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Thread: Attenuator for 2/56/2

  1. #1
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    Default Attenuator for 2/56/2

    Hi Fryette-Users,

    I was wondering if anyone is using an attenuator with their stereo power amp/cabinet rigs? Would I need to run two attenuators, since there are two channels, or are there two-channel attenuators out there that work great with the 2/56/2? Thanks!

  2. #2

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    You need two - maybe. What's the rest of your rig?

    There are solutions like this one (the height of insanity, I know, but kills)...

    STEVIES RIG WITH DUAL LOAD AMP.pdf

    I have the Two/Fifty/Two power amp set up with each channel driving a different load box. Channel A runs in Class AB mode and drives the Palmer PGA-04 @ 8 ohms. Channel B runs in Class A mode and drives the THD Hotplate @ 16 ohms.

    Using the power amps channel volumes and the output levels on the loads, you can achieve completely different dynamic response and saturation characteristics. Each channel/load connects to a dedicated Digital Music GCX loop so they can be switched in between the GP3 and the TC2290 on the fly or as part of a MIDI preset, thus forming two 50W EL34 based distortion pedals

    If the mood strikes, I can run them both in series

    And then there may be a more ratrional approach depending on your set-up and needs...

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    In this example, preamp or head line out signal goes into Channel A Input. One of the two Channel A speaker out jacks goes to a load box and gets cranked. The other Channel A output is plugged directly into Channel B INPUT. Simon says it's OK as long as you have a load on Channel A. You can also use the line out of the load box if available, but this works just as well and keeps the wiring short and clean. Simply set Channel B to low input sensitivity using the front panel level switch. Channel A is the distortion generator and overdrive amount is set by Channel A Volume. Channel B output goes to a speaker cab and overall playing volume is set by Channel B Volume.

    Sometimes I think I should write a book about all the crazy things you can do with tube amps that most people wouldn't dare try...
    Last edited by sfryette; 02-20-2013 at 02:25 PM.
    Steven Michael Fryette
    Rantmeister In Chief
    www.facebook.com/steven.fryette


    "What I create, I can destroy!" - Boris Karloff (Nightkey, 1937)

  3. #3

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    Bloody hell ! How much signal are you feeding into channel B like this Steve ? Input impedance attenuator divided by input impendance channel B times 50W ?

    Giga

  4. #4

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    Quote Originally Posted by Giga View Post
    Bloody hell ! How much signal are you feeding into channel B like this Steve ? Input impedance attenuator divided by input impendance channel B times 50W ?

    Giga
    Exactly the response I expected

    Remember Ohms Law (an actual law that must be obeyed - unlike jaywalking and managing investors portfolios) means it's only 50W across an 8 ohm load. The calculation is 20V across a 100K load (the input stage impedance) divided by the voltage divider on the level switch, divided by the voltage divider formed by the Volume pot. So using the Volume pot, it's no problem to get the level down to 1V. All of the appreciable power transfer is across the dummy load or speaker cab (4, 8 or 16 ohms) just like on an amplifier line out, right?. So this is legal and safe - if a little risky should the speaker cable get pulled out
    Steven Michael Fryette
    Rantmeister In Chief
    www.facebook.com/steven.fryette


    "What I create, I can destroy!" - Boris Karloff (Nightkey, 1937)

  5. #5

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    Wow ! If you could somehow build the effect this gives into a regular amp I bet you'd have a guaranteed bestseller Steve !

    Suddenly, running the amp normally sounds very flat and one-dimensional

    Awesome ! Thanks for the tip

    Giga

  6. #6

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    Quote Originally Posted by Giga View Post
    Wow ! If you could somehow build the effect this gives into a regular amp I bet you'd have a guaranteed bestseller Steve !

    Suddenly, running the amp normally sounds very flat and one-dimensional

    Awesome ! Thanks for the tip

    Giga
    Steven Michael Fryette
    Rantmeister In Chief
    www.facebook.com/steven.fryette


    "What I create, I can destroy!" - Boris Karloff (Nightkey, 1937)

  7. #7

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    I'm not enough of a tech to get this on the first go-round so I'll review it a couple more times. But, I wondered - have you ever done this load box approach with an iso-cab?

