I bought one just last week and thought it was OK !
"Pushtone" in another thread said " Plug in, powerup and REDUCE the level on the lower 2 bands -100/200Hz and listen through your amp "
Result = HISS !! - and LOTS of it ... shock horror ... why ?
So I searched through various GE-7 threads, but could only find the "opamp" change suggestions.
I found a schematic in my collection, drawn by Jon Halveson, which looked "good" but the component numbering
didn't quite match my "2006" GE-7 , so I had to do lots of looking, tracing and writing stuff down !
Here's what I found from a combination of Jon's schem and my actual unit :
There's three 8pin DIL opamps which are TL022's
Two further opamps are SIL types, which I dont have any of
There seems to be three 1uf electro caps in the signal path
There are five tantalum caps used as part of the tone stack, one to each of the bands ( the other two smallest ones are poly caps )
I guess that the tantalums were used in the larger values because of size, but Poly caps DO fit, if you're careful about placement
around the central "screw" that holds the top board down.
Here's the changes that I made, with board numbering from the 2006 unit NOT the schem, though some did match up :
--Boss GE-7 HiFi Mod--
Remove the three TL022's, install sockets and fit NE5532 opamps ( other low noise versions are fine, such as TL072 )
( watch the pinout as you do this, all three opamps have pin 1 facing the top "open" end of the board)
Remove the three 1uf electro caps , C21 C22 C32 and replace with 1uf poly caps ( they are available, mine were 10mm high )
If they are hard to find, then perhaps 680n or 470n would be fine ..
Tone caps:
Remove C10 ( 1u5 tantalum ) and replace with a 1uf poly cap ( closest value but may effect the 100Hz band a little, pushing it up to 150hz ?)
Remove C9 ( 0.68uf tantalum) and replace with a 0.68uf poly cap
Remove C8 (0.33uf tantalum) and replace with a 0.33uf poly cap
Remove C7 (0.15uf tantalum) and replace with a 0.15uf poly cap
Remove C6 (0.1uf tantalum) and replace with a 0.1uf poly cap
DONE !
Result :
No noise increase when same test as above done, pedal seems silent when engaged and the bands
seems much smoother sounding to me.
Well worth the couple of bucks and the 25 minutes to do the mod :D
If anyone can add anything to this - please do !
Enjoy,
Marty.
Excellent work Marty!
This GE-7 hiss has been bugging me since the first day.
I asked a couple of other players about theirs and they had the same HISS results.
The stock GE-7 is just plain noisy.
I was fairly confident that yours would do the same.
I'm going to open mine up this weekend.
I wonder how long until we see some website offering commercial mods for the GE7 based on your work?
Thanks Push ! I dont give a sh** who uses it, I've had my fair share of info here and just
hope it helps some people ditch the "hiss" :D
If it's for sale somewhere .... what the heck should I do about it ! It's a Boss anyway's :icon_wink:
Just one other thing, the final output cap is a 10uf tantalum (C11) this could probably work
as another 1uf poly cap and be a bit cleaner sounding ...
To keep the 100Hz band the same, a 1uf poly with a 470n in parallel would work, however
there's just not room for them between the two boards .... I may try and squeeze it in ( ooh eer ! )
( there's not much 100Hz in a gtr low E anyway huh ? just makes your amp turn to mud )
MM.
oops
Jeez - 150 views and one reply !!
Anyone got any comments/additions to this ?
:icon_eek: :icon_eek:
sure i got a comment on this.
way cool :icon_cool:
i just wish i could find a used ge-7b to perform those mods on (i´m sure the bass version is not that much different except cap values for the eq), been searching for 2 years now.
then all that would be left for me to find would be pq-3b ;)
cheers,
lowstar
i wonder if these mods will work for the Behringer EQ700 ???
