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Old 15th February 2005, 09:42 AM   #1
imagine is offline imagine  Hong Kong
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Default How to make this 6C33C better??

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I'm using this 6C33C tube amp(orignal from japan),
but the bass was too light...mid tone was not warm enough
is there have anyway to make it better by changing the value
of the component??
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Old 15th February 2005, 09:48 AM   #2
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Get a more substantial driver stage. A 6J5 running at a meagre 3.8mA of current is a bit wimpy for driving a big valve (and input capacitance). You might think about ditching the global feedback as well.
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Old 15th February 2005, 11:26 AM   #3
imagine is offline imagine  Hong Kong
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Quote:
Originally posted by audiousername
Get a more substantial driver stage. A 6J5 running at a meagre 3.8mA of current is a bit wimpy for driving a big valve (and input capacitance). You might think about ditching the global feedback as well.

Hi, Jason

I'm very new on tube amp, can you give me some idea on the driver stage??
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Old 15th February 2005, 12:07 PM   #4
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Quote:
Originally posted by imagine
I'm very new on tube amp, can you give me some idea on the driver stage??
Basically using something with a little lower rp and running at higher current. Do you have any valves on hand, or would you like me to suggest something?
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Old 15th February 2005, 12:19 PM   #5
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Hi,

The 6C33C is not that power hungry as it seems, the input capacitance is ~150pF and grid current is more or less non existent, (100k is no problem as a grid leak), therefore a 6J5 is quite enough for driving a 6C33C, (you get a -3dB cutoff at >100kHz).

However it is quite often so that cathode followers or in some cases SRPP's are used to drive the 6C33C. Some years ago I bought a kit amplifier from San-ei in Japan designed by Dakesue, (he was the first one to use 6C33C outside USSR). In this amplifier a cathode follower is used, DC coupled to the grid of the 6C33C, it works very well, see here http://www.tubetvr.com/se.html

What is the specification of output transformer? impedance ratio? specified DC current, primary inductance? if you have weak bass I would suspect the transformer first.

Regards Hans
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Old 16th February 2005, 11:38 AM   #6
Fuling is offline Fuling  Sweden
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Quote:
The 6C33C is not that power hungry as it seems
I´m not so sure about that.
I don´t have any experiences of my own when it comes to 6C33, but a friend of mine had quite a bit of trouble to get full HF bandwith out of his 6C33 SE amp.
His resistor loaded 6SN7 driver didn´t manage, so he ended up with a CCS loaded EL82 (trioded) driver.
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Old 16th February 2005, 12:36 PM   #7
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Quote:
His resistor loaded 6SN7 driver didn´t manage, so he ended up with a CCS loaded EL82 (trioded) driver.
It is difficult to understand why this is the case, I have myself confirmed the value input capacitance and (lack of) grid current in 6C33C, (by indirect measurement) and I cant see any problem to get 100kHz or more BW with a 6SN7 as driver. If you want to go close to or in to class A2 I recognise the need for a high current driver but not otherwise.

Do you know more details about the circuit and measurement values?

Regards Hans
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Old 16th February 2005, 04:25 PM   #8
Fuling is offline Fuling  Sweden
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tubetvr:

For more specific details, ask user Lord at hififorum.nu
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