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It is currently 23 Sep 2018, 14:01

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 Post subject: Re: KT120 Oddblocks
PostPosted: 25 Jun 2018, 10:26 
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Joined: 23 Jun 2018, 16:07
Posts: 3
Mr. Heran Any thoughts on using GU50 tubes with your PP oddblock design?
Thanks


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 Post subject: Re: KT120 Oddblocks
PostPosted: 26 Jun 2018, 16:48 
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Joined: 04 Jun 2008, 20:59
Posts: 3787
Location: Arizona, USA
Hi, I did that a while back and while they will work IMO they didn't sound nearly as nice as any of the KT77, KT88 or EL34s did.

Good listening
Bruce

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 Post subject: Re: KT120 Oddblocks
PostPosted: 27 Jun 2018, 14:50 
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Joined: 23 Jun 2018, 16:07
Posts: 3
Thanks for the prompt response. Did you try them with the cathode tied to grid 3 or just leave it floating?
thanks


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 Post subject: Re: KT120 Oddblocks
PostPosted: 27 Jun 2018, 21:53 
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Joined: 04 Jun 2008, 20:59
Posts: 3787
Location: Arizona, USA
Hi, Cathode tied to grid 3.

Good listening
Bruce

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 Post subject: Re: KT120 Oddblocks
PostPosted: 19 Aug 2018, 16:05 
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Joined: 29 Mar 2013, 20:37
Posts: 130
Location: Italy
Finally went around building the chassis. This is my first time doing wood working so I am happy with the results. Drilling the 1.5mm thick steel panel was the worst part. Now the fun part. Time is a limited resource right now sadly, hopefully it will be done for the next month

Image

Image

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 Post subject: Re: KT120 Oddblocks
PostPosted: 01 Sep 2018, 01:19 
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Joined: 21 Aug 2018, 14:09
Posts: 5
Hi, I have a couple of well-constructed output transformers in the house
70w
5,5k
0-4-8 ohms
with UL sockets, can it be used for the construction of this kt120 power amp without changing the values?
how much power will I lose with using 5.5k?
thank you so much


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 Post subject: Re: KT120 Oddblocks
PostPosted: 01 Sep 2018, 02:49 
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Joined: 31 Aug 2018, 09:13
Posts: 3
Hey Bruce!

Regarding the transformer referred sometimes below, would you recommend using the Toroidy one?

Polimorph wrote this a few years ago:
TTG-KT88PP http://www.tme.eu/ro/Document/77cb69431 ... T88_PP.pdf with 4kOhm in primary, 300ma, 43% taps, 80w power


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 Post subject: Re: KT120 Oddblocks
PostPosted: 01 Sep 2018, 17:10 
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Joined: 04 Jun 2008, 20:59
Posts: 3787
Location: Arizona, USA
Hi, Probably less than 10%. A side benefit is that the higher loading will likely reduce the distortion slightly.

Good listening
Bruce

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 Post subject: Re: KT120 Oddblocks
PostPosted: 02 Sep 2018, 09:48 
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Joined: 07 Mar 2017, 03:14
Posts: 72
I'm planning to use JB 2g 104k caps (0.1uF) on the heater power supply circuit. Do they do the job? What kind of capacitor does better job for the purpose?


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 Post subject: Re: KT120 Oddblocks
PostPosted: 02 Sep 2018, 11:02 
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Joined: 04 Jun 2008, 20:59
Posts: 3787
Location: Arizona, USA
Hi, They should be fine. Since it is only a precaution to eliminate noise in the circuit I use low voltage polys from any good brand. Vishay, Kemit, Panasonic, really probably nearly any would do. 25 volt rating or more. In the main power supply the bypass ones should be good quality and any of those brands, and my preference is audio grade Jantzen (cross caps) , Audyn Q4 or Solen. In that application they can make a difference.

Good listening
Bruce

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