[larcenasb]

Nice build, Kitchener! When I first started modding, I'd carry the Crack under one arm to my garage, but I felt a bit uneasy...thinking the glued wood base would break apart. So, I now always carry it with two hands just to be safe. Your IRONCLAD Crack will never have that problem haha! What a tank-like beast! Happy listening!

 

[bloodhawk]

This is pretty much a straight copy of my post over at Bottlhead, but I figured maybe someone over here might appreciate it as well. Whore for attention, that I am.

Let me present my, pretty much finished (for now), Crack:

IRONCLAD
​

-or Brass ****house, alternatively.


Mods:
Speedball
Output Caps: Mundorft MKP, 100uF 250V
Choke: Hammond 157M
Pot: TKD 2CP-601
Power Bypass Cap: JB JFX, 2.2uF 250V

​

Cosmetics:
Polycoat for base
Clearcoat for transformer bell
Knob: Elma Marconi Classic British Wing Knob from HifiCollective
Brass corners: Heart of Brass Etsy store

​

Pictured tubes:
Mullard 6080
Mullard 12AU7
-just because they fit the IRONCLAD (capital letters required) theme

​

Before I move on to some more detailed descriptions of the mods, let me just make it absolutely clear that I am an awful audiophile.
I have almost no frame of reference, my experience with amps is limited to once owning an APPJ "something" and still owning a couple of broken down old Tandberg receivers (next project: restoring them!).
To be completely honest, I just did all this for the fun of building.
And to be even more honest, I thought the Crack sounded wonderful without mods, and after mods it ...errr still sounds wonderful. But I can't for the life of me tell what's different.
But I did find the bass more punchy and clear after the Speedball, so that's nice.

Speedball:
Not much to say, order the kit and stuff it in.
Audible difference: Nicer bass.

Choke:
I debated wether to suspend the choke from the top plate or mount it in the base.
In the end I decided to screw it to the inside wall of the base, where I think it fit rather nicely.
I might stuff in another choke just to adhere to the IRONCLAD theme...nah.
Audible difference: Not that I could hear. My Crack was dead quiet before and is still dead quiet.

Power bypass:
The small film cap was cheap so I figured "why not".
Bypassed the last cap in the PSU.
Audible difference: Nah.

Pot:
There was a slight, expected, imbalance at lower levels with the stock pot.
So I figured, "why not".
Went for a TKP pot just because lot's of people go for the Alps.
The stock pot was just as smooth as the TKP, I find the TKP takes a little more force to rotate.
The TKP fits in the plate hole, so no need for filing.
But the “locking tap” makes the pot’s terminals face away from the nine pin socket and it’s considerably smaller than the stock pot, so you might have to choose between running longer wires to and from the pot or figure out how to mount the TKP facing another way.
I ended up putting an extra nut on the pot, so the locking tap didn’t reach the plate. But the pot is still a little small, so my wiring to and from the pot is a mess, gonna fix it up some day.
Audible difference: better channel balance at lower volume levels.

Output caps:
These are probably my favourite.
Not because of the sound, just because I like the look of them.
But soldering the fat leads with a 15W iron was an enormous pain in the ass; took ages to heat up.
They’re suspended below the top plate by metal mounting clamps. I quite like the clamps as they’ll let me swap caps quite easily if needed and they look sturdy.
Audible difference: sorry, can’t hear it.

Brass corner pieces:
I wanted some square, metal feet for my Crack.
It was pretty much impossible to find exactly what I pictured so I landed on these metal corner guards that I mounted like legs.
While I quite like the look, the Crack has gone from an intriguing oddity on my desk to a brutal and ostentatious behemoth.
Audible difference: by far the largest sonic improvement of any modification.

​

Conclusion:
As I’ve said, I have a poor frame of reference and a poor audiophile ear.
So when I say that I can’t hear an improvement in the sound of my Crack, it’s just that: I can’t hear it, not saying it’s not there.
Besides, by the time I’ve actually installed a mod, I’ve forgotten what the damn thing sounded like before!
I had a stock Crack about three months before I started modding it.
I’m still not quite done with the Crack. I’m going to put in some new wires to and from the pot, reflow a couple solder joints and I’ve also got two bypasses for the output caps lying around. But after that I’m probably done.
As for the whole IRONCLAD thing, I’m well aware it’s just a pretty ordinarily modded Crack with tacky tat screwed on. But it’s mine. IRONCLAD!

