Fried my nifty seventy?!?

Discussion in 'Amps and Cabs [BG]' started by bentheosatagen, Jun 21, 2005.

  1. OK so here's the deal, I like to circuit bend things, so naturally when I went from my microbass' headphone out into my mixer and it made crazy really high lift your brain out of your head frequencies I played with it for a while and looked at my brain. That was fun so I figured the Danelectro nifty seventy would also be an interesting journey through evil frequencies, sure for about 5 minutes it was doing about the same thing and I was enjoying myself, HOWEVER I put the guitar right up to the speaker and started twisting knobs on my guitar and went all the way up on my volume and the thing just cut out completely! Totally flatlined! The light still comes on but it doesn't produce a sound at all anymore. :crying:
    I'm happy I got to record the crazy noises BUT I really miss the clean tone of the amp now and wish it still worked. I took it apart and checked things inside and can't see anything that looks burnt but I'm wondering if anyone knows what that would blow on the inside and what I would need to replace, hopefully not the whole amp. I checked the fuse and thats still good. At least I still have my microbass but that thing barks out mean punchy tones not the soft clean tones I got from the nifty. The only thing I can think of is I bought it used and I think it should have an 8ohm speaker in it but it looks like it says 4ohms on the speaker, so I'm wondering if it just happened to die at the same time I was messing around and would have eventually died anyway.
    Well any advice is welcomed, I'm new at all this amplifier electronics business but I'm willing to rebuild it...
  2. Eric Moesle

    Eric Moesle Supporting Member

    Sep 21, 2001
    Columbus OH
    You want advice? Here's mine:

    Take the amp to a qualified electronics tech, pay to have it fixed correctly, and STOP using these things in ways not intended. Plug headphones into the headphone jack, fer chrissakes . . . . :rollno:
  3. See I knew that's what I'd get in response to my post.

    I think from the results of my experiment I'm well aware that it was a bad/stupid thing to do. But thanks for the advice...

    I posted my tale here to:
    1. Help other curious people like me avoid frying their own amps.
    2. To see if there is anything I can do to fix it on my own.

    So it's obviously a stupid thing to have done, can we get past that?
    Now, I'm sure I could take it to a tech and pay them more than I paid for it in the first place ($55 used) but that wouldn't really teach me anything 'cept how to open my wallet and let more green stuff out. At least I've immortalized the way it sounds to kill an amp in such a way, it will be featured on my next album called "Dumbass Kills An Amp"
    So any ideas how to fix this thing, or should I just get another amp that's broken in other ways and combine the working parts to make a frankenamp?
  4. The PARTS alone to fix your amp will cost more than what you paid for it. I suggest you find a good tech and donate your amp to him for parts. It sounds like you're going to NEED to have a friend who's a tech.
  5. Eric Moesle

    Eric Moesle Supporting Member

    Sep 21, 2001
    Columbus OH
    I like how people get angry when they get a rational response when they ASK for advice.

    What, you want someone to tell a total novice to open up an electronic device, change things around, then plug it back into a 120 volt power source potentially electrocuting them or burning their home down, when this person wasn't even capable of USING the darned thing properly in the first place? I don't think so . . . not going to happen.
  6. ESP-LTD


    Sep 9, 2001
    That's a new term for me.

    You will find that changing random elements in a circuit with solid state devices just turns them into garbage. A tube circuit would likely be more tolerant of misadventures (but is more likely to kill you).

    For a constructive suggestion, you might explore building your own effects and experimenting; there are plenty of references online. If the instructions seem technical and complex, that's because the subject IS technical and complex.

  7. either way, something flatlines eh
  8. I had that amp and ran into a similar situation, but what happened to mine was the volume pot is circuit board mounted and the board cracked. My uncle located a new one and soldered it back on but something else fried as a result of the broken pot(s) and the amp was pretty much irrepairable. Kind of a sucky amp anyway.
  9. So the volume knob I turned was on the guitar not the amp, and what other people call garbage I bend on the computer and turn into sweet sweet music. So think as you wish, and at least I'm not ashamed to be a novice at something and come clean with that information.

    However nobody seems to get that I didn't circuit bend the amp itself, I know that can be lethal with tubed amps and very unpleasant with a solid state, and I've never messed around inside my amp at all just took it apart for my friend to resolder stuff. But your responses are all very clever for people who don't read things thoroughly and like to ignore certain facts. I circuit bent a distortion pedal that runs on a 9 volt battery (because that wont kill you and it sounds great) through the amp and that was fabulous, sounds much like the sounds you can get from a synth modular for those of you who don't know, and with the feedback from a guitar or bass floating through all that it really does sound randomly beautiful, TO MY EARS. And I don't have any issues circuit bending anyway, evidently going out from the headphone jack to the mixer is a well known no no in the world of amplifiers, but I didn't get a manual with this amp and have never been told you couldn't do that. I've plugged many an item with a headphone out jack directly into my mixer and never had anything tweak out like this, so amps must be different in some way, anyone know how they are different and why they do tweak out? It's quite obvious now not to do it again, but I'm curious what really went on there. But I can gather that's why other amps come with a "balanced line out" and tell you it's for recording, sorry I've never owned one and only had a bass for a few months and just obtained my amps. So one is dead, big deal guys, breaking stuff almost always proves to teach a lesson and open the eyes wider. Good for me.

