DIY Airbrake...

[reverbus]

Readings are taken from empty input.
Speaker is connected to the output.
...as how amp see it.

[angelodp]

Sorry to be still confused by this. Do you mean the end that goes into the guitar?

[reverbus]

Output = here is speaker connected to the att.
Input = here is amp connected to the att. (output from amp - not during measuring)

No end goes into guitar.
Attenuator is placed (and connected) between speakers and amplifier.

[rooster]

Ange - Did my PM answer your question????

[angelodp]

Hey rooster, many thanks, my unit is up to snuff and i appreciate the help.

a

[brownie778]

Could someone please email me this info? (schematic and Layout)

Thanx

brownieqq3@hotmail.com

[JaimeGibson]

I would really like to have the schematic of the airbrake attenuator too please.

my jcm800 non-mastervolume is a beast.

please send it to jaimebongaarts@hotmail.com

Thanks a lot!!

[dobbhill]

http://ampgarage.com/forum/viewtopic.ph ... c&start=30

[madditch]

Does it mater if the switch is shorting or Non-shorting?

[MasterDisaster]

The switch in this layout is of the "shorting" or (Make-Before-Break) type.
If you use the "non shorting" (Break-Before-Make) type you might experience a pop when you switch attenuation levels.

From a technical standpoint a BBM switch would be more suitable for higher currents, but the jury might still be out on that as we have other concerns to take into account.

HIFI attenuators tend to be BBM but then we are talking about Line Level signals.

Mike

[madditch]

Where should the adjustable lug that is connected to the 8R 25W resistor(circled in red) be positioned? (Measured in ohms.)

[rawnster]

Where should the adjustable lug that is connected to the 8R 25W resistor(circled in red) be positioned? (Measured in ohms.)

12.5 ohms

[ettepostkonto]

Finally soldered it together today and first impression is - I'm impressed!

Sounds a lot better than the Weber MASS 50 I used to have - less sound degeneration, just a nice drop in volume. OK the extreme settings at bedroom level aren't that good - but that's not how I plan to use it.

Thanks everyone!

[murky69nz]

Hi All

The speced Rheostat (mouser RJS150E) seems to have the following specs:

- Ohms: 150 max
- Watts: 50
- RMS Voltage: 750v Max
- Current: .575A Max

And the Shunt(L100J25E):

- 100w
- 2845v
- 25 ohms


Q1: doesn't .575A max for the Rheostat seem a little low? What sort of current typically flows from a 50/100w head speaker out?

Q2: Why does P = V x I not seem to reconcile for the above Rheostat figures?

Q3: What's the max current rating for the Shunt? P=VI gives me .035A max. Again seems a little low?

Thanks
R

[rosspix]

Ok, silly question time...

I finally got round to looking at my box of parts to build my AB and had a quick play with the rheostat. I fastened it to the panel using a star washer and a couple of nuts, but the whole thing rotates when I turn the knob. If I hold the rheostat body in position, it's fine.

Have I got to drill a small "locating hole" for tab on the bottom washer, or screw the rheostat body down? From what I've seen, other builds don't appear to have done this.

Have I got a clunker, or am I missing something *incredibly* simple? I've replaced plenty of (admittedly, smaller) pots on guitars in the past but have never had this problem before...

Cheers,


Ross.