MXR - M-108 Ten Band EQ new version  [schematic]

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

MXR - M-108 Ten Band EQ new version  [schematic]

Postby apollomusicservice » 13 Jul 2012, 18:29

this is schematic for new 10 band EQ m-108 and some gutshots
You do not have the required permissions to view the files attached to this post.

For this message the author apollomusicservice has received thanks: 39
Broadcaster (25 Sep 2012, 17:17), floris (06 Dec 2017, 18:29), IvIark (13 Jul 2012, 18:31), lietuvis (14 Jul 2012, 10:03), lolbou (27 Sep 2012, 14:41), modman (09 Feb 2013, 16:09), rs (14 Jul 2012, 16:00), Silent Fly (14 Jul 2012, 10:47), sinner (13 Jul 2012, 19:28), toneman (19 Feb 2013, 17:53) and 29 more users
User avatar
apollomusicservice
Resistor Ronker
 
Posts: 323
Joined: 04 Jun 2012, 12:54
Has thanked: 60 times
Have thanks: 689 times

Re: MXR Ten Band EQ M-108 new version schematic

Postby IvIark » 13 Jul 2012, 18:32

Excellent post, thanks for that :thumbsup
"If anyone is a 'genius' for putting jacks in such a pedal in the only spot where they could physically fit, then I assume I too am a genius for correctly inserting my legs into my pants this morning." - candletears7 - TGP
User avatar
IvIark
Tube Twister
 
Posts: 2298
Joined: 02 Jan 2008, 00:59
Location: Manchester UK
Has thanked: 662 times
Have thanks: 667 times

Re: MXR Ten Band EQ M-108 new version schematic

Postby Dirk_Hendrik » 14 Jul 2012, 09:13

Thanks indeed!
Sorry. Plain out of planes.

http://www.dirk-hendrik.com
User avatar
Dirk_Hendrik
Old Solderhand
 
Posts: 4134
Joined: 03 Jul 2007, 09:44
Location: Old Amsterdam
Has thanked: 248 times
Have thanks: 986 times

Re: MXR Ten Band EQ M-108 new version schematic

Postby drewl » 06 Aug 2012, 16:48

Any idea where to get those lighted sliders?

Got one here with a couple broken, and none of the frequency sliders light up, only the gain and volume.

Thanks for the schem, it will be a big help!
drewl
Breadboard Brother
 
Posts: 85
Joined: 11 Feb 2010, 15:56
Has thanked: 0 time
Have thanks: 2 times

Re: MXR Ten Band EQ M-108 new version schematic

Postby night-butterfly » 25 Sep 2012, 17:08

Do somebody know wich type are these SMD zeners?
User avatar
night-butterfly
 
Posts: 20
Joined: 10 Nov 2010, 06:48
Has thanked: 10 times
Have thanks: 11 times

Re: MXR Ten Band EQ M-108 new version schematic

Postby xeroxdc12 » 27 Sep 2012, 13:15

Thanks to the shematic.
One question.
Which diode is D1, D2, D3, on shematic is not presented notation.
Symbol is Zenner diode, but which voltage end etc.
:?:
xeroxdc12
 
Posts: 1
Joined: 11 May 2012, 22:00
Has thanked: 0 time
Have thanks: 0 time

Re: MXR Ten Band EQ M-108 new version schematic

Postby apollomusicservice » 27 Sep 2012, 17:50

D1=D2=D3=BAS40
General-purpose Schottky diodes in small Surface-Mounted Device (SMD) plastic packages. BAS40
User avatar
apollomusicservice
Resistor Ronker
 
Posts: 323
Joined: 04 Jun 2012, 12:54
Has thanked: 60 times
Have thanks: 689 times

