John Curl's Blowtorch preamplifier part III

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Yeah however they claim the contacts are perfect and that the fuses are directional. They also believe in sound improvements by "hiend" fuses, best gold plated.

Actually a friend suggested marketing gold plated fuses to the audiophile crowd well before anyone else was doing it. The problems were finding a decent quality source then meeting UL and other standards. It was just assumed folks would buy them if they were high priced.
 
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At high power, cap input supplies will draw high value Phaversine current. The losses at peak will be high.

When the fuse resistance is increased, the haversine peak is lower, and the charging current is spread out over more time.

Ed, your powerless calculations will only apply to a pure resistive draw accurately.

Dan, I suspect you are violating code. Also, you may be making your house appliances more susceptible to lightning damage.

jn
 
JN,

Already showed a charging waveform that had the peak current tips bend a bit. The charging time does depend on the effective series resistive but since it doesn't start until the charging voltage exceeds the voltage on the capacitor the time is already short.

As the capacitor charges the transformer unloads a bit and the voltage then rises a bit but it still does not reach the same peak as if there were no AC mains resistive loss.

Next my use of haversines is for spherical calculations, not sure how you are using it here.
 
One of the old tests on televisions under warranty was before going on a service call to ask the customer to try pulling out the AC plug, turning it over and plugging it back in to see if that solved the problem. Frequently they would respond that it did.

Saved a lot of service calls for dead televisions that were just unplugged.

With a hot chassis it could end service calls with dead customers.
 
Because TVs were new and radios didn't get service calls, they were carry in service by that time.

The point was, why does this only work on tvs. How many fridges, stoves, were "fixed" by this method? Never heard of that, and a fridge turns on and off 100 times a day. Plugs for 120v are a completly different thing than for 1volt (RCAs).
I remember my first days in a recording studio regularly cleaning 100 patch cords with brasso
 
Scott,

Hot chassis had polarized plugs. Turning it over was never important. If the caller was asked is it plugged in, they would always say "yes." It was just an effective way to be sure it was really plugged in.

CB,

TVs were often moved for cleaning, white goods rarely.


This is the night of the year when the movie "Night of the Living Dead" is presented on some channel almost around the clock. The guy in the basement (Karl Hardman) and the woman (Marilyn Eastman) with him were old friends. I know or knew quite a few of the folks involved. Never met the actor playing the little girl. (Karl's daughter.)
 
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The way things were made in the past was to insulate the chassis from the user with a non conductive case and plastic knobs. This way, it did not matter which way a plug was put in. I had both radios (all American 5) and TV's that were built around this principle. Later, they polarized the plugs by making one pin larger than the other. Even UL accepted this back in the early '60's.
 
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back in the day..... I had a pair of Magapan speakers and I had heard subtle distortion in one side/channel. I reversed amp channels and still that same side had distortion. So, it ws something inside the speaker.

The cloth cover was stapled to frame. But, I could not stand to listen to it. Some would maybe not notice but i listen critically to the sound.

I cut the cloth near the speaker terminals and found a cap and and a fuse with fuse holder.

After I cleaned the fuse and holder, the distortion was gone. I replaced their fuse holder with gold plated one and never had a contact/corrosion issue again.



Yes, gold plated contact holders and fuses were available way back then, too. From Little-Fuse company and most all fuse mfrs.

Today I solder fuses in place as they should never blow unless there is a failure. Minimum is to replace with gold plated clip type holders.

https://m.littelfuse.com/~/media/el...s/littelfuse_fuse_block_658_datasheet.pdf.pdf




Oops. I am not here.


THx-RNMarsh
 
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So it is not unreasonable as originally expressed for an audio amplifier to perform differently with the fuse bypassed. It might sound different and would certainly be unsafe. A good compromise would be to change the fuse to one of the lower resistance name brand ones in the 5 x 20 mm package with the same current ratings.
Hi Ed, this all ties in with What's inside a high end power cable?.

BTW, did you return to the guitar cable experiment ?.


Dan.


 
Dan, I suspect you are violating code. Also, you may be making your house appliances more susceptible to lightning damage.
Possibly violating code but the MEN link inductor is comprised 3mm diam wire so that would be the last to fail.
Lightning around here is pretty rare so I am prepared to accept that risk, and in any case anything in this house that is not in use is switched off or more usually unplugged.
When I am hi-fi listening usually the only other item plugged in is the fridge......no smps psu's, nothing to inject noise back onto the mains.
Under these conditions of dead quiet AC is when I prove my 'odd' findings like cable direction or 75R across speaker lines or Goop etc.

I am willing to bet that nobody else here ever runs their house with the only load being the Hi-Fi DUT.......I find laptop chargers, phone chargers, iPad chargers, router psu's, washing machine at idle etc are audible more especially when on the same AC circuit as the Hi-Fi.
It is worth the experiment during critical listening to disconnect/isolate all other loads in the house including the fridge and kitchen oven with electronic display/control......the results in improvement in low level detail and musicality may come as surprise !.
And objectors please direct your comments to Mr Denon and you try to tell him that his industry standard power supply/power regulation stages are 'badly designed' and/or inadequate.

Dan.
 
... I am willing to bet that nobody else here ever runs their house with the only load being the Hi-Fi DUT...
IIRC I once was chasing an RFI source, had >150 mv fuzzy MHz envelope repeating at 50 Hz at PSU+. Had everything out including the fridge except for the amp and scope, still had ~ 10-15 mv of the weird RF envelope. Quite a while ago, before the spread of smartphones here. Could not remember enough details. One of the reason I prefer shielded split bobbin EI to toroids.
Yesterday I ran an experiment in altering the house wiring protective earthing arrangement...
Risky alteration I would avoid unless no other solution can be found. As you noted, ground stakes of houses around your area are not ideal, your good earth will absorb substantial percentage of neutral current of your neighborhood should any failure happened to the neutral line to the distribution transformer.
 
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