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    Building, troubleshooting and testing of these amplifiers should only be
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    the safety precautions around high voltages.

5687 for Aikido

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flg

Member
2005-07-06 1:13 am
North East
I just recieved a GlassWare Bd for 5687. I havent decided on values yet though. Broske suggests around 20mA. I was thinking of running close to 100 ohms Rk at about 125Vp/tube. It's a balance though of what you want to run for the input tube unless you split the supplies? I was thinking maybe a 6FQ7 on the input?

Any other ideas :bigeyes:
 
Good suggestion!

My homebrewed Aikido amp uses 6CG7's as input tube.
Try to find the RCA cleartops. Other brands of couse still ok.
Run the amp with a B+ a little higher then suggested, let's say 200 to 250 Volt. Bias the tube with 4 to 5 mA is a good choice.

My opinion is that a 6CG7 starts to sing wonderfull with a plate voltage of 100 to 150 Volts.

As output tube I tryed the 5687 and 6N6p.
There is almost no sonic difference between these tubes.
Mind the difference in pinning layout between those two!!
Have fun, greetings,
Hansel
 
Hello Burnedfingers and all music lovers!
It looks, that we have almost the same Aikido amp.

Do you use a regulated power supply for the heaters?
In my amp, when I used AC on the filaments, I hear a clear hum, during soft passages with my headphones.

After I used DC, the hum was gone.
In my other preamp, also with the 6CG7, at AC no hum at all....

Is it possible the RCA cleartops are a little more sensitive, then the Electro Harm. or the GE?

Now I use a power supply with skottkey rectifiers, aerovox 100uF, 5 H choke ,aerovox 470 uF , each channel.
This gives me a B+ of about 210 V.

The sound is very good.Maybe better than with a tube rectifier.
When I use it as a pre amp ,she makes a very good match with class D power amps.

Greetings, have fun.
Hansel.
 
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