I am not sure that this "fix" addresses in any way the original issue you raised.
Can you be more specific about the nature of the problem you are having and the topology of your amplifier?
If installing a choke raises the source impedance of your power supply significantly this is not going to necessarily result in either a perceived or measured improvement in bass performance, quite possibly just the reverse.
There are other good reasons for adding the choke, like lower ripple on the supply and better voltage regulation under varying loads, although with a class A SE output stage this factor is irrelevant as the load current is invariant. (Choke regulation does NOTHING at all for line regulation and IMHO this is a big issue.) **However** You need to assure that the resulting output voltage is within a stone throw of what you now have otherwise both output power and linearity will be affected, perhaps adversely.
Kevin
Can you be more specific about the nature of the problem you are having and the topology of your amplifier?
If installing a choke raises the source impedance of your power supply significantly this is not going to necessarily result in either a perceived or measured improvement in bass performance, quite possibly just the reverse.
There are other good reasons for adding the choke, like lower ripple on the supply and better voltage regulation under varying loads, although with a class A SE output stage this factor is irrelevant as the load current is invariant. (Choke regulation does NOTHING at all for line regulation and IMHO this is a big issue.) **However** You need to assure that the resulting output voltage is within a stone throw of what you now have otherwise both output power and linearity will be affected, perhaps adversely.
Kevin
Many factors here
SE or PP amp?
Power or preamp?
SE power amps likes lots of stored energy where as PP power amps are more constant current & forgiving in Class A.
Where do you want to place the choke?
What is PS now? CRC, CLC, LC,, etc.
Just not enough info from your question to give an answere here.
SE or PP amp?
Power or preamp?
SE power amps likes lots of stored energy where as PP power amps are more constant current & forgiving in Class A.
Where do you want to place the choke?
What is PS now? CRC, CLC, LC,, etc.
Just not enough info from your question to give an answere here.
Re: Many factors here
It's power amp with PP config using 2 300B per channel that supposedly puts out 22W per/ch.
Could you guess how much RMS current consumed per channel on average?
I am trying to find a suitable thermister so this info could be helpful.
Here is the schematic:
http://www.geocities.com/hai_vu1/schematic.JPG
I am now thinking of NOT using a choke since it will reduce the B+ voltage and change the entire ouput stage altogether.
After doing some research and asking around here, I plan to use a thermister instead which is a lot more simple.
I plan to use a manual bypass switch to take the thermister out of the circuit once the amp is turned on.
Thanks.
amperex said:
It's power amp with PP config using 2 300B per channel that supposedly puts out 22W per/ch.
Could you guess how much RMS current consumed per channel on average?
I am trying to find a suitable thermister so this info could be helpful.
Here is the schematic:
http://www.geocities.com/hai_vu1/schematic.JPG
I am now thinking of NOT using a choke since it will reduce the B+ voltage and change the entire ouput stage altogether.
After doing some research and asking around here, I plan to use a thermister instead which is a lot more simple.
I plan to use a manual bypass switch to take the thermister out of the circuit once the amp is turned on.
Thanks.
You should locate the thermistor in the primary side of the power transformer, and although some do switch it out of circuit once the amplifier is on I think this is unnecessary.
Take a look at Ametherm, I think what you want is a device rated at about 4A, with a cold resistance of 15 - 20 ohms and less than 0.5 ohms warm.
Their site is www.ametherm.com and here is a device I think would be suitable for this use: http://www.ametherm.com/Data Sheets/SL12 15004.pdf
You might even be able to get a couple of samples since your need is limited.
Also you could replace the existing 100 resistor with a choke of about equal resistance say 10H/30mA/~100 ohm and get a quieter supply rail to the driver stage.
You can delay the application of B+ to the output tubes with a timed relay if you are concerned about cathode stripping. Note that this may cause a pop when it switches.
edit: added additional info
Kevin
Take a look at Ametherm, I think what you want is a device rated at about 4A, with a cold resistance of 15 - 20 ohms and less than 0.5 ohms warm.
Their site is www.ametherm.com and here is a device I think would be suitable for this use: http://www.ametherm.com/Data Sheets/SL12 15004.pdf
You might even be able to get a couple of samples since your need is limited.
Also you could replace the existing 100 resistor with a choke of about equal resistance say 10H/30mA/~100 ohm and get a quieter supply rail to the driver stage.
You can delay the application of B+ to the output tubes with a timed relay if you are concerned about cathode stripping. Note that this may cause a pop when it switches.
edit: added additional info
Kevin
Agree with kevenkr
Replace the resistor with same DCR choke. PP is easier on a PS, I have no concern here.
A thermistor on primary is a good option to reduce cold filament start-up current.
The last cap in the PS filter should be an oil type as used in electric motors as the 'run' capacitors. Not enough room? Solen polyproplyene are good quality & available at 630 volts DC.
Replace the resistor with same DCR choke. PP is easier on a PS, I have no concern here.
A thermistor on primary is a good option to reduce cold filament start-up current.
The last cap in the PS filter should be an oil type as used in electric motors as the 'run' capacitors. Not enough room? Solen polyproplyene are good quality & available at 630 volts DC.
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