My EQ700s will arrive in a few days :)
Probably all surface mount(?) :P
Will check for hiss............... :)
thanx for the tutorial!! 8)
lowstar- U can make your own 7b from the 7...it's just a few caps :-X
I've done some swapping like that which usually makes a difference in noise, but sometimes subbing films for alu electros makes it sound too clear or have too much low end, which I suppose is the difference in freq. characteristics. Is there some general rule such as "halve the value when you sub a film for a alu electro" to doing that (say, for coupling caps)? Anyone have a hard time finding big films, try surplus places, sometimes you can find bigger ones cheap or relatively inexpensively.
Quote from: Dai H. on November 18, 2006, 10:36:42 AM
I've done some swapping like that which usually makes a difference in noise, but sometimes subbing films for alu electros makes it sound too clear or have too much low end, which I suppose is the difference in freq. characteristics. Is there some general rule such as "halve the value when you sub a film for a alu electro" to doing that (say, for coupling caps)? Anyone have a hard time finding big films, try surplus places, sometimes you can find bigger ones cheap or relatively inexpensively.
I'm not aware of a "rule" like that Dai, however, before I got hold of my 1uf poly's, I often used .47uf poly's
when replacing 1uf electro couplingcaps, actually anything around .22uf and above should work fine.
Also several Fuzz's which call for 10uf electro's work great with 1uf poly's !!
Where possible, I alway's replace electro's and tantalum caps from the signal path, unless the "grainy" sound
is something that you're after. ( this could be a good thing in many "fuzzy" FX pedals )
MM.
Quote from: toneman on November 18, 2006, 10:25:36 AM
i wonder if these mods will work for the Behringer EQ700 ???
My EQ700s will arrive in a few days :)
Probably all surface mount(?) :P
Will check for hiss............... :)
thanx for the tutorial!! 8)
lowstar- U can make your own 7b from the 7...it's just a few caps :-X
The EQ700 doesn't seem to suffer with a "hiss" problem, the crappy parts/sockets etc are more
to worry about !
MM.
Quote from: MartyMart on November 18, 2006, 11:24:05 AM
Quote from: Dai H. on November 18, 2006, 10:36:42 AM
I've done some swapping like that which usually makes a difference in noise, but sometimes subbing films for alu electros makes it sound too clear or have too much low end, which I suppose is the difference in freq. characteristics. Is there some general rule such as "halve the value when you sub a film for a alu electro" to doing that (say, for coupling caps)? Anyone have a hard time finding big films, try surplus places, sometimes you can find bigger ones cheap or relatively inexpensively.
I'm not aware of a "rule" like that Dai, however, before I got hold of my 1uf poly's, I often used .47uf poly's
when replacing 1uf electro couplingcaps, actually anything around .22uf and above should work fine.
Also several Fuzz's which call for 10uf electro's work great with 1uf poly's !!
Where possible, I alway's replace electro's and tantalum caps from the signal path, unless the "grainy" sound
is something that you're after. ( this could be a good thing in many "fuzzy" FX pedals )
MM.
thanks Marty,
another type to look into might be the "audio use" alu electros such as Nichicon MUSE, Rubycon Black gates, etc. They can sound clearer than regular alu electros and have the same sort of size advantage being electros compared to films. I scrounged up some used/removed ones for the mixer section headphones area in a casette Portastudio, and there did seem to be a slight improvement (seems there is usually a 100 to 470uF or so to ea. side of the phones output, maybe there are more noticable since directly connected?). Ordinary ones seem to have a bit less definition which is probably good sometimes. Also, I don't know if you can get them in your locale, but there are SIP versions of 5532s, NJM makes a 5532S (9 pin SIP) and 5532L (8 pin). I have some some 5532S which I bought maybe ten years or so ago.
Quotelowstar- U can make your own 7b from the 7...it's just a few caps Lips Sealed
i don´t even have a ge-7 to start with. ;)
May I put some attention to this post I did a while ago:
http://www.diystompboxes.com/smfforum/index.php?topic=47296.0 (http://www.diystompboxes.com/smfforum/index.php?topic=47296.0)
(get the schemmo of a GE-7 to see which components are mentioned as RA, RB etc.)
