Nice 400-ll to rebuild

[grapplesaw]

My next amp is going to be a 400-ll. It is in good condition and has somewhat rare long fin in full extrusion format heat sinks. The person ( only initials -BR- on tag) who built it took quite a lot of pride on the original build as you can see by the tidy wiring of which I have already started to mess up. Not may hours on this puppy as you can see the lack of any heat discoloration of the control board.

this will be my tweeter amp for the corner horns in a tri amp setup

I may use a D board or a G board. I like the sound of the D and love the channel seperate on of the G. Decision yet to be made

I will add a few tricks so follow along

 

[laatsch55]

That is a nice one Glen..

 

[WOPL Sniffer]

Just like the 400II i'm doing with this 700B

 

[grapplesaw]

So first mod is to add a fifth output to the row. We saw this done before on a custom build by ? Forgot his name.

I did up a pair of carver c-500’s. It has 5 outputs per channel so wanted to try one. Using the approach from above design (see photo) i am adding a pair of mjl21195/96 to each channel. Just sorting best location now.

 

[NeverSatisfied]

Holy mad scientist Batman, that is some cool shizzle right there.
Glen, can you explain what your going after with your mods please?
I am just being curious and amazed.

 

[grapplesaw]

Holy mad scientist Batman, that is some cool shizzle right there.
Glen, can you explain what your going after with your mods please?
I am just being curious and amazed.

first the photo of the control board is from this thread

https://forums.phxaudiotape.com/thr...wer-amplifier-–-refurbished-on-ebay-now.8765/

Steve Mantz did it. read the thread and ignor the negative stuff. There is some good stuff there’s.

now what I am up to is to do what I did to the C-500’s

here are some photos

 

[George S.]

Very cool Glen, I like this mad scientist stuff. Your really pushing the modification boundaries. Keep the info coming.

 

[grapplesaw]

George I also change almost all the fuse holders now to AGC You cannot put a AGC fuse in a AGX holder and I would advise against putting a AGX in. AGC holder.

this amp is so unused I will reuse the old ones with main power AGC and rails AGX

 

[NeverSatisfied]

first the photo of the control board is from this thread

https://forums.phxaudiotape.com/threads/vintage-phase-linear-400-power-amplifier-–-refurbished-on-ebay-now.8765/

Steve Mantz did it. read the thread and ignor the negative stuff. There is some good stuff there’s.

now what I am up to is to do what I did to the C-500’s

here are some photos

To be honest, that was weird but interesting.

 

[George S.]

Agreed. Interesting reading, and I understand very little of what was discussed. Too bad it became confrontational. Was almost like politics. Sigh.

 

[grapplesaw]

In the thread someone said “So he added 4 additional output transistors (2 per channel) to a 400 series one, what will this achieve?”

well my reasoning is why not - the more outputs the lower distortion. It’s not about more power

also may be a better load share in 4 ohm setting

 

[grapplesaw]

With the new year being quite around here,sad, I did a little this morning to the build.

 

[grapplesaw]

Making progress
I am adding a power switch and meter switch.

 

[NeverSatisfied]

A 400 with 700 power switch and db attenuation?
Nice, I always disliked that 400’s don’t have power switches.

 

[grapplesaw]

It’s coming together

 

[grapplesaw]

Got the insides done. Now for the meters, switches and rca inputs.

 

[laatsch55]

Moving right along.......dig the new avatar...

 

[grapplesaw]

Moving right along.......dig the new avatar...

Thaks Lee. Go big or go home I guess is the message these days.

 

[laatsch55]

Amen!!

 

[grapplesaw]

It’s alive!!
Just setting up.
small fuses for an hour the we boogie.
Bias .36v
Offset .22 mv right 1.19mv left
Voyage board 30.86/88
Rails with 118 v in 170.6 total( she a hottie)
noise is low
Plastic outputs are 10* hotter at idle