Did some testing with Dem201s and Plx

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

  1. 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.