Voltage limit to Speedball (C4S)?

[Sonido]

I finally got around to installing the Speedball to my Crack. I read more about what it is exactly and looked up more info on the C4S. A website mentioned that if too much voltage is put through it, it will smoke. Obviously, not wanting this to ever happen, I was wondering is this limit easy to reach? I'm also using the Quickie as a preamp to my Crack. Are there any warnings to doing this relating to the input voltage from the Quickie now that I have the Speedball installed? Should I not turn the Quickie up too much?

[Grainger49]

The voltage mentioned refers to the incoming B+ (high voltage for the tube plate).  The input voltage is inconsequential in relation to that.

You noticed that the big transistors on the big board were different than on the little boards.  Not to mention the substantial heat sinks on them.  These produce more heat than the others and are therefore heatsinked to allow for the additional heat being put off by the larger transistors.

If you were to use Speedball in another amplifier you could run into a problem of too high a voltage.  Bottlehead knows this design is substantially robust for their application.

[mcandmar]

As Grainer says there are two different issues here,

The C4S takes power from the main power supply rail (B+) and regulates it before feeding the tubes, your not going to change those voltage levels unless you do something drastic with the power supply design so that's a non issue.   Any elecy circuit will release the magic smoke if too much voltage is put through it, but i don't know where that comment came from in relation to the C4S, your never going to harm it unless you try to, or accidentally short something out during installation.

Its possible input voltage may be too high with a quickie installed and the volume turned up 100%, however its not going to harm anything, only thing that will happen is the sound will become distorted.  I just happened to be playing with mine last night and found anything over 3/4" volume on the quickie was distorting the signal however my battery's aren't that fresh which may have something to do with that.

[Sonido]

Thanks guys. I noticed the distortion as well when turning up the Quickie all the way, so I just set the Crack to 12 o'clock and the Quickie to 9 or 10 o'clock. I found that the Crack even with Quickie in chain is pretty silent. No audible hum until past 12 o'clock on the Crack, and even maxed, the hum is very slight. I'm wondering if adding the PJCCS upgrade will create any noise problems with the Crack. I know the output impedance of that Quickie gets doubled with that upgrade from 2K to 4K ohms. Anyone know if this will cause a noise issue with the Crack? What's the input impedance of the Crack exactly?

[JamieMcC]

Hi, I don't suppose you would mind sharing some details on how the Crack sounds with the Quickie added to the chain?

[Sonido]

Hi, I don't suppose you would mind sharing some details on how the Crack sounds with the Quickie added to the chain?

Impressions with HD800: https://www.head-fi.org/t/650510/the-new-hd800-appreciation-thread/7500#post_10166679

[Sonido]

Thanks guys. I noticed the distortion as well when turning up the Quickie all the way, so I just set the Crack to 12 o'clock and the Quickie to 9 or 10 o'clock. I found that the Crack even with Quickie in chain is pretty silent. No audible hum until past 12 o'clock on the Crack, and even maxed, the hum is very slight. I'm wondering if adding the PJCCS upgrade will create any noise problems with the Crack. I know the output impedance of that Quickie gets doubled with that upgrade from 2K to 4K ohms. Anyone know if this will cause a noise issue with the Crack? What's the input impedance of the Crack exactly?

Ok I found the answer to my own question. Somehow I didn't see it earlier on the Crack main page:

"The approximate specs are input impedance 100K ohms, output impedance 120 ohms, gain about 15dB into a 300 ohm load like a Sennheiser HD600, max output about 10V into a 300 ohm load."

So this pretty much greenlights adding the PJCCS to my Quickie for use with Crack. Only concern is use with my Emotiva MiniX which has only 10K ohm input impedance. I guess at worst, I'd just have to buy another Quickie. 

[Sonido]

So two hours later and I have completed adding on the PJCCS upgrade to the Quickie. Once again, Bottlehead doesn't cease to amaze.

First thing before even playing any music, I had to address my concerns on the noise floor and gain staging. Before without PJCCS, the Crack would be dead silent up to 12 o'clock, and even at max (4 o'clock) the background noise wasn't as bad as say the Emotiva. With the PJCCS, the silent noise level has been pulled back to 9 o'clock on Crack, and after 12 o'clock it gets quite noticeable. This makes sense that the max silent position got cut in half (6 o'clock is zero volume) since the PJCCS doubled the output impedance of the Quickie. As expected as well, the volume level of the Quickie remains the same with the Crack pulled down to 9 o'clock from 12 o'clock.

As for sound, the most apparent thing was the bass. There is just simply more bass! The bass has better impact and more body. As for anything else, I haven't really picked up anything as apparent, and having to compare by memory with stock Quickie, it's not as easy to pick out minor differences.

The other difference I believe I'm hearing now is more transparency and clarity. The Quickie can congest the sound a bit at times when a lot of stuff is going on, but less so now with PJCCS.

So the verdict: Quickie with PJCCS synergizes well with Crack. Imo for around the same price, this is a better upgrade to Crack than Speedball. Speedball improves technicalities more, but the Quickie affects the sound signature more, and works very well with my HD800, and makes it more euphonic and enjoyable. But why not have both? Quickie with PJCCS + Crack with Speedball + HD800 = <3