    To me a straight close mic recording never sounds right, much less one sitting in an iso-box. I like room sound. But I've often thought of recording with:

    Guitar > Amp > Iso Box / Guitar Speaker > Close Mic > Mic-Pre > Tube PowerAmp > Full Range Speaker > Room Mic > Mic Pre > Board.

    the intent being to separate tone generation from sound dispersion as much as possible - so they can be messed with as separately as possible. Swapping in different power sections and speaker combinations through switching always sounded more fun to me than switching patches on a modeler.

    Never pulled the trigger on the gear though for fear of going down a road that some well-traveled rambler already knows is a dead end.
    Nick Neilson

    "Any sufficiently advanced technology is indistinguishable from magic." -Arthur C. Clarke

  8. #8

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    Quote Originally Posted by mildbreakup View Post
    I'm not enough of a tech to get this on the first go-round so I'll review it a couple more times. But, I wondered - have you ever done this load box approach with an iso-cab?
    Yes. An iso-cab is a compromise compared to whatever is your preferred cab. So to me, if I'm going to compromise on that, using a reactive dummy load is not a huge compromise compared to an iso-cab given the convenience of the dummy load.

    Quote Originally Posted by mildbreakup View Post
    To me a straight close mic recording never sounds right, much less one sitting in an iso-box. I like room sound. But I've often thought of recording with:

    Guitar > Amp > Iso Box / Guitar Speaker > Close Mic > Mic-Pre > Tube PowerAmp > Full Range Speaker > Room Mic > Mic Pre > Board.
    Well, that's one way to do it, for sure And I agree that even given that it's a lot of hardware, it's more satisfying than a modeler, and I think there is another aspect that get's lost in all this. The stuff is fun to experiment with. Much more interesting and rewarding than tweaking patches on a modeler. And you learn a lot. The biggest lesson is more of a reminder than a revelation - you always sound like you, and no modeler or any other kind of gear is going to change that. In that light, experiment with and maximise your knowledge of tube gear. The satisfaction quotient is much greater, and honestly, you're more likely to stumble across something really great because you're focusing on your creative impulse more than you would bending your intellect to deal with drilling down menu options...

    Quote Originally Posted by mildbreakup View Post
    Never pulled the trigger on the gear though for fear of going down a road that some well-traveled rambler already knows is a dead end.
    I wouldn't say it's a dead-end, although I do find that I'm mostly looking for ways to get away with playing the amp I want to play at the volume I want to play at.

    Seriously, I put that rack together with a "because I can" attitude. I think I needed to go there to see what was there. It's way over the top, but it sounds ridiculously good. I have a CD of the sound of it somewhere I should try to find.

    Now that I know what's there, I feel I can always find a combination of gear that sounds that good to me. But I learned a lot from that exercise, and I got some design and product ideas out of it. Some bits have shown up in other gear, some are in the que, so to speak.
    Last edited by sfryette; 02-21-2013 at 02:39 PM.
    Steven Michael Fryette
    Rantmeister In Chief
    www.facebook.com/steven.fryette


    "What I create, I can destroy!" - Boris Karloff (Nightkey, 1937)

  9. #9

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    Thanks for the reply Steve.

    Quote Originally Posted by sfryette View Post
    An iso-cab is a compromise compared to whatever is your preferred cab. So to me, if I'm going to compromise on that, using a reactive dummy load is not a huge compromise compared to an iso-cab given the convenience of the dummy load.
    Breaking it down a little further then - in your experience:

    Having the speaker interacting with an acoustically well-designed cab would outweigh any improvement in tone gained by allowing the speaker to work harder in an iso-cab?

    I.E. - you'd expect more satisfying in-room tone and playability going through four P-50-E speakers in a Deliverance cab at moderate volume than one P-50-E blasting full volume in a mic'd iso-box?

    I really appreciate the idea of "going to see what's there" when approaching gear and tone. It's a reminder that if we're not having fun playing then something's not right.

    In my experience, things are a lot more likely to end in fun when you stop searching for the world's best bag of 12000 series plexi-dust and just start turning the dials.

    A big part of that for me has been understanding the design philosophy behind the gear - thus my continued pestering
    Nick Neilson

    "Any sufficiently advanced technology is indistinguishable from magic." -Arthur C. Clarke

  10. #10
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    Arrow

    Really interesting thread .....
    The fact that Stephen appears from nowhere, is sentenced to death in an emotional public trial without anyone interfering at all and is then altogether forgotten as if nothing happened, is already suspicious.

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