Cagey’s Neurochrome Modulus 686 build

Awesome work, a first build as well.

No pics as of yet!

The amp has been playing faultlessly all day, and no magic smoke has escaped.

I must have done it right. 

Thanks Robbie.
Doing the build myself was the only sensible option. Shipping the completed amp would not be cheap.
With the latest amps, there is less work to do, as you can only buy the V1.1 boards fully populated.

Apparently, they are quieter than the "old" 686 as well, not that many people would be able to tell the difference.
I can see why Oli likes his so much though.

We’ll never have identical systems.
My wife won’t let me spend much more on HiFi. 

The differences are about 1.5db thd + noise. The difference between- 120 and -121.5db really isn't audible. That's not to say they don't add up

Thinking about things this morning, I think the fuse I fitted may be too big.
It's a 6.3 amp fuse.

If I assume that my transformers are 80% efficient, then I should be able to use a fuse around 4.3 amps, or am I missing something?

I have a soft start fitted.



2 x 400VA transformers are fitted.

I did the extra psu board a month or two ago, that seemed to give them a bit more grip with the volume wicked right up. The only other things left to do are as follows.

1. Add a front panel led to show when they are plugged in. There's a hole for that in the panel already and there's an led on the soft start board that could be lifted to the front panel that would provide this, its on when they are plugged in already its just hidden as its not visible from outside.

2. Add a switch on the back to flip the signal input and an extra set of speaker outs so I can run each mono as either a bridged amp or a stereo pair at half power. I might do this if I go active plus dsp for the bass driver. So the mid and ribbons will each get their own 80 watt amp board supplying them.

I could vent the cases, but they don't even get mildly warm

Yeh, there's really nothing to do to them that isn't f-ckery window dressing.

I could put a 686 board in each chassis instead?

Next project is room treatment, prime number diffusers.

I've never liked the WBT, had the same problem on kit in for repair/modification.

I'll chalk that one up to experience, or rather, lack of it.

and speaker manufacturer's emphasis WBT posts in their adverts! Sorry about that Cagey, it's just another job to do

You haven't dropped it?