1. Please take 30 seconds to register your free account to remove most ads, post topics, make friends, earn reward points at our store, and more!  

Problem with Kern IP-777, electronic experts needed!

Discussion in 'Amps and Cabs [BG]' started by weeks82, Feb 9, 2004.

  1. weeks82


    Oct 10, 2001
    This weekend I was cleaning up the cabling in my rack. I have a Kern IP-777 with the wall wart plug. After finishing with the cables I noticed the Kerns powerlight was dimmer than usual. The power light was glowing dim, and when i flipped standby to on, both lights dimmed. Plugged in there was barely any volume. I check the adapter with a voltmeter and it was reading a very miniaml voltage (about 1 or less). I figured the adapter was blown, so i went to Radio Shack and bought a new adapter, making sure to get the exact same volts and amps (12 volt 1.5 amp). I hooked up the adapter and still have the same problem. The lights glow properly now though. There minimal output off the 1/4" and the XLR out. Also the transformer gets very hot, burning hot after about 5-10 minutes. Im guessing the transformer is blown. Could anything else have been damaged? Any thoughts ?

    Is this something I would be able to fix myself( if i could get parts) ? I'm fairly decent at electronics.

    If that fails, I guess i will probably send it back to Kern. I think i've seen someone post an email address or phone number for Kern around here, if so could you post it. If it comes down to that Id like to have it converted to a normal plug also.

    Any help/insight would be great as I need to get this fixed ASAP.


  2. KB


    Jan 13, 2000
    Chapel Hill, NC
    From their site:


    PHONE: 847-491-0500
    Flynn Guitars and Music
    2522 Green Bay Road
    Evanston, IL 60201


    U.S. MAIL:
    KERN Electro-Dynamic Ltd.
    P.O. Box 16
    Prospect Heights, IL 60070-0016



    contact info for them. You could see if they could send another transformer to you.
  3. notanaggie

    notanaggie Guest

    Sep 30, 2003
    It sounds like the original wall wart might have been killed by the unit. it sounds like the unit has a problem, possibly a relatively simple one in the power supply.

    Hot transformer suggests a lot of extra current being drawn. That suggests a "short" in the unit. It does, in fact, "sound like a short"*.

    Assuming no warranty issues, if it were me, I would pop the top on the unit and see if I could find the "short" etc in the power supply. Or elesewhere, if nothing obvious showed up there.

    Most problems of drawing extra current end up to be power supply problems, like one shorted diode in the bridge rectifier, etc. Depends how it is set up, some have voltage multiplier setups, etc.

    * Back in my bad old retail repair days, customers used to bring in units, plonk 'em down on the counter, and announce "this box is shorted out!".
    Didn't matter if it was just a scratchy control, it was "shorted out". Got to be a standing joke, we'd let the customer leave, put our ear to the unit, listen a moment, and solemnly announce "sounds like a short"........
  4. BillyB_from_LZ


    Sep 7, 2000
    I work not too far from Evanston and could go visit Flynn if need be...
  5. weeks82


    Oct 10, 2001
    Thanks for the help guys. I tried the email from the Kern page with no response as of yet. I'll try and contact Flynn tommorow. I've poked around for a short in the preamp and didn't find anything, but i think ill have another look.

    I may not have been clear, when I say the transformer is getting hot i mean the transformer in the preamp, not the AC adapter

    thanks again.

  6. To Brian:

    Les and I are very good friends. He was responsible for my meeting my wife. I just called him at home and left a message asking him to call me back in regard to your problem. I will try to put the two of you in contact directly. Les is an electronics genius and one of the nicest people I know. Feel free to contact me directly either here at talk bass or through my e-mail address at MJBruso@aol.com. Take care.

  7. BillyB_from_LZ


    Sep 7, 2000
    Bravo Mark!!! Just one more reason why TalkBass is such a wonderful place to hang out...
  8. weeks82


    Oct 10, 2001
    Much thanks to Mark, he has put me in contact with Les and hopefully ill have this fixed soon. Thanks to all for the help.

  9. I am glad that I was able to help. I only like to spend my money on companies that treat musicians with respect and that behave ethically. Kern is just such a company.

    Much of the music world is so vicious that it is nice to have a place to come where people give freely of themselves to try to help others. That tradition at talk bass is a proud one.

