open ckt idling high tension pt ac detrimental?

[hewo]

here are pics

ftp://cchftp1.honolulu.gov/5F1_Hum.pdf

account: cchftpuser
password: cchftpuser

[hewo]

pics request delivery

ftp://cchftp1.honolulu.gov/5F1_Hum.pdf

login: cchftpuser
password: cchftpuser

[Leo_Gnardo]

You have built a single ended amp. Push pull amps naturally cancel out hum from the B+, but your single tube cannot do that. So the ripple that would sound OK in a push pull, sounds hummy in a single ended. Note your plates (OT) take B+ right off the first node. Now compare to the 5E1, note the OT takes its B+ AFTER the first node and choke, over at the second node. That design will have lower hum than yours.

That's it right there, +1 Enzo. I've added CL "pre filters" to black & silver champs to knock down hum & so can you. A 22 or 47 uF cap and same choke that's used in a Twin Reverb power supply. Do it and wave hum goodbye. No need to get lost in analysis or dream up nonexistent failure modes. Couple bucks in parts and 15 minutes, you're done. And happy.

"Oh but it sounds different!" Right, yes it does. Now it's "Hubert." AKA Hum-free. Enjoy guitar unmodulated by power supply hum.

[Enzo]

Yep, but remember, there are many sources of hum, and this only affects the B+ ripple kind.

[Leo_Gnardo]

Yep, but remember, there are many sources of hum, and this only affects the B+ ripple kind.

True 'nuff, and in those amps I mentioned there were no wiring follies that raised hum level, you know the usual suspects. I found it didn't make any audible difference to go thru the trouble of re wiring filaments so they weren't "one sided" the way Fender built them, another tedious but useless exercise avoided. Hewo's amp already has balanced filament line so leave that alone, no worries.

Hey you're back to posting a lot, must be feeling better, good to see it Enzo.

[hewo]

Okay, gotta hunt down premaster electrolytic and inductor that can fit existent accommodation, electronically too, as the 5y3 does have limitations concerning how much current it can deliver without over-extending itself.
The sound will get spongy because the inductor stores and releases energy for the droop demand recovery

[R.G.]

If no energy is drawn out from pt secondary winding (s) the primary winding becomes a mere coil load to the utility company's feed of line power.
Think of the tungsten filament heating inside incandescent bulb fed by utility company ac feed.
So I think the weak link is the primary winding, as it appears just like said tungsten filament, only less resistive being copper filament

You're over-thinking it.

The time spent energized is not what kills a light bulb - what kills a light bulb is the high temperature literally boiling metal off the surface of the filament. An incandescent bulb's filament is current-limited by its resistance, and it heats up until the rising resistance from heating balances the current flow heating it.

This is not the same as a PT. The current in a PT's primary is limited to quite a low value by the inductance of the primary coil. It simply cannot heat up like the filament in a bulb. The temperature is so low that there is no wear of the copper wire, and so leaving the primary connected to the AC power line causes no significant wear to the primary wire at all. In fact, it is so little temperature rise that it causes no significant aging of the insulation, which is really what ages transformers.

So the concept of "wearing out" the primary wires is incorrect. Transformers do not age that way.

Fusing the dc ht feed to ot dramatically changes sound, why?, is fuse choking current dynamic demand (s) based on musical signal dynamics?

It does not do this. Where did you get this idea?

[Leo_Gnardo]

Okay, gotta hunt down premaster electrolytic and inductor that can fit existent accommodation, electronically too, as the 5y3 does have limitations concerning how much current it can deliver without over-extending itself.
The sound will get spongy because the inductor stores and releases energy for the droop demand recovery

Millions of amps made with choke in the power supply, never heard a complaint of spongy response or rectifier meltdowns. Put in an way oversize primary filter cap, that will wreck your tube rectifier but even with that, in actual experience (which counts for something I hope...) caps 2x in excess of the RCA manual suggested values work just fine. 10 - 20 - 30 years in daily service, the amps keep on working.

Also keep in mind Champ was conceived as a cheap no frills student amp. That's it's charm. Gussy it up too much & you have an overengineered hi fi SE rig. Beyond reducing hum all I'd recommend is play Champs thru a bigger speaker. Surprise, recorded music sounds great thru that kind of amp, like great grandpa's old livingroom radio. Just can't get disco-loud.

[Tom Phillips]

In addition you must remember that a single ended amp is class A operation and there is very little change in current draw between idle and full volume. Therefore, there is little B+ voltage sag as the amp is used. Even a fairly large resistance in the B+ line feeding the power tube will not cause audible sag like you would experience with a Class AB1 push pull output stage.

[hewo]

Here's stats: General electric 5y3, sovtek black obscured 6v6, sovtek 12ax7wa non-pewter colored plates

1) utility 120vac 60hz
2) htr leg1 3.346vac, leg2 3.347vac
3) 5y3 htr 5.46vac
4) 300ht engaged, 8ohm load:
4a) node1 ripple 3.5vac versus 279vac, 336vdc
4b) node2 ripple 0.0vac, 292vdc
5) gain&mv peaked, no musical demand:
5a) node1 ripple 3.5vac versus 284vac, 336.8vdc
5b) node2 ripple 0.0vac, 290.5vdc

[nickb]

here are pics

ftp://cchftp1.honolulu.gov/5F1_Hum.pdf

account: cchftpuser
password: cchftpuser

The pics are just chassis shots. I thought we were going to get some revelations about fuses and power supply transient response.

e.g. to save others the bother.



PS: I hope the username and password are (a) not used for anything else and (b) there is nothing else on the ftp site that shouldn't be public. If either of those are true you might want to delete the posts.

[Tom Phillips]

It is best practice to post relevant photos directly into the thread using the attachments feature that is part of the MEF software application. You will find the attachments button (Paperclip icon) on the "go advanced" reply screen.

[Enzo]

5Y3 over extending itself? It is just a two tube Champ. The 5Y3 can handle a lot more amp than that.

As was pointed out above, the Champ is a class A amp, the current draw is steady, there is no sag. And if a choke was going to make is spongy,m then so would the filter caps. They also store energy.

[hewo]

Nickb I can't find the remove button for concerned posting.
Do I ask forum moderator?
And yes, data is intracorrespondence of the outside to govt, viceversa, purged periodically.
I need a helping hand to effect transient data acquisitions, you know, pluck attack on a p90.
Have two identical textronic 60mhz dual trace (analog), galaxy s3 camera, haven't fused htac ct to earth yet, gotta create equivalent shorted fuse for comparison

The pics are just chassis shots. I thought we were going to get some revelations about fuses and power supply transient response.

e.g. to save others the bother.

[ATTACH=CONFIG]36588[/ATTACH]

PS: I hope the username and password are (a) not used for anything else and (b) there is nothing else on the ftp site that shouldn't be public. If either of those are true you might want to delete the posts.

[nickb]

Try Edit->Advanced-> Delete.

If that doesn't work edit your post to remove the offending info.