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DEMETER VTBP-201 ISSUES

Discussion in 'Amps and Cabs [BG]' started by lowphatbass, Jul 2, 2008.

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  1. Jul 2, 2008 #1
    lowphatbass

    lowphatbass **** Supporting Member

    Feb 25, 2005
    west coast
    Intermittently the amp drops in volume or loses a lot of bottom end, at least that how I perceive it. I would assume that the failure is either brought on by heat or a random issue, I don't think it is vibration related as I have isolated the amp from cabinets/stages and still had the issue. It always sound good and strong when I first turn it on and midway through the first set I hear and feel the drop and it seems to cycle in and out fairly randomly. There is nothing obviously visually wrong with the amp inside or out, and OF COURSE THE TUBES ARE NOT THE ISSUE as I have tried several pairs. My question is, has anybody experienced this? Is there a part/component(s) I should "shotgun" before taking the time and expense of packing it up and sending it in?

    Thanks!!

    LPB
     
  2. Jul 2, 2008 #2
    LowBSix

    LowBSix

    Mar 25, 2008
    818 ~ 805 ~ L.A.
    Endorsing Artist: GHS Strings
    If you're playing active basses.... Check your battery...
     
  3. Jul 2, 2008 #3
    synaesthesia

    synaesthesia

    Apr 13, 2004
    UK
    If you have something patched in your efx loop take it of and see if it makes a difference.
     
  4. Jul 2, 2008 #4
    unlined4string

    unlined4string Supporting Member

    Mar 18, 2000
    Baltimore County, Md.
    Tarnished contacts on the effects loop send and return jacks can cause this kind of thing. If it works properly when you run a cable from the send to the return that's probably it. To clean the contacts try dipping a quarter inch plug in contact cleaner or alcohol and insert and remove it a number of times (both the send and return).
     
  5. Jul 3, 2008 #5
    Pickebass

    Pickebass Supporting Member

    Jul 12, 2004
    San Antonio, TX
    one of the most reliable pieces I ever owned. The effects loop would be where I would check first. Not alot can go wrong with the unit... I assume this is the 1.5 rack unit correct??
     
  6. Jul 7, 2008 #6
    lowphatbass

    lowphatbass **** Supporting Member

    Feb 25, 2005
    west coast
    Thanks for the responses folks, sorry it took so long to respond, it's been way to busy for me lately..
    I never use the effects loop, it would make sense that they would likely be dirtier than every other jack on the amp. Are you implying that this could effect performance even when the loop is not in use? It doesn't seem like it should but electronics has been always been a humbling experience for me and being unfamiliar with the circuit(s) involved I don't want to rule anything out, even at the risk of sounding uneducated.
    Oh, it is the 1 1/2 space unit Pickebass.
     
  7. Jul 7, 2008 #7
    unlined4string

    unlined4string Supporting Member

    Mar 18, 2000
    Baltimore County, Md.
    Yes the effects loop can cause the problem you describe even though you never use it. The jack isn't just a two contact female 1/4". It's designed to close the circuit when nothing is inserted, to provide a connection that bypasses the loop. Inserting a plug breaks the bypass connection. Tarnish can completely or partially break the bypass connection, causing signal dropout when nothing is inserted.
     
  8. Jul 7, 2008 #8
    lowphatbass

    lowphatbass **** Supporting Member

    Feb 25, 2005
    west coast
    I'll give it a try and report back!!
    Much appreciation!!
     
  9. Jul 8, 2008 #9
    Hoover

    Hoover Inactive

    Nov 2, 2007
    New York City
    Call Jim or Stacy @ Demeter. They are unbelievably helpful folks who take a sincere interest in making sure all their products are working 100% regardless of how old or how many users they've been through.
     
  10. Jul 15, 2008 #10
    lowphatbass

    lowphatbass **** Supporting Member

    Feb 25, 2005
    west coast
    Well, it doesn't appear to be the effects loop at fault. I did a few gigs where I was running very low stage volume(others not so much)and running fat in the house and thought the problem was licked. After doing a gig with no PA support I quickly realized my amp was still broken. I checked out Demeter's website and they have a fairly standard(understandably pretty hefty) bench charge. I emailed them just to see if they recognized the symptom(s) enough to give me an idea for what I may be in for financially if I decide to put money into it. I let you know the outcome of that.
    On a side note...before grabbing my other amp out of the car after the first set I tried plugging directly into my power amp. Bridged it, dimed it, and it sounded great. God bless 18V preamps!
     
