Playing through both channels on DRRI...

Discussion in 'Amp Central Station' started by aarondowns22, Jul 17, 2012.

  1. aarondowns22

    aarondowns22 Tele-Meister

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    Just bought a DRRI and had a buddy of mine tell me that he gets an A/B splitter and plays his guitar in both channels of the amp. He says he puts channel 2 on 5 just to where it starts breaking up and controls the volume of that on channel 1. Can anyone tell me technically what the advantages/disadvantages to this are and also how it sounds???
     
  2. Bob W.

    Bob W. Tele-Meister

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    Playing through both channels of a 2-channel amp is not really a big deal. Theoretically, you are just summing the two signals into the output section. This allows for a bit more gain, and overlapping EQ. I've experimented with this on several amps in the past, and I really only found it useful for getting more gain out of an amp that didn't have enough drive.

    With the Deluxe Reverb, it's a bit tricky to do, because the channels are phase inverted with respect to each other. The signals from each preamp will actually subtract from one another. If you really want to try it, you will need a method of flipping the phase into one of the channels, so a passive "Y" connector won't do it. You'll need an audio transformer or an active phase reverse of some kind.
     
  3. RockerDuck

    RockerDuck Friend of Leo's

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    Radial makes an aby that is passive, with a ground lift and isolation transformer. It inverts the phase too.
     
  4. Wally

    Wally Telefied Ad Free Member

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    This 'daisy chaining' of channels does not 'stack' one channel on top of the other, and therefore this method does not increase gain....contrary to many folk's thinking. You are simply playing through both channels....in effect 'y'ing the gutiar's signal to more than one channel of amplification.
    As BobW states, all two channel FEnder reverb amps have channels that are out of phase. So, playing through both channels with settings eual, the result will be quieter and thinner sounding----out of phase---than either channel alone. AS Rocker notes, there are tools that will invert phase so that the signals do not cancel one another out.
    There can be some tonal variety found with this technique....moreso with amps that have a bright channel and a dark channel....as Hendrix's Marshalls or an AB165-AA371 BAssman.
     
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  5. Martin R

    Martin R Friend of Leo's Silver Supporter

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    Unless he's playing through one channel at a time. (He says A/B, not A/B/Y.)

    I have a BF Deluxe and have one channel set slightly louder than the other. An A/B pedal makes it easy to increase volume for leads.

    (And I think the channels on the Deluxe Noverb are in phase. Makes no difference to me, I don't daisy chain the inputs.)
     
  6. Wally

    Wally Telefied Ad Free Member

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    Martin, you might reread the OP.....his buddy is playing both channels at one time....out of phase....adn his buddy thinks that he is stacking gain stages. that is not what is going on.
    I understand exacatly what you are doing...and it adds versatility to that non-verb...which indeed has channels that are in-phase....but voiced just alike so A+B doesn't do much for things anyway....unless you ever wanted the trem function to be mixed with the straight channel, right??? Taht gets interesting.
    IF you are ever plugged into an AB165 BAssman or a Super Lead Marshall, try running both channels. ITis ear-opening....esepcially with single coils. There is a reason why Hendrix did it.
     
  7. waparker4

    waparker4 Doctor of Teleocity Ad Free Member

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    I can jumper the channels on my DRRI... But that's because of the Fritz mod...

    I don't usually need more gain than just 1 channel though
     
  8. figaro

    figaro Tele-Meister

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    It's a very simple mod. Just move one wire connection and both channels will be in phase and also have reverb on both channels.

    Locate the wire that runs from the .047 cap of normal channel to the 220k resistor that feeds the phase inverter. Unsolder it's end at the 220K resistor and resolder it to the input (near edge of the board) of the 3.3M/10PF cap for the reverb circuit.

    Done!
     
  9. Wally

    Wally Telefied Ad Free Member

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    I don't know what the Fritz mod is; but if it is simply adding the reverb to the Normal channel, this does put both chanels in-phase. However and once again, running through both channels DOES NOT stack gain stages and thereby incease gain. What happens is that you are simply running through two separate preamp channels. The reasons for doing this would be to have tonal variety, the ability to set one channel for 'hotter' operations as noted in one post above, versatility in assigning outboard effects to whichever channel, and the ability to have onboard effects in one channel mixed with a dry signal in the other channel. With the BF/SF two-channel reverb amps....excluding the Vibroverb, vibroverb RI and the Custom Vibrolux REverb that is bbased on the 6G16 Vibroverb RI....mixing that dry channel with the vibrato effect in the other channel keeps the opto-isolator vib function from sounding so 'sharp' at its cut-off points. The simpler bais vary vib functions as in the PRinceton and Princeton REverb amps and the two-channel amps mentioned above as well as the non-reverb BF/SF with vib fucntion are more pleasant to some simply because they do not exhibit that sharp cut-off that the opto-isolator circuit yields.
     
  10. vjf1968

    vjf1968 Poster Extraordinaire

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    You can just get one of these. Nice "swiss army knife" of pedals.
     
  11. E5RSY

    E5RSY Doctor of Teleocity

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    Oooooh...cool pedal.

