DIY Airbrake...

[benoit]

Well, this has been a long enduring thread and there ought to be a bunch of airbrakes out there. I'm curious what people think of them??

I've been attempting to get bedroom volume and big league tone for a few years now and I'm just about to convince myself that it's not gonna happen... not to say I haven't got some cool tones at reasonable volume, just seems my ears tell me that two watts cranked isn't a scale model of 50 watts cranked.

When I get the airbrake to squeeze down a Fender Deluxe, it seems sorta buzzy and not all that cool... as I back off the brake, the tone just seems to get better as the volume gets louder.

Anyone else have a similar experience?

Do you think it works better on some circuits than others?

rj

Keep in mind that no matter how transparent the attenuator, the fact remains that people hear differently at different SPL. Perhaps you're already familiar with the research of Fletcher/Munson, which shows that the frequency response of our hearing is very different depending on how loud the sound source is. Also, the power rating of your speaker(s) in relation to the power the amp is putting out (or rather the power the speaker sees due to the attenuator) definitely could affect the difference in tone: for example, a speaker that is rated at 30 watts being driven by a 30 watt amp cranked is going to sound way different than that same amp cranked but also attenuated because you're not pushing the speaker nearly as close to its limit.

Hope this helps. Correct me if I'm wrong on any of this.

Ben

[kec]

Hey guys! First time post on this fantastic site

I didn't see this mentioned, but there is sound clip of the Airbrake in action from the Kometamps site: http://www.kometamps.com/sounds/demoalex8.mp3

[tweedeluxe]

Well, this has been a long enduring thread and there ought to be a bunch of airbrakes out there. I'm curious what people think of them??

I've been attempting to get bedroom volume and big league tone for a few years now and I'm just about to convince myself that it's not gonna happen... not to say I haven't got some cool tones at reasonable volume, just seems my ears tell me that two watts cranked isn't a scale model of 50 watts cranked.

When I get the airbrake to squeeze down a Fender Deluxe, it seems sorta buzzy and not all that cool... as I back off the brake, the tone just seems to get better as the volume gets louder.

Anyone else have a similar experience?

Do you think it works better on some circuits than others?

rj

RJ,

I am very curious to know if it reacts differently to higher/lower gain amps too. With my 2 Tweed amps (all I own right now), it starts to buzz only at extreme attenuation levels - with the rheostat almost all the way down. Does is start buzzing earlier than that on high gain amps?

As far as transparency goes, speakers seem to play a big role, in my experience. With a 150W rated 15" 102+db efficiency speaker, which REALLY boosts the headroom on my Tweeds, the Airbrake seems very transparent. My amps sound just like my amps, only quieter, which I assume is because the speaker isn't compressing to begin with.

The other speaker I use with these amps is a Blue - which brings the headroom way down but sounds so sweet. However, the Airbrake makes that speaker sound thin and lifeless to me, because it doesn't let the Blue compress the way it normally does.

That's my understanding of it, at least. Maybe the reason it seems to suck your tone with the Deluxe is because it doesn't allow your speaker(s) to break up.

As an experiment, I tried the Airbrake last Friday with my 5E3 and the big clean 15". We keep our stage volume very low and mic the cabs - so the 15" is usually too much, even with a 15w amp. With the brake set 4 clicks down and the amp turned up, I was getting some really great tones, with no perceived "suckage."

Hope that helps.

[RJ Guitars]

Well you guys are speaking directly to my question and I am greatly appreciative... The Fletcher/Munson stuff is great and I think goes a long way toward explaining my inclination that I'll never get my major league tone at dinner conversation volume... that is to say that my ears are playing tricks on me and I wouldn't necessarily recognize an exact scaled down tone if I had it... I really think that is a great topic for a thread all to itself

Having said that, it seems that many airbrake (and other attenuator) users are getting some great scaled down sounds. I've only tried my brake through a couple amps since I finished it. One of them was noticeably more pleasing than the other (a low wattage push/pull triode output amp). My Deluxe circuit sounds much like the one "TWEEDELUXE" describes with the blue speaker.