    So here's the deal, the guy who says I could use a friend who is a tech, I have one and that's why I'm wondering what to tell him he could do for me, he replaced one of the dohickeys that looks like a barrel on the board because it looked like there was oxidation on it and he said it could have been blown, but we're just trying to figure out what exactly happens when you simply go out from the headphone jack into the mixer and why it fries the amp. If your all so smart then tell me what exactly happens, I can explain things about computers to those I fix them for. But all I've heard so far is yeah that's stupid.

    So once again, yes I know it's not good, and it made crazy sounds, but why and what part on the amp got fried, just looking for some more info before taking it back to my friend and telling him what else he can try because he is the soldering master and worked at an electronic repair shop for about 4 years. See even they don't know and would have to find out the information but really are just familiar with electronics more than me and are tallented in the art of soldering unlike my shakey handed self.

    So am I to conclude that this forum is a bunch of people who do nothing but take their gear to other people and have them fix it? If so can someone point me to the forum where people interested in doing it yourself help eachother learn?
  10. Eric Moesle

    Eric Moesle Supporting Member

    Sep 21, 2001
    Columbus OH
    I think you'll find that people here are VERY eager to help out even total strangers. That willingness diminishes rapidly with attitude, though. I know mine did. We can tell you're a novice, so we aren't going to tell you to open it up and perform surgery. Even your "soldering guru" doesn't sound like he knows what he's doing if he can't look at the very simple guts of your amp and tell what's wrong after using a meter on various components on the circuitboard.

    No, there isn't 'something special' with amplifiers that you shouldn't use the headphone out for different things, you've just been LUCKY with doing that with other things that they haven't fried yet, or that you haven't fried yourself.

    Personally, I think STOP is quite good advice, only seconded by a reccomendation of a book on humility . . .
  11. Passinwind

    Passinwind I Know Nothing Supporting Member

    Check out Ampage at If you spend a few months following all the links, and hang in the forums, you'll know quite a bit about musical electronics eventually.

    Headphone outputs aren't all the same, and some are actually fine to run into line level devices like a mixer's line input. It's usually better to insert a 10-30dB pad inline with the line input though. Radio Shack sells some, or you can do a search and learn how to roll your own.

    A lot of bass and guitar amps are gonna dislike that hot of a signal into an instrument level input. One likely failure point is the first gain stage if it's a solid state amp. Sometimes just replacing the first opamp (if there is one) will get you back up. Have your tech scope the input signal through the first stage, and go from there. If you sent the amp into oscillation, the power amp stage or power supply could easily cook too. The lack of a blown fuse is encouraging though, you might've lucked out.


    ----------Charlie Escher
  12. Cool, so thank you very much to Passinwind who was able to actually read and comprehend my posts here. I feel like I've got a slightly better understanding of what happened and why and a direction to go in. Thanks for pointing me to Ampage I'll definitely spend some hours there picking up what I can. And I spoke to a friend of mine on the phone today who says he has one of those 10-30dB pad inlines that he doesn't use to give me, so thanks very much for the tip, but I'm thinking that using a mic for recording has produced the best sounding results, really I did this late at night and was playing with my headphones and started on to something that sounded cool I wanted to record so I couldn't mic it at that hour so I tried the headphone out and you know the rest of the story from there... So how would I know if I sent it into oscillation, if it were making noises on it's own without my moving something or turning a knob? If so then I don't think so. And the speaker having been replaced with a 4ohm rather than an 8ohm, wouldn't have eventually caused the amp to fry? My understanding of wattage and ohms and what kinds of combinations to use is pretty much non-existent. But my friend with the pad inline says he thinks if you have an amp that is built for an 8ohm speaker using a 4ohm will eventually over tax the amp and fry it, but he is speaking from car audio point of view so that may be very different, I don't know. I'll have my tech buddy check the things you mentioned and post back here if that was the case or not. So thanks again and rock out!