Re: MXR Ten Band EQ M-108 new version schematic

Postby Duckman » 27 Sep 2012, 21:39

The dumb question of the day: There is a technical basis to use all these fixed 470 resistors and vary only the remaining components in each gyrator or just a designer choice? I mean, you could also set one value for all the bias resistors and so the other being those to be adjusted to the needs of each gyrator, so... is there any difference?
User avatar
Duckman
Opamp Operator
 
Posts: 1526
Joined: 20 May 2009, 02:45
Has thanked: 364 times
Have thanks: 122 times

Re: MXR Ten Band EQ M-108 new version schematic

Postby Duckman » 27 Sep 2012, 23:13

The dumb question of the day II: That´s not exactly True Bypass, right?... or yes it is?
User avatar
Duckman
Opamp Operator
 
Posts: 1526
Joined: 20 May 2009, 02:45
Has thanked: 364 times
Have thanks: 122 times

Re: MXR Ten Band EQ M-108 new version schematic

Postby night-butterfly » 01 Oct 2012, 07:49

Yes that's not a true bypass but it can be modified to be that way easily

For this message the author night-butterfly has received thanks:
Duckman (01 Oct 2012, 18:37)
User avatar
night-butterfly
 
Posts: 20
Joined: 10 Nov 2010, 06:48
Has thanked: 10 times
Have thanks: 11 times

Re: MXR Ten Band EQ M-108 new version schematic

Postby dorothegreat » 01 Oct 2012, 11:34

noob question:

1) can I eliminate certain frequencies (e.g. 4kHz to 16kHz); and

2) can I eliminate certain frequencies in between two frequencies? (e.g. 8kHz only)

thanks in advance. :hug:
dorothegreat
 
Posts: 15
Joined: 04 Apr 2009, 13:56
Has thanked: 16 times
Have thanks: 1 time

Re: MXR Ten Band EQ M-108 new version schematic

Postby Sweetalk » 01 Oct 2012, 12:46

Duckman wrote:The dumb question of the day: There is a technical basis to use all these fixed 470 resistors and vary only the remaining components in each gyrator or just a designer choice? I mean, you could also set one value for all the bias resistors and so the other being those to be adjusted to the needs of each gyrator, so... is there any difference?


The 470 resistor sets the Q and gain of the gyrator, so, in order to have a similar Q on each band uses the same resistor. The GGG eq uses the same negative loop resistor and the same pull up to bias resistor and only changes the caps...

For this message the author Sweetalk has received thanks:
Duckman (01 Oct 2012, 18:38)
Sweetalk
Solder Soldier
 
Posts: 152
Joined: 12 Dec 2009, 05:13
Has thanked: 23 times
Have thanks: 17 times

Re: MXR Ten Band EQ M-108 new version schematic

Postby Duckman » 01 Oct 2012, 18:50

Sweetalk wrote:
Duckman wrote:The dumb question of the day: There is a technical basis to use all these fixed 470 resistors and vary only the remaining components in each gyrator or just a designer choice? I mean, you could also set one value for all the bias resistors and so the other being those to be adjusted to the needs of each gyrator, so... is there any difference?


The 470 resistor sets the Q and gain of the gyrator, so, in order to have a similar Q on each band uses the same resistor. The GGG eq uses the same negative loop resistor and the same pull up to bias resistor and only changes the caps...


Yeah, I was checking that in every gyrator based EQ that I found in the net and seems like none of them are very picky about Q, so values can be very approximate, but nothing perfect. In fact, most of them uses a 1M pot in series with the bias resistor to vary the frequency, but that means a change in Q from 1 or 2 (up freq) to 4 or 7 (low freq) :!: in some cases (depends on the arrangement of the gyrator)
User avatar
Duckman
Opamp Operator
 
Posts: 1526
Joined: 20 May 2009, 02:45
Has thanked: 364 times
Have thanks: 122 times

Re: MXR Ten Band EQ M-108 new version schematic

Postby Duckman » 01 Oct 2012, 18:53

dorothegreat wrote:noob question:

1) can I eliminate certain frequencies (e.g. 4kHz to 16kHz); and

2) can I eliminate certain frequencies in between two frequencies? (e.g. 8kHz only)

thanks in advance. :hug:


1) yes, you can
2) yes, you can, but... check this
EQ INFO.pdf
You do not have the required permissions to view the files attached to this post.

