Dr. Z - Air Brake

Tube or solid-state, this section goes to eleven!

Dr. Z - Air Brake

Postby vanessa » 02 Apr 2008, 01:17

vanessa
Cap Cooler
 
Posts: 468
Joined: 08 Jul 2007, 18:51
Has thanked: 0 time
Have thanks: 10 times

Re: Dr. Z - Air Brake

Postby tlpruitt » 04 Apr 2008, 20:45

Nice.

Thanks Vanessa!

-Tim
tlpruitt
 
Posts: 23
Joined: 30 Oct 2007, 18:56
Has thanked: 1 time
Have thanks: 0 time

Re: Dr. Z - Air Brake

Postby DWBH » 04 Apr 2008, 23:37

This one was on a website that was floating around somewhere in this forum....
DWBH
Cap Cooler
 
Posts: 505
Joined: 24 Aug 2007, 17:26
Location: portugal
Has thanked: 14 times
Have thanks: 4 times

Re: Dr. Z - Air Brake

Postby guyg » 05 Apr 2008, 00:47

guyg
 
Posts: 29
Joined: 26 Jul 2007, 16:46
Has thanked: 0 time
Have thanks: 0 time

Re: Dr. Z - Air Brake

Postby AL » 08 Apr 2008, 18:02

Hey thanks !! 8)

AL
AL
Breadboard Brother
 
Posts: 146
Joined: 14 Aug 2007, 18:26
Has thanked: 0 time
Have thanks: 0 time

Re: Dr. Z - Air Brake

Postby AL » 09 Apr 2008, 13:11

I'm curious how to mount those big resistors. What is everyone using for this?

Thanks

AL
AL
Breadboard Brother
 
Posts: 146
Joined: 14 Aug 2007, 18:26
Has thanked: 0 time
Have thanks: 0 time

Re: Dr. Z - Air Brake

Postby madditch » 09 Apr 2008, 13:47

I believe those resistors have an L-bracket attached to each end, at least the ones in my Dr Z air break do.
madditch
 
Posts: 9
Joined: 04 Apr 2008, 22:08
Has thanked: 0 time
Have thanks: 0 time

Re: Dr. Z - Air Brake

Postby AL » 09 Apr 2008, 18:25

So they just bolt to the chassis?

AL
AL
Breadboard Brother
 
Posts: 146
Joined: 14 Aug 2007, 18:26
Has thanked: 0 time
Have thanks: 0 time

Re: Dr. Z - Air Brake

Postby beerbunny » 09 Apr 2008, 18:37

FWIW, here's the schematic. I can't remember where I got it from.

John
You do not have the required permissions to view the files attached to this post.

For this message the author beerbunny has received thanks:
grind (30 Jan 2016, 22:23)
beerbunny
 
Posts: 2
Joined: 04 Mar 2008, 13:05
Has thanked: 0 time
Have thanks: 1 time

Re: Dr. Z - Air Brake

Postby vanessa » 09 Apr 2008, 18:58

Thanks John!
vanessa
Cap Cooler
 
Posts: 468
Joined: 08 Jul 2007, 18:51
Has thanked: 0 time
Have thanks: 10 times

Re: Dr. Z - Air Brake

Postby JiM » 09 Apr 2008, 20:11

By the way, there is a guts picture right in the official manual !
http://www.drzamps.com/manuals/Airbrake.pdf
User avatar
JiM
Diode Debunker
 
Posts: 908
Joined: 11 Mar 2008, 23:56
Location: France
Has thanked: 30 times
Have thanks: 37 times

Re: Dr. Z - Air Brake

Postby noelgrassy » 10 Apr 2008, 04:22

madditch wrote:I believe those resistors have an L-bracket attached to each end, at least the ones in my Dr Z air break do.



Yep, and when you order these resistors you must order 2 per wirewound resistor of these brackets 'cause they're
not included.
I eliminated the large rheostat on my build. For one it's something I could add later if I needed it. Second,
the folks who generated that first layout remarked that the tone changes at "bedroom" level were unacceptable.

madditch, do you find this to be so with your Trainwreck approved Airbrake?
Copyright does not protect facts, ideas, systems, or methods of operation, although it may protect the way these things are expressed. US Copyright Office
User avatar
noelgrassy
Resistor Ronker
 
Posts: 388
Joined: 28 Nov 2007, 03:43
Location: Vacuum Tube Valley, Cali
Has thanked: 11 times
Have thanks: 3 times

Re: Dr. Z - Air Brake

Postby soulsonic » 10 Apr 2008, 05:34

All I can say is that it sure doesn't even begin to match impedances with the amp - if it's turned down all the way with a 16 ohm cab, the amp is seeing around 22ohms; with an 8 ohm cab it's still around 22 ohms... With the bedroom level set to 50%, it about 20 ohms with an 8 ohm cab, etc, etc... Any time you start messing with impedance mismatches like that it's bound to change the sound. Unfortunately, nearly all the commercial attenuators out there do it from one degree to another.
User avatar
soulsonic
Old Solderhand
 
Posts: 3530
Joined: 27 Jun 2007, 04:38
Location: Buffalo, NY
Has thanked: 56 times
Have thanks: 268 times

Re: Dr. Z - Air Brake

Postby noelgrassy » 10 Apr 2008, 08:07

When I finished building the Airbrake, I found I was happier with this old-as-hell Altair with
pre-Flinstonian components. It doesn't fidjit with the tone to my ears.

