Ross flanger Reticon Sad1024

[thedefog]

Is it typical in failure of the Sad1024 for half to be working and not the other? I see clock signals on both sides, have input signals on both sides, but delay output on only 1 side. And if it is bad, does anyone have a source to get a hold of one?

[Govmnt_Lacky]

Terrible News: Sourcing SAD1024 chips is difficult and EXPENSIVE (Usually not less than $45/each)

Bad News: If only one side is outputting a delay signal then the other channel is DEAD! I have had this happen and still have a 1024 on hand that has one bad channel.

Good News: You can use 1024 chips with one bad channel in an Electric Mistress build. I have heard of them working just fine with 1/2-bad chips.

[thedefog]

Crap, I figured as much. Now I just need a part source. I'm willing to pay $40-50 for it.

[jimbanzini]

i came across that problem in a ross flanger.  you can amputate the dead side to get the flanger working again.

[thedefog]

Thought these ran in series so that it needs both sides to have the full effect.

[jimbanzini]

it'll still work w/o the 2nd side; the one i did it to sounded fine and the customer loved the sound of it.

[Govmnt_Lacky]

It WILL run however, it will sound greatly diminished compared to a fully functional chip 

Also, keep in mind that the circuit will most likely need a modification to remove the "dead" output from the signal path.

New chip OR circuit mod. It depends on what you are willing to do 

[LaceSensor]

Any merit in adapting to mn3007?

The leg work from the Ada conversion might work, just a guess

[Scruffie]

Any merit in adapting to mn3007?

The leg work from the Ada conversion might work, just a guess

It will, in fact, there's a thread here where someone with a damaged SAD1024 did that swap.

You could also use half the chip and adjust the clock to accomodate.

Whatever you do, don't throw that chip out, half may be broken but a working half is still useful.

[Govmnt_Lacky]

You could also use half the chip and adjust the clock to accomodate.

Whatever you do, don't throw that chip out, half may be broken but a working half is still useful.

I agree  

DO NOT throw the chip out BUT, you will need to alter the series circuit to remove the dead leg from the chip. Then, adjust clock, bias, etc to compensate.

EDIT: If you plan on keeping the SAD in the circuit of course 

[oldschoolanalog]

The search function is your friend.

[Govmnt_Lacky]

WOW!

Long time no post Dave 

[oldschoolanalog]

Life got very complex.
Things starting to look to up now...

[Govmnt_Lacky]

Things starting to look to up now...

Very GOOD! 

[Fender3D]

...
You could also use half the chip and adjust the clock to accomodate.
...

Nope,
Adjusting the clock to achieve the same delay time as with a fully working chip means clock freq. just above 12-15KHz 
Clock will bleed indeed...
Better work with just half chip...

[12Bass]

The A/DA circuit uses the SAD1024A in parallel-multiplex, which is essentially just two 512 stage devices used simultaneously to double the number of samples per clock cycle.  Using only half of the SAD1024A chip would result in the same delay time as A/DA (with the same clock frequency), just without the doubled samples.  Some great sounding flangers use 512-stage BBDs, so I would suggest trying to make it work as is rather than swapping in an MN3007.

The most dramatic flanging occurs with short delay times (~ 0.5 ms) sweeping down to moderate delay times (8 ms).  Although I haven't looked closely at the schematic, it doesn't make much sense to use a SAD1024A in series (1024 serial stages) for a flanger.... for chorus, perhaps.  Modifying a serial BBD circuit for half the number of stages would reduce the delay time by half and raise the frequency of the flange effect by one octave.  That's not not necessarily a bad thing at all, as it may sound even better than the original design.  Some slight circuit modifications and clock adjustment should be able get the Ross flanging better than ever.   

[moosapotamus]

Hi Dave!

Life got very complex.
Things starting to look to up now...

I can certainly relate to that, my friend!

~ Charlie

[jdub]

@ thedefog:

See this thread: http://www.diystompboxes.com/smfforum/index.php?topic=93646.40.  Thanks to Federico (Fender3d) and the other flanger guys, I was able to adapt my MXR flanger to accomodate for a bad side in my SAD, and it worked great.  You will have to perform some mods to the board, however, in order to bypass the non-functioning side.  After doing this and tweaking a little, I can't really tell a diff- it might even sound a bit better. 

For what it's worth, I also did the MN3007 retrofit.  It sounded great too, but I would personally try the SAD mod before going that route. 

[thedefog]

thanks for the info. This is a repair for a friend, so I'll have to ask him first. If this were mine I would have modded it for a cool audio clone, and replaced the crappy 4558s. but he may wanna sell it eventually.

[12Bass]

thanks for the info. This is a repair for a friend, so I'll have to ask him first. If this were mine I would have modded it for a cool audio clone, and replaced the crappy 4558s. but he may wanna sell it eventually.

The SAD1024A will happily sweep up into the nether regions, making it well suited for flangers.  The MN3xxx series needs some help (clock buffering) to get up there, which would mean adding even more modifications.