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Crest causing schroder hiss???

Discussion in 'Amps and Cabs [BG]' started by Vinpaul, Mar 30, 2006.

  1. Vinpaul


    Aug 24, 2005
    Melbourne, Aus
    Hey everyone. I got a Crest LT 1500 power amp today to go with my newly acquired eden nav. My cab is a schroeder 410. I im running the power amp at 4 ohm bridged (1800 watts I believe). The problem is the tweeter in my schroeder is producing a loud hiss. When I turn the tweeter off its gone. I never had this problem with the tweeter before. I am running the power amps both channels on full, and funnily when I roll off channel A the hissing stops and most of the vilume goes away, but when I roll off channell 2 the hissing stays and so does most of rthe volume. Could someone explain to me whats going on? What is the problem, power amp, cab, pre? I hooked up a hatke cab just to see what would happen, and the hiss from the tweeter was noticable but nowhere near as loud. This really sux it took me a fair bit of saving to put this rig together (Im still studying). Help please:crying:
  2. A tweeter will only reproduce the hiss coming from an amp or preamp, so its not the cab.

    The tweeter in your Schroeder (depending on the particular tweeter) is very powerful and a lot of sound comes out of it (hence the 'increased hiss' between the Schroeder and your other cab).

    I'm a treble fanatic, but run the Selenium tweeters in my Schroeders at the 9:00 setting AT THE MOST... and I like a Marcus Miller type tone. So, one thing is you might have the attenuator set too low (i.e., turned up too much).

    Also, my experience with Eden amps is that they are quite 'hissy' when your turn up the treble compared to other amps, so make sure you don't have the enhance or treble control cranked.

    Finally, if it's really loud, I wonder if you need to replace the preamp tube. If you Navigator was shipped, that tube might have gotten damaged. However, I'm not sure that would cause his... and I've heard of this problem posted with Nav's before.
  3. GeorgeG

    GeorgeG Commercial User

    Jun 15, 2005
    Sydney, Australia
    Owner of Bass Gear Direct
    Hey Vin,
    Make sure the switch on the front panel of the Navigator is set to stereo mode not bi-amp mode and the Balance knob is set straight up the middle.
    Also if you are running the amp in bridge mode make sure you have a lead going from either the Right or Left Mains Out on the rear panel not the Left or Right Main DI Outs of the Navigator going into channel 1 input of the crest.
    Not sure with the configuration switches on the Crest LT amps but on the CA series amps if you are running bridge mode you go into Channel 1 Input and you have to make sure that the configuration switch is set to Bridge Mono Mode. (A>AB).
    Hope this helps or if it makes any sense.
    cheers, man.
  4. tadawson


    Aug 24, 2005
    Lewisville, TX
    The other thing is to check your gain structure. You state that the amp is wide open, but do not mention levels out of the pre. If the pre is only delivering a very small signal to the amp (output level is set very low) then the noise from the pre will be much more prominent in the overall output, since the huge gain in the power amp will amplify it too. It would be a better choice to set the output of your preamp to a fairly hot level that sounds good, and then bring up the power amp level to get the overall volume you want, and I think you will find that your overall noise level will be much lower as well.

    - Tim
  5. +1
  6. ibz


    Apr 14, 2005
    Columbus, OH
    +2 A strong pre signal tends to have less noise when being run to the poweramp.
  7. bassjigga


    Aug 6, 2003
    What kind of bass are you playing? I've had similar experiences and I have found it usually stems from noisy bass electronics. Especially since you mention it seems to come from your tweeter. If you have an active bass, try setting all your tone nobs flat, and then even cut the treble and see if it goes away.
  8. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Commercial User

    Jul 3, 2001
    Santa Ana, Calif.
    Former Technical Communications Developer, QSC Audio

    Good gain structure is the key to good signal-to-noise.
  9. Turock


    Apr 30, 2000
    Try a different toothpaste.
  10. GeorgeG

    GeorgeG Commercial User

    Jun 15, 2005
    Sydney, Australia
    Owner of Bass Gear Direct
    Forgot to mention this in my post but yeah I used to run the Navigator Preamp knob from 1-3 o'clock with my Custom 5 string with a Aguilar OB-1 preamp. So don't be scared to pump it to the point where the "Set Level" green led light flicks on and of. Eden recommends this as being the "sweet spot" for setting your preamp level.
    Try setting this with by-passing the compressor at this stage.

    Then turn your volume controls on the power amp to 2/3 of the way up.
    Then adjust the "Master Volume " level on the Navigator to the required level with the red led lights on the led meter only occasionally flashing, on the Loud peaks such as a loud thump on your E or B string.
    If you need more Volume then adjust the Volume further on your power amp.
  11. Vinpaul


    Aug 24, 2005
    Melbourne, Aus
    Thanks for all the responses guys. Its weird it seems like the schroeder tweeter is real sensitive, but it wasnt a problem when I was powering it with my hartke. I have reduced the problem by doing as suggested, running both channels bout half way up , gain about 12 or 1 oclock, and master probably 10 oclock. Its funny, I could get this power amp to go into the red no matter what, hasnt hit the red and Ive been playing/trying it at some ridicolous volumes lol. I still find with the tweeter if I do as suggested its best to roll the treble on the amp a little bit and a bit of the high mids that helps, and I can add a bit of bite on my bass pre without adding hiss. If I crank the power amp past halfway the hiss gets progressively worse. Oh well I can live with it it wont be an issue in a gig situation, it was just a shock coming from a place when this wasnt an issue before. Thanks heaps to everyone:)
  12. I misunderstood your original post, and thought you were comparing your Eden/Power Amp through the Schroeder versus a Hartke CAB....

    So... given you don't hear the hiss with the Hartke HEAD through the Schroeder... you can ignore my tweeter comment... sorry for the confusion.

    You might want to do a search on the Navigators... I seem to remember reading quite a few comments/posts about them having this problem, even when optimally set up, but not sure. I'm sure also following the comments above on optimal signal to noice settings, etc will help also.

    Good luck.

  13. tadawson


    Aug 24, 2005
    Lewisville, TX

    The Hartke, being an complete head, got their gain structure correct between pre and power amp. Being a bass head, they may also have rolled off the high freqs, which a separate power amp will not.

    - Tim

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