How to Detect and Avoid Sourcing Fake MN3005s

[LaceSensor]

Hi

My orignal build is dead, so if you want a board to mess with, ill send you it when I receive my replacements ive ordered at the end of the month.

LMK

[Scruffie]

Yeah if you're offering that'd be great, I can certainly use it and if I fix it and sort the issues I can send it back to you.

Something about a doppleganger too?

Cheers man!

[LaceSensor]

Ill PM you

[lloyd17]

change there clock cap to 120pF
4 x 3205s

That's interesting. Was noise related to delay time settings on the 3205 builds? Could be a sneaky route since voltage doesn't seem to be much of a factor in sound. Thinking aloud, please disregard any stupidities.

[Scruffie]

change there clock cap to 120pF
4 x 3205s

That's interesting. Was noise related to delay time settings on the 3205 builds? Could be a sneaky route since voltage doesn't seem to be much of a factor in sound. Thinking aloud, please disregard any stupidities.

Well noise will always be more prevelant at longer delays, adding more BBDs but having less delay will add more fiddelity but may require a 4049 clock buffer to drive the chips to reach shorter delays.

Thinking now i'm a little more awake, I doubt this is the issue making the chips distort, but it may well help as a 3005 should have less noise (although more distortion) than a 3205, when I get Laces build i'm gunna try out a few different mods once i've got it working again.

First on the agenda is playing with the voltage to the BBDs to see if tweaking there can help, looking at the datasheet for the 3205, while a voltage like 8V2 which I suggested originally as it has worked well for builds in the past is better for THD, higher voltage seems it may be better for the input level of the chips if i'm understanding correctly.

Following that rebiasing the compander to its proper half voltage point and limiting the input signal by altering the input to the chips while keeping the frequency roll off the same at a few key points should fingers crossed, solve the issue.

[LaceSensor]

change there clock cap to 120pF
4 x 3205s

That's interesting. Was noise related to delay time settings on the 3205 builds? Could be a sneaky route since voltage doesn't seem to be much of a factor in sound. Thinking aloud, please disregard any stupidities.

Well noise will always be more prevelant at longer delays, adding more BBDs but having less delay will add more fiddelity but may require a 4049 clock buffer to drive the chips to reach shorter delays.

Thinking now i'm a little more awake, I doubt this is the issue making the chips distort, but it may well help as a 3005 should have less noise (although more distortion) than a 3205, when I get Laces build i'm gunna try out a few different mods once i've got it working again.

First on the agenda is playing with the voltage to the BBDs to see if tweaking there can help, looking at the datasheet for the 3205, while a voltage like 8V2 which I suggested originally as it has worked well for builds in the past is better for THD, higher voltage seems it may be better for the input level of the chips if i'm understanding correctly.

Following that rebiasing the compander to its proper half voltage point and limiting the input signal by altering the input to the chips while keeping the frequency roll off the same at a few key points should fingers crossed, solve the issue.

Ill post it friday, you might get it for the weekend.
hopefully this will give something back if you can figure out some other mods.

[pickdropper]

Well, it sounds like the distortion issue isn't totally fixed.  Maybe I will have to build a 3005 after all (or 4x3008).

[djaaz]

It is.

Check the errata section.

[Scruffie]

Yup, it is fixed, i'm just going a different route and perhaps 'optimising' it to my tastes while investigating the issues that can arrise of a 3205 switched from 3005.

Bean did a great job and a lot of work to get it working nicely like the new EHX memory line.

And if you read the first post before this went entirely off topic... sourcing 3005s is gunna be hard and cost you a lot.

[LaceSensor]

the MN3005 I sourced off eBay is genuine. woop!

[pickdropper]

Yup, it is fixed, i'm just going a different route and perhaps 'optimising' it to my tastes while investigating the issues that can arrise of a 3205 switched from 3005.

Bean did a great job and a lot of work to get it working nicely like the new EHX memory line.

And if you read the first post before this went entirely off topic... sourcing 3005s is gunna be hard and cost you a lot.

Yeah, and to be honest, I don't feel like dealing with ebay on this.  I read about the fix in the notes, but I wasn't clear on its efficacy.  If it is good to go, I'll start off with a v3205 build.

[djaaz]

Here you go a build report of a v3205 version:

http://www.madbeanpedals.com/forum/index.php?topic=3380.0