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 NEW  Matt presents bias and operation data for the 6V6 tube in SE operation - 6V6 Single-Ended (SE) Ultra Linear (UL) Bias Optimization.

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 Post subject: Re: KT120 Oddblocks
PostPosted: 29 Oct 2018, 09:10 
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Joined: 07 Mar 2017, 03:14
Posts: 94
Bruce, what is your solution for LM317HVs? (thermal pad or any other diy method:)


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 Post subject: Re: KT120 Oddblocks
PostPosted: 30 Oct 2018, 05:12 
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Joined: 24 Oct 2010, 07:05
Posts: 283
As far as I know in the kit the heatsink does not touch any other part of case and the LM is not insulated from the heatsink. There is a cover preventing any touch of the outside part of the heatsink.


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 Post subject: Re: KT120 Oddblocks
PostPosted: 30 Oct 2018, 08:43 
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Joined: 04 Jun 2008, 20:59
Posts: 3860
Location: Arizona, USA
Hi, In the kits the heatsink is isolated from the chassis. I extends through a cut out in the chassis. The LM317s are fastened to it directly. In DIY when this is not suitable (rather often) I use the insulating wafers with heat sink compound and the feed through insulator for the bolt. Both the mica and plastic wafers seem to work just fine. BTW the three pin mini cables often found in PCs work quite well for connecting to the LM317 pins. My original Oddblocks use them as do some other of my prototypes. Alternatively you can solder wires to the pins.

Good listening
Bruce

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 Post subject: Re: KT120 Oddblocks
PostPosted: 17 Nov 2018, 04:00 
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Joined: 07 Mar 2017, 03:14
Posts: 94
Hi,
There is RC snubber across the DPST switch. I won't ask you what it is for. I get 220 VAC eventhough the switch is open. Isn't it weird?


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 Post subject: Re: KT120 Oddblocks
PostPosted: 17 Nov 2018, 08:42 
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Joined: 04 Jun 2008, 20:59
Posts: 3860
Location: Arizona, USA
HI, With a high impedance meter you can measure that. It is a rather small amount of current. It is dependent on a number of factors, but will be under about 5 ma. Using switches rated at 10 amps, without the arc suppressor the switch is nearly certain to arc and fail within the first 6 months to a year. The surge current and spikes are quite large. With one in place they last forever. One way to avoid any current there is to have you system on a single power strip or power conditioner. Have it handle the on-off chores. They have built in suppression (usually) and the switch never has to handle the spikes. I have mine all on a wireless remote control that engages an APC 1500 watt power conditioner.

Good listening
Bruce

EDIT: BTW, there is no way I would have any of my gear on the AC mains directly. It is too prone to noise, spikes and voltage fluctuations. You only have to kill one piece of gear (like a medium to high end CD/DVD player to understand the need. Even a plain surge suppressor is helpful.

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 Post subject: Re: KT120 Oddblocks
PostPosted: 25 Nov 2018, 05:24 
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Joined: 07 Mar 2017, 03:14
Posts: 94
Hi,
For the signal ground center (bus), what should be the sequence? Driver cathode ground, then kt120 grid grounds?


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 Post subject: Re: KT120 Oddblocks
PostPosted: 01 Dec 2018, 10:30 
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Joined: 29 Mar 2013, 20:37
Posts: 139
Location: Italy
hello everyone, and Hello Bruce, i finally got around to finish my Xmas present before Xmas.. thank you so much for this design.. it sounds AMAZING there is lot of 50hz hum tho but i think that must be something in my construction. i will check that out later, thank you again for all the assistance, i love it.


Image
Image

the LM317HVs were expensive as hell but they give a nice touch. and they are well cooled like this


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 Post subject: Re: KT120 Oddblocks
PostPosted: 01 Dec 2018, 11:35 
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Joined: 29 Mar 2013, 20:37
Posts: 139
Location: Italy
I decided to add a little touch, the power button led breathes while the tubes are warming up, once the relays turn on the main the led stands still

https://i.imgur.com/jXYO9Oz.gifv


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 Post subject: Re: KT120 Oddblocks
PostPosted: 03 Dec 2018, 16:04 
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Joined: 07 Mar 2017, 03:14
Posts: 94
Houston, I have a problem. The relay is closing after about 50 seconds but opens again after a few seconds. What might be the problem?


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 Post subject: Re: KT120 Oddblocks
PostPosted: 03 Dec 2018, 16:32 
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Joined: 04 Jun 2008, 20:59
Posts: 3860
Location: Arizona, USA
Hi, Hummm. It sounds like the 555 is acting like a "one shot" and timing out. Check the connections to it and the pin connections.

Good listening
Bruce

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