Factory docs indicate a max of 6.6 L at any setting. Where does one measure the actual impedance
on an attenuator? Is this measured out of circuit? I meant, with the attenuator not driving a load.


That would involve reflected L's and equashums I'd bet.

I suppose that's math I've never performed before. :oops:
You do not have the required permissions to view the files attached to this post.
Copyright does not protect facts, ideas, systems, or methods of operation, although it may protect the way these things are expressed. US Copyright Office
User avatar
noelgrassy
Resistor Ronker
 
Posts: 388
Joined: 28 Nov 2007, 03:43
Location: Vacuum Tube Valley, Cali
Has thanked: 11 times
Have thanks: 3 times

Re: Dr. Z - Air Brake

Postby soulsonic » 10 Apr 2008, 08:56

I always take the speaker into account when I calculate it because it's part of the complete circuit, and the amp definitely sees it when the thing is in use. To keep it simple, I just treat the speaker like a resistor and calculate the straight resistance of the whole circuit. Without knowing the actual values of the reactive elements of the other components, it isn't really possible to calculate the AC impedance of the circuit. The surest way to measure it would be to send signals through it at various frequencies and measure what comes up. I'm content with just dealing with the resistance because it will definitely let you know if you're in the ballpark. In my mind, the ideal attenuator would be purely resistive anyway, so that there wouldn't be any reactive components to interfere with the sound or kick bad mojo back at the amplifier. The speaker is reactive enough on its own - it really doesn't need any more added to it by a clunky attenuator. My opinion of course, but I say this after having played with reactive attenuators alot and not being too happy with the results.

I'd really like to see more of that Altair. I've never even heard of one before. I love studying attenuators.
User avatar
soulsonic
Old Solderhand
 
Posts: 3530
Joined: 27 Jun 2007, 04:38
Location: Buffalo, NY
Has thanked: 56 times
Have thanks: 268 times

Re: Dr. Z - Air Brake

Postby noelgrassy » 10 Apr 2008, 11:22

soulsonic, Sir, we can put your call through nowImage



This is a cleaner version of mine;

Image
Image
Image
Image

I'll get some gut shots of mine for you.
Some of the resistors resemble the heating element in a hair dryer.
Copyright does not protect facts, ideas, systems, or methods of operation, although it may protect the way these things are expressed. US Copyright Office
User avatar
noelgrassy
Resistor Ronker
 
Posts: 388
Joined: 28 Nov 2007, 03:43
Location: Vacuum Tube Valley, Cali
Has thanked: 11 times
Have thanks: 3 times

Re: Dr. Z - Air Brake

Postby bacaruda » 15 Apr 2008, 18:19

I love my DIY Airbrake - use it all the time. The sound man is always telling me my 5E3 is too loud (HA!), so I usually dial in my tone with the Airbrake set 2 clicks down, then I have some room to increase my stage volume during the set without affecting my base tone too much. According to Ken Fischer, this was what the Aribrake was designed it for. It's not great for bedroom level attenuation (like any really are), but it's very transparent until the bedroom level is engaged.

Here's mine:
Image

And here is a excellent graph Randall Aiken plotted showing the actual impedance of the Airbrake with various setups. :hmmm:
Image
bacaruda
Breadboard Brother
 
Posts: 68
Joined: 25 Aug 2007, 00:03
Location: USA
Has thanked: 0 time
Have thanks: 1 time

Re: Dr. Z - Air Brake

Postby JHS » 16 Apr 2008, 08:26

The Atair and the Rockman Power Soak are attenuators from the '70th. Soundwise, if uses with tubeamps, are both plain crap like any attenuator working with big wattage Rs. Even on the 4db level the tone sucks with a tubeamp 'cos there's no feedback/reactance from the speaker(s) anymore. The sound is stiff and liveless, similar to a trannie amp.

Soundwise a lot better are the attenuators from Palmer and VHT.

IMHO the best sounding attenuaters for tube amps are from GT and Marshall. The Marshall Power Break is a bit different due to a tapped transformer in the output but as good as the others, but none of them sacrifice the sound of a tubeamp.

JHS
JHS
Cap Cooler
 
Posts: 484
Joined: 14 Jul 2007, 12:20
Has thanked: 0 time
Have thanks: 3 times

Re: Dr. Z - Air Brake

Postby bouipoz » 29 Apr 2008, 08:30

very good idiagrams but doesnt specify the caps, knobs or brackets for the power resistors. I think i found some appropriate ones on mouser.com -the brakets are on the same catalogue page as the resistors and the theres loads of control knobs although it did take a while to find as mouser is BIG. Ill post product numbers when i can find them.
bouipoz
 
Posts: 3
Joined: 27 Apr 2008, 19:01
Has thanked: 0 time
Have thanks: 0 time

Re: Dr. Z - Air Brake

Postby dai h. » 29 Apr 2008, 09:19

JHS wrote:Soundwise a lot better are the attenuators from Palmer and VHT.


I think you meant to say THD(?)

p.s. Have you heard the Palmer attenuator ("The Sponge")? Seems they were pretty rare.
dai h.
Solder Soldier
 
Posts: 242
Joined: 24 Nov 2007, 19:42
Has thanked: 42 times
Have thanks: 11 times

Next

Return to Amplifiers

Who is online

Users browsing this forum: No registered users and 9 guests