Hartke HyDrive 112C buzz/distortion problem

KryZehk

KryZehk

Sep 1, 2022
7
2
801
Spain.
#1
Hello! This is my first post in TalkBass although I've been reading you guys for years.

So, today I bought a Hartke Hydrive 112C for a really good price, and when I was omw to getting it (200KM in car), the seller called me to say that the amp was doing a strange buzz on low frequencies while the amp had a high input signal. In compensation for this problem, he gave me another amp for the same price.

When I came back home, I disassembled the amp, both the head and the cone, to look up for burnt circuits (the amp had a recent electronical maintenance), bad soldering, unplugged cables, etc. The head seems just fine, and the cone is in perfect shape, at least at naked eye view. Took out the cone, cleaned it, put it back in, tightened the screws, and then I tested the amp and here's what I got:

The cone doesn't get to notably vibrate unless I put the master volume knob at 75% or more. When it's gonna start vibrating it does like an electrical buzz (I'll leave an audio recording with the sound), but only on low frequencies (5th and 4th string). Also, it doesn't sound loud at all: Compared to the Warwick Take 12.1 (80w). The Hartke (250w) needs to be at full volume to do what the Warwick does at 20-25% of master volume.

When I plug it via DI XLR, it sounds fine, so I guess the preamp works 100% (although I get a 2 to 5db decrease in sound when I activate the Drive module it has integrated).

I don't have any other cab/head to try that matches in watts and ohms, so I don't really know what else I can do.

Also, I tried with 2 different basses, one active and one passive, so it can't be a dying battery. I'd really love to fix this myself and not having to pay a specialist, just because I'm in a low budget, and also think this may help me learn a little bit more on how gear works.

Thanks everyone for reading through this, and I hope I explained myself right, because English is not my main language.
 

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#2
If he's overdriving the speaker or clipping the power amp, that's what will happen.

The comparison between the two amps may not be valid because you don't know the sensitivity of the two speakers. For example, if the Warwick speaker is 3dB more sensitive (likely), then the effective power of the Warwick compared to the Hartke would be 80 watts x +3dB = 160 watts compared to 250 watts (assuming that Hartke has a 4 ohm speaker). That's not much of a difference now.

Also, if the Hartke has an 8 ohm speaker installed (I can't find the specs of the specific speaker used in the combo version), than it's real power will be more like 125-150 watts.

The different tapers of the volume controls can also account for large variations between different models and manufacturers.

There's more to this than you might realize, which is why a "specialist" might be necessary. If you don't understand electronics and how to service them SAFELY, or what I posted above, you should not be attempting to repair your combo beyond the basic operational testing of the features. Most damage will be completely invisible to the naked eye, and that's assuming there really is a defect.

My gut feeling is that there isn't, and maybe the Warwick amp is just a better choice for your needs and taste.
 
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#3
Make sure the desicant pak that came with the speaker when shipped isnt still hanging out inside the cabinet, myself as well as a couple other TBers have had the same problem.(poor shipping practice)The desicant pack busted open in shipping and some of the balls became stuck on the inside of the speaker surround making a terrible buzzing sound,as strange as it may sound it did really happen.And im not a specialist either.
 
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#4
MartinLY said:
Make sure the desicant pak that came with the speaker when shipped isnt still hanging out inside the cabinet, myself as well as a couple other TBers have had the same problem.(poor shipping practice)The desicant pack busted open in shipping and some of the balls became stuck on the inside of the speaker surround making a terrible buzzing sound,as strange as it may sound it did really happen.And im not a specialist either.
Click to expand...
Certainly a possibility, but that’s an odd one!
 
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#5
I listened to the clip, that sounds pretty brutal. My uneducated guess would be a loose solder point that’s cutting out when the low frequencies shake it enough. You can isolate the speaker or power amp though. First, you should be able to take the cables out of the hartke and the Warwick and swap them, using the amp from the Warwick with the hartke speaker. If that sounds fine, then move in to the power amp. Plug directly in to the effects return, which should bypass the preamp and go straight to the power amp. If you don’t get enough volume, you can also plug the bass into the Warwick and take a cable from the send of the Warwick to the return of the hartke.

Good luck!
 
#7
Hello guys!

MartinLY said:
Make sure the desicant pak that came with the speaker when shipped isnt still hanging out inside the cabinet, myself as well as a couple other TBers have had the same problem.(poor shipping practice)The desicant pack busted open in shipping and some of the balls became stuck on the inside of the speaker surround making a terrible buzzing sound,as strange as it may sound it did really happen.And im not a specialist either.
Click to expand...

Already did some research and thought it could be this, but it isn't.

PotsdamBass8 said:
I listened to the clip, that sounds pretty brutal. My uneducated guess would be a loose solder point that’s cutting out when the low frequencies shake it enough. You can isolate the speaker or power amp though. First, you should be able to take the cables out of the hartke and the Warwick and swap them, using the amp from the Warwick with the hartke speaker. If that sounds fine, then move in to the power amp. Plug directly in to the effects return, which should bypass the preamp and go straight to the power amp. If you don’t get enough volume, you can also plug the bass into the Warwick and take a cable from the send of the Warwick to the return of the hartke.

