Crack-a-two-a as Preamp?

BNAL · 2250

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Offline BNAL

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on: November 19, 2017, 12:06:58 PM
I have read on the Crack forum about people using the Crack as a preamp, but have not seen anything for the Crack-a-two-a as a preamp. Has anyone tried it? if so what were the results? I would think that it would edge out the Crack, because of the shunt regulation and larger power transformer.

Brad Nalitt
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Offline Paul Birkeland

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Reply #1 on: November 19, 2017, 12:15:27 PM
It will very much edge out the Crack as a preamp, but certainly not the Smash!  There's also a little more room in the chassis for another set of RCA jacks.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline larcenasb

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Reply #2 on: May 03, 2018, 08:51:18 PM
I'm very interested in this as well. Paul, could you please explain what advantages the Smash would have over the Crackatwoa as a preamp? Would it not be subtle?

For me, having multiple inputs and a balance control is very appealing (which both have obviously). But with the Crackatwoa, I could use my prized 6F8G tubes with an adapter, and have a great headphone amp as well. Just seems like a great all-inclusive centerpiece to my audio system.

Doc has said about the Crack as a preamp: "Gain is about 15dB. Rule of thumb is about 10dB for a line stage." Is this the same for the Crackatwoa? Also, I padded the volume pot on my Crack, would doing this to the Crackatwoa lower the 15db closer to 10db? Sorry, for being a noob and thanks for any help!

P.S. Wish I could be there for the Bottlehead meet but I'm in Sunriver, Oregon with family. Hopefully next time, I'd love to hear the Kaiju!
« Last Edit: May 03, 2018, 09:12:00 PM by larcenasb »

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Offline Paul Birkeland

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Reply #3 on: May 04, 2018, 03:50:22 AM
The Smash will sound much, much better as a preamp than a Crack or Crack-a-two-a.  This is going to be measurable as less distortion, but it qualitatively more complicated than this since the Smash is a zero feedback design.

The 6F8G would work just fine in the Smash-up as the regulator tube.

Crack-a-two-a has the same gain as the Crack, but the combination volume/balance control has a few dB of insertion loss, so it ends up being a bit less.

The Crack-a-two-a, much like the Smash, can accept our attenuator upgrade.  This removes the low level tracking issues that some pots have. 

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man