My 6C33C SING WITH No SPEAKER ! - diyAudio
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Old 19th August 2007, 06:56 PM   #1
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Default My 6C33C SING WITH No SPEAKER !

Hello

tying a new filter on my speakers which is not yet erady , I just hear my 6c33c tube 60 watts amp acting as a speaker . I can hear some sound coming out from the tube ????

how can this happen ?


Thank for support .

ger56
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Old 19th August 2007, 07:10 PM   #2
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Are you sure it's not coming from the output transformer?
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Old 19th August 2007, 07:13 PM   #3
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Hello

Thank you for your answer .

I believe it comes from my amplifiers . Now I don't know if it is the output transfer or the tube . But the sound comes from the 2 mono tube amp !!!!.

I am just wondering if anything is wrong !

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Old 19th August 2007, 07:33 PM   #4
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Nothing is really wrong. Output transformers, unless potted can sing. Especially if bolted with no damping to a large metal plate.
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Old 19th August 2007, 07:55 PM   #5
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Thank you Analog !

Ger56
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Old 19th August 2007, 08:09 PM   #6
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No speaker?
Or with speaker?

No speaker = no load = power dissapation in the output transformer = sound.

Tubes can make noise too. Parts can move under power.

With speaker?
Possibly you have a really really bad reactive load?
Not good.
Check the impedance of your xovers, looking into the xover and see what you get. You may have very HIGH Z peaks, and/or very LOW Z dips. Both bad usually, especially with tubes.

Xovers are NOT equal with the parts placed in alternate positions!!

Like:

in--->C1------C2---->load
|
L1
|
GND

(edit: ascii representation of a 3rd order filter seems to fail when posted, assume it is an 18db/oct high pass...the "L1" is connected to ground inbetween the two caps...ok?)

is not the same impedance as the C2-C1 being reversed, unless they are the same value... check it and see fer urself. The load may see the same freq response, but the amp will not see the same load!

_-_-bear

PS. some transformers do "sing" - that can be reduced by isolation mounting, making the windings tight to the core, or better still: vacuum potting.
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Old 19th August 2007, 10:16 PM   #7
kevinkr is offline kevinkr  United States
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Probably not a very good idea to run the amplifiers without a proper load on the transformer secondaries. Most of the noise you are hearing is probably windings in the transformer vibrating with variations in signal. (Better not be the core stack - this indicates very poor transformer construction practices.) With no load applied it is possible to get very large voltage excursions on the primary, further, driving the output tubes into the cutoff region will result in the primary acting like a flyback transformer, and very large voltages can be developed - more than enough to destroy the transformer insulation.
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Old 20th August 2007, 01:18 AM   #8
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Hello Bear

Should I mesure the Xover impedance with the speaker connected or not ?

What should be a the impedance I should get to be ok ?

Regards

Ger56
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Old 20th August 2007, 08:23 AM   #9
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Default Re: My 6C33C SING WITH No SPEAKER !

Load Resistance : 600 ohm : 0 . 4 . 8 .16 ohm

Frequency response:20Hz ~ 55KHz (- 1db)
10Hz ~ 100KHz(- 3db)

Power Output (approx):12.5W

Distortion:3%

Hope you can help
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Old 20th August 2007, 08:31 AM   #10
coresta is offline coresta  France
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Hi , my OTLs do it too without any load I'v been repairing a sanded amp and was testing on a dummy load ( 200watts continuous on 32 ohms paralleled resitors) and could ear the dissipators sing : the transistors, the resistors even the wire
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