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Heads Up for SWR IOD Owners

Discussion in 'Amps and Cabs [BG]' started by Tapp, May 8, 2003.


  1. Tapp

    Tapp

    Aug 29, 2001
    USA, Mississippi
    I have a WeberVST Mass 50 which is a speaker load box similar to a THD Hotplate but uses an actual speaker motor and as such works more like a true speaker load.

    I got the idea that this unit may give other tonal choices for the IOD. As we know, the IOD is a small tube amplifier and uses a small output transformer. When nothing is connected to the "Speaker Output" jack on the back side the OT "sees" a fixed 8ohm/10W resistance. When a speaker is connected the character of the OT will change due to how the speaker reacts and all sorts of complicated mathematics that I don't fully understand (but on a basic level) and is not worth delving into. So I connected the Mass to the "Speaker Out" jack and was able to definitely hear tonal changes. The Mass has a rheostat "Speaker" control that allows you to control how much signal goes to the Mass motor and in this case acts as a tone knob.

    I can't tell you if the Mass will make the tone better or worse, but it definitely makes a difference. With the Mass "Speaker" control on 1 (ie. signal going fully to the Mass) I notice my volume dropped a little but the tone seemed cleaner in the mids and cut thru better. With the control on "10" (ie. less signal going to the Mass) the sound became more reminiscent of the trad. SWR scooped mid full kinda sound. I have not messed around with the blend and drive controls on the IOD so that would open up new possibilities too. I keep my blend around 11:00 and drive around 10:00. I run a fairly flat eq with mids and bass boosted a tad with highs less. I ran this test with a stock '73 Jazz thru an SWR Stereo 800 bridged mono into an Eden 2-10XLT on a Gramma platform.

    Tapp
     
  2. jasonbraatz

    jasonbraatz

    Oct 18, 2000
    Oakland, CA
    wow, this sounds like something i'd like to try. how big is this box? big enough to stick in the back of a rack?


    sounds intriguing :) good heads up man!
     
  3. Tapp

    Tapp

    Aug 29, 2001
    USA, Mississippi
    Jason, it's probably 5"X13" and it's got a little weight due to the speaker magnet. It may be a little big for the back of a rack but I just set it on top of my rack. They make a 20W version too that would do fine for this application and may even give a different sound. I have the 50W version that I use with my guitar amps too.

    Tapp
     
  4. I'm a bad IOD owner:

    Bass - Flat
    Mids - Flat
    Treb - Flat
    Drive - Off
    Aural - Off

    And left that way all the time.
     
  5. jasonbraatz

    jasonbraatz

    Oct 18, 2000
    Oakland, CA
    so, if you have your drive all the way off, you must have the blend knob all the way to the 'direct' side, right?

    why not just have a grand prix then? ;)



    i push the drive knob up until it just starts distorting on my loudest notes and back it off just a little from there. mmmm sweet tubey goodness.
     
  6. alexclaber

    alexclaber Commercial User

    Jun 19, 2001
    Brighton, UK
    Director - Barefaced Ltd
    I use a Grand Prix myself, but do the IOD and GP sound the same when the IOD is set to clean? I'd have thought they'd be quite dissimilar judging by their overall approach.

    Alex
     
  7. Tapp

    Tapp

    Aug 29, 2001
    USA, Mississippi
    When the IOD is set to direct it's just going through the initial 12AX7 and basically bypasses the EL84 tube amp section. So it's character is similar to the other SWR preamps. I don't have a GP but I think there is a lot more EQ options on it.

    Tapp
     
  8. Devnor

    Devnor

    Nov 13, 2001
    Dallas TX
    Interesting thread..I was considering trying the Hotplate to improve the overdriven tones in the studio.

    What power amps are you guys using w/ your IOD? I just got my new IOD this week...sounds great thru my Baby Blue but I need a bit more power =)

    These Stewart vs. QSC vs. input sensitivity threads have me concerned the IOD doesnt have enough output drive for either of these amps.
     
  9. Tapp

    Tapp

    Aug 29, 2001
    USA, Mississippi
    In "direct" mode on the Blend control the IOD doesn't have enough output voltage to drive either of the amps to full power. Now, whether or not it's loud enough is a whole other matter. I have not had the opportunity to really crank my rig up really loud but I've not had any problems so far using an SWR Stereo 800 amp.

    Here's the rest of the story.... When your using the IOD toward the "line" position on the blend control you are dialing in more of the EL84 tube amp side of the pre. In this case you substantially increase your output voltage to more than enough to drive any of the amps you are looking at. In fact, you should be able to notice that when you have the blend around 12:00 or more and raise your drive knob you should hear a drastic increase in volume coming from your rig due to the increase in output coming from the pre.

    Tapp
     
  10. JPJ

    JPJ

    Apr 21, 2001
    Chicago, IL
    I have a Stewart 2.1 running an IOD. I usually set my IOD level at 3:00 and my bridged mono amp level at 12:00. While this isn't enough to make you lose control of your bowels, it is more than enough to compete with two LOUD lead guitarists, and LOUD drummer, and to cut through in clubs and bars. The rig gives me all the low-end support I need without ever really hitting the yellow zone on the amp....still have room to spare. I suppose there really wouldn't be anything wrong with running the preamp full out and cranking the amp more if you needed it, but I haven't had a need for more volume. However, by comparison, the IOD doesn't seem to give much of a kick at the front end of things, but luckily my amp can handle things.
     
  11. monkfill

    monkfill

    Jan 1, 2003
    Kansas City

    First of all, yes, the GP has a much more flexible EQ.

    But, in my opinion, running a GP with the EQ flat versus an IOD with the EQ flat and the knob all the way to direct (so you're getting the 12AX7 only, none of the EL84s), the GP seems to have somewhat of a thicker and punchier tone. Not thicker in terms of tube warmth/thickness obviously, but a thicker punchier "hi-fi clean" sound. I really don't think the IOD was intended to be run entirely direct. . . also its unfortunate that the one midrange control that it has isn't sweepable. . .

    I haven't had either of these two preamps long and I've never bothered to check if one is running a different preamp tube than the other, so I suppose that could be part of the difference.
     
  12. Tapp

    Tapp

    Aug 29, 2001
    USA, Mississippi
    Both use the same preamp tube 12AX7. It doesn't surprise me that you find the GP more HiFi; that's really it's purpose. The IOD was primarily created as a drive preamp to get the cranked tube amp tone in a preamp package. I happen to run the IOD direct when I use my TL5 that runs an 18V Bart onboard pre and I get a really nice Hifi fat tone.

    Tapp
     
  13. JPJ

    JPJ

    Apr 21, 2001
    Chicago, IL
    My IOD is currently being serviced due to a problem with the tube stage. I had to use it with the blend rolled hard left for a couple of gigs (to effectively work around the problem with the preamp), and I thought that the IOD sounded even more "hi-fi" than my Redhead. I would assume that they should essentially be the same, so it might just be perception, but the non-tube tone seemed pretty clean and modern to me.
     
  14. monkfill

    monkfill

    Jan 1, 2003
    Kansas City
    My GP is the green-face model and IOD is the blue-face model, so they've been around a while. . . what I meant is that along the way, someone may have put a different variant of 12AX7 in one or the other, causing a slight variation from its "original" tone. . .