DIY Airbrake...

Express, Liverpool, Rocket, Dirty Little Monster, etc.

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murky69nz
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Joined: Sun Sep 20, 2009 3:43 am

Re: DIY Airbrake...

Post by murky69nz »

I just bent mine back a bit so that it presses real tight against the casing when the nut is tightened. seems to be working ok.

What I can't work out is how to attach the base plate - no predrilled/threaded holes or anthings. How has everyone else done it?
Cliff Schecht
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Re: DIY Airbrake...

Post by Cliff Schecht »

For locking down the rheostat, you need to install a star washer and crank down the nut on top pretty tight. The star washer digs into the rheostat and the case and should immobilize it.
Cliff Schecht - Circuit P.I.
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danotron
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FYI on switch

Post by danotron »

Found a nice switch to use....expensive but good...I was woried about how robust the cheap switch is so I went with this:

Mouser Part #: 633-HS16-2SN-RO
The Blues is my Business....
and Business is good.....
MasterDisaster
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Joined: Sat Feb 06, 2010 3:54 am
Location: Stockholm/Sweden

Re: DIY Airbrake...

Post by MasterDisaster »

Pi updated with Impedance Matching.


I have added a Pi Attenuator and a L-PAD calculator in the files section so check them out.

Mike
jcruppe
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Airbrake ohms question?

Post by jcruppe »

THe Airbrake owners manual states the following. When using the Airbrake with older vintage amps, mismatching the load will be a safer way
to operate. This will eliminate any overheating of the output transformer. For example, a
Vox AC30 or vintage 100 watt Marshall should be run at 8 ohms through the Z Airbrake with
a 16 ohm speaker load.


I was thinking that if you set an amp at 8 ohms into a 16 ohm load that would cause the output transformer to work harder? I thought tat the other way around, 16 into 8 would work the tubes harder and ease up on the tranny?

What am I missing?

Thanks
MasterDisaster
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Location: Stockholm/Sweden

Re: DIY Airbrake...

Post by MasterDisaster »

By switching your amp to 8 Ohm you are actually decreasing the mismatch as the Airbrake will start at around 10 Ohm with a 16 Ohm load.
The load will then increase with attenuation to about
22 Ohm with a 150R Rheostat.

Ken Fischer quote:
"On these high powered British amps, due to their unique
transformer designs, when using a single 16 ohm cabinet I recommend setting the impedance selector
to 8 ohms when using the first two levels of attenuation."



Mike
sjturbo
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Joined: Mon Mar 22, 2010 12:38 am

Late to the Party

Post by sjturbo »

Very late to the party but I would much like a schematic and layout for the Airbrake! I intend to use with a MM112RD50. Please P.M. and I will send email.
Thanks much!
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M Fowler
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Location: Walcott ND

Re: DIY Airbrake...

Post by M Fowler »

sjturbo,

Did you read page 24 which as the schematic and final layout?
sjturbo
Posts: 14
Joined: Mon Mar 22, 2010 12:38 am

Re: DIY Airbrake...

Post by sjturbo »

Thanks M, I thought I had gone through all of them but I guess not. Thanks again!!
phase100
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Joined: Sun May 09, 2010 2:12 am

Layout/Schematic?

Post by phase100 »

May I get a copy?
Aaron Smith
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Location: Arlington, TN

Re: DIY Airbrake...

Post by Aaron Smith »

rosspix wrote: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.
I built mine last night. I did drill locating holes for the tab on the rheostat, and the pin on the rotary switch. It's easy to figure out where to put the hole for the rheostat tab; just stick the threaded shaft through your big shaft hole, press the tab against the metal and move it in a circle. The tab will score a line on the metal; use that line to center your hole. The pin on the rotary switch was a bit tougher to locate, but I just worked at it with the side of a drill bit until the switch pin fit. At any rate, both components are very stable.

So now the good news- the Airbrake works incredibly well. I've had it complete for 12 hours, and already I'm wondering how I've survived 20 years of playing tube amps without one. Even on the bedroom setting at the lowest volume, the tone is shockingly good. For the first three clicks, the tone is (to my ears) completely indistinguishable from the bypassed tone- just quieter. What an awesome tool!
timg
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Re: DIY Airbrake...

