Did some testing with Dem201s and Plx

Discussion in 'Amps and Cabs [BG]' started by Big String, Jul 18, 2003.

  1. Big String

    Big String Supporting Member

    Apr 22, 2000
    Northwest Indiana
    Did some more testing with my Demeter 201s and QSCPLX 2402 in to Bergantino HT322.

    I mostly play my Lakland 4-94 Deluxe with Bartolini preamp and pickups. My favorite bass. The Barts have always had a little to much mid range for me. I would get a sort of fluttering when I hit my E string on the F note. Not a "farting" but almost. I noticed my clipping indicators getting close to the red and even flickering the red occasionally. I tried bridging the amp and it helped with headroom but still retained the same tones. I made a few calls to the OEM's and got some suggestions.

    1. Turned down the Bartolini on board preamp on the 4-94 to about 3/4 full.
    2. Opened up Dem201s and raised the internal trim pot (same as master vol.) to about 3:00. Note Demeter advised to keep it a 12:00 or less. I tried it and did not like it, so I went the other way turning it up to 3:00.
    fyi: The trim pot is to match the input sensitivity of any power amp. I believe the 2402 is 1.7v. I probably could have turned it up all the way. Doing this I believe I reduced the overdrive on the input tube that way. This was advise from another party.

    My findings: I got a better, more clear sound with seemingly more headroom in the stereo/parallel mode of the PLX. On the Demeter I went from 11:00/12:00 volume settings to 9:00/10:00 setting and the clip light was not going as high or in the red at all.

    Further: I replaced the 12ax7EH tubes with the two matched JJ ECC83S I got from Eurotubes a few weeks ago. I've read about some reliability issues and microphonic problems with these tubes, but they sound so fat and round and totally eliminated the F-note "fluttering" unless I add the grind/midrange on my bass when desired. Totally quiet too. Hopefully they stay that way for a while. In defense of the EH tubes, they sound good too, not as round and fat but quiet also. They may have been damaged by a AC power problem on a recent gig. Anyway so far the JJ sound better.

    Just a note on this subject.
    When I used my Mesa 400+ all the time I actually had similar settings. I ran the Master at 7.5 and the pre side at 3 all the time and got the most juicy round sound I could ever want. Too dang heavy to cart around though... Anyhoo, the setting on my Dem/PLX are same as far as I'm concerned. Made sense to me.

    I learned from talking to very knowledgeable OEM's (original equipment manufacturer) that some careful experimenting can have some pleasing results. Although I have not gig tested this new setting format, sounds like "Butta" in my practice room. Sunday I play and outside gig and will use this setup but adding my HT112 on top of the HT322. By just opening the gain for the 112 to about 1/2 on the plx sounds E-freakin-normus. I can just hear my geeetar player bit-chin' now. heh heh...:D
  2. boogiebass


    Aug 16, 2000
    Yup. Sounds about right. My experience with a PLX (in my case, a 1602) is that you have to feed it a very hot signal from the preamp. I imagine what you did with the Dem is right on.