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Warwick Hellborg Power Amp - distortion


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I've had a Warwick Hellborg pre and power rig for around 18 months (bought on here).  The pre is outrageously good, as is the power amp when it works properly.  In my opinion, the power amp introduces some distortion behind each note - it's not a massive amount but to me it's there.  I've had this at two of the top amp gurus in the North West and both say there isn't any distortion.  Indeed, on a scope, there's no visible distortion whatsoever.  I've spent a fair amount of cash on getting this sorted but to no avail.  I've even been told that my bass settings (mid scooped but with a lot of bass and bridge pickup favoured) could be part of the issue.  I don't buy the latter as it doesn't seem to be a problem with other amps.  I know that the Hellborg principles are a little unusual - transformer in the power amp output - but any advice on what might be introducing distortion would be very welcome.  I've tried various pres into the power amp and various basses and cabs and to me, the distortion is always present.  Any advice too on a brilliant tech near Manchester that might deal with SS amps would be helpful (I've tried two of the big names in the ongoing list but the results haven't been great).  Any opinions or advice are very welcome - I'm coming to the end of my patience with this! 

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Thanks Fretmeister, I'd agree that the scope is usually an important arbiter - I can definitely hear the distortion but nothing appears on the scope.  I've tried all the permutations - different preamps, different cabs, leads, different tone settings on amps and bass but still it's there.  I'm getting to the point of selling for spares or repair - I'd love to have the amp fixed - the techs have commented on what a brilliant, over-engineered amp it is but I don't really want to throw any more money at it.

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  • 9 months later...

The transformer needs to warm up.

More if the amp was in a cold dump place.

This is something that in a tube amp with its stand by switch and heat from the tubes takes less time....

Just start it 10-15 minutes before use and the distortion will go.

If the amp is not in a humid cold place this will not happen. 

Other reason can be a damaged transformer for mismatched Impedance switch selection at some point during use. More on the 250 stereo version with the bridge option that changes the Impedance switch position and makes confusing when connecting cabs.

This is not a fool proof bass system.

You need to know what you doing.

Edited by musicavenger
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Thanks musicavenger, an interesting point. I tried every permutation - soaks, warm-up etc. But the distortion remained. A few of us found the same thing - my 500 is now gone (I bought a new 2x250 and it did exactly the same thing - so that was returned). I’m now using the power section of a db750 with a Hellborg pre - wonderful (in terms of my personal tone goals)

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19 hours ago, musicavenger said:

Unfortunately the key secret of the Hellborg System is the sound of the output transformer, more than the preamp that is also high quality.

You wont get the same transient attack and punch with any other amplifier. 

I have tried. 

 

I suspect that you’re absolutely correct here and the OT is a key ingredient in the sound. After trying the pre/power combo in the studio, rehearsal rooms and even in the lab, I had to conclude that it’s a sound that really doesn’t work for me. I play Alembics and the fur/distortion is not something that I welcome. Not everyone can hear it, and some that can find it desirable. For me, sadly not and the transients from the db750 are pretty impressive.

For anybody with an interest in experimentation, there’s a Hellborg 500 on BC for £200 at the moment and I think that Thomann are still knocking them out new at £500. The distortion-transients compromise isn’t something that works for me... and I really tried to love the Hellborg power amp

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  • 4 years later...

Sorry for resurrecting this thread, but...

 

I hear you, three! I've been through Hellborg 4 power amps, all three types, and yes, they do distort.

 

But it's not your common distortion (signal clipping, tube amp "harmonic enrichment" etc.): it's intermodulation distortion.

 

I sent in my original mono500 three times, under warranty, fortunately. Warwick Germany looked "into it", couldn't find distortion and returned my amp without replacing one thing. The third time around Warwick sent me a different amp in exchange - which distorted the same way. Yes.

 

Unfortunately, I had forgotten to communicate that the problem was IMD. Then again the technician who worked for Warwick (certainly not *at* Warwick) did not speak German at all, only broken English. So some Warwick help desk employee "translated" my notes/E-mails  into "English" for the technician... (They were so proud of this process, they even sent me a video of it.)  

 

I may have to mention that: I do not (/cannot afford to) play Alembics, Foderas etc. And yet, I regularly got IMD out of all three types of Hellborg power amps with every single bass I picked up. Passive, active, flat eq-ed preamp, different preamps, extreme eq settings, different strings, eq by onboard preamps only (active basses directly into the Hellborg power amps), different loudspeakers, different rooms. I was able to record it off of a loudspeaker with my iPhone7, too!  Then I recorded the same "sonically critical" riff from my TC looper through another power amp as well. A/B-ing the two recordings showed the differences almost as clearly as the difference between night and day.

Store staff could hear it through gear at their store and we could discern the two recordings on my iPhone7 (back then...) through their boom box behind the counter.

 

So, it's not our ears. It's about the technicians who don't look with their scopes and what-not for the correct *type* of distortion. 

 

I plan on contacting the company in Germany which designed and built(!) all of the Hellborg amps for Warwick, and ask them about possible modifications that may, hopefully, eliminate the problem. I reckon it may soon become somewhat awkward, as I will be coming in as an end user hitting up those seasoned engineers about some of their "old mistakes". 

 

Why do this? Because I totally dig the sound signature of the power amps - minus that freaking IMD, of course.

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