Post by timg »

Aaron Smith wrote: ....So now the good news- the Airbrake works incredibly well. I've had it complete for 12 hours, and already I'm wondering how I've survived 20 years of playing tube amps without one. Even on the bedroom setting at the lowest volume, the tone is shockingly good. For the first three clicks, the tone is (to my ears) completely indistinguishable from the bypassed tone- just quieter. What an awesome tool!

I would second that! I finished the one below a week or so ago and have compared it to a new HotPlate (with deep/bright switches) and an older one (no switches) and it humbles them both. I tried it on my Boogie MKIIB, a VHT Ultralead and a new express build, it is frightening how much better it sounds than the hotplate. I would also add that it was a very easy build, as I had never built anything electronic before... :D
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DR.Z
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Re: DIY Airbrake...

Post by DR.Z »

Nice job Tim on the Airbrake, but a couple of observations if I may.
First the grey wire off of the varable res. end , the one that feeds the pot
is touching the var. res. I might ty wrap that wire up with the purple and other grey to get them up out of the way of the HOT res.

Second the stand off feet need to be pushed in the body of the resistors more. They can come loose they way you have them mounted and they are very fragile and can crack. Pinch the open V end with a plier and then insert the the V in deeper. This will hold the res. more secure, but you'll need to redrill the mounting screws.

Z
timg
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Re: DIY Airbrake...

Post by timg »

DR.Z wrote:Nice job Tim on the Airbrake, but a couple of observations if I may.
First the grey wire off of the varable res. end , the one that feeds the pot
is touching the var. res. I might ty wrap that wire up with the purple and other grey to get them up out of the way of the HOT res.

Second the stand off feet need to be pushed in the body of the resistors more. They can come loose they way you have them mounted and they are very fragile and can crack. Pinch the open V end with a plier and then insert the the V in deeper. This will hold the res. more secure, but you'll need to redrill the mounting screws.

Z
Hi Dr. Z! Thank you for your kind words and for taking the time to look closely! It's very difficult to tell in the photo but that grey wire as well as the purple and other grey wire lay almost down on the bottom plate when the unit is right side up. I am hoping that will keep them down out of the "oven" without adding any concerns from the extra wire length. The resistor mount clips were a challenge, I toyed with the mounts for a couple hours and finally seemed to be able to control how tightly the resistor bodies were "locked" in by rotating the clips on the non-jack side to be angled about 20-30 degrees off of horizontal. This seems to pinch the resistor not only end to end but side to side as well. It also angles the hollow tube slightly up which I am hoping will create a bit of a convection airflow to aid in cooling. Although I must add that I ran it pretty hard tonight and it doesn't seem to get very hot at all! Again Dr Z thanks for taking the time to look at my "newbie" efforts! Tim Grace
timg
Posts: 17
Joined: Thu May 06, 2010 8:42 pm

Re: DIY Airbrake...

Post by timg »

DR.Z wrote:Nice job Tim on the Airbrake, but a couple of observations if I may.
First the grey wire off of the varable res. end , the one that feeds the pot
is touching the var. res. I might ty wrap that wire up with the purple and other grey to get them up out of the way of the HOT res.

Second the stand off feet need to be pushed in the body of the resistors more. They can come loose they way you have them mounted and they are very fragile and can crack. Pinch the open V end with a plier and then insert the the V in deeper. This will hold the res. more secure, but you'll need to redrill the mounting screws.

Z
Hi Dr. Z! Thank you for your kind words and for taking the time to look closely! It's very difficult to tell in the photo but that grey wire as well as the purple and other grey wire lay almost down on the bottom plate when the unit is right side up. I am hoping that will keep them down out of the "oven" without adding any concerns from the extra wire length. The resistor mount clips were a challenge, I toyed with the mounts for a couple hours and finally seemed to be able to control how tightly the resistor bodies were "locked" in by rotating the clips on the non-jack side to be angled about 20-30 degrees off of horizontal. This seems to pinch the resistor not only end to end but side to side as well. It also angles the hollow tube slightly up which I am hoping will create a bit of a convection airflow to aid in cooling. Although I must add that I ran it pretty hard tonight and it doesn't seem to get very hot at all! Again Dr Z thanks for taking the time to look at my "newbie" efforts! Tim Grace
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