One year of Crack happiness

[Nathan]

I received and built my Crack about a year ago and have never enjoyed headphone listening more than I do now. My Crack isn't stock, but nothing not mentioned somewhere on this forum either. My Crack, with HD600's and Cardas cable, is pure sonic joy.

My build, beyond stock, consists as follows

Speedball
Tung Sol 5998 output tube
Millard CV4003 12AU7
1st and 2nd power supply caps replaced with 470uF caps
3rd power supply cap bypassed with a film cap
Triad CX7 choke in power supply
Output caps bypassed with Teflon caps
PEC 100k ohm audio taper volume pot
Cardas RCA jacks
Padded down volume control

Really isn't too much to do, if I choose to do any more. All I can think of is a different headphone jack or film output caps. I would likely tackle the audio output caps first.

[Paul Birkeland]

1st and 2nd power supply caps replaced with 470uF caps
3rd power supply cap bypassed with a film cap
Triad CX7 choke in power supply

Without looking at simulations, my gut tells me that the two 470uF caps and the choke between would allow you to simply remove the last RC filter completely.  The voltages will move around a little bit, but not intolerably so. 

[Nathan]

Any downside leaving in the last RC filter?

[ZacharyP]

Any downside leaving in the last RC filter?

I'm interested in the answer to this too!

[Nathan]

For what it's worth, I'm letting my ears be the judge and that said, I've never enjoyed headphone listening as much as I do these days.

[grausch]

Without looking at simulations, my gut tells me that the two 470uF caps and the choke between would allow you to simply remove the last RC filter completely.  The voltages will move around a little bit, but not intolerably so.

Eliminating the last cap from the PS would really free up a lot of real estate in my Crack and keep the costs of my upgrades down a bit. Would the last 470uf cap then be in the output current loop as per PJ's post here http://bottlehead.com/smf/index.php?topic=3498.msg30955#msg30955? I may be mistaken, but based on PJ's post, would using this approach yield a better / safer result than using a film capacitor as the 3rd cap since the power supply signal voltage won't exceed the signal output voltage?

[Paul Birkeland]

Eliminating the last cap from the PS would really free up a lot of real estate in my Crack and keep the costs of my upgrades down a bit.

That's part of why I suggested trying it.

Would the last 470uf cap then be in the output current loop as per PJ's post here http://bottlehead.com/smf/index.php?topic=3498.msg30955#msg30955? I may be mistaken, but based on PJ's post, would using this approach yield a better / safer result than using a film capacitor as the 3rd cap since the power supply signal voltage won't exceed the signal output voltage?

470uF vs. 220uF as the last power supply capacitor is not going to make much of a safety difference in terms of signal voltage imposed on the power supply.  It will, however, certainly sound different.

[grausch]

Thank you for the detailed response.

If I don't like the sound, can I add in a 270 ohm resistor and another 470uf cap or should I always have the choke in place of the last resistor?

Edit: Found an answer - http://www.audioasylum.com/cgi/t.mpl?f=bottlehead&m=46537 & http://diyaudioprojects.com/Forum/viewtopic.php?f=9&t=3513&start=30. Based on this CLCRC is the preferred choice while the current recommendation for the Crack is CRCLC. Not sure how that will affect things.

Another example of a CLCRC power supply - http://bottlehead.com/smf/index.php?topic=5829.0

[ZacharyP]

That's part of why I suggested trying it. 470uF vs. 220uF as the last power supply capacitor is not going to make much of a safety difference in terms of signal voltage imposed on the power supply.  It will, however, certainly sound different.

If real estate isn't a concern for the crack circuit, would a CLC or CLCLC perform better; generally speaking?

Reason I ask this in particular is because if I went the CLC route I would experiment with the first C being a high quality electrolytic between 250 and 470uf, followed by the choke, and the last C would be two Obbligato 100uf PSU film capacitors in parallel.

Really the best route would be to experiment with different values of C in both CLC and CLCLC, but that might be a bit too much soldering and not enough enjoyment!