The only mod I can recommend is the Speedball.

The other stuff I just did for the fun of tinkering, and if you like that sort of thing: go for it!
Just don’t expect to have your mind blown.

​

Nice!

This is exactly the reason why i said in the past the changes are at most 10-5% IF at all.

People will exaggerate the extent of placebo changes to oblivion, end of the day all that matters is good tubes, PERIOD.
Along with that how cleanly you are able to avoid inductance / RFI.

The most anyone will ever hear is a blacker background and slightly more clarity. And the latter will be very much so be because of the former. That too with headphones that cost 3 to 4 times the crack itself.

All that matters is that you are happy with it!

I recently modded two LD MKVI+'s and that is an amp you can hear the differences in, but those are also ONLY audible when very specific parts are changed. But people still go ahead and spend 100's of $$'s on part that maybe make like 0.1% of a difference by making the signal cleaner.

Here are some images - https://imgur.com/a/7JKlF4o

And the only way i COULD tell that there was a difference, was because i ABX's both the amps (one post mods and one unmodded). Even then the main difference was noticed using better tubes. (both had same tubes for comparisons)

But there are people who will argue with me that the Dale resistors that not advertised as non inductive and cost $1.30 a pop are WORSE (and sound worse lol) than the MILLS resistors that cost $6 a pop. The funny thing is that they are made in the same factory lol. At least i couldn't hear a smidgen of a difference between the two.

 

[Kitchener]

Nice!

This is exactly the reason why i said in the past the changes are at most 10-5% IF at all.
...
All that matters is that you are happy with it!

Thanks!
Good, level headed takes all round.

I’m quite happy with it, apart from a scratching noise sometimes when I adjust the volume.
I tried asking over at Bottlehead but no bites yet.

 

[attmci]

Thanks!
Good, level headed takes all round.

I’m quite happy with it, apart from a scratching noise sometimes when I adjust the volume.
I tried asking over at Bottlehead but no bites yet.

That sounds like a pot problem. Did you upgrade the pot?

Try to recycle it several times when the amp is off.

 

[Kitchener]

That sounds like a pot problem. Did you upgrade the pot?

Try to recycle it several times when the amp is off.

Yeah it’s a new pot, been using it a week.

Here’s a copy of my post over at Bottlehead:

I speedballed my Crack a week ago.
I installed a new pot (TKD 2CP-601) a week before that.

After installing the Speedball there has been a slight scratching noise when adjusting the volume on the Crack.
It's barely noticeable on my HD6XX Senns (but much more prominent on my 80 Ohm Beyer DT770s)

Some observations:
The scratching is not constant; only slight stabs of scratching when I twist the pot,
the quicker I twist the louder the scratch,
it goes away after a while.

Is this expected behaviour or indicative of some malady?



Just to go off topic right off the bat:
After speedballing, my 80 Ohm Beyers really stopped playing nice with the Crack.
I notice the bass seemingly dropping off sometimes, like the headphones can't keep up.
This does not happen with the 300 Ohm Senns.

 

[attmci]

Yeah it’s a new pot, been using it a week.

Here’s a copy of my post over at Bottlehead:

I speedballed my Crack a week ago.
I installed a new pot (TKD 2CP-601) a week before that.

After installing the Speedball there has been a slight scratching noise when adjusting the volume on the Crack.
It's barely noticeable on my HD6XX Senns (but much more prominent on my 80 Ohm Beyer DT770s)

Some observations:
The scratching is not constant; only slight stabs of scratching when I twist the pot,
the quicker I twist the louder the scratch,
it goes away after a while.

Is this expected behaviour or indicative of some malady?



Just to go off topic right off the bat:
After speedballing, my 80 Ohm Beyers really stopped playing nice with the Crack.
I notice the bass seemingly dropping off sometimes, like the headphones can't keep up.
This does not happen with the 300 Ohm Senns.

Get another pot to see if you still have the noise. I hate noise.

Crack is not recommended for your 80 Ohm Beyers. Try to use a 5998/421A/two 6bl7 to see if you may get better results.

