PPIMV bypass with 4 way switch. (Power Broker)

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

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rooster
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Re: PPIMV bypass with 4 way switch.

Post by rooster »

Hm. This is interesting. I have to say that I built a few of the Airbrakes for customers with Rockets and Express's. Then I installed the PPIMV on one of my Express amps and my Rocket, as well. I thought the resultant sound was way better. So I called my ppl up and offered to do this for them - for free - and if they didn't like it I would take it out, no problem. The vote was unanimous, they all preferred the PPIMV - and by quite a margin.

Ha, so I'm kinda stunned to here that RJ likes the Airbrake better than the PPIMV. I thought we had reached a consensus that the Airbrake was not so great. Certainly not better than the PPMV. :?
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M Fowler
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Re: PPIMV bypass with 4 way switch.

Post by M Fowler »

I don't like the airbrake period and install PPIMV when asked.
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RJ Guitars
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Re: PPIMV bypass with 4 way switch.

Post by RJ Guitars »

Edit: To add clarity...
1st - It's maybe significant that I am focused on listening for the sound of the amp on the lower end of the audio output capability. Something like "half as loud" or less.
2nd - The other item that might be worth mentioning is that I prefer the sound of the attenuator overall but it's not always what I think is best in all situations. As you can see from my earlier posts I've gone to some trouble to make a MV control that I think is useable and for some players it is the right answer.

Great sounding amps at lower volumes is something I have been in pursuit of for years now. It's gone two ways for me with the pro players I am sponsoring but it always seems to be using amps with all the tubes working hard. One of the better iterations involves using my Power Broker (improved Airbrake) built into mid sized combo amps and the second is playing straight into simple Champ sized amps. The impact of the attenuator over a MV becomes most apparent when I start getting down to the really usable sound levels in a small venue (church usually).

I think Geetarpicker also prefers the attenuator... in fact his might even be an airbrake although I don't think he advocates that everything is perfect with them... maybe he will weigh in?

It's usually Love/Hate with the attenuator and I think that it's generally that they require a lot more effort and expense to setup. I've started building them into combo cabinets and these are really working great and require no added complexity to setup.

FWIW - I played with a hotplate and I didn't hear it as sounding immensely different than the airbrake but it had a lot more rules.

I think the issue with the MV and the VVR is that there are other changes that you should probably make to keep things in balance when you dial down the signal. The preamp and the poweramp are not working together the same as they do at full power... this could be done but it's complicated.

I also have different isolation cabs and for me they simply suck for doing anything useful... but some folks really do well with them.
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rooster
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Re: PPIMV bypass with 4 way switch.

Post by rooster »

OK, RJ, it's really whatever ppl prefer, not a problem. I was just surprised to see this pop up...

Oh, and if Geetarpicker does jump in, and if he does support the Airbrake type attenuator, I would need to know if he has tried the PPIMV in an Express.

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Re: PPIMV bypass with 4 way switch.

Post by Roe »

I prefer the fryette power station and the alex attenuator, although the larmar works ok in hot rodded plexis and in blackface and silverface fenders
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Guy77
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Re: PPIMV bypass with 4 way switch. (Power Broker)

Post by Guy77 »

RJ Guitars wrote: Wed Oct 05, 2016 12:13 pm I think you'll like the Airbrake. I prefer that sound to any form of MV or power scaling but still at bedroom levels they all sound kinda ratty. I think you can actually get lower volume and still have some tone character left with an attenuator but nothing is ever as satisfying to my ears as "Loud" is.

Interesting thing on the Airbrake - I have done the opposite thing of my MV scheme in replacing the fixed resistors with a big Rheostat. You have to consider a lower wattage limit for the final unit based on the wattage of the available rheostats. http://diyguitaramps.prophpbb.com/topic33.html



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Sorry to wake up this old thread but I was looking at the design of the Power Broker attenuator (8 ohm version) mentioned in your link here RJ and I saw a part labelled R5 . It is an 8ohm resistor. This part was not mentioned in the Parts list you listed. Is this R5 resistor needed or am I reading the diagram wrong and it is just the actual 8ohm speaker.
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Re: PPIMV bypass with 4 way switch. (Power Broker)

Post by joeboo88 »

Hey Guy - if you look at the picture of the power broker you can see that 2 of the resistors are stacked on top of each other and the other resistor on the other side
of the enclosure - I am building one as well and RJ gave me 3 big resistors and the big rheostat.
I thought the same when I saw the schematic and thought ? but was made clear when RJ sent the parts and looked at the picture
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Re: PPIMV bypass with 4 way switch. (Power Broker)

Post by sluckey »

R5 is a dummy load resistor. The only time it's even in the circuit is when there is nothing plugged into J2, IOW, no speaker cab plugged in.
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Re: PPIMV bypass with 4 way switch. (Power Broker)

Post by RJ Guitars »

Exactly, it is a dummy load and in a combo amp is entirely redundant with the speaker.

However, if you were to use this in building a direct line-out option... (a hint at the rest of the project), then you really don't even have to have a speaker plugged in to make the amp safely function. Now this idea is fraught with unknown peril but in theory it would work. I actually think the speaker with it's ever changing impedance is part of the magic of tone so maybe the load resistor is really just a good speaker protection in the event you forget to plug one in... but a direct out box is so useful I'll need to pursue the idea to determine if it really does what I want it to.
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Guy77
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Re: PPIMV bypass with 4 way switch. (Power Broker)

Post by Guy77 »

Thank you everyone for your quick reply's! I see now that I could actually do without this resistor but it would also add a layer of protection just in case! I will be using this for my Rocket amp. I am finding attenuators so handy to have I am surprised the big amp makers like Marshall and Fender do not include them with there amps.

Cheers!

Guy
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