Although the component values of a GE-7 are well chosen for the frequencies they have to filter (as in, pretty accurate) recalculation of the component values for for instance the Bore-ringer mentioned above coud give good results im making the thing sounding more musical.
Quote from: Dirk_Hendrik on November 19, 2006, 08:01:27 AM
May I put some attention to this post I did a while ago:
http://www.diystompboxes.com/smfforum/index.php?topic=47296.0 (http://www.diystompboxes.com/smfforum/index.php?topic=47296.0)
(get the schemmo of a GE-7 to see which components are mentioned as RA, RB etc.)
Although the component values of a GE-7 are well chosen for the frequencies they have to filter (as in, pretty accurate) recalculation of the component values for for instance the Bore-ringer mentioned above coud give good results im making the thing sounding more musical.
Good stuff, thanks Dirk :D
I didn't really change much with this mod, just got rid of the Hiss, but might have a look at my EQ700 now !
MM.
so basicly the GE-7 design isn't noisy but the components are? that's good to know since i wanted to use the design for another effect... thanks for this thread :)
So, modding a GE-7B should be pretty much the same?
ehm... :icon_eek: twenty bucks per auction for your work
http://cgi.ebay.it/Boss-GE7-GE-7-Equalizer-Mod-Kit-Clean-Boost_W0QQitemZ270087174271QQihZ017QQcategoryZ101973QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
Well, he does have a long list of satisfied customers !!
Doesn't sound unreasonable for a complete instruction kit :icon_cool:
QuoteIs there some general rule such as "halve the value when you sub a film for a alu electro" to doing that (say, for coupling caps)?
Cap Substitution:
1. Never use an aluminum electro in an application where the exact frequency matters, as in filters. Never. Use aluminum only where you only need enough.
2. Never use tantalum unless you have no other choice.
3. For coupling capacitors, doubling the cap extends frequency response down by one octave; halving the cap increases the lower cutoff frequency by one octave upwards.
4. For simple one-L, one-C filters, the frequency is proportional to the square root of either component. Changing the cap by 2 changes the frequency by 1.414.
The doubling/halving/square root things are gross overgeneralizations based on the simplest possible cases.
There is no real substitute for knowing the circuit and doing the math.
When doing mods like this, you need to consider at least 3 specs: noise performance, current draw and input impedance. Here are some comparisons for the TL022 vs. the 5532.
Noise Performance (at 1kHz)
NE5532 = 5 nV/√Hz
TL022 = 50 nV/√Hz
Current Use (per amplifier)
NE5532 = 8.000ma
TL022 = 0.130ma
The noise is definitely lower but the current consumption is WAY up! Multiply that by the 6 amplifiers in the chips you are subbing and battery life is drastically shortened...
Input impedance on the chips is another matter... the TL022 is very high since it has a jfet input but the 5532 is quite low, even for a bipolar input. The change in input impedances may cause the pedal to perform differently than how it was designed... the RC4559 is a better choice than the 5532 as a sub... noise is not quite as low but input Z is higher and current use is only about 1.6ma per amplifier. Even the TL072 would be a decent sub: TL072 = 18 nV/√Hz and 1.4ma per amp.
Just about anything is better than the 50nV noise on the TL022 but most dual chips will draw more current since the 022 was designed for low current consumption...
regards, Jack
thx R.G.
I'll add another one:
never add extra power supply bypass caps to a 488 mkII Portastudio even though there is a space for them on the mixer PCB because if you do, you'll blow out your headphones from excessive low frequency response... :icon_lol: :icon_redface:
which I guess goes back to...
QuoteThere is no real substitute for knowing the circuit and doing the math.
Quote from: amz-fx on February 15, 2007, 04:21:58 AM
When doing mods like this, you need to consider at least 3 specs: noise performance, current draw and input impedance. Here are some comparisons for the TL022 vs. the 5532.