 

[Kitchener]

Got another pot to see if you still have the noise. I hate noise.

Crack is not recommended for your 80 Ohm Beyers. Try to use a 5998/421A/two 6bl7 to see if you may get better results.

Might have to ask the retailer if they think the new pot might be covered by some sort of warranty.
-or just put the stock pot back in.

I brought up the Beyers pretty much just because I finally seem to have discovered what using unsuited headphones might sound like

The scratching is barely noticeable with my 300 ohm Senns, though. And seems to go away completely after the amp heats up.

 

[Allanmarcus]

Sounds defective to me. Best to swap it out now than deal with it.

 

[bloodhawk]

Thanks!
Good, level headed takes all round.

I’m quite happy with it, apart from a scratching noise sometimes when I adjust the volume.
I tried asking over at Bottlehead but no bites yet.

Its odd for TKD pots to be defective. Does it always happen at the same positions?

I had a similar issue in my MK VI+, but it went away after a while, turned out one of the solder joints was cold after all the mods. I had to go over all joints close to a power tube as the voltages around that tube were a bit wonky.

Might help to do a voltage check, and see if anything odd shows up, or do the poke with a wooden chopstick test.

 

[Kitchener]

At least all the voltages on the Speedball were good right after assembly.
I'm going to give the whole build a good do over with the soldering iron, just need to get it home from the office.

 

[larcenasb]

Okay, I think I'm done! First off, the value of the Crack is simply astounding...plus the learning experience of trying out different upgrades makes this a totally worthwhile long-term investment. As a rule, I limited the cost of any one upgrade to $20 max (besides the Speedball of course). Cree Schottky diodes, Triad C-7X choke, Alps pot, Mogami input cable, Audyn Q4 ouput caps & last PS cap ($16.70 ea...), Jantzen Superior-Z to bypass last PS cap, Nippon Chemi-Con 470uF PS caps, ClarityCap PX 4.7uF bypasses for other two PS caps, 6SN7-to-12AU7 adapter, 1940s 6SN7 tube (patience on eBay), preamp circuit...all under $20. So, over the course of a few years, this made the cost of the end product very easy to live with. Not to mention getting to listen through it each night is never-endingly satisfying.

Sadly though, it's been the end of my upgrade journey for some months now. And, so, just for kicks, I thought I would just do one final upgrade. I decided to replace the Jantzen bypass with an Audyn Tri-Reference 0.68uF (my film caps are 68uF). The Audyn truly looks kingly, and so unsurprisingly the price was a little steeper ($25 shipped)--I finally violated my cost rule haha. It's difficult to say what exactly changes in the sound with each upgrade, all together though, the film caps and PS upgrades seem to allow a more dynamic and smoother sound. Improvements I can be certain about however, are that the PS upgrades made the scratchy interference go away when the volume is maxed; the Alps pot fixes the channel imbalance at low volumes; a 6SN7 greatly improves the width, body and weight in the sound; and padding the pot allows for more range in volume before it gets too loud. The rest is more comfort, just knowing the guts of my amp are top notch. Hope all of you are enjoying your learning and experimenting with this gem of a kit. Happy listening!

EDIT: It's important to note about any possible subjective changes in the sound...that the stock kit with the Speedball is already fantastic and totally satisfying. More important to good sound is good cans, a good source (don't skimp on this), and good tubes.

 

[Kitchener]

I’m a little intrigued by the funky looking electrostatic Stax Lambdas.
But I’m a little confused by their specs.

Would the Lamba SR Pro work with the Crack via their SRD-series adaptor?

It seems like the Stax adapters have an input impedance of 30 Ohms, but I’m not entirely sure so I figured it might be best to ask.

EDIT!
Never mind:
https://www.head-fi.org/threads/the-entry-level-stax-thread.676272/page-191#post-14251653

 

[hawkwindx]

Which DAC, if any, are you all using with your Crack?

 

[DavidA]

Which DAC, if any, are you all using with your Crack?

Teac UD-301, Biforst Uber, and Bifrost MB

 

[bloodhawk]

Which DAC, if any, are you all using with your Crack?

NFB 11.28 or the Topping DX7s.