[Rocket]

Hi,

Well after having imported a pair of Ampzilla monoblocks into Australia 9 months ago I finally have had an opportunity to listen to them in my home.  When I initially installed the amps in my system I kept blowing fuses and didn't appear to be stable with 240v 50hz power.

I sent them to a repairer in Melbourne in November 2009 and I had a lot of delays and broken promises.  I had to apply pressure to the repairer and luckily he has repaired them and I collected them today and they appear to be working fine.  I did experience a bit of buzzing in one channel of the amp but after turning it off and then on again it is working fine.  The amps have been operating for a few hours.  I'm not even sure if they are broken in as I only listened to them for a few minutes last year.

Anyway after this experience I think it may have cured my upgraditis for hifi equipment.  How do they sound?  Well as far as I can tell they sound fairly good (early days) and perhaps a little more transparent than my Son of Ampzillas.  Definitely they have a deeper bass.

I think if I could sell the amps and get my money back I'd be happy with that because the SOA' perform quite well  .

Regards

Rod

[Rocket]

Hi,

Okay so I've been listening to the amps for a few hours now.  The sound is quite refined and I can hear the inner nuances more clearly than compared with my SOA.  I blew a fuse when I turned off my preamp but the amp does seem to be more stable than before.  Blowing fuses was the main problem that I experienced before.

The problem that I am having at the moment is one of the monoblocks appears to have a noisy transformer which I can hear from my seated position.  Is this common with amplifiers?  I can hear transformer hum when I place my ear close to my Son of Ampzilla and the other monoblock.  My seated position is about 8 - 9 feet from the amps.

Regards

Rod

[Construct]

Hi,

Okay so I've been listening to the amps for a few hours now.  The sound is quite refined and I can hear the inner nuances more clearly than compared with my SOA.  I blew a fuse when I turned off my preamp but the amp does seem to be more stable than before.  Blowing fuses was the main problem that I experienced before.

The problem that I am having at the moment is one of the monoblocks appears to have a noisy transformer which I can hear from my seated position.  Is this common with amplifiers?  I can hear transformer hum when I place my ear close to my Son of Ampzilla and the other monoblock.  My seated position is about 8 - 9 feet from the amps.

Regards

Rod

The transformer may be humming at 50hz.  Iron core transformers can be pretty loud if not implemented right.  I am wondering if the fuse issue is due to poor transient suppression.  That is, nothing to pad the arc when the switch makes or breaks contact.   Is the amp grounded properly?  (could be a ground loop issue- if in a circuit with cable TV that can induce hum as well)

[DanTheMan]

I've never heard a transformer that loud FWIW.  You're sure it's the transformer?

Dan

[jtwrace]

Fairly common.  It could be DC on the line.

PS Audio and CIA make products for just this.

[Construct]

I've never heard a transformer that loud FWIW.  You're sure it's the transformer?

Dan

Ever brought US spec amps overseas?  I did...and I can say firsthand that some of the nastiness induced has to be heard to be believed.  LOUD hum from either the step down transformer from 240/50 to 120/50 needed to run the gear -or- loud hum from iron-core transformers.  Our stuff runs quiet on 60hz, but lower the cycles and ...ugh.  Sounds like a motorboat.

[NekoAudio]

There may also be something else on the circuit introducing noise into the AC line, which in turn is causing transformer hum. Removing everything else plugged into that circuit might help.

[Rocket]

Hi,

The amplifiers were configured at the factory for 240v 50hz operation.

Do you use clipsal safety switches in the US?  My house is fitting with these devices that switch off the power if there are any electrical issues.  I already have a Son of Ampzilla amplifier that I have successfully used for 5 years with no problems.  These amps have massive transformers and are rated at over 300 watts per channel and I wonder whether the operation of turning the amps on is causing the safety switch to activate?  I think there may be a relay inside the amps and it appears to activate when the amp is turned on.

I also use a monolithic power supply for my perpetual technologies dac which was located next to the ampzilla monoblock and I have moved it to another location further away.  The hum appears to have reduced quite a bit.  I can bearly hear it at the seated position. 

One of the amps appears to be quieter and the transformer appears to be the sound level as my Son of Ampzilla.  I'll try swapping the components around and see whether I can localise the problem as suggested.

Thanks for your input.

Regards

Rod

[Rocket]

Hi,

Do you think a humbuster II from PS Audio might do the trick?

Got hum? Bust it! Many pieces of equipment, from large power amplifier and projectors, to smaller preamplifier, DAC's and integrateds have a noisy transformer inside. If you can hear hum coming from inside your equipment, chances are the Humbuster III can fix it. Hum inside equipment is generally caused by DC voltage on the AC powerline. This voltage will make transformers in equipment buzz and hum. The Humbuster III will fix the problem. The HB III is capable of handling any size power requirement from the largest to the smallest power requirement. need more than one piece of equipment "busted"? Simply purchase a Juicebar II power extender and place this after the HB III. No sonic degradation or dynamic restriction with the HB III. Try it at home and if it doesn't do the job, send it back!

Thanks for your help.

Regards

Rod

[DanTheMan]

Ever brought US spec amps overseas?  I did...and I can say firsthand that some of the nastiness induced has to be heard to be believed.  LOUD hum from either the step down transformer from 240/50 to 120/50 needed to run the gear -or- loud hum from iron-core transformers.  Our stuff runs quiet on 60hz, but lower the cycles and ...ugh.  Sounds like a motorboat.

Interesting.  Thanks for the tidbit.  I may be moving to Japan in a couple years and that means new stereo equipment then.

Thanks,

Dan

[Construct]

Interesting.  Thanks for the tidbit.  I may be moving to Japan in a couple years and that means new stereo equipment then.

Thanks,

Dan

FWIW:  In Europe a buddy had a Carver M400t.  It made a horrible motorboating for several hours usage.  Then it went "poof".    (this was through an iron core step down transformer with a 115v/50hz output). 

[DanTheMan]

Yea, I wouldn't think of doing it w/o a power adapter, but it sounds dubious regardless. 

Dan