    So, which side would you run the negative and positive outputs to, respectively???

    p.s. Never mind. I just read the directions for A/B use and I think it broke my brain.
     
    Last edited: Jul 19, 2012
  12. tjalla

    tjalla Friend of Leo's

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    Go to TGP "list of pedals that invert phase"

    There's a likelihood you already have something that'll do the job - even if to test the concept. Best is something that inverts phase both bypassed AND engaged. Danelectro Tuna Melt is one example.
     
  13. PeterUK

    PeterUK Poster Extraordinaire Silver Supporter

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    I use both channels of my DR on a regular basis and I've never noticed an increase in gain or volume but I do like the combined tone.

    I use a Radial Switchbone AB/Y pedal. It works superbly, has LEDs which remind you what channel you are using and if using both, which channel it will default to if switching to just one channel, and it also has a clean boost. It handles the channel phase issue; I've never had a problem with this.

    It's probably the best pedal I've ever bought and gets used every gig. The only downside is it uses a 15v power supply so I opted for the enormous (in size and expense) Burkey Flatliner power supply as my main pedalboard power supply. Burkey offer a mod to cater for the odd voltage required by the Switchbone.

    Here's my pedalboard:

    [​IMG]

    I've also got a custom DR footswitch on the pedalboard too and this also has LEDs so I can see as well as hear where I am with the reverb and vibrato channels. It's the small pedal above the blue CE2 Chorus and next to the power supply.

    I connect it alll through a pedalsnake so I've only got one cable running to the amp other than the power line to the Flatliner.

    :) Peter
     
  14. Bob W.

    Bob W. Tele-Meister

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    I beg to differ, but if you drive both channels in parallel, and have the signals in phase as they arrive at the inverter, the amp will have more overall gain. You will be driving the power amp stage with about 6dB more signal, if the two preamp channels are putting out equal level and are summed at the input of the power amp. This obviously doesn't make more preamp gain, and so it doesn't give you more front-end overdrive, but it will break up sooner at the power amp if you push it.

    Back in the '70s I once had a Bandmaster Reverb that was modded to cascade the channels in series. This was a major front-end gain increase, but alas, it was not a particularly pleasing sound. I ended up reversing that mod...
     
  15. Wally

    Wally Telefied Ad Free Member

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    So, BobW, if there are two separate guitars, each running through one of those separate preamp channels, will the amp distort earlier tha if you have only one guitar running through one channel?
    I have been running daisy-chained channels for a long time. I hear no major difference between running thorugh one or both of those channels. Maybe I have been over-looking something....but hwen I take one channel out of the equation, theother channels works just like it did when both channels were on. I'll pay more attention the next time. 6db difference would be something that one would not be able to ignore, ime, though.
     
  16. waparker4

    waparker4 Doctor of Teleocity Ad Free Member

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    No because they are not passing the same signal at the same time.

    However I don't really know the answer to this particular discussion.
     
  17. uriah1

    uriah1 Telefied Gold Supporter

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  18. Bob W.

    Bob W. Tele-Meister

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    My answer assumes that the amp is like a mixing console in that the output from each channel preamp is summed into the power amp section. This is essentially true in the case of traditional black-face Fender amps, with the caveat that the 'Reverb' models have an extra gain stage that reverses the phase of one channel.

    So, if you feed a signal into one channel and set that channel's volume to, say, '5', a certain signal voltage appears at the input to the power amp section (the phase inverter, to be accurate). If you mult that same signal through the second channel with the same settings, you would expect to get twice the signal voltage into the power amp (assuming you've already sorted out the reverse phase issue), yielding a 6dB increase in output.

    Now, in reality, the way the signals sum in a tube amp is not exactly the same way they would sum in a mixing console's bus. I'm not certain that you would get exactly 6dB, but I'll bet its fairly close.

    If you have two guitar players sharing the amp (I remember when we actually did this), each into a channel, the guitars will sum into the amp's output section. If either player turns up enough to overdrive the amp's ouput, it will steal headroom from the other and they'll both be in overdrive. This doesn't happen if you're only overdriving a preamp section.

    Have I confused things even more? An old-school two channel combo amp is really a vacuum tube mixer, feeding a mono power amp into a speaker. Splitting an instrument's signal into two channels will result in a few dB hotter signal going into the phase inverter. It's not a radical amount of extra gain, and doesn't drive either preamp any harder. It's kinda like just going through one channel and raising the volume control from 5 to 6 or so...
     
  19. Wally

    Wally Telefied Ad Free Member

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    Thanks, Bob. I'll keep an 'ear' on that the next time I am daisy-chaining.
     
  20. SpacemanSpiff

    SpacemanSpiff Tele-Meister

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    Old thread I know, but I happened to stumble upon it as I'm considering using both channels on my DRRI as well (through a barber launch pad).

    @PeterUK: I was intrigued by your custom vibrato/reverb footswitch. What type of cable do you use to connect it to the DRRI? Did you get it in Europe?

    Also, int terms of sound, what would you say is the benefit - if any - of blending both channels?

    Cheers,
    Tiago
     
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