700B Build

Hexis22 said:
I have a question regarding preferred AC wire routing on 700B amps. I'm contemplated with respect to placing all AC wires across the middle of the backplane boards, or run AC along the top (Perry's method).

Here are my initial thoughts:

Top placement
- Greater seperation between AC and most other components
- AC closer to sensitive RCA and Control board Op Amp input circuits

Middle placement
- Potential for AC coupling to greater number of surrounding components and wiring
- Greater distance to sensitive input signals

Or, if you route AC in and out wiring closely together it makes little difference...
Click to expand...


I don't run any AC across the boards middle of the boards. . All the AC I do goes across the top. It produced the quietest amps I've built.
 
Made a small change in AC wiring between the fuse holder and fan socket to keep line and neutral running together as much as possible.

I didn't like how line and neutral originally formed a loop around the DC rail fuse holders.

Before:

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After:

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Completed most of the wiring and performed resistance checks.

Initial power up tests completed with DBT and Variac without issue and expected rail voltages at 120V AC input. Hearing the relays click sounded almost as good as music...

Control board bring up is next.

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Control board all wired up and tested without issue, +/-15V supplies measured as expected.

Lots of practice inserting outputs into backplane boards with 700's... No shorts to chassis ground and powered up cleanly with +/-104V rail voltage at 120V AC.

Set initial Bias at 350mV on both channels and output offset measured 0.000V on Left and 0.001V on Right.

Could not be more pleased with how this powered up and measured so far.

Sound test is next...

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Thanks George.

When I have tunes crank'n and a soldering iron in my hand, the hours just fly.

My 400 Series 2 sits right beside my bench and the dancing LED's are a joy to watch while working. It's a good feeling knowing you built it by hand and it sounds so good.
 
WOW!!!!!! I must say Eric I am totaly impressed with your work. I definitely am happy with this build. I can jot wait to hear this amp. Any idea as to when.you will get the LED kit?
 
You may be able to find a blue filter (front panel insert) from one of the builders here.
 
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