    In response to DeadRBassistNJ; yeah I read about that happening on harmony central to other folks before I bought mine used for $55 but figured 55 bucks isn't much so if it dies so be it, and so it be. Not really the same cause of death here though, I think we can conclude that the amp is a cheapie, but I really thought the sound from that little thing was unique and clean at low levels, but at least I got some recordings with it using the mic before I put it to death. The best sound I got from it was using my room mate's tele custom through an OCD pedal, beautiful feedback and nice crunchiness. But if it can't be fixed I'll totally buy another off ebay for around the same no sweat, and will be making a frankenamp out of the nifty's carcass if it can't be fixed, I've heard about taking old tube record players apart to build amps, and my parents have one waiting for me in their attic, perhaps it was all meant to be...

    Now to respond to our dear Eric Moesle; slack cut.

    End book 4 re:trashed nifty.
  13. Plain Old Me

    Plain Old Me

    Dec 14, 2004
    Did you happen to have phantom power on? I know it can kill a DI, but I'm not sure what it could do in the headphones jack.
  14. Trevorus


    Oct 18, 2002
    Urbana, IL
    You probably just blew the speaker. Most times, if you fry an output transitor, it'll also blow a fuse. Not always, but often times it will. Like I said, though, it just sounds like a blown speaker.
  15. Passinwind

    Passinwind I Know Nothing Supporting Member

    So how would I know if I sent it into oscillation, if it were making noises on it's own without my moving something or turning a knob?

    Maybe, but the oscillation can often be at higher frequencies than we can hear, and it'd take a tech watching with an oscillosope to really know. What matters now is getting it fixed, or at least learning something from the experience, no?

    The pad just is called a pad, or attenuator, and I was saying you put it inline with the signal, typically at one end of the cable.

    The lower impedance of the replacement speaker definitely could be to blame, and if you haven't already tried another speaker, that is the first thing I'd do.

    Sometimes I'm reluctant to get involved in this sort of thread, for a bunch of different reasons. I'm glad I could help a little, but I'd like it if you'd consider cutting Eric and the other guys a little slack. Seems like there was maybe a bit of misunderstanding on both ends, but Eric and Psycho are both good, knowledgeable guys, in my experience.

    In any case, you have to start somewhere if you want to learn about this stuff, and a relatively inexpensive, but potentially still useful piece like this one might work for that, especially if you can look over your friend's shoulder a bit. I'm glad to hear I'm not contributing to burning your house down too, that worries me a little when I encourage people toward working on electronics. :cool:

    Have fun!


    PS: you might start here before you start on Ampage: Talkbass Amp FAQ
  16. "Did you happen to have phantom power on?" - Plain Old Me

    No phantom power, doesn't that come from microphones? I was using a passive bass plugged into the amp and using a 1/4 jack mono guitar cable out from the headphone out into my mixer...

    "You probably just blew the speaker." - Trevorus

    No I didn't blow the speaker, it's fine, I hooked it up to my Microbass and it sounds fine. And it wasn't playing through the speaker at the time of death, the signal was being sent through the headphone jack into my mixer then into my computer on an m-audio audiophile 24/96 and out into my headphones.

    "...the oscillation can often be at higher frequencies than we can hear, and it'd take a tech watching with an oscillosope to really know." - Passinwind

    Well the sound it made really left me feeling like I'd had my brain massaged. The frequencies were pretty high pitched and I'm just about certain dogs for miles could hear it coming from my headphones, luckily they were around my neck and not over my ears or I may have damaged my hearing too, at least I had enough forthought to take them off my ears before turning on the amp.

    "The lower impedance of the replacement speaker definitely could be to blame, and if you haven't already tried another speaker, that is the first thing I'd do." - Passinwind

    I don't have an 8ohm speaker at the moment to try it out with, but wouldn't deadNifty at least make some sort of noise on any speaker if it could? I also have a tiny epiphone amp with a two inch speaker that says 2ohm on it, right after I had killed it I hooked deadNifty up to that little speaker and it didn't make any noise there either. But I guess I'll get my hands on an 8ohm speaker to test that out if you really think it's worth it.

    Well one thing I hadn't tried since my buddy soldered the new barrel thing (transistor?) on there was to try plugging headphones into the headphone jack, so I did and to my surprise it does make sound, a distorted sound and way way way too quiet with the amp's volume turned all the way up. So the sound it makes is like it would sound if it was going through a distortion pedal first but really really quiet. But nothing to the speaker when you unplug. So I guess I'll get my hands on an 8ohm speaker to test that out if you really think it's worth it.
  17. Passinwind

    Passinwind I Know Nothing Supporting Member

    Yeah, if you've substituted a speaker you know to be working, it's time to look elsewhere for the problem. You really need someone with an o-scope to jump in at this point.
  18. Trevorus


    Oct 18, 2002
    Urbana, IL
    yeah, you fried something. Probably in input transistor. running too much current to one of those smaller transistors will fry it easily.