Does anyone have a Boss GE7 gutshot?

[liddokun]

I was doing a Hifi mod on mines, and one of the wires broke. I don't know where it goes, it's still attached the the pcb, it's labelled P4 and it's light gray.  I have the newer GE7 version.  If anyone can just put a picture up of the guts or just tell me where the P4 gray wire is supposed to go?  That would help a lot.

[frokost]

On my GE-7 it goes to the input jack.

[liddokun]

Ok thanks, I'll give it a try.

[frokost]

Should work. By the way, thanks for inspiring me to finally replacing the opamps on this one. That's all I did and the noise isn't bothering me anymore.

[liddokun]

Hey, no problem. I'm glad it worked out for you, thanks for the tip on the wire, it was the input tip grounding wire. 
Yes, swapping out opamps really does improve the noise level. I used NExxxx I forgot the entire parts number.  I also did the cap swaps too.  Sounds great now.

[fuzzo]

I replaced the aop of mine by NE5532 and now the noise has disepeared.

[liddokun]

Yea, that's the chip I used.  The name just slipped my mind.  NE 5532. 

[fuzzo]

it exists some additionals mods to take off the noise , change some cap. Other mods too , to transform the Ge7 for low tunning guitar and to have fender amp simulation.

Say me if you want, I'll post the pics and infos about that.

[liddokun]

It'd be pretty cool if you could share some of those mods, especially the Fender sounding one.

[fuzzo]

ok , i'm gonna post all mods i got.

[fuzzo]

ok so :

noise mod
C33 = .001µF (film)
C21 = 1µF (film)
C22 =1µF (film)
C32 =1µF (film)
C2 = .001µF (film)


Change IC to TL072 or NE5532

I didn't change the caps, just the ICs to NE5532 and the sound is better (noiseless)

Vox/fender

R9 = 100oms 3.2K and 6.4K sliders transform to a "presence control". Not tested I don't kown if it sounds like vox or fender but it's to simulate the characteristic frequencies of these amps.

Basse mod (can be used for 7 guitars , barytons, and guitar lower than E key standart)
R20= 100ohm

increase basse level.

R5=  Resistor for LED.

pics

[George Giblet]

noise mod
C33 = .001µF (film)
C21 = 1µF (film)
C22 =1µF (film)
C32 =1µF (film)
C2 = .001µF (film)

These cap values don't match up with the schematic.  I'd be a a little worried about changing the caps unless you can guarantee it's OK.  Not only the version match but also that the mods make sense.

> I didn't change the caps, just the ICs to NE5532 and the sound is better (noiseless)

IMHO, this is safer.   The evil TL022's are the main noise source.

[fuzzo]

The values i wrote it's the values of the mod .

I haven't tried mods 'cause change AOP reduce a lot of noise. I didn't need change others stuffs ( just the LED for a blue )

[liddokun]

noise mod
C33 = .001µF (film)
C21 = 1µF (film)
C22 =1µF (film)
C32 =1µF (film)
C2 = .001µF (film)

These cap values don't match up with the schematic.  I'd be a a little worried about changing the caps unless you can guarantee it's OK.  Not only the version match but also that the mods make sense.

> I didn't change the caps, just the ICs to NE5532 and the sound is better (noiseless)

IMHO, this is safer.   The evil TL022's are the main noise source.

The 3 1uF caps do match up (C21, 22, and 32) but they're electrolytics, which  are prone to noise.  So I did change these to films. 

[George Giblet]

> ps do match up (C21, 22, and 32) but

The info I have for right picture shows quite different board designators for the caps in those positions:

-  Top left cap is C9,  original value 680nF Tantalum;
    Function: determines 200Hz band frequency (and Q)
    Mod:   Drops the frequency down to 78Hz and affects Q quite a bit.

-  Next to that C7, original value 330nF Tantalum
    Function: determines 400Hz band frequency (and Q)
    Mod:   Drops the frequency down to 226Hz and affects Q quite a bit

-  Middle 0.047uF cap in centre is C13 original value 56nF
    Function: determines 100Hz band frequency (and Q)
    Mod:   Increases the frequency to 104Hz (original 96Hz) and affects Q quite a bit

I believe these are some sort of bass mod not a noise mod.  They as messing around with the frequencies.
It looks like a haphazard mod since the 200Hz band is now below the 100Hz band.

> but they're electrolytics, which  are prone to noise.

The tantalums can add some distortion but I doubt they are adding much noise.

[liddokun]

Yea, the picture one the right is older Japanese made one.  All the Hifi mods that MartyMart came up with were based on the newer Taiwanese made one which is the same one I have, and is the more common one. 

[frokost]

A little bit of searching the forum leaves me with the impression that electrolytic capacitor noise is an issue mainly when they're really old. Otherwise, the downside with electrolytics and tantalums is that they have a less than desirable frequency response and therefore colors the tone. But since we're talking about the GE-7, an EQ, designed for altering the frequency response, and all GE-7 units are relatively new, I don't see much use in replacing the caps. Please, correct me if I'm wrong.

[George Giblet]

liddokun:

> picture one the right is older Japanese made one.

OK, most of the schematics and overlays on the web are for this version.  The pic actually says nouvelle for the right hand one, I'm sure that means new, I think it should say old!   Are there any links to schematics and/or overlays for the new one?

frokost:
> electrolytic capacitor noise is an issue mainly when they're really old.
Electrolytics can but in effects pedals, because they don't get hot, they still last some time.  Electrolytics actually dry out.  Tantalums are polarized like electrolytics but they are manufactured completely differently - they last for *ages* in audio circuits.

> desirable frequency response and therefore colors the tone.
That's a bit of a myth.  For caps in the audio path with the impedances used in preamps etc the frequency response aspects are not an issue.   There are some distortion aspects of capacitors and tantalums produce more than electrolytics.

> I don't see much use in replacing the caps.

Me either.

[liddokun]

George, nouvelle does mean new (unless my canadian quebecois french has gotten that bad), so it confused me at first too.  Perhaps the labeling was done wrong because the newer version was labeled "ancienne".  Anyways, I don't really know of any schematics and/or overlays for the new version, might be some floating around though. I know MartyMart's Hifi's mods were based on the new one (3 dil opamps and 2 sil IC's). 

[fuzzo]

hi,

"nouvelle" means "new" and "ancienne" means "old".

this schema (http://www.freeinfosociety.com/electronics/schematics/audio/bossge7.pdf) seems to correspond with the newer boss GE7. I see into my GE7 (old version even if i bought it one year ago) and the values don't correspond with the schema's values.