Good luck!
Click to expand...

I'm gonna spend the rest of the morning trying this, thanks for the help! Also, I spoke with a friend that fixed some amps, and he told me that it's most probably going to be the power amp section, and he said that's expensive to fix :crying::crying::crying:
 
#8
PotsdamBass8 said:
I listened to the clip, that sounds pretty brutal. My uneducated guess would be a loose solder point that’s cutting out when the low frequencies shake it enough.
Click to expand...

I'm going to second this one because the sound is otherwise clean, ruling out an overheated and loose voice coil as a dominant cause (I had that once, it sounds more like a fuzz box! Nice, but not when you don't want it..).

When yours is distorted, it's also very complex, more so than gain stage clipping might be. It sounds to me like a mechanical failure being that complex and scratchy a sound, so either a solder joint, or metal fatigue in the thin braid that goes to between the cone and the terminal. Either way, a bit of flux from a flux-dispensing pen, and a brief dab with a soldering iron, might be enough to fix it, but it might need a tiny bit more solder too, just enough to cover the need to bind any frayed strands if you find them.

Check other connections to the cab because vibration might hit those too. Also, if your amp has parts that run hot, that can cause a solder joint to fail. If there is any chance your cab is vibrating that amp, it's worth looking for that too if resoldering the speaker braid doesn't help.

EDIT: That's a WAV, in an MP3's clothing. :)
 
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#10
PotsdamBass8 said:
I listened to the clip, that sounds pretty brutal. My uneducated guess would be a loose solder point that’s cutting out when the low frequencies shake it enough. You can isolate the speaker or power amp though. First, you should be able to take the cables out of the hartke and the Warwick and swap them, using the amp from the Warwick with the hartke speaker. If that sounds fine, then move in to the power amp. Plug directly in to the effects return, which should bypass the preamp and go straight to the power amp. If you don’t get enough volume, you can also plug the bass into the Warwick and take a cable from the send of the Warwick to the return of the hartke.

Good luck!
Click to expand...

So... I tried to plug the warwick amp into the Hartke cone, and one of the Warwick's fuses broke... I think that's kinda strange, as the WW is only 80w, and I had the volume on 50%....
 
#12
Lostgallifreyan said:
Any chance you were driving 4 ohms with an amp that is meant to drive 8 ohms?
Click to expand...
The Warwick is meant to drive 4 ohms, and the hartke cone is made to be driven either with 4 or 8 ohms, so I don't really know what happened...

EDIT: I forgot to add that, when I plugged the Warwick amp into the Hartke cone, It sounded distorted, but not like with the Hartke head, it sounded more like a real overdrive. I guess this is because the WW amp couldn't provide enough power to move the Hartke cone?

I guess I'll be handling the Hartke to a professional for him to figure out, I don't wan't to mess it up tbh... Although, If any of u guys see something clear with the video and audio, let me know, thanks every1!
 
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#13
KryZehk said:
I'm not sure, but I already ordered the fuse...

I guess I'll be handling the Hartke to a professional for him to figure out, I don't wan't to mess it up tbh... Although, If any of u guys see something clear with the video and audio, let me know, thanks every1!
Click to expand...

No problem, if you're replacing with same type fuse, the worst that might happen is it could blow again if there is too much load on the amp. Just bear in mind that they don't blow for no reason, something needs to be checked..
 
#14
You didn’t have the two amps plugged into the same speaker at the same time did you?

I think this might be a good time to stop messing around with something you do not understand before you cause even more damage. You now have 2 problems to fix.

For a QUALIFIED service tech, the Hartke is not a difficult amp to repair. It is not repairable by an end user without a real understanding of electronics however.
 
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#16
Yes, the thermal compound all over the place is a good indicator that if they couldn't care about this, there are a lot of other things that they likely didn't care about either.

Now there are 2 amps with 2 problems.
 
#17
S-Bigbottom said:
Who did this recent Maintenance and why?

They did not do a good job, if it was a shop there may be a warranty.

Sorry, the seller dumped his junk on you. This is not a good deal as they made it seem. :(

Any chance of getting your money back?
Click to expand...

I really think I still have a chance to make it a good deal, if the repair isn't too expensive... It got maintenance cause the seller wanted it to be in good shape before selling it. I saw the bill from the repair workshop. I also tried to get in contact with them, but they won't answer.


agedhorse said:
Yes, the thermal compound all over the place is a good indicator that if they couldn't care about this, there are a lot of other things that they likely didn't care about either.

Now there are 2 amps with 2 problems.
Click to expand...

Welp, the Warwick problem is an easy fix, only replacing a fuse, so It's not a real problem. The Hartke Pre works fine, and I think the speaker too, so it's going to be something from the power amp section. I'll post again after taking it to repair and I'll leave whatever the technician tells me. Hope this can help other people in the future.
 
#19
The Hartke got fixed finally. It seems it had some part of the power amp section broken, and a weld too. It was only 40 euros to fix it, so it's definitely worth it. I'll have to fix the Warwick tho, and It'll be a bit more expensive, like 70 euros or so. I'll be able to get my money back selling the Warwick :)
 
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