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2359glenn | studio - Page 339

post #5071 of 10366
Quote:
Originally Posted by Xcalibur255 View Post
 

 

I would like to get some custom O'netics transformers from Bud Purvine for my future 300B monoblocks, but maybe it would be easier to just do Lundahl again.  Glenn seemed to really like the Lundahl main power transformers too.

 

I still will use the Lundahl Power transformer on all amps that have output transformers. No mater what the cost of them are.

So the output transformer don't pick up hum from the power transformer Lundahl have very little magnetic field around them.

post #5072 of 10366

My 300b does make some noise, luckily it's not audible when listening

post #5073 of 10366

That is why I am using only Lundahl power/mains transformers from nowon

Tyrells amp is dead silent no hum pickup from the power transformer.

Your R core transformer is not that bad as E-I transformers I will only use

these with OTL amps from now on.

OTLs have no output transformers to pick up the hum.

post #5074 of 10366

Anything I can physically do to reduce it maybe? Like change the feet or something? (A suggestion from Stavros)

post #5075 of 10366
Quote:
Originally Posted by Ultrainferno View Post
 

Anything I can physically do to reduce it maybe? Like change the feet or something? (A suggestion from Stavros)

You can try to change the feet the transformer could be vibrating at 50Hz and be picked up by the tubes.

Make sure you take off the bottom plate and remove the nuts or you will break off the screws trying to remove them.

The plate is threaded and the nut locks it.

But it is probably the magnetic field being picked up by the output transformers. This is why I am switching to

Lundalh power/mains transformers.They do not radiate a magnetic field like other transformers.

You can look in the Leben CS300 thread they have the same problem and that is a very expensive amp with

a cheap power supply. But it is the power/maines transformer that is causing the problem.

post #5076 of 10366
Don't get me wrong, the buzz is not audible trough the speakers or headphones (luckily)n like I said it is the best sounding amp for my he-500. You can just hear the amp buzz on the table.

So maybe changing the feet might decrease the contact with the table and maybe that would reduce the buzzing impact
post #5077 of 10366

It seems that your are talking about the mechanical hum not hum thru the lines. If this happens to me I sometimes check the mounting screws for the transformer making sure they are tight and/or use rubber washers. Tall rubber feet for the bottom of the unit is something that I would look into.

post #5078 of 10366
Quote:
Originally Posted by Ultrainferno View Post

Don't get me wrong, the buzz is not audible trough the speakers or headphones (luckily)n like I said it is the best sounding amp for my he-500. You can just hear the amp buzz on the table.

So maybe changing the feet might decrease the contact with the table and maybe that would reduce the buzzing impact

Changing the feet might do it I guess the transformer is vibrating at 50Hz  I didn't notice this at 60Hz in the US

but maybe it was there and I didn't notice it. And the table I had it on when listening had a Slate top that weighs

a tun. Don't think it can transfer vibrations into that.

 

Also maybe putting something under the amp will stop it.

 

Just remember to remove the bottom and remove the nuts before trying to unscrew the feet

post #5079 of 10366
I can attest that my amp is dead silent. The noise floor is remarkably low for a tube amp. The 45 tubes themselves seem to make a high pitch whine, not in the headphones but physically in a way you can hear anywhere in the room. Might just be these particular tubes.
post #5080 of 10366

My Glenn Amp 300B mono blocks sound incredibly fine now. The bass has opened up and the highs are clean without rolling off. Midrange is excellent too. But it took about 6 months to settle on a tube: The Russian 5U4G black plate rectifier. Since I was rolling rectifiers I think that the Russians just needed time to break in. Also up there with the Russian is the RK-60. Very close in sound but ever so slightly warmer. The next are the GZ37 and the Tung-Sol 5U4GB. The GZ37 are the warmest and give the amp a little more oomph.

 

There is a slight hum that comes out of the speakers but you can't hear it from where I am sitting which is 5 feet away from the Zu Audio Omens.

 

I am very happy. :)

post #5081 of 10366
Quote:
Originally Posted by 2359glenn View Post
 

Changing the feet might do it I guess the transformer is vibrating at 50Hz  I didn't notice this at 60Hz in the US

but maybe it was there and I didn't notice it. And the table I had it on when listening had a Slate top that weighs

a tun. Don't think it can transfer vibrations into that.

 

Also maybe putting something under the amp will stop it.

 

Just remember to remove the bottom and remove the nuts before trying to unscrew the feet

 

I'll upload a small video later to show you what it does :smile:

post #5082 of 10366
Clayton, what drivers are you using with the 300Bs?
post #5083 of 10366
Quote:
Originally Posted by dminches View Post

Clayton, what drivers are you using with the 300Bs?

C3g Post (still clad in its stealth-black shield).

post #5084 of 10366
Me too. What a coincidence biggrin.gif
post #5085 of 10366

Never mind my excellent video skills :rolleyes:

 

 


Edited by Ultrainferno - 9/30/13 at 1:07pm
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