The Amp Garage

I am not sure I see those on RJ’s layout either?
I am using his ‘Rockster Reverb - Rev 3.5 - Feb 4, 2012’ layout.

I am having some difficulty understanding what you mean exactly Mark. This is 100% because of my inexperience in amp-building, I am sure of that. Might also be of slight changes I made to RJ’s layout myself (and there could be important mistakes in that). Would you mind elaborating a little more (on...

Thanks Mark. I will check that out.

Have been working on the amp today. I figured it was finally time to hook up the reverb tank, and to wire up the mids control the right way. I did find a problem though, and I hope someone here could put me on the right track: When I turn up the reverb, a ticking/popping sound appears. It is a very ...

Finally my Rockster Reverb is alive! This took me a loooooong time to finish. For a number of reasons this project stood 95% finished on my workbench for a couple of years. This weekend at last I found the time and motiviation to complete it. And I must say, I was not disappointed! First of all, it ...

Yes, that's the exact same thing I noticed: Resistors get considerably hotter than with the regular Airbrake design. I haven't played through the modified design longer than 30 min at a time. It didn't give any problems at that. I agree: be extra careful not to overpower the resistors. This is proba...

Got back from my holiday yesterday, so I thought I would put the 4 Ohm Airbrake together today. No problems with that, takes just a little more effort than a regular Airbrake to build. Just check everything with your digital multimeter to be certain you connected everything the right way. It sounds ...

I have all the parts, but no opportunity to solder for 1 or 2 weeks. Gonna take some time, but I'll keep you posted.

Yes we have. The total impedances I mentioned are what the amp "sees" with the attenuator and cab connected. By using a combination of a series and a shunt resistor it is possible to keep that load quite constant.

Another update: I discovered that Mouser doesn't sell Ohmite wirewound power resistors, adjustable lug and 100W at values of 15 Ohm. They do have 10 Ohm resistors (as Peesinstew already mentioned). It wasn't to much of an effort to make the calculations for the 10 Ohm resistors though. The total imp...

Just a progress-report. I discovered that the Duncan load calculator that Peesinstew suggested not only calculates the total impedance, but it also calculates the power going through each speaker (or in this case one speaker and two resistors) for you. If I then take the method Mark mentioned for ca...

Thanks again Mark. I figured it would have something to do with good old Ohm's law, but I didn't know how to convert to dB. I want to try to use some of your ideas to adapt the Airbrake to a more constant load and convert it from a 8 Ohm to a 4 Ohm device. Before I order my power resistors I'll chec...

I did know about R.G.'s website from my effects building days, but I didn't know he talked about tube amp stuff to this extent. This is great stuff and answers a lot of my questions. Nice detail: On the Komet website their version of the Airbrake is described as being built exactly according to KF's...

I guess even the EE types are at a loss with this one?

No ideas about how to calculate the level of attenuation when the used resistor values are known?