  11. Jul 15, 2008 #11
    mikezimmerman

    mikezimmerman Supporting Member

    Apr 29, 2001
    Omaha, Nebraska
    I sometimes have a similar issue with my VTBP-201s--not exactly the same preamp, but I'm assuming the circuit is fairly similar. Intermittently (but fortunately not very often) it seems to suddenly lose a lot of bottom end. The odd thing is, if I spike the input--do a little heavy slapping, for instance--the bottom end seems to suddenly come back.

    It may be a dirty contact somewhere, but I'm not sure where.

    Mike
     
  12. Jul 16, 2008 #12
    lowphatbass

    lowphatbass **** Supporting Member

    Feb 25, 2005
    west coast
    It appears that my email to Demeter could not be delivered because their box is full. That's nice.
     
  13. Jul 16, 2008 #13
    mikezimmerman

    mikezimmerman Supporting Member

    Apr 29, 2001
    Omaha, Nebraska
    There are many, many companies for whom email is not the best means of communication. It sounds like Demeter is one of them. On the other hand, the phone tends to work really well for a lot of small companies. You might try calling.

    Mike
     
  14. Jul 16, 2008 #14
    Zooberwerx

    Zooberwerx Gold Supporting Member

    Dec 21, 2002
    Virginia Beach, VA
    +1. Call 'em....leave a message on their machine if necessary. Jim Demeter is really good about returning calls. He'll help as much as possible over the phone but there's a good chance you'll have to ship it for eval / repair. I had a similar experience with my HBP-1 (phantom power blew a chip) which required service. Jim made the repair and did some type of upgrade while in the chassis. I think I now get the Disney Channel or something.

    Riis
     
  15. Jul 16, 2008 #15
    synaesthesia

    synaesthesia

    Apr 13, 2004
    UK
    I'd also suggest a phone call, which is what I did first. It identifies you from the the rest of the speculative/junk/legit emails that most businesses get. Once I spoke with them, they knew what I was after and who I should be in touch with, and email was the continuing form of comms, email is not the best form of initial communication.

    My comms with them was about a transformer swap, they responded but they took their time and I was in no hurry. It was not a warranty issue and I was getting a new power transformer for a different continent for the older VTBP. Bear in mind that they will help you, but following up on non warranty sales or service is not their core or priority business. They will follow up though.
     
  16. Jul 16, 2008 #16
    conebeckham

    conebeckham

    Jun 27, 2008
    Bay Area CA
    I have an early one, the two rack space one with toggle switches instead of rockers. They had to fix something, and I sent it back through my dealer and they took care of it...back in the mid 90's. I haven't changed the tubes or anything, though I probably should....my bright switch is still "backwards"--i.e., it's bright when switched "off" and not bright, but middy, when switched "on."

    I love it.
     
  17. Jul 16, 2008 #17
    synaesthesia

    synaesthesia

    Apr 13, 2004
    UK
    You can DIY and reverse the toggle bright switch, it is a physical thing rather than an electronic fix. you fit it in 180 deg around.
     
  18. Jul 17, 2008 #18
    lowphatbass

    lowphatbass **** Supporting Member

    Feb 25, 2005
    west coast
    Thanks for the responses everybody. I purchased the preamp new about ten years ago, obviously not a warranty issue. I've been a fan of James' work ever since I got an Eden VT-.25 almost 20 years ago now, well maybe 17 or 18! I understand that some companies don't excel in email correspondence. As a business(or anything really)you almost NEED a website to exist. There's a part of me that thinks if a website is "up and running" with visible links they should be usable. The bottom line is that they really don't need to hear from me in that particular format or else they would devote more resources to monitor it, and that's definitely their business decision to make, they're obviously doing well enough.
     
  19. Feb 5, 2009 #19
    slybass3000

    slybass3000 Inactive

    Nov 5, 2004
    Montréal,Qc,Canada
    Hi there, by doing a search I did find this thread which is what I'm having right now:A drop of gain once in a while and that bothers me a lot because it is a great piece of gear that I bought from James in his garage in 1990. I have an old model VTDB-201. I had the unit check by a local tube specialist and didn't find anything.So I bought a used VTBP-201 and I thought I was getting the same unit as mine but it isn't.

    Beside the cosmetic change of the switches I noticed that the Presence EQ is not voiced the same and I now have a switch in the back for the DI level I think which is Mic level and then may be -10 and +4 but I'm not sure.

    So I have two questions:
    1) Has someone found a cure for the drop?

    2) What is the difference between the VTDB and the VTBP beside what I noticed?

    Thank you

    Sly
     
  20. Feb 6, 2009 #20
    slybass3000

    slybass3000 Inactive

    Nov 5, 2004
    Montréal,Qc,Canada
    He Ho !!!!

    I can't believe after a day my post is down to page 5 already.

    No user of Demeter Pre's in here any more?


    Sly
     
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