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May 24, 2019, 12:21:30 pm

Recent Posts

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Crack / Re: High Voltage on T2, T4, T9 & Generally Voltages on the High Side
« Last post by Deke609 on Yesterday at 01:01:57 pm »
I once got similar voltage readings from my mains power and it turned out to be a problem of weak batteries in my meter. With fresh batteries, voltages dropped to around 120 VAC.  So check your batteries!
Crack / Re: High Voltage on T2, T4, T9 & Generally Voltages on the High Side
« Last post by mr_wilton on Yesterday at 12:09:31 pm »

Thanks! Time is my only issue with having to go to classes.
With NEETS, did you mean the "Navy Electricity and Electronics Training Series"?

Do you/Bottlehead run workshops, etc?

Thanks again!

If you're an ME, an easy-ish option is to do a few community college classes.  Lots of folks recommend the NEETS course that you can just download online for free.
Crack / Re: High Voltage on T2, T4, T9 & Generally Voltages on the High Side
« Last post by mr_wilton on Yesterday at 11:58:32 am »
Hello Paul,

Thank you for the super quick reply!!!
You are awesome!

Woah, ok! Thanks for the heads-up. It did seem high to me too, but I simply thought, well, that's what it is.
I'll get a line voltage checker and measure the rest of my house and then report to the power company.
We did have an LED ceiling light fail on us after moving in, but I thought it was faulty, but now ... who knows, maybe the high line voltage.

Thanks for the power transformer recommendation. The Hammond 168B indeed seems reasonable in price and I can build my own little power box for the Crack and my DAC.

Great, thanks for the confirmation that the Crack will work/I didn't screw it up. I was worried.

May I ask if you have any recommendations on some reading material, etc to get into some electronics understanding? I am a mechanical engineer and as the majority of us, mechanical engineers and electronics is almost like oil and water; it's almost a mystery to me, but I'd like to learn.

Thank you again!

Hello Wilton,

I would strongly suggest calling your power company and reporting your line voltage.  That is way, way too high and can cause issues with many appliances you would otherwise expect to be totally reliable (incandescent light bulbs will also be very short lived).

If your power company ignores you, I would suggest getting a 120:110 step-down transformer around 200VA and using it to reduce the line voltage going into your Crack.  A Hammond 168B could be used to accomplish this without spending a whole ton of money.  If you have more components in your system, it would probably be worth going with a bigger transformer/autoformer to put between your components and the wall.


PS - as far as the Crack goes, yes, you're going to have high voltages.  Your tubes will have moderately diminished lifetimes, but otherwise the kit should still work just fine.
Hello all,

Like many here, I've just finished assembling and soldering my Crack Amp (Stock).
During the voltage check, I noticed a few voltages outside the tolerance as written in the manual. See values below.

But first, my Powerline Voltage Test gave me a voltage of 134-137V AC, so I configured my transformer per page 25 "Voltage greater than 115V AC and less than 130V AC", since, well no other option.
I am using the Crack 1.1 Manual (09-20-16) and I am located in Los Angeles, California.
I am also using the BH Power Cord Kit.

All resistances are within tolerance per page 47.

Both halves of each tube (6080 and 12AU7) glow during glow test and both LEDs light up.

T1 - 99V
T2 - 213V (outside 10% of 170V requirement, i.e. 187V)
T3 - 0V
T4 - 213V (outside 10% of 170V requirement, i.e. 187V)
T5 - 103V (within 10% of 100V requirement, i.e. 110V)

T6 - 0V
T7 - 125V (barely within 10% of 115V requirement, i.e. 126.5V)
T8 - 0V
T9 - 130V (outside 10% of 115V requirement, i.e. 126.5V)
T10 - 0V

I've seen the following 2 threads, but it wasn't quite like my readings.

Thank you in advance!

Crack / Re: Crack w/ only small PCB Speedball upgrade
« Last post by Paul Birkeland on Yesterday at 10:47:59 am »
My specialty has never been explaining other people's preferences. 

It's easy enough to swap the big board and 3K resistors to make your own observations, then you can let us know what you think.

Crack / Re: Crack w/ only small PCB Speedball upgrade
« Last post by Crackawaka on Yesterday at 09:37:15 am »
I too would like to know. I plan on building the speedball upgrade over the weekend and noticed this in the speedball upgrade manual as well (and also wondered what the difference is sonically).

Based on what Paul B. wrote above, I’m guessing it means the signal gets a bit “cleaner”?
Crack / Re: Crack w/ only small PCB Speedball upgrade
« Last post by ncsMD on Yesterday at 08:39:18 am »
The large PCB provides a high impedance load for the cathode follower output stage.  When using the amp with this board, nearly all the AC current available from the 6080 is delivered to the load, while this is not really the case with the 3K loading resistors.

Can you explain why I would prefer this sound over the stock crack and the stock crack + speedball upgrade? Does it represent some middle ground between the tubey warmth of the stock vs the fast speed of the speedball upgrade?
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