Yeah .. cool stuff.. I'm motivated to set up an LCD screen above my bed so I can read it all....
Check out this related thread
http://www.diyaudio.com/forums/showthread.php?s=&threadid=73781&highlight=
Check out this related thread
http://www.diyaudio.com/forums/showthread.php?s=&threadid=73781&highlight=
Power supply:
the 500v supply:
8x220uF 400V caps for the power supply
2x 0.47uF 630V
4xBY228 fast diodes (1.5KV / 2A)
And the bias power supply (bridge diodes + 470uF)
Phantom load for measurement (6 ohm)
the 500v supply:
8x220uF 400V caps for the power supply
2x 0.47uF 630V
4xBY228 fast diodes (1.5KV / 2A)
And the bias power supply (bridge diodes + 470uF)
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Phantom load for measurement (6 ohm)
An externally hosted image should be here but it was not working when we last tested it.
Long time ago since my last post.
The project is going well. I have to make some adjustments (Feedback, etc)
some pictures:
In this next picture, look just below the PSU transformer. It's the 10H 250ma choke
good support for the PSU trans.
What do you think? isn't beautifull??
The project is going well. I have to make some adjustments (Feedback, etc)
some pictures:
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
In this next picture, look just below the PSU transformer. It's the 10H 250ma choke
good support for the PSU trans. An externally hosted image should be here but it was not working when we last tested it.
What do you think? isn't beautifull??
zafira1981 said:I didn't know about that. I hope you're wrong
By the way, it only has a little hum that I still have to fix.
No, actually he is right, but in this instance you may get away with it. (or not) In your next project though you definitely want to mount the output transformers at right angles to the power transformer.
How about some pictures of the underside of your amplifier? May help some of us identify other potential sources of hum in your amplifier.
rotating the two output transformers will be boring and annoying but can be made simply. In fact, i think i could use the same holes.
Here is a pic of the connection side.
It's not finished. I'm making a little bit of order. When I used the amp for the first time it was a mess , really a mess of cables & stuff.
Here is a pic of the connection side.
It's not finished. I'm making a little bit of order. When I used the amp for the first time it was a mess , really a mess of cables & stuff.
An externally hosted image should be here but it was not working when we last tested it.
Definitely twist all heater wires, this is particularly critical the low level input stage and driver stage. There should be no heater wire loop around the socket, arrange things so that the wires pass entirely around one side or the other of the socket, not both sides.
The filament circuit(s) should not be floating, if there is a center tap available it should be grounded or elevated above ground with a bypassed voltage divider. Elevating the filaments above ground will help with filament/cathode breakdown voltage ratings in LTP and cathodyne (split load) inverters by reducing the voltage difference between the two. Usually this also results in much quieter operation as it reduces leakage in the insulation from filament to cathode. Just be careful not to exceed the insulation rating of any tube filament sharing that filament supply.
There should only be one connection between the chassis and the amplifier ground. Use a star ground arrangement or buss grounding with only one point connected to chassis. There should also be a connection for mains safety ground to chassis right at the point where power enters the amplifier.
You should use rubber grommets anywhere wires pass through the chassis. (Output and power transformers)
Since you say it is relatively easy to rotate the output transformers 90 degrees I'd do this. This will virtually eliminate the mutual inductance between the power and outputs and greatly reduce coupling between them.
Grid stopper resistors should be used on all tubes - 1K should be sufficient for most types. These must be mounted right at the socket to be effective.
220 - 1K resistors on the screen grids of your KT88 will save you a lot of grief by preventing parasitic vhf oscillations in the output tube.
A number of use have had reliability problems with some small metal films in this location (me included) so I would recommend a 1W resistor and I generally used carbon film for this purpose.
edit
The filament circuit(s) should not be floating, if there is a center tap available it should be grounded or elevated above ground with a bypassed voltage divider. Elevating the filaments above ground will help with filament/cathode breakdown voltage ratings in LTP and cathodyne (split load) inverters by reducing the voltage difference between the two. Usually this also results in much quieter operation as it reduces leakage in the insulation from filament to cathode. Just be careful not to exceed the insulation rating of any tube filament sharing that filament supply.
There should only be one connection between the chassis and the amplifier ground. Use a star ground arrangement or buss grounding with only one point connected to chassis. There should also be a connection for mains safety ground to chassis right at the point where power enters the amplifier.
You should use rubber grommets anywhere wires pass through the chassis. (Output and power transformers)
Since you say it is relatively easy to rotate the output transformers 90 degrees I'd do this. This will virtually eliminate the mutual inductance between the power and outputs and greatly reduce coupling between them.
Grid stopper resistors should be used on all tubes - 1K should be sufficient for most types. These must be mounted right at the socket to be effective.
220 - 1K resistors on the screen grids of your KT88 will save you a lot of grief by preventing parasitic vhf oscillations in the output tube.
A number of use have had reliability problems with some small metal films in this location (me included) so I would recommend a 1W resistor and I generally used carbon film for this purpose.
edit
but is a good moment to polish the aluminium 
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