Bottlehead Forum
Bottlehead Kits => Kaiju Stereo 300B amp => Topic started by: Doug on September 13, 2018, 04:33:16 PM
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Hello Glass Heads
Kaiju up and runnin! Ive been listening to it for a few days and it sounds great, actually more than great, sounds fantastic!
My only concern is the pwr transformer has a buzz. It runs around 116 deg.F and I cant feel it vibrating and yes its bolted down good and all voltages are good. (never had a tube amp thats ran 500+ volts). Does it warrant a concern?
Doug
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If the voltages are all good, then the power transformer is happy. I would recommend an extra 1/4 turn on each of the transformer mounting bolts.
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My power transformer also buzzes. The bolts are tightened to the point where I can't turn them any more. (Maybe I need to develop more strength.) I don't feel any mechanical vibrations either. With the music on I don't notice the buzz, so I'm just going to leave it alone for now.
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This can sometimes be due to noise on the power line. I went thru three months of hell trying to get our neighbors to replace the crappy $10 dimmer they were using on about 30 bulbs in a single fixture. It was putting so much crap in the building's transformer (sits behind the stairwell to the listening room) that it buzzed so loud we couldn't use the listening room. It also permeated the gear and buzz came out the speakers too.
So you might investigate if there is something else on your power that might be putting noise on the line like a dimmer, LED bulbs, or an appliance.
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Thanks, Doc. Based on your story, I went and powered the amp off of different circuits in the house by moving it into various rooms - bedrooms, living room, family room, garage, kitchen, bathroom - while making sure other devices were off (except for the refrigerator.) None of that changed the transformer buzzing. Oh well, at least I got a good exercise from moving the beast around, as evident from my sore biceps and back. :o
-Raymond
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Save -your back. Put the Kaiju on it's expected outlet and selectively turn off/unplug items until the buzz is gone. It's going to be something causing hash in your power lines, probably not the lines(circuits) themselves unless your in an old knob and tube wired house or have trashed your circuit breakers. Also, do you have internet over powerline plugs?
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No internet over power lines. At this point, I don't think it's interference through the AC lines, at least not for me. The house (wiring) is not quite 20 years old, and I've never had problems with the wiring or breakers. I think the mechanical buzz is what it is. I have yet installed the DC filament supply. I'll give turning the bolts one more try then. Again, I don't notice the buzzing when music is playing.
-Raymond
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Thanks for the info guys!
I too think its a mechanical buzz but I am wrong most of the time. None of my other amps pwr trfmer buzz except for a old eico hf-35 I had and that transformer got hot as molten magnesium. I can also hear it through my speakers when the volume is turned down.
My house is new and there is not a house within 300 feet from me. I hooked it up through a good line conditioner today and that didnt help! Ill do more investigating tomorrow.
Doug
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I am having a similar issue. I was in the process of trouble shooting it when I saw this. So far I have tried several different outlets and a big isolation transformer, going to try a UPS tomorrow
It is a steady buzz that doesn't vary at all over time, about 48 db one foot from the amp. I have swapped several different tube amps in and none are exhibiting this problem...John
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Thanks for the quantitative data. 48dB at one foot from the amp is pretty quiet. The sticky point with these threads can be that people have different levels of sensitivity to sounds. One person's loud buzz might be another person's faint hum that is inaudible with any background noise or music playing. So sometimes it's difficult to say if two people have the same noise issue or different issues.
I'm not trying to deny that anyone is having an issue. Just trying to get a handle on what is going on. We have been discussing this among ourselves and we're kinda stumped because we have Kaijus (I use three of them in my room) and they are all very quiet.
Do these amps have the DC filament upgrade? Using stock tubes?
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Well this is a whodunit isn't it? So the causes are either physical (mechanical vibration), electrical (causing a mechanical vibration) or psychological (not enough scotch) ;)
If everyone has torqued there transformers down sufficiently and passed the voltage checks then move on to the electrical potentials outside the amp. What is the normal line voltage and what value did you set the transformer to?
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I just installed the DC filament supply. It didn't make any difference to the transformer buzz. (It did however do its job at completely removing all hum from the speakers. Very happy with that.) All tubes (and components) are stock. Line voltage = 120V when measured during the build. All voltages are within spec. The transformer bolts are as tight as I can make them.
Again, I'm not concerned about the buzz as I can't detect it when music is on.
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I have a few more data points. First, this is a bone stock build, no DC filament supply.
I turned it on and confirmed the buzz was still present, I let it rest for an hour or so, then pulled the 300B's. Powered on, no buzz. I brought it down to the shop and first took a good long look at the PS. I measured the resistors double checked the diode and cap orientation, all is correct. I was thinking that maybe too much current was drawn but I get 19.6vdc across the first 120 ohm resistor for about 160 ma, which seems about right. B+ at T14 is 460vdc, both 300b filaments are 5.3vac, at 125v mains.
In all other respects the amp works perfectly, no issues at all with any of the checks, drivers set to 175vdc.
The only thing was my kit was missing the little plastic Godzilla that is supposed to help with the wiring and hold one of the meter leads for you, I had to substitute a kitten. but I figure ounce for ounce, Tokyo is toast. Hope this helps, let me know if you would like me to take more measurements...John
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I sprung for the dc filament kit this morning to verify the buzz is not reaching the speakers.
I also like this amp as it doesnt generate a whole lot heat, especially down here in the arm pit of the states (106 deg heat index today(.
When trouble shooting is there any not to do when powering up the beast (running with out inputs, speaker connections or tubes removed)?
Doug
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You can fire up a Kaiju without anything connected to the inputs or outputs. If there are no 300B tubes in the sockets, the raw B+ will be very high, but still way under the ratings of the power supply caps.
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Just as another datapoint, I finished my Kaiju a couple of weeks ago. I ordered during the last sale. There's zero transformer hum or vibration. One day I was chasing a 60Hz hum between channels, swapping tubes and changing outlets, but it was due to a cleaning pump that had been plugged into the house circuit.
I do have a low but noticeable hum at the speakers (Zu Soul Supreme which are 16 Ohm and 97dB/W sensitivity). I've ordered the DC supply which I anticipate will clean that up.
And by the way, it sounds fantastic and can push the Zu's to high volume very easily, much more powerful sounding the First Watt F3 that's been in the system lately which is rated as 10W into 16 ohms. The Kaiju has a jump factor that is almost shocking for a 300B SET amp but with that holographic presentation that I'm always looking for. It think the Kaiju also pushes deeper into the bass with more authority.
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it was due to a cleaning pump that had been plugged into the house circuit.
I have a foundation water collection system with a sump pump that will throw some noise into my system as well.
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I have nothing useful to add to this thread but just wanted to say I love the kitten picture!
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So today I removed the shoulder washers and torque the mounting hardware down as far as I thought it would stand, and let it sit for awhile then I reinstalled everything and retorqued everything to a more prudent level. The buzz is still there. At this point I am looking for suggestions ...John