Tube Rolling w/Crack

[Laudanum]

I have been listening to the Crack with a 5998 and 4003 and it sounds very good. The only thing I don't like is that it does not use a lot of the volume control, maybe 10%. Even with the 6080 and 6AS7Gs I don't need a lot of increase in volume. Not sure if I should just leave it that way or add resistors to the input. I'm not a big on adding anything to the signal path though.

My source is a modded Squeezebox2, so it only puts out about 1v. Also, I'm using the stock potentiometer, but it seems to track well at the lowest volumes.

Which headphones are you using? 

In case you decide to attenuate the input ... This is from the Goldpoint site for their stepped attenuators,  but would work with the pot just as well ...  http://www.goldpt.com/mods.html

[Beefy]

I have been listening to the Crack with a 5998 and 4003 and it sounds very good. The only thing I don't like is that it does not use a lot of the volume control, maybe 10%. Even with the 6080 and 6AS7Gs I don't need a lot of increase in volume. Not sure if I should just leave it that way or add resistors to the input. I'm not a big on adding anything to the signal path though.

I don't see any issue whatsoever with something else in the signal path. A good quality metal film resistor will impart far less audible effect than even the best pot.

But it is not a good idea to just jack up the input impedance too far above the stock 100kohm. My solution was to use a 50kohm pot (TKD 2CP-2511) with a 50kohm resistor (PRP 1W) in series, giving the same 100kohm input impedance for the amp. This gives about 6dB of pre-attenuation.

[BNAL]

I'm using HD-650s.

Thanks for the link. I have to take a look and see what good resisters I have to use.

Brad

[Laudanum]

I'm using HD-650s.

Thanks for the link. I have to take a look and see what good resisters I have to use.

Brad

I just thought of something.  Probably just a shot in the dark here but ...  the stock pot, I believe is an Alpha pot.  Alpha makes both linear and log taper 100K dual pots.  If Im not mistaken (and I may be), a linear taper pot will get "loud" very quickly compared to a log/audio taper ...  most within the first 50% of it's range I think.   I dont know how sensitive the HD-650's are compared to my 250 ohm Beyers, I beleve that they are moreso.  But using a 5998 in my amp and Beyerdynamic 250 ohm phones, Im usually at or below 11 O'Clock (giver or take, depending)  but that is with a 3.5 volt source (the Tjoeb CD player).   11 O'Clock is much closer to 50% or the pots range than 10% that you are using.  So, Im wondering if it's possible that a linear taper pot was accidentally included with your Crack kit.  Again, just a shot in the dark.  But only having 10% of the knob to work with seems kinda extreme.    There may be an identifier on the pot casing.  Maybe something like "A" for audio or "L" for linear    Might be worth checking into just to make sure.  Maybe the experts here can chime in. 

[Doc B.]

I can only comment that when this idea was first proposed we checked our 100K pot stock and they were all log taper. Not that few linears couldn't have gotten mixed in, but we couldn't find any.

[Laudanum]

Like I said, a shot in the dark  :-)

[Grainger49]

Longest thread, by number of posts, on the board. 

I think that shows the enthusiasm for the Crack, or the level of addiction.  Either way!

[BNAL]

I have a Ratshack Alps 100k stereo potentiometer that I could through in and see if it makes a difference. Everything sounds good I just want a little more adjustment. In the future I want to upgrade the pot, but want to wait.

[Grainger49]

Brad,

If I am following you you need to get more turn from your volume pot.  It gets loud too early, right? 

If so then changing the pot, or the resistance of the pot will not make a difference in the range of travel or resolution in the volume control.  If you put in a nice $4 resistor before the existing pot it will make a difference.

For instance, if you had a 10k (audio taper) volume control at 9:00 you will have the same volume in your headsets as you do now with the 100k volume control. 

To make a difference you have to waste some of the incoming voltage with a series resistor.

[BNAL]

Grainger,

I have room to change the volume to a listenable level, so I'm not that concerned. I was just wondering if others were experiencing the same thing. Now if the problem was that as soon as raised the volume it was too loud I would have a major issue.

If I do feel like I need to attenuate the volume I will probably use the Goldpoint solution that Desmond posted earlier.

Brad

[s1]

By the way I put the RCA 6AS7G and CIFTE back in and they pair nicely together.

Thanks to Brad .  I too , am enjoying this pairing with a Bifrost and the HD650

[BNAL]

s1,

Yes the CIFTE is a very nice driver, but I think that the Mullard 4003 box plate is a little better. It adds a little more to the mid range. I have to say that the drive seems to make the biggest difference in sound as compared to any of the power tubes I have tried, i.e. 6080, 6AS7G, or 5998. I want to try a couple of different drives and see what they sound like.

Brad

[btrancho]

s1,

Yes the CIFTE is a very nice driver, but I think that the Mullard 4003 box plate is a little better. It adds a little more to the mid range. I have to say that the drive seems to make the biggest difference in sound as compared to any of the power tubes I have tried, i.e. 6080, 6AS7G, or 5998. I want to try a couple of different drives and see what they sound like.

Brad

+1 on this.  I'm really enjoying my combination of the Speedball, RCA 6AS7G, Mullard 4003 & HD600s.  I'm still frequently breaking into a smile while listening to something I haven't played before through my Crack.

[Dr. Toobz]

Just to add to the many variants of the Crack out there, I'm now running a 7236 in the power socket, and an E80CC in the driver position, with 330uF low-ESR Panasonic electrolytics bypassed by some 1uF Solens I had laying around. This arrangement seems to work very well into my low-ish impedance AKG's (K702; 62 ohm). The sound is very clean and well-controlled, with low apparent distortion.

[Noskipallwd]

Angelo, so you like the E80CC as a driver in the Crack, what brand do you have? A friend offered a couple of phillips mini-watts, maybe I should take him up on that.

Cheers,
Shawn