Airbrake attenuator done/readings needed

[garfo]

I'm building my Trainwreck attenuator.I haven't tested yet since I broke the rottary switch and now I'm in doubt about the type of switch to reorder.
I made my shopping on Mouser but to order only a switch is very expensive(20€ just for transportation).Now my doubt is, does it matter if the switch is "make before break" or "normal"; I know it should be 2 x 6.
On Banzai I saw one that is 1x2x6;it looks very tough and sturdy. Will this one do the trick, or does it have to be 2x6???
Here's the link http://www.banzaimusic.com/Rotary-Switch-1-level-1x2x6.html
(For anyone else building this project make sure that the big open resistor isn't in contact with the chassis, that will change the resistance of the resistor.)

[Guitarmageddon]

Those plastic switches are very easy to break.
That's the same switch I used when I built mine. If it means what t says, "MBB" would be better so the amp always sees a load.
Mine works great!

[alanp]

Test your resistances for the taps on the bottom power resistor with your DMM. There have been reports in the past that people have needed to lightly sand some lacquer off the exposed windings, so it'd pay to check now.

[garfo]

Test your resistances for the taps on the bottom power resistor with your DMM. There have been reports in the past that people have needed to lightly sand some lacquer off the exposed windings, so it'd pay to check now.

Yes, that's done.I was having some trouble with the readings after mounting everything and realized that the outer pins were in contact with the box and was reading 6 ohms everywhere through the resistor.I fixed it isolating it from the box with tape.

[ch1naski]

Nevermind all that....you have Trainwreck?

Sent from my SPH-L710 using Tapatalk 4

[garfo]

The amplifier I have is a Bugera 50 watts(v55).
I've replaced the switch and did three different wirings that were given to me by a ampgarage member.I used Fuinal C, Final C 140 and the standard wiring diagram.The result appears to be the same.
I also took some readings:
(The reading for position 1 is very weird, there is no attenuation compared to Position 0.)

I connected one probe to input jack and another probe to output jack.
Position 0= 00.6 ohms
Position 1= 00.6 ohms
Position 2= 07.4 ohms
Position 3= 13.0 ohms
Position 4= 18.1 ohms
Bedroom Level at zero = 24.1 ohms
Bedroom Level full = 174 ohms

Anyone here who can take the readings and see if this is normal!?

[Guitarmageddon]

Well these are not particularly usefull for you because my airbrake is a different design to yours, I built the one without the rheostat for bedroom level. Bear in mind the position of the adjustable taps will effect things from build to build too.
I'm pretty sure I've seen a graph of measurements over at Ampgarage. Someone suggested using the 16ohm tap for half the attenuation steps because it better matched the load.
Anyway, here's how mine measures (without a cab):
0
22.3ohm
24.1
12.1
18.1
24.2 (most attenuated)
Here's my attenuator, not as pretty as yours.



Here's my Wreck.

[ch1naski]

Sorry for an ot question, but is that an Ken-built  amp?

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[Guitarmageddon]

Hell no, Ben-built!

[alanp]

That's a C'tone faceplate, I'm guessing C'tone kit?

Gah... been thinking about getting something Wreck-ish for awhile, either Liverpool, Rocket, or Express.

[Guitarmageddon]

Ceriatone Express(ion)
Possibly the most un-effect pedal friendly amp you can own   but so awesome I don't mind.
I guess the attenuator counts as an effect, and you sure need it, it's unbelievably loud.
Sorry about the de-rail garfo, I see you've asked at the AG, likely there'll be a reply more usefull than me over there.

[alanp]

Er... apologies from me as well  (Leaning towards a C'tone TW Rocket -- heard it's quite pedal-friendly...)

[ch1naski]

I was going to grab a ceriatone before I bought my Tone King.....now my kid has hijacked it so I'm stuck without.
Apologies also for the thread hijack

Curt.

[garfo]

Regarding the loading match, I did read somewhere that there were different ways to do that.I remember someone suggesting that if your amp is running a 16ohm cab and it's switched for 16 ohms on the amp itself, if it was set to 8ohms even when running through a 16 ohm cab and through the attenuator it would better match the load.WOuld this be correct"?
And, if so, my cab is 8 ohm, should I turn the amp to the 4ohm position when using the airbrake?

Well these are not particularly usefull for you because my airbrake is a different design to yours, I built the one without the rheostat for bedroom level. Bear in mind the position of the adjustable taps will effect things from build to build too.
I'm pretty sure I've seen a graph of measurements over at Ampgarage. Someone suggested using the 16ohm tap for half the attenuation steps because it better matched the load.
Anyway, here's how mine measures (without a cab):
0
22.3ohm
24.1
12.1
18.1
24.2 (most attenuated)
Here's my attenuator, not as pretty as yours.



Here's my Wreck.

[Guitarmageddon]

Those numbers I posted have been bugging me, so I've been thinking about this and re-measured.
Here's what I know.
Matching loads can effect power and tone, but what is most important is that done wrong it can kill a transformer.
My box has 2x12 8ohms in series for 16ohms. If I measure that with my DMM set to ohms it reads 23ohms. That doesn't bother me because I know my meter can't really do this well and the measurement is frequency dependent. Besides, Celestion have been building them for years, it says 8 on the back, two in series = 16, how could they be wrong? 
Then I connect the speakers and attenuator and measure, 23 ohms with no attenuation. Cool, now the readings (from least to most attenuated) are:
22.5
11.7
11.6
8.5
9.6
9.7
...so I set my amp to 8 ohm.
I know amp on 8 will handle an 8ohm or more load safely, so any of those settings will be cool
.
IIRC, at AG, someone had measured the settings and thought that three were closest to 16ohm+ range and the others closest the 8ohm, and elected to adjust the amp accordingly. Seems reasonable to me.
Interestingly, I've preferred the third most attenuated setting, it's tonally not perceptible but still significantly quieter. I now see it's also the setting with the closest match to the amp output.
If I were to use the smallest attn., 22.5 ohm, I'd probably use the 16ohm setting.
I would suggest measuring your speaker, then with the attenuator connected. See what you get. If it's 8 or more, the 8 ohm setting should be fine. Get any sixes or sevens, I'd go with 4ohm.