Recent Posts

91

Mainline / Re: Mainline ten years in

« Last post by JamieMcC on May 04, 2025, 01:39:58 AM »

Hi Paul yes still using the original 6C45 tubes (other than the 12au7) which was rolled simply to try about five years ago. Funny how time flies Its never even entered my thoughts that I'm still running on the original tubes must be thousands of hours on them so far as I have also used my Mainline for preamp duty Infront of a solid state power amp for many years as well as for headphones use .

I have acquired several new pairs of 6C45 tubes as well so looks like I'm easily covered for tubes for the Mainline to the end of my days.

Only thing I do is a bias check  every 6 six months or so if and when I remember.

Any thoughts on preventative maintenance/servicing I should  consider to keep things running smoothly or is it a case of don't mess with things if all working well for the time being?

Cheers

92

Moreplay / Re: 20 Ohms at 9

« Last post by Dread31 on May 03, 2025, 03:19:26 PM »

Will do.

I fattened up all of those lean joints and the reading at 9 came down to 15k. So, were getting there.

Thanks.

93

Moreplay / Re: 20 Ohms at 9

« Last post by Paul Birkeland on May 03, 2025, 11:22:42 AM »

You can also check the resistance of every terminal on each pot where a black wire lands.  They should all read 0.

94

Moreplay / Re: 20 Ohms at 9

« Last post by Dread31 on May 03, 2025, 11:09:13 AM »

Okay, Thanks, Paul. I'll get busy on that.

95

Mainline / Re: Resistance check errors

« Last post by Colman on May 03, 2025, 09:31:21 AM »

Yes, it is wired for 120V. It's a plan!

96

Mainline / Re: Resistance check errors

« Last post by Paul Birkeland on May 03, 2025, 09:27:07 AM »

If you have the power transformer wired for 120V, then yes.  You'd want to use the power transformer configuration listed for "Less than 115V" that starts on page 44.  When the power issues are resolved, you can go back to 120V. 

97

Mainline / Re: Resistance check errors

« Last post by Colman on May 03, 2025, 09:24:20 AM »

My line voltage is 109V, which I think is low. I'm having power issues in my house, which I am looking into. Would that cause the 242VDC?

98

Mainline / Re: Resistance check errors

« Last post by Paul Birkeland on May 03, 2025, 09:00:48 AM »

What is your incoming AC powerline voltage, and how is your power transformer wired?  That 242V is enough for the amp to work, but it would make me wonder a bit about the power transformer wiring, as well as how the solder joints are on the 270 ohm resistor on the power supply board (you can post the DC voltage on each leg of that resistor, which is also somewhat helpful).

99

Mainline / Re: Resistance check errors

« Last post by Colman on May 03, 2025, 08:59:18 AM »

Voltage checks OK. Except terminals at +275VDC and both IAs at AB all measure 242V. I believe that's within the 15% acceptable tolerance. Let me know if it is not though, and may cause issues later! The bias adjusted as they should. My Mainline powered up with no issues. My initial impression of how it sounds is excellent! It has a beefy, energetic sound with nice headroom. The Coarse and Fine Volume controls are handy to have. They tailor the music to suit a person's listening preferences. The release on the ¼" TRS jack is sticky though, but I hope it will loosen up over time. Overall this is a great kit and fun to build! Thank you, Paul, for your help!

100

Mainline / Re: Mainline ten years in

« Last post by Paul Birkeland on May 03, 2025, 07:01:14 AM »

Still on the original 6C45s too?