Am I just imagining it?

[adamct]

So, as several of you know, I replaced the electrolytics in the Crack power supply with film caps. (And if you don't know, see here.)

I did it mostly for the fun of mounting the caps to the Crack, and because the caps themselves were quite cheap (about $10 each). I wasn't expecting any audible changes, let alone any significant audible changes.

But it certainly appears to me that the bass on my Crack is greater in quantity, tighter and hits harder than it did before. Resolution also seems slightly improved, but that is hard to quantify and I wouldn't bet on it. The change in bass seems obvious to me, however.

Is there any logical, technical, scientific explanation for why this might be so? Or do you think this is just the power of suggestion and the effect of perception changing to meet subliminal expectations? At least consciously, I REALLY wasn't expecting any changes, so I don't feel like I am twisting things to validate any sort of hypothesis or conscious expectation going in. But the subjective change in bass is so large, that I don't trust myself. Am I just imagining it, or is there a plausible explanation?

Best regards,
Adam

[w0lfd0g]

Did you make any other modifications simultaneously with the change of power caps that may have contributed?

Whether the changes are the result of suggestion or any actual physical modification, I say just enjoy the results!  Some would say that perception is reality.   

Cheers

[Grainger49]

To quote Paul Joppa, "the output is just the power supply modulated."  So what you hear is the power supply.  He has also said he never saw an improvement to a power supply he didn't hear. 

The film cap will release energy into the circuit faster because of the lower ESR (Equivalent Series Resistance) of a film cap.  So it is quicker.  That should improve the transients in the bass where the power supply is drawn upon.  Transients in high frequencies don't drain a power supply like bass does.

[adamct]

Nathan: Nope, no other changes. I initially used a different input tube, but I've verified the increased/better bass holds up with other input tubes as well.

Grainger: that makes sense, thanks! I'm going to cautiously assume that I'm not crazy, and what I hear is real. If so, this is a mod I would recommend that everyone consider. It has made a bigger difference than upgrading the volume pot or (for the most part) tube rolling.

Best,
Adam

[w0lfd0g]

FWIW, I replaced the final power cap with a nice Clarity Cap TC capacitor @220 uF.  Incredible bass speed and extension.  More's the pity, though, that I didn't build the Crack initially as stock for later comparison. 

http://www.partsconnexion.com/capacitor_film_clarity_tc.html

Cheaper than many film caps, but perhaps not as much of a bargain as Adam's find.  Not as "manly" either

[adamct]

Nathan,

That's a very nice cap, and one of 2 that I was originally considering (the other was the Solen 220uf FastCap). But ultimately I decided to go the budget route. If I ever build a 2nd Crack from scratch, I'll have to revisit that ClarityCap TC cap. It is certainly more attractive than the ones I used!

Best regards,
Adam

[corndog71]

I concur with your observations.  When I built my modded ST35 amp I used Panasonic electrolytics and it sounded pretty damn impressive for a little 17.5 watt amp.  When I found out about the TC caps I was really curious to see if a difference could be heard.

The change was immediately obvious to me and a friend familiar with my rig.  For one there was a layer of hash that was stripped away that wasn't noticeable until it was gone.  The music had a speed and jump to it that it just didn't have with the panasonics.  Separation of instruments improved.  And bass was as you said quicker, deeper, tighter.  Going back to older recordings I could more clearly hear and follow the bass guitar.  It was almost like going from monitors to towers.

[adamct]

Thanks. I'm just surprised that in all the discussions around mods to the Crack, this hardly gets discussed at all. People talk about bypassing the last electrolytic in the power supply, but rarely propose replacing it (and the other two electrolytics) entirely. I suppose this is because if you use audiophile / boutique film caps, it is quite expensive to buy three 200uf (or 220uf) caps that are rated for at least 250V. But I managed to do this for about $45 altogether. And I found this mod had a MUCH greater impact that upgrading the volume pot, for example.

[adamct]

Also, just to be clear: I didn't notice much of a difference as a result of bypassing the last electrolytic in the power supply.

[adamct]

OK, I am now 100% positive I'm not imagining it. My Crack sounds flat out amazing. Replacing the power supply caps made an enormous difference. It got me wondering...would it be possible to upgrade the transformer, similar to what some have done with their S.E.X. Kits? Is there a Magnequest transformer that would be suitable? (To be clear, if I decided to replace the transformer, I would start over with a new build.)

Are there any other improvements that could be made to the power supply?

Best regards,
Adam

[Paul Birkeland]

It got me wondering...would it be possible to upgrade the transformer, similar to what some have done with their S.E.X. Kits? Is there a Magnequest transformer that would be suitable? (To be clear, if I decided to replace the transformer, I would start over with a new build.)

I'm not aware of any power transformer that could be considered an upgrade for the stock transformer in the Crack, though I am aware of a great many other power transformers that could work, and would be vastly inferior. 

[adamct]

PB,

Great, thanks for saving me time and money!

Best regards,
Adam