Jump to content

The Menace


n_maher

Recommended Posts

Nice work!

Question: have you considered mounting the bias LEDs such that they can be seen through the top panel? It looks like it would be a bit of a pain to do, but it would give a visual indication that input tubes are up & running with the bias current flowing through them. Something similar could also be done for the B+ supply, when all the LEDs light up you know the amp is good to go, and if something doesn't light up you know where to start looking for the problem.

Link to comment
Share on other sites

Nice work!
Thanks!

Question: have you considered mounting the bias LEDs such that they can be seen through the top panel? It looks like it would be a bit of a pain to do, but it would give a visual indication that input tubes are up & running with the bias current flowing through them. Something similar could also be done for the B+ supply, when all the LEDs light up you know the amp is good to go, and if something doesn't light up you know where to start looking for the problem.

Actually yes, I had given that some thought and it wouldn't be hard to do with the two existing LEDs. What I had considered doing was drilling an LED sized hole in the terminal board and just poking the LED through that way. Since I have a ring of holes around the base of each tube for ventilation I'm pretty sure you'd be able to see the LEDs light. In the end in the interest of time and actually not wanting any sort of "tube illumination" I abandoned that concept.

Question though, how would you propose to tap an LED off of B+?

Link to comment
Share on other sites

Question though, how would you propose to tap an LED off of B+?

In my case I stuck a 150k resistor in series with the LED and wired the whole thing between B+ and ground. Adjust the value of the LED to get the current and LED brightness you want, and also keep in mind that you might need multiple resistors depending on the B+ voltage in your amp so that you don't exceed the voltage spec on the resistors.

Link to comment
Share on other sites

...Adjust the value of the LED to get the current and LED brightness you want...

Had a brainfart, that should say adjust the value of the resistor.

cetoole's solution is the neater one, it whacks all the problems at once. If you're doing the heater bias, you already have the resistors in place for the LED.

Link to comment
Share on other sites

Thanks guys. Ari and I will be working on her a bit this weekend to see if we can tweak some of the buzz out of the output. It's pretty ok with even low impedance open headphones but not with closed cans. We've got a pretty good idea where to start so I'm hopeful she can be made to have an acceptably black background. These types of things are to be expected with PTP builds so I'm not surprised.

Link to comment
Share on other sites

The 307A based MenaceTC is slated to start construction some time in December and god-willing be fully burned-in in time for CanJam. I've acquired the lion's share of parts for that beast but the layout is about 10x as complex as the "Lite" version so it's going to take a lot of planning.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.