Maxon - AD-900 MN3008 version [schematic]

[armdnrdy1]

A few years ago, I put together a smaller build of the AD-900. (MN3005 version)
Since that time, the price of MN3005s has skyrocketed!
MN3008s can still be sourced for a reasonable price..so...I decided to explore the AD-900 MN3008 version.

Using soulsonic's schematic from this thread, viewtopic.php?f=1&t=7356 I figured out the differences between the two versions by studying component side images of the MN3008 version. I was able to produce a schematic..but wanted to verify the drawing before I posted it.

I made a request in "I'd like to see the guts of" thread, for any trace side images, and Dirk Hendrik was gracious enough to provide trace side images...and more! Thanks again Dirk!

With the info that Dirk provided, I was able to verify the schematic. (The circuit was correct but I had some of the component numbering wrong)

Dirk also provided an overlay (silk layer) that I took the liberty of adding component designations to, and the trace side art which was unfinished. (There were a few areas that were highlighted in red that the "artist" was unsure about)
I also took the liberty to fix these "problem" areas.

I'm not sure who put together the silk layer and trace side art but...credit and thanks go out to you!







I have PDF files of all of the above. If needed...please request. Also...if there are any talented forum members out there that are good at resizing the trace side board image while keeping high resolution...I have a large BMP file if needed.

[sinner]

Thanks for all above

Can i have schematic in pdf?

[Dirk_Hendrik]

Nice job! Glad to have been of help

[armdnrdy1]

I built the (4) MN3008 version, and it sounds great! I added a voltage regulator, TBP, and a tails mod.
The AD-900 is a bit darker than some delays. I'll be experimenting with the cap values in the filter sections to see if I can brighten things up a bit.



Here is the build document:
https://dl.dropboxusercontent.com/u/532 ... cument.pdf

[Dirk_Hendrik]

I missed that one!
Very, very nice!!

[sinner]

The AD-900 is a bit darker than some delays. I'll be experimenting with the cap values in the filter sections to see if I can brighten things up a bit.

Most analogue delays have similar topology. I've noticed that C44 cap from your schematic is not present on Boss DM-2

Also in emphasis/de-emphasis circuit Maxon does have much bigger caps, specially on the output - Boss 1uF, Maxon 10uF

That might be a reason behind much darker tone

[Dirk_Hendrik]

C44 should't make (much of a) a difference in tone.

Those 2 caps (let's refer em as C43) should give tha Maxon a somewhat better bass response but will not have much influence on the character of the sound as in "dark" or "bright".

The emphasis and deemphasis circuit "should" not influence the tonal characteristic of the sound as the result of the 2 is flat (from a frequency perspective, phase is another story). However, tens of Boss pedals tell me different (the "bad" buffer in Boss pedals). I should spend some time on that.

Still,
This maxon layout, as well as many other analog delay designs, provide a fine platform to experiment with different filtering configurations. Build a maxom but use the filter values of a DM2. Could be fun!

[armdnrdy1]

Just so I'm clear..the repeats are what sound "dark" to me with the AD-900

I actually did experiment with the filter values of the DM2.
I built a daughter board for the AD-900 to switch different filter sections in.....it didn't work too well.
For some reason that I don't understand...it changed the bias of the BBD.

I tried a few other things that didn't work before I found what I was looking for.

C40 (4.7µf) and R52 (10K) coupled with IC1A make up a first-order high pass filter.
With the large value of C40...it acts more like a low pass filter.

I experimented with different cap values for C40 and lowered the value of R52 to make up for the apparent signal loss by cutting the low frequencies.
Once I found a good combo, I made a daughter board to switch between bright and normal.
I feel that this is a great addition to this delay and makes it more versatile.

Imagine if the solo section of Sabbath's Heaven and Hell were played with a bright sounding delay...or
U2 songs played with a dark sounding delay....no chiming sound.

The switch allows for both.

[DFX_PEDZ]

A few years ago, I put together a smaller build of the AD-900. (MN3005 version)
Since that time, the price of MN3005s has skyrocketed!
MN3008s can still be sourced for a reasonable price..so...I decided to explore the AD-900 MN3008 version.

Using soulsonic's schematic from this thread, viewtopic.php?f=1&t=7356 I figured out the differences between the two versions by studying component side images of the MN3008 version. I was able to produce a schematic..but wanted to verify the drawing before I posted it.

I made a request in "I'd like to see the guts of" thread, for any trace side images, and Dirk Hendrik was gracious enough to provide trace side images...and more! Thanks again Dirk!

With the info that Dirk provided, I was able to verify the schematic. (The circuit was correct but I had some of the component numbering wrong)

Dirk also provided an overlay (silk layer) that I took the liberty of adding component designations to, and the trace side art which was unfinished. (There were a few areas that were highlighted in red that the "artist" was unsure about)
I also took the liberty to fix these "problem" areas.

I'm not sure who put together the silk layer and trace side art but...credit and thanks go out to you!

[ Image ]

[ Image ]

[ Image ]

I have PDF files of all of the above. If needed...please request. Also...if there are any talented forum members out there that are good at resizing the trace side board image while keeping high resolution...I have a large BMP file if needed.

Anyone got the higher res image of the schematic please?

[uncleboko]

https://www.dropbox.com/s/66i1c0y6pma4y ... n.pdf?dl=0

[DFX_PEDZ]

https://www.dropbox.com/s/66i1c0y6pma4y ... n.pdf?dl=0

excellent, thanks