Speedball downgrade or new volume pot?

[orri]

Hi,

I installed the Speedball upgrade to my Crack but I have to say I acutally think I prefer the Crack without the upgrade.
The amp feels a bit too powerful with the Crack (paired with my HD650s) and I get fatigued rather quickly. I am not sure if this is due to the changed sound signature after the upgrade or because I feel it is difficult to listen to the amp at low volumes without channel imbalance.

Would I get a broader "volume range" by changing volume pots? Or could I "downgrade" the Crack back to the basic version?

My source is iMac>Bifrost Uber>Crack.

Thanks!

 

[Paul Birkeland]

See Crack FAQ #3 here: http://bottlehead.com/smf/index.php?topic=4295.0

A stepped attenuator will give you better balance at lower volumes, but the mod described in the FAQ will recenter the listenable level in a more reliable portion of attenuator rotation.

The Speedball does increase the gain, which may be a bit of what you're perceiving.  It also decreases the distortion substantially, which reduces the tubey haze a bit.

-PB

 

[Jimb0]

Hi,

I installed the Speedball upgrade to my Crack but I have to say I acutally think I prefer the Crack without the upgrade.
The amp feels a bit too powerful with the Crack (paired with my HD650s) and I get fatigued rather quickly. I am not sure if this is due to the changed sound signature after the upgrade or because I feel it is difficult to listen to the amp at low volumes without channel imbalance.

Would I get a broader "volume range" by changing volume pots? Or could I "downgrade" the Crack back to the basic version?

My source is iMac>Bifrost Uber>Crack.

Thanks!

Interesting point Orri,

I too had noticed the Crack sounding better without the Speedball upgrade. After some mods and tube rolling I found myself liking the sound signature once again. You mentioned you had an issue with power, but I did not have the same feelings about it. After installing the Speedball I thought the vocals weakened but the separation of instruments sounded more distinct. If I were you, I'd do another test run without the Speedball upgrade just to see if your opinion on it changes or not before swapping the volume pot.

 

[orri]

Thank you both for quick replies!

I'm guessing its the increased gain you mention that I dislike. The standard Crack sounded so smooth and relaxing.
Is the Speedball reversible? Do you know where I would order the parts needed?

 

[JamieMcC]

My own experience was to initially go with the resisters to pad down the volume I later fitted a Valab 100k stepped attenuator and found I now longer required the resistor to pad the volume down. The $30 for the attenuator was one of the best bang for the buck upgrades I have done.

Depending on what you are using for your source if its software based you might be able to try experimenting with sliding the volume down on it to give you more range at the pot which would also help with any the low level imbalance.

 

[Nathan]

Shortly after building my Crack last May I recognized I needed to pad down the volume. Following the directions in the FAQ was a perfect solution.

Now initial thoughts after building the Speedball was hmm, should I not have bothered? Swapped in a different 12au7, and all was well. The Speedball does change things. It's cleaner, deeper and more detailed. The 12au7 comes in such variety that the Crack is sensitive to just what 12au7 you're running. So in my set up, a different 12au7 led to sonic happiness which now I can say exceeds the pre Speedball Crack.

Disclaimer- my Crack is not quite stock anymore. All nos tubes, audio caps and one power supply cap bypassed, etc.

 

[orri]

I guess I'll try some tube rolling before de-installing the Speedball upgrade.
The 12bh7 has less gain than 12au7 and 5963 if I understand correctly?

 

[Paul Birkeland]

I guess I'll try some tube rolling before de-installing the Speedball upgrade.
The 12bh7 has less gain than 12au7 and 5963 if I understand correctly?

The 12BH7 has about the same gain as a 12AU7.  If you'd like to use the 12BH7, some modifications need to be done to the stock circuit.

 

[Nathan]

Before modifying the Crack circuit maybe you want to try a Mullard CV4003 which I think is great (being used with a Tung Sol 5998).