Boss GE-7 Mods

A forum devoted to mod, tips and suggestions for upgrading and rehousing your VERY CHEAP commercial stompbox to near boutique excellence.
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vhollund
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Post by vhollund »

Hello Ramsay
How did you like the result ?
Do you experience saturation tube like mojo from the 4558s when pushing up the sliders ?
Ramsay wrote: 25 Mar 2015, 21:58 Finally I made mods in my Boss GE7.
In the gyrators, I pulled out the three TL022 and put three RC4558P.
In place of the two 4558 "in line" put two Burr Brown OPA2134 through sockets installed in two mini-card.

I turned on and all that the "hiss" practically disappeared, and the sound, at least apparently, is more transparent, more hi-fi.
But this I will only know for sure when playing loud guitar at the weekend.

Below a picture of the pedal after the changes:

Image
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Dirk_Hendrik
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Post by Dirk_Hendrik »

vhollund wrote: 06 Nov 2024, 16:31 Hello Ramsay
How did you like the result ?
Do you experience saturation tube like mojo from the 4558s when pushing up the sliders ?


:beatdeadhorse: :beatdeadhorse: :beatdeadhorse: :beatdeadhorse:

Ofcourse not.
The 4558, in a Tubescreamer circuit, is already source of much controversy. In the TS circuit the 4558 is very directly involved in a distortion generating circuit. In this EQ case it's part of a set of filters. Why on earth would it suddenly sound like tube saturation (mojo). A 4885 is an opamp. it amplifies a lot but has very little influence on tonal character of the material fed into it.

Or,
Could we please stop linking every 4885 circuit we see to the sonic capabilities/character of a tubescreamer?
Sorry. Plain out of planes.

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vhollund
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Post by vhollund »

I never said anything about a tubescreamer
So if you don't want to see the reference then don't make it
And if you think the question is stupid then don't answer
Treating people like they're idiots is not helpful

Dirk_Hendrik wrote: 07 Nov 2024, 17:08
vhollund wrote: 06 Nov 2024, 16:31 Hello Ramsay
How did you like the result ?
Do you experience saturation tube like mojo from the 4558s when pushing up the sliders ?


:beatdeadhorse: :beatdeadhorse: :beatdeadhorse: :beatdeadhorse:

Ofcourse not.
The 4558, in a Tubescreamer circuit, is already source of much controversy. In the TS circuit the 4558 is very directly involved in a distortion generating circuit. In this EQ case it's part of a set of filters. Why on earth would it suddenly sound like tube saturation (mojo). A 4885 is an opamp. it amplifies a lot but has very little influence on tonal character of the material fed into it.

Or,
Could we please stop linking every 4885 circuit we see to the sonic capabilities/character of a tubescreamer?
Vaughn Hollund

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Post by Dirk_Hendrik »

Please don't play wiseass.

You refer to a 4558 and ask if it sounds tube like when pushing the siders up. You know just as well as I do there's only one reason the 4558 is linked to tube like claims and that's a TS.

And if a remark is adding to false/untrue/incorrect claims, mojo crap and boohteek bull I will say so, If that hurts your feelings, so be it. Or stay out of the kitchen.
Sorry. Plain out of planes.

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Post by vhollund »

So now I'm a liar too
What a sweet boy you turned out to be ;)
As my post above indicates, I am actually considering putting 4580D as that is what Analogman does
My reasoning is maybe flawed but it is that putting opamps in Ge-7 that are more prone to saturation than Burr Brown OPA2134, might add something noticable.

Ge-7 is not the cleanest EQ to begin with but many like its mojo and use it among other things as a booster pedal.
And when i say mojo i mean
"Noticable acceptable musical saturation."
I haven't used a Tubescreamer for 25 years because I don't like the mid honk and besides that, you can use a similar opamp in a tubescreamer circuit and the difference will be minimal

In a forum where we are supposed to share ideas and help out i think you might consider turning down the shitty narcissistic attitude.

Nobody cares, even if you came straight from MIT, if you can't help being a demeaning pr*ck then don't answer questions on a forum with people who aren't to your "high standards"

Go build something important for Tesla and leave us guitarists to our mediocre faith.
it's too easy to be a toxic prick treating people as if they are idiots and liars from the get go.

