Custom Audio OD-100 has arrived... Help with Questions please!

Discussion in 'Amps and Cabs' started by visualrocker69, Jun 3, 2008.

  1. visualrocker69

    visualrocker69 Member

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    Hi, just got my OD-100 :D after going through Fedex hell for a nearly a MONTH!!! :x

    So I have a few questions...

    1) Is it an OD-100 or OD-100+? Is a serial number check possible? It came with a printed out manual from Custom Audio Electronics, rather than from Suhr. I don't see it refered to as a + at any point, but at a glance it looks identical to the amp advertised on the Suhr website. What are the obvious (and not obvious) differences between the original and the (+) version? Is there any reason the original would be desirable in a different way, or is the (+) simply an objective improvement?

    2) Somewhere in this month of being reshipped THREE times with lottts of Fedex drama in between, a power tube dissapeared. I'm guessing it just shattered and is somewhere loose in the amp... Frankly, I'm dying from allergies and can't take a look until they settle down.
    Now, according to this manual, the amp can run on the two inner tubes. Is this accurate? Will I experience any changes in tone from running it with all four tubes? I guess there will be less headroom, right?

    3) Can I just replace that one tube or do I have to replace the pair (inner? outer? how are they paired?) or is it necessary to do the whole quartet? Which tubes does it come with from the factory (power and pre)? These power tubes in the amp look like Tung-Sol 5881's but I'm not sure. I'll take a look tomorrow when the allergies die down.
    Is it possible to retube with different tubes? What kind? I'm assuming I have to stick in the 5881 category, but is it possible to use different brands like Groove Tubes or something else? How about 6L6's, are those fair game/

    4) Now that I've stepped outside of the happy world of Mesa's fixed bias, I have a whole new problem on my hands... BIASING!!! Hell, I don't even know WHAT biasing is, just that I never needed to think about it with Mesa amps...
    Can someone give me a quick explanation on what biasing is, how it affects me, and can I make these adjustments myself or should I leave it to a tech?

    5) Can the channel selecting & boost be controlled via external switching like a Ground Conrol Pro with GCX switcher? I don't know anything about interfacing all of this stuff, but it'd be great to get a headstart. I assume this equipment would communicate with it in the same way that the footswitch does - via stereo cable?
    While we're at it... why no footswitchable Ch. 1 boost? That seems like it would make things a hell of a lot more convenient, no?

    6) About the Ch. 2 boost... WHAT is an "internal trim pot"? Is this an adjustment I can do myself or should it be left to a tech?

    Well, thats about it for now. I'm looking forward to a very rewarding experiencve with this amp as soon as I'm feeling better!
    Thanks!
     
  2. davyped

    davyped Member

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    Call or email John Suhr. he is easy to get a hold of.

    Dave
     
  3. MARK1970

    MARK1970 Member

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    On the first question, I believe the OD100 came with the red lights and the SE or SE+ came with the blue. I purchased a OD100, after a couple of month, I sent it in to have it change over to an SE. When I received it back the little lamps on the amp were change from red to blue. Also in the back, the serial number has SE+ added with a marker. This should help as far as seeing if it is a standard or SE.
     
  4. gainfreak

    gainfreak Member

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    1) Call John Suhr to find out what model it is.

    2) You can run the amp with 2 tubes but it will change the headroom and tone a bit plus it will be down on power.

    3) Tubes are usually matched in pairs. In a 100 watt amp The two outer power tubes work together and the two inner tubes work together and they should be matched. I would not recommend that you get one tube to save money because of many reasons.
    Tubes usually burn in together so id recomend that if the remaining tubes arent brand new that you re-tube the whole amp instead of just getting 2 new replacement tubes for the amp. trust me, you would be better off getting 4 new power tubes and having a tech install them and bias tehm properly. If your amp runs 6l6 based tubes you can use 5881's or 6l6's of any brand. A 5881 is just a lower powered 6l6's type tube.


    4) Tube bias refers to the idle current of the output tube (power tube). Much like the idle in your car’s engine, a tube amplifier needs to have the output tubes (power tubes) biased properly, for optimal performance. If the output tubes are under biased (idle current is set too HIGH), the audio signal will tend to distort earlier and the tube life will be shortened. This condition is sometimes referred to as biased “too hot”. If the output tubes are over biased (idle current is set too LOW), the audio signal will deteriorate more quickly and the amp will sound thin, cold and sterile. Therefore, this scenario is sometimes referred to as biased “too cold”. Typically, a hotter bias will give you louder, punchier and fuller sound; a colder bias will give you a cleaner, thinner sound. You can definitely bias an amp if you are handy but id recommend that you take it to a tech until you do some more research on the subject.

    5) Im pretty sure that you can control the amp with a GCX type switcher but you should check with John Suhr. Im not sure how the channel switching is setup on the CAE's

    6) You can definitely mess around with the internal trimpot yourself


    I hope this helps

    Ralph
     
  5. Rayneman

    Rayneman Supporting Member

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    When I had one, it was originally an SE, but it had blue lights and 5881 tubes.

    I sent it to John for the SE+ upgrade. When it came back, the visual differences were EL34's (of course) and a bigger tranny supported by a block of wood.
     
  6. MARK1970

    MARK1970 Member

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    How did you like the EL34s to the 5881s. ? I've been thinking about taking mine in for the EL34 and Plexi tranny.
     
  7. visualrocker69

    visualrocker69 Member

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    Oh I know it's not an SE. But there's a standard and standard + version too.
     
  8. JDouglee

    JDouglee Member

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    +1000.
     
  9. Rayneman

    Rayneman Supporting Member

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    I liked the "+" mod 10,000,000,000,000,000,000,000,000x better than non +. I cannot say with certainty how much of the difference was due to tubes, or tranny, or any other changes, however I am referring to the change in its entirety.

    I hope I was clear about that.

    Though I didn't end up keeping the amp, that mod made all the difference IMO, and even Suhr himself all but insisted. I cannot recommend the mod enough.
     
  10. JDouglee

    JDouglee Member

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    From what i understand, the Standard+ is a pretty big change from the old style. I heard it at NAMM and it stood out as my favorite of the OD 100 series. Major balls.
     

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