Bottlehead Forum

Bottlehead Kits => Crack => Topic started by: tvr2500m on February 27, 2025, 09:11:34 AM

Title: 12AU7 -> 6CG7 Use and LEDs
Post by: tvr2500m on February 27, 2025, 09:11:34 AM

I don't have any issues with the 12AU7. I've had experience with it forever in other gear, as well as the Crack. Also, using the 6CG7/6FQ7 forever I have a lot of them and really like this tube. I'd like to try the Crack with the 6CG7.

I've got the pin mapping down to connect the 6CG7. I have a question about the HLMP6000 LED. These are used to bias the tube to 1.56V, or close, like 1.6V according to the datasheet. The two LEDs are connected to pins 3 and 8, the cathodes, of both the 12AU7 and 6CG7; it's the same. Is there any need to change the value of the LED from the 12V tube to the 6V tube? Can I use the HLMP6000 for the 6CG7?

Thanks.

Title: Re: 12AU7 -> 6CG7 Use and LEDs
Post by: Paul Birkeland on February 27, 2025, 02:51:53 PM

Just leave the HLMP-6000 diodes as they are.  All you need to do is change the heater wiring (green twisted pair).

Title: Re: 12AU7 -> 6CG7 Use and LEDs
Post by: tvr2500m on February 28, 2025, 08:25:12 PM

Roger that. Easy enough. Thanks.