For this message the author Duckman has received thanks: 2
DuctTapeRiot (07 Feb 2014, 23:22), GodSaveMetal (03 Oct 2012, 01:52)
User avatar
Duckman
Opamp Operator
 
Posts: 1526
Joined: 20 May 2009, 02:45
Has thanked: 364 times
Have thanks: 122 times

Re: MXR Ten Band EQ M-108 new version schematic

Postby SFTFN » 22 Jan 2013, 23:37

I just troubleshot one m-108 eq that had a problem with half of the EQ LEDS being off and rest of the LEDs on. It turned out that an LED socket had gone bad on one of the sliders.

Fortunately only one socket was bad so I rearranged the sliders so that all EQ frequencies have their LEDs lighted up, but the gain and volume slider LEDs are off... At least it looks symmetrical now.

Anyway, does anyone know are these sliders possible to get anywhere? They're 20k miniature type with center detent.

For this message the author SFTFN has received thanks:
DuctTapeRiot (23 Jan 2014, 23:57)
SFTFN
 
Posts: 7
Joined: 10 Jul 2009, 13:27
Has thanked: 3 times
Have thanks: 4 times

Re: MXR Ten Band EQ M-108 new version schematic

Postby SFTFN » 07 Feb 2013, 13:45

Well, I contacted MXR/Dunlop about the broken slider and they promptly sent me a replacement slider!! :horsey: My pedal wasn't even under warranty anymore, so they sure seem to care about customer satisfaction.
You do not have the required permissions to view the files attached to this post.
SFTFN
 
Posts: 7
Joined: 10 Jul 2009, 13:27
Has thanked: 3 times
Have thanks: 4 times

Re: MXR Ten Band EQ M-108 new version schematic

Postby artaommahe » 08 Feb 2013, 16:01

Is R48 place correct? I have a simulation at LTSpice and when connect gyrators in/out there is -10db pit. If R48 removed and gyrator's out conected to ICD4 13th leg - all is fine.
artaommahe
 
Posts: 22
Joined: 16 Sep 2010, 14:32
Has thanked: 18 times
Have thanks: 2 times

Re: MXR Ten Band EQ M-108 new version schematic

Postby apollomusicservice » 08 Feb 2013, 20:09

Thanks artaommahe, I checked again and found mistake.
You do not have the required permissions to view the files attached to this post.

For this message the author apollomusicservice has received thanks: 2
floris (06 Dec 2017, 18:31), underwood (31 Mar 2015, 07:59)
User avatar
apollomusicservice
Resistor Ronker
 
Posts: 323
Joined: 04 Jun 2012, 12:54
Has thanked: 60 times
Have thanks: 689 times

Re: MXR Ten Band EQ M-108 new version schematic

Postby artaommahe » 08 Feb 2013, 23:41

apollomusicservice wrote:Thanks artaommahe, I checked again and found mistake.

thx ) just now did so in the simulator and came to write =)
artaommahe
 
Posts: 22
Joined: 16 Sep 2010, 14:32
Has thanked: 18 times
Have thanks: 2 times

Re: MXR Ten Band EQ M-108 new version schematic

Postby artaommahe » 08 Feb 2013, 23:48

apollomusicservice, at first schematic we have 12n at IC4C, 15n at IC4D and 2.2n at IC2C. At last - all of them 1n. Last one is correct?)
artaommahe
 
Posts: 22
Joined: 16 Sep 2010, 14:32
Has thanked: 18 times
Have thanks: 2 times

Next

Return to Modern Stompbox Effects (1975 - ...)

Who is online

Users browsing this forum: brejna, fahri, wilqen and 20 guests