    My wife asked me to switch from guitar to bass just about two years ago (she is a professional blues singer) for two reasons: first because good bass players are so hard to find, and second because the bass is the most important instrument in the band to her. The good people here at talk bass have helped make me very happy with the decision.
  10. Its a shame about your Kern, I've heard great things about these preamps and would still like to try one but I thought that these things were top of the line "audiophile" quality using high end components. Also the whole "wallwart" thing is kind of dumb and I would look for some good NOS pre tubes to really make it sing. Good Luck!
  11. I understand that you can get an older wall wart IP-777 converted to the newer style unit for around $25.

    I know when I got my 777 Brian Barrett was very helpful in communicating with Henry Kern.

    The 777 is a wonderful preamp. I hope you get your problem resolved easily.


  12. mgmadian


    Feb 4, 2002
    Austin, TX
    I use a Kern pre and highly recommend it, very phat/big sound. They've come standard with the AC adapter built-in for a few years. Mine apparently had a wall-wart originally, but previous owner sent it back to Henry Kern and had the wall-wart moved onboard for $50. Henry's pretty easy to reach on the phone and is always helpful.

    One thing to recommend: I replaced the stock ElectroHarmonix 12AX7-EH tubes with a pair of Sovtek 5751s and really liked the result -- clearer, a bit more modern. THe original tubes sound great too, but I prefer the 5751s.
  13. There are a few points that must be cleared up:

    (1) Henry Kern is no longer invoved with Kern Engineering. Les Plopa has taken over the company completely and moved it from Wisconsin to Illinois. The above addresses (both web and mail for Kern Electro-Dynamic Ltd.) are the correct ones.

    (2) Les is in the process of changing the way in which service on the units is done so that it will go directly through him. If you have any service issues, contact Les at the above web or P.O. Box addresses, or you may contact me, Blues Basser, here at talk bass, or you may e-mail me directly at MJBruso@aol.com. I can get a hold of Les quickly in case you are not able to do so. Also, Les will allow you to mail the units directly to him for service. He is the only person who will be repairing the Kern IP-777 in order to keep the service standards up to his specifications.

    (3) Les will retrofit the older units with a wall wart for $50. This price will include other power supply improvements as well.

    (4) There are 3 tubes in the IP-777: two preamp tubes and one line driver. The preamp tubes are 12AX7-EH tubes and the line driver is a NOS (Phillips or GE) 12AU7 tube. The 5751 tubes have lower gain than the standard tubes and thus can work well with high output instuments.

    (5) The components in the Kern IP-777 are of the highest quality. The capacitors are Solen capacitors, the transformers are made by TMI (Matchless, Audio Research, Harmon Kardon), the capacitor caps are Illinois capacitor caps, the resistors are all 1-2% flame proof metal film rated at 10 times their operating conditions, the pots are CTS pots, and the switches are E-switches that cost $5 a piece to buy. The chassis is made from cold rolled steel that is welded for stability.

    Trust me when I tell you that there are few companies in existence that are more obsessed about getting the details right than Kern. If I can be of any assistance with regard to Kern do not hesitate to contact me. Les is one of the best people I have known in my life and it is a privilege to be able to help him out.

  14. mgmadian


    Feb 4, 2002
    Austin, TX
    Great to know... thanks Mark! Amen to the quality design of the IP-777. I've had mine now for about 3 years and love the sound. I've had a chance to A/B it (with my QSC 2402) against a number of well-regarded heads (Boogie 400+, Boogie MPulse 600, SWR 900, a few others) and consistently heard a phatness and presence in the IP-777/QSC that was not present in the others.
  15. Great thread, I too have had my Kern 2 1/2 3 yrs. Fitted it with Syl 5751's, run it flat and I love it! Brian Barrett was a huge help.
  16. boogiebass


    Aug 16, 2000
    I dealt directly with Henry last year when I had my 777 modded to get rid of the wall wart. He also threw in an upgrade to the power supply for a very reasonable price (something like $40 which included return shipping) and recommended tubes that brought out a more modern tone (i.e. EH over the vintage NOS that were in there).

    On the downside, he promised the preamp would be shipped numerous times and then didn't do it. He's apparently one of those guys that has trouble telling the truth to customers regarding his workload, priorities, etc. Eventually, he flat-out lied to me and said the preamp was shipped on a certain date when it wasn't. It took me months to get it back but when I finally did, the work was top-notch.

    While I wouldn't have Henry work on anything again, I highly recommed the 777. Great preamp.

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.