Have a *wonderfull day* and don't inhale anymore of those tin vapors.
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Post by FiveseveN »

vhollund wrote: 10 Nov 2024, 13:47 mojo
All of this could have been avoided if you picked up a book on electronics instead of relying on your magical thinking.
Sorry, we don't tolerate bullshit here. Try an audiophile forum if you find the truth "demeaning".
Ignorance more frequently begets confidence than does knowledge. (Charles Darwin)

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Post by vhollund »

I've been very explicit with what i mean when using the term
How about "unforseen but pleasing saturatuon from using imperfect cheap components."

Real enough for you psychos ?

How about adressing the question i pose instead of obsessing over one f*cking word?
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Post by vhollund »

I'll try again :)

Has anyone here tried different opamps and noticed a sound difference other than noise reduction ?

I put a OPA2134 in IC4 / the buffer and I do get colouration when the pedal is off. It's a hifi opamp, could it be not complètely linear and maybe caused by not getting 12V ?

There's something happening to the highs, like loss of complexion
And something wierd slightly phasey happening to the mids

The question is if another opamp can change it, or if it is the colourartion is caused by the Boss buffer circuit, no matter the correponding type of Opamp

I have other pedals that are basically on all the time that have great buffering
The TC electronics Flashback 2 buffer f ex sounds great, even arguably better when on.
I have tested it outside the pedalboard too with same result
It sounds processed when off

Someone knowledgable must have tried to make the Boss buffer circuit more transperant at one point
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Post by FiveseveN »

vhollund wrote: 11 Nov 2024, 09:31 Real enough for you psychos ?
The issue was not one of terminology, it's with understanding the circuit.
vhollund wrote: 15 Nov 2024, 10:38 Someone knowledgable must have tried to make the Boss buffer circuit more transperant at one point
This isn't the typical Boss buffer circuit, the signal still goes through the preemphasis/deemphasis process in bypass.
I put a OPA2134 in IC4 / the buffer
Are you sure that's the "buffer"? That's labeled IC5 on this schematic and it's a single SIP op amp, as opposed to the OPA2134 which is a dual one in DIP or SOIC.

Do you know what a null test is? "Loss of complexion" and "something wierd slightly phasey" are not diagnostics that can lead to a solution. And no, it's almost certainly not because of the different op amp.
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Post by vhollund »

- The issue was not one of terminology, it's with understanding the circuit.

Yes, I think the idea of wanting to help people who come to this forum, get a deeper understanding of electronics, is good intended and noble,
However it must not come as a surprise that +70 % of people who'll come here for advice are guitarists and musicians that aren't usually well versed in electronics, even the slightest, but they probably will be able to solder and troubleshoot diy kits and mods, even check for errors, without necessarily being able to understand why theres a 1uf cap in c11.

Personally I have neither the ambition or the time to learn the craft profoundly or for becoming able to make the necessary calculations and conclusions

What I'm hoping when i come here, is that someone, with the skills that I don't have, has already comme to same sonic conclusion as I, since 1981, and has come up with a solution to f ex the buffer.

I guess maybe installing a clickless true bypass might be simpler that redesigning the buffer circuit. (?)

As a musician who has also worked extensively in sound engineering, i do have a developed hearing.

I am also pretty sure that people who come up with classic designs, didn't just calculate but experimented, from overdriving the first cap in a fuzzface, with their ears as guide, they came up with solutions, that they since have developed emperical evidence, for which adapted solutions works sonically.

It would be strange if diy owners of Boss GE-7 havent already experimented with different type opamps and buffercircuit modifications and come to some sort of sonic conclusion.

If it doesn't matter at all / doesn't change the sound or responsiveness, to employ say a JCR 4580D, in this type of circuit, versus an Opa2134, then I'm perfectly happy with learning from the emperical and calculated experience of others, and go from there.

No need to reinvent the wheel.

And I am PRET-TY sure my approach to this is most common amongst visitors here so...
Why fight it ?

I have no idea if the IC5 is the buffer, but I read and was told the IC4 is part of the buffer
And that the IC 1 2 3 is the filters and that the filters amplify the signal by looping the signal through the opamp.

In my simple understanding of overdrive circuit, this could overdrive the opamp slightly if the opamp is an opamp that has little headroom.