I'm going to try Glens suggestion and lift one end of the orange drop bypass cap and see what happens at lower levels.

In the end I think mine works really well at knocking the sound down a notch or two, it isn't as good at notch three and kinda falls apart when I get into that bedroom volume regime.

Again, I'm really pleased to hear the comments and learn from all you guys.

rj

[benoit]

Incidentally I listened to a great sounding deluxe today. Limited run red tolex, 2 channel w/ reverb. Very tasty. Had a v30 in it. It was a little boomy but that probably had a lot more to do with the tiny music shop amp-testing room than anything else.

[JimiB]

Anybody built this without the rheostat? I echo the sentiment that they are usefull for 2-4 clicks down but past that I should probably be using a different amp!

[kec]

Anybody built this without the rheostat? I echo the sentiment that they are usefull for 2-4 clicks down but past that I should probably be using a different amp!

I'm in the process of building one without the rheostat, since I use lower wattage SE amps, I don't need the extreme attenuation. I will add an extra tab on the variable resistor in place of the rheostat.

[rhubarb9999]

I built mine without the rheostat. It works great. Things get really fizzy on that last click anyway (with my Komet 60 clone). I can't imagine the rheostat making things any better.

I actually really like the sound through the brake 2-3 clicks down from wide open. It loses some of that 'in your face' Komet tone .. but sounds more like a recorded amp.

[dave g]

Can I get a copy of the schemo/layout as well? Thanks in advance!

received - thanks!

[poipounder57]

Hi everyone...I just finished my Airbrake and I have a couple of questions. Sorry if the questions are kinda at the first grade level (Newbie)
I tested the lugs...first from the right reading 1-5.0 ohms, 2-10.0 ohms and 3-15 ohms. Should they be exactly like the diagram?
Second question...What is the functions of the Rheostat and Lorlin switch?
And one more question please...is there a way for me to test it before I try it out?
Thanks!!!

Aloha

[poipounder57]

Thanks!!!

[kec]

Hi everyone...I just finished my Airbrake and I have a couple of questions. Sorry if the questions are kinda at the first grade level (Newbie)
I tested the lugs...first from the right reading 1-5.0 ohms, 2-10.0 ohms and 3-15 ohms. Should they be exactly like the diagram?
Second question...What is the functions of the Rheostat and Lorlin switch?
And one more question please...is there a way for me to test it before I try it out?
Thanks!!!

Aloha

Poi,

The resistance doesn't have to be exact - you can tweak it to whatever you want. I think the values were calculated for 3db attenuation on the first step and 1.8db for each step after - according to the Guitar Player review (see attached).

The rheostat is used when the switch is in the "bedroom" mode, or position 1 on the schematic. Then you can attenuate even further with the rheostat.

Use an ohm meter and check the resistance between the input and output at each step. Resistance should go up as you increase attenuation.

[RJ Guitars]

I agree with Poi...

I made a couple "extra features" that basically allow me to keep my total output impedance right on or extremely near 8 ohms at all the settings...

Now that it's done - it's an insignificant factor to the best of my ability to hear any difference.

I'd even go as far as to say, choose three places that give you three nice steps in volume and don't worry if they turn out to be 6, 12, and 16 ohms, or whatever the schemo calls for.

My 2 cents,

rj

[poipounder57]

Thanks guys for all the help!!! It was a fun project...once I started didn't quit till it was finished. I'm reading up on basic electronics...My next project will be a amp
I plugged the Airbrake into a 8 ohm cab. Bedroom level wide open on the rheostat switch I got a 14 ohm reading and a 22 ohm at it's lowest position. Highest position on the Lorlin my reading was 8 ohms.
I tried it out and nothing blew up It was nice a quite in all the position and it didn't color up the tone. And it works!!! Plus by building it myself I save a few $$$'s!!!
The Amp Garage is a great place to hang out!!! It's giving me a new kinda G.A.S...and I thought I was cured
Thanks again everyone for all the help!!!

Aloha

[thom_rees]

Can I get a copy of the layout please