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Oddwatt Push Pull Tube Amplifier Projects
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Author:  gofar99 [ 22 Apr 2019, 11:01 ]
Post subject:  Re: Oddwatt Push Pull Tube Amplifier Projects

Hi, Nice build. I considered the TDRs but the cost was more than I felt needed. Mostly for looks now all my amps have the thermal delay tubes. I bought up a bunch when they were cheap. Not so any more. They went from $5 to $40 ...ouch. I now use a LM555 IC timer in all the commercial kits to handle the delay. Simple, since there is already a source of 12VDC and they are reliable, just not as cool looking. The LM317s in all my amps, plus all the commercial ones do not use fans on the heat sinks as none have proved to be needed. If yours are quiet and don't introduce any noise then fine. Yes I have run into some caps that pick up noise and hum and have done the same thing (shield them). In my personal system that uses fairly sensitive speakers (92 dbw) I don't need a lot of power output. I have found that running KT120s at about 60-65 ma each with an 8K load (as specified in the KT77/88 amps) sounds wonderful. If you only need about 20 watts I would try it since you are getting the tubes anyway. If you have the 4K (appx) transformers and 8 ohm speakers you can try using the 4 ohm tap on the transformers and changing the resistor to get the 60-65 ma range. A cheap possible mod that might be to your liking. The resistor value would be about 22 ohms / 1watt is OK.

Good listening
Bruce

Author:  Wattfan [ 23 Apr 2019, 10:14 ]
Post subject:  Re: Oddwatt Push Pull Tube Amplifier Projects

Hi Bruce,
Thanks fir the feedback and suggested options.
I started my build with the initial intention for KT88's ... purchased the tubes etc.. then discovered the KT120 option and adapted my my build to your Power Amp Circuit (Version Date: May 19,2013) and Unified Schematic (Dated: May 6, 2015) and purchased the following Edcor transformers:
Power: XPWR267
Output: CXPP70-MS-3.5K
My understanding is that I meet all the required transformer ratings to experiment across the range so I look froward to trying different options both my sets of KT88 and KT120 in due course. In. my limited experience I am of the opinion that the KT88's are somewhat more alive at 92ma than the KT120's ... just a perception and time will tell when I experiment some more.
Two questions:
- I realized that when I replaced the two parallel 100 ohm resistors (5 Watt each) with a single 50 ohm (50 Watt - Dale) it removed form the circuit a "fusible" link, based upon some clarification in your earlier writings .... these resistors became exceptionally hot hence the change I made ... now 50w ones run quite arm to touch after a few hours. Any suggestions.
- I am running a 3 amp (slow blow) fuse in the main AC supply ... Is this OK or should I reduce the rating?

Thanks again for your help ....

Author:  duderduderini [ 25 Apr 2019, 04:50 ]
Post subject:  whats the latest schematic?

Hi Guys.
i have been away for a few years and now wish to complete the kt88 version of this build with the amperites etc. With 200 pages of topic, could some one please direct me to the latest circuit(s) i should be using?
Thanks and I hope all of you are well
Nick

Author:  duderduderini [ 27 Apr 2019, 19:52 ]
Post subject:  Re: Oddwatt Push Pull Tube Amplifier Projects

Hi again
Thanks to poty, I now have them

Author:  kcom00 [ 10 May 2019, 01:03 ]
Post subject:  Re: Oddwatt Push Pull Tube Amplifier Projects

Hi,
Does anyone know if Oddwatt sells their kits overseas (Australia in this case)?
I'm been trying to buy a single Oddblock series 2 octal kit to supplement the single unit I already have.
I have emailed the contact email address listed on the Oddwatt audio website requesting a quote for shipping but I never get a reply.
If someone can help out that would be greatly appreciated.
Thanks, Steve.

Author:  poty [ 10 May 2019, 02:36 ]
Post subject:  Re: Oddwatt Push Pull Tube Amplifier Projects

Not sure about Australia, but I bought the OddWatt from Russia (deliver here too) without a problem.

Author:  kcom00 [ 10 May 2019, 03:35 ]
Post subject:  Re: Oddwatt Push Pull Tube Amplifier Projects

Thanks Poty,
I didn't think it would be an issue so it is a bit odd:)

Author:  gofar99 [ 10 May 2019, 17:41 ]
Post subject:  Re: Oddwatt Push Pull Tube Amplifier Projects

Hi, Yes we do. Resend the request to support@oddwattaudio.com. The main sales office and center was obligated to move and is just now getting back to something like normal. It has been very disruptive and unfortunately a lengthy process. Sorry for the problems.

Good listening
Bruce

Author:  kcom00 [ 12 May 2019, 18:49 ]
Post subject:  Re: Oddwatt Push Pull Tube Amplifier Projects

Thanks Bruce,
All good now.

Author:  polimorph [ 04 Jun 2019, 15:37 ]
Post subject:  Re: Oddwatt Push Pull Tube Amplifier Projects

I would try the 6P3S-E as power tubes and 6N9S as drivers for this design. What B+ and CSS settings would be optimal? Should I go with Oddblock design, or Oddwatt 225?

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