But maybe there aren't anyone left here who dares talk about it. 😀


Personally have no shame of being bad at something that my real job doesn't depend on, and I don't think anyone should be ashamed because they think what they think, about 4458 being popular for it's oerdriven sound and known from tubescreamer. Or what ever.

I'm thinking there's a sonic reason for Analogman using a 4580D that they also use in the KOT.
I saw some shootouts of overdriven opamps and 4580D overdriven was very ballanced frequencywise.

What actually concerns me most is the buffer, because you can't turn it off and it does change the sound and response significantly
The pedal sounds great when on ,doing what it's supposed to, but off it's too much of a difference, from not being in the chain.

Experimenting with différent opamps is less important

Either i modify for better buffer or true bypass or I move on and try another EQ pedal.
Maybe the Maxon GE601
The clips ive heard have some nice added caracter.


The idea of an EQ with some nice added "mojo"/ saturation/colouration, is also from the fact that I already have and use a completely transperant digital EQ in the Line6 M9

Have a good fight night [Tyson/Jake]
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Post by vhollund »

I found this sound test that shows how the boss buffer colours the signal
But it is a very noticable sonic difference

One might be able to install a clickless /relay switching true bypass without any drilling

From 11 minutes


Discussion about the GE-7 buffer vs TB :

https://www.diystompboxes.com/smfforum/ ... ic=46182.0

》The second option is using a small 2PDT relais for the signal switching and using the original flipflop circuit in the pedal for the control of this relay. By using this approach the mod is 100% reversibe in case of a screwup."

The quote is from Dirk Hendrik from almost 20 years ago.

R.G. wrote:

》I had a PM question about converting Boss and Ibanez pedals to true bypass with relays.

If you don't need to run on batteries ever, the simple thing to do is to just use the discrete flipflop that's already there in the pedal that runs the LED and switching FETs. Just remove the FETS and solder jumpers to make the signal path always on, and connect up a MOSFET, diode, and DPDT relay to do the bypassing. This will be a NON-latching relay, of course, so it will use power all the time.

If you can stand to use a 14 pin chip and two transistors instead of an 8 pin microprocessor, you could use the circuit here: http://www.geofex.com/FX_images/ltchrly.gif on a baby board with the relay. That circuit's been at geofex for about 10 years now. Not as sexy as an 8 pin microcontroller, but works the same.

If you can stand doing a small surface mount board, the 14 pin SO14 package is about the size of an 8 pin dip, so it's not even at that much size disadvantage.

This is almost in the category of too simple to do a PCB, but the PCB is trivial too."

》Power depends on the relay. You want a miniature "low signal" type relay rated at 9V. These tend to be about 200-600 ohms for the coil resistance, so at 9V they pull
15-45ma of DC. Mouser stocks the Panasonic TQ-2 9V, which should be a good one for this application. It's coil resistance is 579 ohms, which is nice and high, and it pulls 15-16ma of DC, which is remarkably small. That's not much more than an LED. They weren't this good last time I looked at relays.

Here's how to do the mod:
With reference to http://www.freeinfosociety.com/electron ... ossds2.gif, which I grabbed as representative,
1. Remove Q3; short drain to source on Q4 and Q21. This makes the electronics board permanently on.
2. Wire the relay contacts as a DPDT bypass to input jack, output jack, and the input and output of the circuit board.
3. Look at Q1 and Q2. The LED indicator is on when Q1 collector is low. That means that when the LED is on, Q2 collector is high, pulled up by its 56K pullup resistor. You want the relay on when Q2 collector is high. Attach a to-92 MOSFET such as the BS170 or 2N7000 with its source at ground, its gate connected to the collector of Q2.
4. Connect the relay coil to +9V and the drain of the MOSFET.
5. Connect a diode across the relay coil, cathode to +9 and anode to MOSFET drain.
6. Enjoy.

》-You rig the existing circuit to be always on by jiggering the FETs.
-Then you hook up the relay contacts like it was a DPDT switch (which it is!) by cutting the wire between input jack and effect board, then connecting input jack and board input to the relay.
-Same for the output jack wire.
- you find the internal flipflop transistor collector and wire that out to the gate of the MOSFET.
- You find +9V and Ground and wire those out to the MOSFET/relay board.


https://www.diystompboxes.com/smfforum/ ... ic=86288.0
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vhollund
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