Transformer hum-pinging Maximillion

66.177.177.194

Posted on February 7, 2016 at 16:53:18

deafbykhorns
Audiophile

Posts: 1067
Location: Florida
Joined: October 17, 2003

I posted my GM 70 build earlier and everything working great except for some mechanical hum in one of my GM 70 filament supplies.
I'm using a Rod Coleman fed by bridge to CLC supply recommended by Rod.
First cap is 22,000uf 35v, choke is common mode with a couple dropper resistors.
One amp is not bad, the other one is much worse and very noisy in a silent room.
I remember Maximillion having some noise issues as well will some hammonds.

Transformer used is a HAmmond 185G20 175 20V C.T. @8.8A

Not sure if I should try to change transformer manufacturer, use isolation mounts or try a LCLC supply.
The current large cap puts a huge strain on this transformer.

Your thoughts?

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RE: Transformer hum-pinging Maximillion

Paul Joppa

13:22:52 02/08/16

RE: Transformer hum-pinging Maximillion

hennfarm

09:36:21 02/08/16

RE: That looks just like the hammond...

deafbykhorns

09:41:26 02/08/16

...

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RE: Transformer hum-pinging Maximillion

Paul Joppa

13:22:52 02/08/16

RE: Transformer hum-pinging Maximillion

hennfarm

09:36:21 02/08/16

RE: That looks just like the hammond...

deafbykhorns

09:41:26 02/08/16

RE: Transformer hum-pinging Maximillion

Triode_Kingdom

21:33:15 02/07/16

2

RE: Transformer hum-pinging Maximillion

dave slagle

07:24:08 02/08/16

RE: Transformer hum-pinging Maximillion

deafbykhorns

07:48:40 02/08/16

Toroidal

Chip647

16:58:17 02/07/16

5

RE: It is over rated

deafbykhorns

17:25:57 02/07/16

4

RE: It is over rated

Eli Duttman

18:43:38 02/07/16

Yes, and the cheap hammond transformers hum

Chip647

18:40:15 02/07/16

2

RE: Any better transformers you recommend?

deafbykhorns

08:09:54 02/08/16

RE: Any better transformers you recommend?

Eli Duttman

11:33:14 02/08/16

Toroidal , posted on February 7, 2016 at 16:58:17
Chip647 Audiophile Posts: 2652 Location: The South Joined: December 24, 2012	The Hammond u-channel mount transformers hum under heavy load. Either overrate by 100% or get a toroidal. Otherwise, mounting with rubber standoffs help. Sound-deaden the chassis., etc.

RE: It is over rated, posted on February 7, 2016 at 17:25:57
deafbykhorns Audiophile Posts: 1067 Location: Florida Joined: October 17, 2003	Over rate by 100% with ripple current? GM70 draws 3amps, transformer rated for almost 3times that amount

Yes, and the cheap hammond transformers hum, posted on February 7, 2016 at 18:40:15
Chip647 Audiophile Posts: 2652 Location: The South Joined: December 24, 2012	No magic solution other than mechanical isolation, vice grips

RE: It is over rated, posted on February 7, 2016 at 18:43:38
Eli Duttman Audiophile Posts: 10455 Location: Monroe Township, NJ Joined: March 31, 2000	Reduce the RMS rating by at least 50%, when BIG cap. I/P filters are employed. The I²R heating in the winding can get nasty. Hammond has been known, on occasion, to be "creative" in their published ratings. BTW, "singing" is a well known problem, when choke I/P filtration is employed. Sometimes, a "fudge factor" cap. will control that troublesome "singing". Eli D.

RE: Transformer hum-pinging Maximillion, posted on February 7, 2016 at 21:33:15
Triode_Kingdom Audiophile Posts: 10047 Location: Central Texas Joined: September 24, 2006	A small-value choke ahead of C1 would be very effective at reducing peak current. Whether this might work in your application depends on how much headroom is available for driving the regulator.

RE: Transformer hum-pinging Maximillion, posted on February 8, 2016 at 07:24:08
dave slagle Manufacturer Posts: 5430 Location: NYC Joined: April 27, 2001	Agreed on the single small value choke but it needs to be mentioned that a common mode choke doesn't help reduce ripple or inrush current. dave

RE: Transformer hum-pinging Maximillion, posted on February 8, 2016 at 07:48:40
deafbykhorns Audiophile Posts: 1067 Location: Florida Joined: October 17, 2003	I figured that one out when I looked at the value of this choke. I have a 10mh 5amp I might try out but it may lower my voltage too much for the Rod Coleman. May need a 22 or 24vac transformer to start out.

RE: Any better transformers you recommend?, posted on February 8, 2016 at 08:09:54
deafbykhorns Audiophile Posts: 1067 Location: Florida Joined: October 17, 2003	I would imagine the core would be much larger and may not fit.

RE: Transformer hum-pinging Maximillion, posted on February 8, 2016 at 09:36:21
hennfarm Audiophile Posts: 535 Location: Oregon Joined: October 8, 2008	Signal A41-175-20 ?

RE: That looks just like the hammond..., posted on February 8, 2016 at 09:41:26
deafbykhorns Audiophile Posts: 1067 Location: Florida Joined: October 17, 2003	Same spec too

RE: Any better transformers you recommend?, posted on February 8, 2016 at 11:33:14

Eli Duttman
Audiophile

Posts: 10455
Location: Monroe Township, NJ
Joined: March 31, 2000

Check AnTek's toriodal stuff out. The prices can't be beat. You can order with adequate VA headroom to easily support cap. I/P filtration. The $64 question, as you stated, is will the buggers fit.

Eli D.

AnTek

RE: Transformer hum-pinging Maximillion, posted on February 8, 2016 at 13:22:52
Paul Joppa Industry Professional Posts: 7296 Location: Seattle, WA Joined: April 23, 2001	Another way to reduce mechanical hum is to use a lower voltage on the primary, so that the magnetic flux stays further away from saturation. You can put the 115v primaries in series (as you would for 230v). You'd have to go to a FW bridge of course, assuming you now have a FWCT arrangement.

Tube DIY Asylum

Transformer hum-pinging Maximillion

66.177.177.194