Norwegian Crack

[Strikkflypilot]

Hi guys!

It's been great fun and I guess it will never quite end.
I have really gotten my taste back for electronics, old school.
Great help from Caucasian Blackplate and good tips from Jamie, Hornet900, probably more and definitely input from more as this has taken time!
I am finally there where I wanted to get and even further.

The end result:
Wood base with something like 15 layers of shellac after coloring.
Bottlehead Crack with Speedball, dead silent thanks to replacement MJE350s.
Neutrik locking Jack that is turned 180 degrees, makes it easy to disconnect headphones.
A great CV3523.
An Alps RK40 AKA "Black Beauty" Pot. Thanks to Jamie for great advice on the goalpost fastening of small speedball PCB for the fit!
Mundorf 100uF 250v and Mundorf Supreme 1uF 600v output caps.
Anodized socket head screw replacements.
A great Eupen Eucaflexplus IEC cable.

Beautiful custom made Forza Audioworks iPod LOD input cables
and also Forza Audioworks Noir Copper Mk2 custom made drop dead gorgeous for my..
lastly: HD580 (Yes, they are still around and sound great with this setup.)


So please, enjoy the pictures!

 

[JamieMcC]

Neat build looks great and I'm really pleased the goal post idea worked out seeing the size of Black beauty you needed all the room you could find.

So two questions

1 How are you finding the beauty?
2 What do you think the Supremes for bypass's add over just the 1OOuf Mundorfs on their own? 

 

[Strikkflypilot]

@Jamie: Glad You liked it. Had to shoot with the chessboard under the amp
1. It sure feels solid, good solid detents. Maybe even more important, the difference in Resistance between the two channels is hardly measurable throughout the 21 detents.
2. I must confess I was really keen on finally getting to finish the build and put them both in at the same time :

 

[Lugnegard]

Wow, that sounds like a pretty max out Crack Would love to hear it. How does it compare to a standard Crack soundwise?

 

[Strikkflypilot]

It does sound great

I find it very hard to explain exactly how it sounds. Psychoacoustics is hard and very subjective.
There are many thorough reviews and writeups around but You might disagree with all of them with regards to what You hear and like .

What I generally easily agree on, using my HD580 headphones, is that the stock crack is a very enjoyable amp, mids and treble live like but a bit "gritty" (There I go, whats thats supposed to mean?)
The speedball makes the amp faster, more responsive in my view.
The film caps made IMHO, and others seem to agree, the upper mids and treble smoother.

BUT, during this process, I have upgraded the headphone cable aswell, to a beautifully custom made hand crafted Forza Audioworks Noir, creating an unknown in the process.

 

[Lugnegard]

I've searched for Forza Audioware but I can't seem to find it, could you be so kind and share a link perhaps?

 

[Strikkflypilot]

Completely gutted crack. Retrofit with Vampire RCAs. Clothcovered wiring, teflon sockets with PCBs. Original crack components for voltage and resistance checks. Drilled holes in chassis for choke and 220uF PSU film cap.

 

[Strikkflypilot]

Interesting to listen to the amp after getting used to speedball.
It is a definite step down IMHO, hard to describe with words.
It is softer and again IMO less defined, although I am sure some would
prefer the softer presentation for a more relaxing experience.

With speedball, my pulse goes higher from endorphins and adrenaline
Can't wait to install the last bits and pieces to finalize this project.  Or does it ever end?...

 

[Atraf]

I've searched for Forza Audioware but I can't seem to find it, could you be so kind and share a link perhaps?

http://forzaaudioworks.com/en/category.php?id_category=36
its pretty expensive though..

 

[Strikkflypilot]

After Yesterdays tribulation and shocking sparks in the 6080, the amplifier is working without hiccups. Still waiting for standoffs to install chokes and the last PSU cap.
I have decided to mount an aluminium grille under the box to make the amp more safe from prying fingers. Should it be grounded?

Pictures follow

 

[Paul Joppa]

The bottom cover should be grounded to the chassis plate, for safety.

I would guess the sparks were some particles inside the tube, that got in the wrong place when you inverted the amp to make voltage measurements. These particles are common in tubes.

 

[Strikkflypilot]

Thank You so much on both accounts. And if I haven't already, for the excellent amplifier!

 

[Grainger49]

The wire mesh you have will need to be cleaned to the bare aluminum before soldering.  I suggest a good crimp first.  Aluminum is not easy to solder to.

 

[Strikkflypilot]

Good point. I believe it is anodized and the black color comes off, just by bending. I actually considered securing the grille to the box with screws and pull a wire around at least one of the screws and lead the wire up to the top plate where I would have to make some kind of secure connection.

 

[Strikkflypilot]

Finally the standoffs have arrived!
The choke is fastened with a couple of locking lugs and nuts for additional spacing.
The 220 uF film cap is fastened to the standoffs with strips and wirestrip brackets.
Couple of solders and finally...done...for now

 

[PassionForSound]

Wow. That's quite a beast!

How does it sound with the choke compared to without it?

 

[Strikkflypilot]

I think I have to say it sounds great. It STILL sounds great
Noticed a bit more fluctuation on the input voltages of the speedball.
About 2 V from about 165 to 167v.
Burn in required?
To say anything more about SQ requires testing under more quiet
circumstance than has been available to me. I am possibly leaning towards cleaner sound altogether. The 220 uF PSU cap is also in the mix.

I am hugely appreciative about how the optical result came
out aswell

 

[Alonzo]

Looks Great!  I have a similar setup and it does take some organization to make everything fit under the hood and not affect the sound. 

If your ever updating again, my Crack improved with bypassing all the PS caps.  And I found that I never change my volume so I removed my Alps for a single resistor.

 

[Strikkflypilot]

Thanks Alonzo! 
It is not circumstantial, I might have more or less copied Your 3rd PSU cap placement.
I have been very happy with the Alps RK40, will probably stick to it.
I am a bit keen on fitting some sort of sleek bias system for input tube rolling.
Ive seen amps with voltmeters to make sure bias is correct for the tubes inserted and then some kind of pot to adjust until happy.

 

[Alonzo]

I thought about that myself, I have 2 analog and 2 digital meters I bought, sitting on the shelf to use.  I just could never figure out how I wanted it to look and if the cuts in my Blumenstein bases were worth it.  I'm thinking of installing test points just to the right of the vents that could be used and not so noticeable.
Good luck, I'll wait to see what you come up with.  Go forth and blaze the trail!!!!