Noise Performance (at 1kHz)
NE5532 = 5 nV/√Hz
TL022 = 50 nV/√Hz
Current Use (per amplifier)
NE5532 = 8.000ma
TL022 = 0.130ma
Interesting. I have a DOD 201 that also uses the TL022. I bought a couple of AD820 (http://www.analog.com/en/prod/0,,759_786_AD820,00.html)s and TL072 (http://focus.ti.com/lit/ds/symlink/tl072.pdf)s a while ago. I guess the AD820 would work better?
Quote from: amz-fx on February 15, 2007, 04:21:58 AM
. Even the TL072 would be a decent sub: TL072 = 18 nV/?Hz and 1.4ma per amp.
Just about anything is better than the 50nV noise on the TL022 but most dual chips will draw more current since the 022 was designed for low current consumption...
regards, Jack
Thanks Jack, I realized this, though I use PSU's 99% of the time, so I went with TL072CP's in mine
and a couple that I've done.
For those who do use batteries, that NE5532 power consumption is a no-no !! :D
Quiet as heck though :D
Regards,
Marty.
Just a correction to Jack / amz - the TL022 is NOT a FET opamp - it's totally bipolar.
Yes, even though the TL022 has fets in it, the chip is really bipolar input... TI claims "High Input Impedance" on the datasheet but does not specify a value so the comments about the 022 vs. 5532 input Z should still be relevant.
re: DOD 201 The AD820 draws slightly less current and has slightly less noise but the TL072 is cheaper and easier to find. Either would do the job well.
regards, Jack
I'm not a GE-7 type of guy, but good work. I'm sure LOTS of people will find this useful.
AC
Hell yeah, this makes a HUGE difference to the unit, it's NOT a subtle "hi-fi"
bullshit type of mod ! :D
You hear it right off the bat ....
MM.
Quote from: g3rmanium on February 15, 2007, 05:26:17 AM
Interesting. I have a DOD 201 that also uses the TL022. I bought a couple of AD820 (http://www.analog.com/en/prod/0,,759_786_AD820,00.html)s and TL072 (http://focus.ti.com/lit/ds/symlink/tl072.pdf)s a while ago. I guess the AD820 would work better?
Of course I mean the AD823 (http://www.analog.com/UploadedFiles/Data_Sheets/AD823.pdf) since the AD820 is just a single opamp.
I picked up one of these on the cheap, it should be coming UPS and I'll be checking for noise. I'd go in and do just the opamps, do ya suppose that'll make a noticeable difference? I dunno about changing the caps; might have to if the switch to '072's isn't enough, tho...
Quote from: MartyMart on November 17, 2006, 09:13:46 AM
Tone caps:
Remove C10 ( 1u5 tantalum ) and replace with a 1uf poly cap ( closest value but may effect the 100Hz band a little, pushing it up to 150hz ?)
Remove C9 ( 0.68uf tantalum) and replace with a 0.68uf poly cap
Remove C8 (0.33uf tantalum) and replace with a 0.33uf poly cap
Remove C7 (0.15uf tantalum) and replace with a 0.15uf poly cap
Remove C6 (0.1uf tantalum) and replace with a 0.1uf poly cap
Sorry to bring this back from the dead. But if someone were to use more 'conventional' cap sizes such as:
C10 1uf
C9 .68
C8 .47
C7 .22
C6 .1
To what extent and how would the frequency bands get f'd up?
It's only conventional if that's the only thing you have on your bench. ;) :D
More than one thing would happen. For those two, they're larger than the stock values, so they'd start moving into the other bands territory. Not fun. The other thing is you'd need to compensate some resistors as well so you don't end up with a nasty bit of boost on those two bands. I speak from experience here.
Seems you have a .1 and .22. So wire those two in parrallel to make a .32. (Close enough for our purposes.)
Same with the .15. Use your .1 and a .047. Even the Rat Shack has those. ;)
Multilayer ceramic makes a good space-saving alternative to poly film (often even smaller than tantalum!), at a moderate price premium.
