Jer's 400, WO Backplane and Comp Conversion

[jbeckva]

Got the goods in today to convert my 400 to fully comp, and with the new backplanes courtesy of Joe!

I'll be full bore working on it soon, but for now I see a quick question I need to pose... Joe it looks to me like we ditch the 410's altogether and end up with 4 95's x 4 96's per side. Makes sense to me (wouldn't imagine seeing an NPN in the negative half, even at the predriver spot). That's a correct assumption, right? Lee with that configuration, what have you measured for clipping on 'em?? Just curious...

Those new boards look fantastic, btw...

 

[Gepetto]

Got the goods in today to convert my 400 to fully comp, and with the new backplanes courtesy of Joe!

I'll be full bore working on it soon, but for now I see a quick question I need to pose... Joe it looks to me like we ditch the 410's altogether and end up with 4 95's x 4 96's per side. Makes sense to me (wouldn't imagine seeing an NPN in the negative half, even at the predriver spot). That's a correct assumption, right? Lee with that configuration, what have you measured for clipping on 'em?? Just curious...

Those new boards look fantastic, btw...

Correct Jer
4 MJ21196 on B+ side (upper) and 4 MJ21195 on B- side (lower) on each channel for the fully comp version. Makes it easy.

In the fully comp version there is no longer that local feedback curiosity that exists in the quasi comp circuit

Good luck Jer and thanks on the board appearance. Spent lots of time getting things just right.

 

[Gepetto]

Got the goods in today to convert my 400 to fully comp, and with the new backplanes courtesy of Joe!

I'll be full bore working on it soon, but for now I see a quick question I need to pose... Joe it looks to me like we ditch the 410's altogether and end up with 4 95's x 4 96's per side. Makes sense to me (wouldn't imagine seeing an NPN in the negative half, even at the predriver spot). That's a correct assumption, right? Lee with that configuration, what have you measured for clipping on 'em?? Just curious...

Those new boards look fantastic, btw...

Also Jer, there is a simple difference list shown in the Assembly Instructions that I sent over to you. Make sure you observe the details for the Fully Comp version since the kit you ordered has components to go either way in it. I have highlighted the bag labels to show the Full Comp version build information to call attention to these small differences.

 

[laatsch55]

Power was slightly more, still mostly dependent on rail voltage..

 

[jbeckva]

Got my round "tuit" tonight. Made a good dent in populating the boards.. Joe - this is one heck of a kit! I am enjoying putting this one together!

 

[Gepetto]

Got my round "tuit" tonight. Made a good dent in populating the boards.. Joe - this is one heck of a kit! I am enjoying putting this one together!

View attachment 10309

Looks great Jer, you are making good progress. And glad you are having fun. My favorite part is populating the transistors after everything else is in. I love putting TO-3's in with real machine screws instead of those sheet metal screws in the old sockets. Based on your population, you are going for the full comp. Good choice.

 

[laatsch55]

Allen head machine screws!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!Stainless!!!!!!!!!!!!

 

[Gepetto]

Allen head machine screws!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!Stainless!!!!!!!!!!!!

You bet Lee, 18-8 SS. I only go for the best. I figure if you are going to put that much work into restoring the amp, you might as well go first class.

 

[laatsch55]

Easier to deal with a long T-Handle 7/64's. Plus it looks soooooo cool.

 

[NavLinear]

Allen head machine screws!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!Stainless!!!!!!!!!!!!

I've always wonder why these were called Allen's head. A resemblance maybe?

Nice job so far Jer!

 

[laatsch55]

Allen Tool Co.??

 

[jbeckva]

Torn down to "parade rest"!

(SIR, YES SIR!! )

Man, lotta work... But it's worth it...

Yes Lee.. I am contemplating introducing the "buss bar from hell"... heheh

 

[Gepetto]

Torn down to "parade rest"!

(SIR, YES SIR!! )

Man, lotta work... But it's worth it...

Yes Lee.. I am contemplating introducing the "buss bar from hell"... heheh

View attachment 10322

You seem to be missing the floating copper plate at the input terminals Jer.

 

[Gepetto]

Bus Bar schema

Here is how I tackle it Jer...

 

[jbeckva]

I'm getting there, Joe. Far as the copper plate, that's my own "mod" or deviation - simplify the inputs. Worked good in the past for me.

 

[laatsch55]

You seem to be missing the floating copper plate at the input terminals Jer.

How can you see what's not in the pic?? Hmmm??

 

[laatsch55]

Here is how I tackle it Jer... View attachment 10331 View attachment 10332 View attachment 10333

I was gonna make a smart ass remark about what a hackjob you did there Joe, but it's too damn pretty....

 

[jbeckva]

Wondering something, Joe - Why bring the unfused from the right channel board all the way back to the caps, instead of jumping off the 2nd set of eyelets on the left channel board?

 

[Gepetto]

Wondering something, Joe - Why bring the unfused from the right channel board all the way back to the caps, instead of jumping off the 2nd set of eyelets on the left channel board?

Personal preference Jer. It is provisioned to handle either method

 

[jbeckva]

Boards are in with some wiring done. Joe I'm contemplating the AC wire I have to run across the back for the DCP. Thinking of either shielding it or using twisted pair with the DCP's ground to star ground. Thoughts?