :scratch:
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Re: EH - English Muffin

Postby tip142 » 18 Nov 2009, 19:28

Sorry but i'don't understand.....
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