Quote from: ayayay! on May 04, 2011, 09:28:50 AM
It's only conventional if that's the only thing you have on your bench. ;) :D
You seem to have interpreted what I was said as: "I don't want to drop any more money on Metal-Film Caps." - You read me correctly.
I'll give the parallel caps a shot. I really appreciate the the quick advice; I'm glad I didn't settle for warping the Frequency bands.
I'm thinking of applying this mod to my behringer eq700. it's not very noisy but at lower frequencies it does a noise...
Do you know if the chip is the same, cause google search says that it might be the same, nothing solid...
I did these mods but something isn't right. I did the mods from the OP. Would slider lube help this? I used Deoxit contact cleaner to clean the sliders but that didn't help. I've gone over all the solder joints and they all check out...I used TL072 chips.
(http://i157.photobucket.com/albums/t54/Beedoola/th_8E450BC5-3975-4231-9BD5-3F8084AAB456-6840-000002F226E7BE30.jpg) (http://s157.photobucket.com/albums/t54/Beedoola/?action=view¤t=8E450BC5-3975-4231-9BD5-3F8084AAB456-6840-000002F226E7BE30.mp4)
http://www.diystompboxes.com/wiki/index.php?title=Debugging
Quote from: amz-fx on February 15, 2007, 04:21:58 AM
Noise Performance (at 1kHz)
NE5532 = 5 nV/√Hz
TL022 = 50 nV/√Hz
the RC4559 is a better choice than the 5532 as a sub... noise is not quite as low but input Z is higher and current use is only about 1.6ma per amplifier. Even the TL072 would be a decent sub: TL072 = 18 nV/√Hz and 1.4ma per amp.
regards, Jack
Hello, resurrecting this one again. My GE-7 is certainly noisy, so I'm thinking about swapping the ICs.
Question 1 - I looked up the RC 4559 data sheet and it lists the EI noise as "2uV/Hz max" while the figures above use square root of Hz, so how do I compare them? Is there an answer that doesn't involve trig? 8~)
Can I get the square root symbol on my standard keyboard ?
Question 2 - How would just changing the op-amps compare to changing both the op-amps and caps listed in terms of noise performance?
by all means try the opamps by themselves. take a very consistent noise listening (or reading) test of some kind so you can compare before and after. I got noticeably good results and I only did the op amps. I think I did 4559s? or were they in there already? Use what is recommended above somewhere.
Welcome.
> RC 4559 data ..."2uV/Hz max" while the figures above use square root of Hz, so how do I compare them?...
The '4559 data *also* specifies "20Hz-20KHz". It is directly the number over the audio band.
Say TL072 = 18 nV/√Hz. To figure this for 20Hz-20KHz, a 19,980Hz band, we find the square-root of 19,980, 141. 18nV/rtHz times 141 is 2,540nV or 2.54u, a hair higher than '4559.
(The '4559 has significant input *current* and above 1.4uV/25pA= ~~56K source impedance it will hiss more than a TL072.)
> Can I get the square root symbol on my standard keyboard ?
"rtHz" works with anybody who knows noise. If a nearby post has the sign, try copy/paste. There are keyboard shortcuts but they may not work for all readers. There is an "HTML entity" for square root √ but this forum software does not interpret it as a special character.
This is what cheeses me off about Boss. (And I do like Boss)
They have a subset of their pedals, or which the GE-7 is a nice example, which are just plain noisy, and which have long-known and simple mods that make them quiet. Yet Boss won't take the trouble to fix them. The CS-3 is another one of these.
I tried a GE-7 a year or so ago and immediately returned it it was so noisy. If I pay $99 or a new pedal from a reputable company, I should NOT have to immediately mod it to make it usable. I'd even be willing to pay an extra $20, if I knew that Boss made these mods and fixed the pedal after all these years.
Instead, Boss makes a big deal out of its Waza stuff and charges an extra $100 or those.
There will probably be a new Waza version of this with a new Waza price eventually, incorporating these very mods.