More IBAM Thoughts

Hi All!
Well we finally got our parts order done and have all the stuff needed for Mr. Bolce's IBAM.
At first we were just going to install it under the chassis and check things from time to time. But now, I think the smartest way to go is to install it in a way that we can check, and adjust, with everything together.
And of course with this after thought rethink also come the realization that we didn't order any sort of test jack thingies!
Guess we'll probably wind up having to do that too!
Would anyone that's done theirs this way please direct me to any photos that might have been posted as to how they did it?
I am a bit reluctant to do a whole lot of drilling and cutting to make it happen, but any tips or suggestion on how to do it in a minimally invasive way would be great! :yes:
Thanks men and Happy Spring!
Phyllis

I did two versions, both of which allow for adjustments from outside the case. One involved not cutting or drilling of the chassis but a lot of external wiring. The other version involved cutting and drilling the chassis.

Pictures can be found in these threads:

http://www.audiokarma.org/forums/showthread.php?t=460526

http://www.audiokarma.org/forums/showthread.php?t=487828

Here is my version. http://mail.audiokarma.org/forums/showpost.php?p=5335803&postcount=38

Phyllis; You can do it like Drew and Bruce did it by either taking out the Aux power plugs and/or drilling 4 holes in an accesible area on the back. What i did with my Sansui was find 4 ventilation holes in the top near the output tubes and reamed out the holes slightly to fit the pin jacks. Then wired up the pin jack to the Pin 5 connection on the tube socket right at the 10oHm resistor. Added 1 pin jack for a total of 5, the 5th soldered to a ground point close to the pin jack. Then because the Sansui has ventilation slot in the bottom, I lined up the pots as close as I could (I still had to cut out a section of the slot). so i can access them from outside.

Instead of opening it up, I flip it on it's side and plug in and adjust. Just be careful of the hot tubes when plugging in the probes.

You might want to mount the pots by themselves on a small board on top, and find some convenient ventilation holes. Or a combination of techniques. There as many if not more variations as there are owners and techs. Try the one(s) that best suits you.

Pictures of my Sansui. The 800-C is buried in the Executive Cabinet right now. I used a variation of Drew's circuit. It entailed changing the resistor values slightly to accomodate the Sansui's circuit. Other than that it's identical.





This shows that a different brand and model, with a similar amplifier circuit, can benefit from the same modifications that the FISHER's get.

Larry

drewbolce said:

Here is my version. http://mail.audiokarma.org/forums/showpost.php?p=5335803&postcount=38

Click to expand...

Where did you put your pots?
Thank you! :yes:
And thanks to everyone!
Phyllis

I mounted mine like this and cut an access hole into the bottom plate. This requires access to the bottom for adjustment. My original thought was that if the bias needed tweaking this would force me to bench the whole thing and give it a going over.

I now wish I had flipped the board over and modified the hole left by the old can cap for access.

The one thing I also did not do is notate the pots and test points. I cannot tell you how many times I have tweaked the wrong pot wondering why nothing was changing. Even the most experienced need proper labeling.

Hi Drew

Do you have another PCB of you IBAM Circuit???

I would like to know if is possible a deal with this!

Thank you!

drewbolce said:

I mounted mine like this and cut an access hole into the bottom plate. This requires access to the bottom for adjustment. My original thought was that if the bias needed tweaking this would force me to bench the whole thing and give it a going over.

I now wish I had flipped the board over and modified the hole left by the old can cap for access.

The one thing I also did not do is notate the pots and test points. I cannot tell you how many times I have tweaked the wrong pot wondering why nothing was changing. Even the most experienced need proper labeling.

Click to expand...

Hi Mr. Bolce!
What are in the 4 spots just above the resistors R121-R124?
One I can see completely is marked as "C82".
This is the older photo we discussed in our PM exchange. :yes:
Thank you (again!)
Phyllis

A couple of days ago I found some really clear pictures & a diagram for the Fisher 500 IBAM board, does anyone know which thread it was in after much searching I can't seem to find it anywhere & I'm starting to think I imagined it.

Thanks for any help (I tried search but it doesn't seem to find this great article)

PShuff said:

Hi Mr. Bolce!
What are in the 4 spots just above the resistors R121-R124?
One I can see completely is marked as "C82".
This is the older photo we discussed in our PM exchange. :yes:
Thank you (again!)
Phyllis

Click to expand...

That was a prototype board and design. I wanted to show the placement, nothing else. Please ignore everything else.

Moko said:

A couple of days ago I found some really clear pictures & a diagram for the Fisher 500 IBAM board, does anyone know which thread it was in after much searching I can't seem to find it anywhere & I'm starting to think I imagined it.

Thanks for any help (I tried search but it doesn't seem to find this great article)

Click to expand...

Probably in the "Common parts for FISHER's" sticky thread.

Moko said:

A couple of days ago I found some really clear pictures & a diagram for the Fisher 500 IBAM board, does anyone know which thread it was in after much searching I can't seem to find it anywhere & I'm starting to think I imagined it.

Thanks for any help (I tried search but it doesn't seem to find this great article)

Click to expand...

Hi!
That's because everything "IBAM" is scattered throughout about 100,000,000 threads! :yes:

http://www.audiokarma.org/forums/showthread.php?t=394064&page=2

Phyllis

drewbolce said:

That was a prototype board and design. I wanted to show the placement, nothing else. Please ignore everything else.

Click to expand...

Hi!
Just was wondering what the shiny black boogers were.
Didn't mean to bother you.

Phyllis

Moko said:

A couple of days ago I found some really clear pictures & a diagram for the Fisher 500 IBAM board, does anyone know which thread it was in after much searching I can't seem to find it anywhere & I'm starting to think I imagined it.

Thanks for any help (I tried search but it doesn't seem to find this great article)

Click to expand...

Mr. Bolce's actual drawing:

http://audiokarma.org/forums/attachment.php?attachmentid=323694&d=1326903198

Phyllis

Thanks Phyllis, it was the first link that was the pictures I had seen.

Wouldn't it be a good idea for someone to write the definitive IBAM guide with all the relevant pics, circuit diagrams and make it a separate sticky to help any future users?

MOKO; Drew's design is one of many, but it's the easiest to understand, build and it does work. How you implement it is up to you. Some people like to have everything on top, some underneath, some point to point, and some on a board. Plus there are the tinkerers who modify their units replacing the Auxiliary power points with the IBAM pots, etc.

It's used on makes other than FISHER, and works well. It's like extra gauges on older cars. some put them under the dash, some on top of the dash, some on the "A" pillar, and some actually on the engine hood. No real wrong way to install them as long as they work. Again it depends on what the user likes, and how he implements it.

Larry

Moko said:

Thanks Phyllis, it was the first link that was the pictures I had seen.

Wouldn't it be a good idea for someone to write the definitive IBAM guide with all the relevant pics, circuit diagrams and make it a separate sticky to help any future users?

Click to expand...

You've got it!
Can't get much more definitive than the creator/designer's schematic! :yes:

Phyllis