New Airbrake III

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

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traktop
Posts: 26
Joined: Mon Jan 27, 2014 3:27 am

Re: New Airbrake III

Post by traktop »

Mark wrote:I have a Weber Mass at home and it just destroys the tone of my 18 watter, I also found it rolled the bass off my Boogie Mark 1 too.

I've tried a Tom Holmz power soak many years ago and I found the tonal trade off too much for me.
I find it is so useful, and sounds acceptable to me, but I got the impression that a PPMV would be much better for my amp.
traktop
Posts: 26
Joined: Mon Jan 27, 2014 3:27 am

Re: New Airbrake III

Post by traktop »

Mark wrote:I'm more inclined to go with VVR in an Express rather than a master volume or an airbrake. I know this isn't your situation, I'm just thinking out loud and giving you an idea of my perspective.
Another way of reducing power that was unknown to me, jejeje. It is about reducing voltage for getting less power, right? But I readed that it only works on certain amps... How does the playing feels at high levels of reduced power?
Mark
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Location: Sydney Australia

Re: New Airbrake III

Post by Mark »

I played through an Express with the pot set half way and it felt fine. I would imagine at very low settings the speakers and the SPL itself would effect our perception.

A technique Ken Fischer used to tell if his amps sounded good was to use ear protection muffs. The idea being you really hear what the amp sounds like at lower SPL. I had this very experience when building a Rocket, it sounded okay, but something wasn't quite right, with the ear muffs on it stank. So it was back to the drawing board.
Yours Sincerely

Mark Abbott
traktop
Posts: 26
Joined: Mon Jan 27, 2014 3:27 am

Re: New Airbrake III

Post by traktop »

Mark wrote:
A technique Ken Fischer used to tell if his amps sounded good was to use ear protection muffs. The idea being you really hear what the amp sounds like at lower SPL. I had this very experience when building a Rocket, it sounded okay, but something wasn't quite right, with the ear muffs on it stank. So it was back to the drawing board.
Interesting Idea. I will check it.
Thanks, Gilberto.
traktop
Posts: 26
Joined: Mon Jan 27, 2014 3:27 am

Re: New Airbrake III

Post by traktop »

vibratoking wrote:if you use half the resistance of a 100W resistor, then the rating must be reduced by half. It can only support 50W in that configuration. I only mentioned this because I thought you were trying to design the circuit to handle a higher power amplifier.
Ok, the attenuator has been working very well.
I´ve recently changed output tubes, so now I´ve got a quad jj 6ca7 on the dr-103 instead of 2 that I had before. In order to use the attenuator with a 100wats amp I just used the wole shunt resistor, (as you told me), instead of half, (same as the original airbrake). But know the readings changed, favouring a 16ohms load, so I guess that I should use the 16 ohms tap of the amp, (before, I used the 8ohms because that is what the amp would find coming from the attenuator).
The thing is that I forgot that the airbrake instructions says that: "it´s better using the 8ohms tap instead of the 16ohms when using old english amplifiers due to the transformer design...".
I know that partridge transformers are strong and so, but I just want to do things right, so...
8 or 16 ohms amplifier tap?
Thanks in advance, Gilberto.
stretch2011
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Re: New Airbrake III

Post by stretch2011 »

Something i noticed in the original post's picture compared to the others. THe first pic has only one tapped power resistor while the other ha 2 tapped power resistors. Can someone explain why or why you wouldnt need two tapped PR's?
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David Root
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Re: New Airbrake III

Post by David Root »

I recently built the Airbrake III and checked the inputs too,

I got 8.6, 7.7, 6.9, 7.0 and 3.9 ohms. So pretty close to 8 ohms which is what it was plugged into, except the last one.

Not sure which connection number on the rotary switch corresponds to which value, I'm very hazy on that part of it.

Perhaps someone could enlighten me in that regard.
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