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 Post subject: Re: KT120 Oddblocks
PostPosted: 23 Dec 2018, 04:10 
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Joined: 07 Mar 2017, 03:14
Posts: 102
Even with high end amplifers there is a puffff coming from speakers even when not playing anything. I don't know if they do it deliberately. Because it provides somewhat warmer presentation.


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 Post subject: Re: KT120 Oddblocks
PostPosted: 23 Dec 2018, 16:01 
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Joined: 04 Jun 2008, 20:59
Posts: 3988
Location: Arizona, USA
Hi, Any inherent noise the amps produce should not be audible with most speakers. I use ones with 96 db/w sensitivity and there is no noise from the power amps. With no input to the power amp there is nothing even with the ear right on the speaker. In use I do get a little hiss originating from the phono preamp when used at a very loud listening level, but then it has a lot of gain is typical of the genre in level. I expect that any reasonable designer and company building amps would want to eliminate as much noise as possible ....subject to their cost constraints. Solid state gear can be quieter as nearly all of it is based on substantial negative feed back control. That will go a long way to reduce noise. The Oddblock amps use a very small amount (and will run fine without any normally) to insure stability. It has virtually zero effect within the audio band and only is active above about 35K HZ.

Good listening
Bruce

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 Post subject: Re: KT120 Oddblocks
PostPosted: 28 Dec 2018, 16:09 
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Joined: 29 Mar 2013, 20:37
Posts: 149
Location: Italy
I "solved" the issue of the hum on my amplifier. For some reason it picks up the noise of the herby pellet stove transformer.. I have no idea why. It does it even with the inputs shorted to ground. Removing the plug from the stove solves the hum.. It is the first time I use a wooden chassis on a project, I always used enclosed steel chassis so maybe the issue has always existed and the chassis made a Faraday cage while the wooden one provides no protection. I will try to get an ups with enough Watts to see if it solves the issue. No noise or hum with other nervy devices unplugged. Weird


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 Post subject: Re: KT120 Oddblocks
PostPosted: 28 Dec 2018, 17:42 
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Joined: 04 Jun 2008, 20:59
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Location: Arizona, USA
Hi, Most electronics are sensitive to EMI to some degree. I suspect that either the stove is directly coupling EMI to the output transformer or to the driver tube. I don't believe I would put an amp close enough to a stove to have that happen. You really don't want to add excess heat to amps (they have a lot already) and cause premature failure of things like electrolytic capacitors. You are correct that steel chassis do shield the components from EMI. It could be a capacitor picking up the hum as well. I build my gear in steel chassis and put a wood outer case on them for looks.

Good listening
Bruce

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 Post subject: Re: KT120 Oddblocks
PostPosted: 28 Dec 2018, 18:02 
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Location: Italy
Hi, the stove is around 4 meters from the amp, heat is not an issue, it is a wodden pellet stove that spreads most heat right the opposite side of the listening equipments. My listening room is underground so that stove is the only way to not sacrifice my body to hipothermy on the altair of the music. The interference is present even when it off. Probably the main transformer for the control board. I will try to shield the insides of the amp


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 Post subject: Re: KT120 Oddblocks
PostPosted: 03 Jan 2019, 14:15 
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Hi,
What is the ideal opt impedance for 300B tubes?


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 Post subject: Re: KT120 Oddblocks
PostPosted: 03 Jan 2019, 21:02 
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Location: Arizona, USA
Hi, I personally have not used any. Their specs make using them in an Oddwatt difficult. The drive voltages needed are a problem, as well as their gain. You might post this as a general question by itself .

Good listening
Bruce

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 Post subject: Re: KT120 Oddblocks
PostPosted: 18 Jan 2019, 15:27 
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Bad boy is still impressing at nights. Listening to "The world is a ghetto" from War.


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 Post subject: Re: KT120 Oddblocks
PostPosted: 21 Jan 2019, 15:16 
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Joined: 29 Mar 2013, 20:37
Posts: 149
Location: Italy
Hi, after years of getting outbidded i finally managed to get my hands on my dream speakers, Cerwin Vega at-100 (not the modern crap, the good old end of 80's series). Holy son of cussing cus word, they absolutely.. blow everything i have ever heard before away with the kt120. You have to play them at fairly high volume but they are a beast on this amp; especially on vynils. it's incredible how this amp, even if completely Vacuum tube built instead of much more aggressive hybrids, can drive them. My neighbours loved "another brick in the wall" so much that they threw a brick at my window to hear it better!


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 Post subject: Re: KT120 Oddblocks
PostPosted: 21 Jan 2019, 20:28 
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Joined: 04 Jun 2008, 20:59
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Location: Arizona, USA
Hi, It is good to hear from happy builders. The amps are surprisingly easy to drive and sound a lot more powerful than you would expect.

Good listening
Bruce

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