Modded Crack - add bypass cap, choke and Cree diodes

[ALL212]

Inspired by other posts but recently by richmi in the gallery:

I replaced the last 270 ohm resistor with the Triad C-7x and "tipped" the last cap with a 1uf Clarity Cap.  Hope to add the Cree diode in there someday but for now this will do. 
I got lucky on the mounting hardware as being a packrat sometimes pays off.  I had the screws and standoffs already in my possession and just had to add the holes to the chassis.  I'm going to see if I can find more of those (they come from a dual monitor stand we use at our offices) and if so, will offer up what I find here.

Need some time to listen but no smoke on power up so we're going forward!

From the front:


From the back:


Full underside:


From the top - new holes just above the t'former holes and a bit to the left.  Transformer holes are 1/4" too close together to use.

 

[ALL212]

Further upgrades following member Richmi:

Cree diode board added.  I didn't drill anything and I think it was Lee Hankins that just let it hang on the wires but I superglued a standoff and then wired it so it already sat correctly on the standoff - then superglued it to the standoff.  Kindof a combination of both.  If the superglue does let go it won't go anywhere as the wires have it.

I used the "recliner" look for soldering them to the board:





Smoothed the overall sound out very nicely.  Bass is noticeably better, darker background.

Nice!  Thanks guys.

 

[Nathan]

I'm interested in installing the choke too but as you've noted, real estate under the hood is tight if there's much in the way of mods and I suspect that a choke is not a typical builder's first mods

 

[ALL212]

If you have the speedball installed what I did comes in just short of the depth of the speedball.  The fun part is figuring out how to mount that and then grabbing a drill and hitting your top plate.  The unsoldering/soldering portion isn't to bad.

If you are a beginner stay away from the Cree diodes - that nice shiny part with the hole in it is hot and I'm guessing if you ground those out some magic smoke could be released.

 

[i luvmusic 2]

After you installed the CREE DIODES did you noticed any difference in sound?

Thanks

 

[ALL212]

'cause it all about dat bass bout dat bass no trouble...

Blacker background.

I'd call what I hear smoother.  Definition, soundstage, "air" around the voices.  It's just that good!

1) Original Crack good,
2) modded crack better - signal path stuff
3) Built a SEX and liked it better than the modded Crack. 
4) Upgraded Crack power supply as above and SEX is sitting on the shelf wondering WTF just happened!!  :'(

 

[i luvmusic 2]

So i'am not imagining/dreaming about what i heard few hours ago after i installed the CREE DIODES.
That is why i asked first.

Thanks

 

[ALL212]

Tell me of your dreams, Usul...

What did you hear?

 

[i luvmusic 2]

Exactly what you described above except for the soundstage i can't tell the difference.

 

[i luvmusic 2]

BTW i just turned the amp off so i can take some photo later.

 

[i luvmusic 2]

Here is mine.

 

[ALL212]

I'll try and be nice to our northern neighbor...but it's gonna be tough...  :

I like the "no holes in the board" approach with just snugging it down - nice!

Ok - maybe soundstage isn't what I've got.  Separation between those things that are making the music.  Each instrument and vocal is placed very specifically,  back ground is so black that the room acoustics are amazing.

Guitar lead in on Jethro Tulls Aqualung track 7 "My God" - I've listened to this many times and never heard it like this.
Alan Parsons Project, Edgar Allen Poe - another album I've listened too many times and I just get the silly grin...  8)

 

[i luvmusic 2]

No worries.
I LOVE HOLES......... ;D

First thing i noticed the first time i fired up my crack after i installed the Cree Diodes is the Separation and even quieter background and the bass and how smooth sounding it is.

 

[ALL212]

What tubes are you using?  And what headphones? 

Stalker alert!! 

 

[Jimb0]

nice modding ALL! What do the cree diodes do for sound?

 

[ALL212]

nice modding ALL! What do the cree diodes do for sound?

Can I just call it "Magic" and get away with it? :

Keep in mind that within 10 days I did the choke, bypass and Cree's so there wasn't a bunch of listening time with the cree's out of the mod.

With all three changes:
Bass is better, tighter, deeper.  Background is inky dark - you hear the room acoustics without effort.  Placement of individuals and instruments is precise. 

This "minor" mod goes a long way in proving the design of this headphone amp is spot on.  Very nice job Doc!

 

[Jimb0]

Very interesting. I'm going to have to try it! Anything to make my Crack sound better!


James

 

[ALL212]

Please be careful of the Cree's - that silver tab is live and is a heatsink so you shouldn't cover them and they cannot touch anything - ever!

 

[i luvmusic 2]

What tubes are you using?  And what headphones? 

Stalker alert!! 

Chatham 6AS7G and Tung-Sol 6SN7GTB(Tall Bottle),HD650 and DT 880 600R.

 

[ALL212]

You converted yours to use the 6SN7's?!  Nice!  Much better than 12AU7's?

I've got a RCA long black plate 5963, Tung-Sol5998 with HD650.  Source is a Squeezebox Duet with a Stello DA-220. 

Just bought another Crack kit.  Going to use it for testing and then, maybe, what I think I'll call a BAC (Big A$$ Crack).