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PostPosted: 29 May 2010, 19:06 
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Joined: 28 May 2010, 20:42
Posts: 20
Hi Benny, happy for you as you really enjoy you new K272A. Mine still on the way to my home. Expected to receive it soon. After reading all the articles related to this amp. It is normal to have one LED stay lit up all the time. I think it is the one nearer to the AA battery. Right?


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PostPosted: 29 May 2010, 20:05 
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Joined: 28 Oct 2009, 02:34
Posts: 501
Location: Utrecht Nederland
Hallo,

yes it is right it is the one in series with the 2 diodes and it is part of the filament supply. The kit really rocks and this one don't hiss, I will maybe leave this one stock and buy another one. This one I will upgrade then and compare. My both old K272 did hiss when used as pre amp and made them for the same reason unusable for me, this one is good, I am kind of afraid of changing anything around. Had it on the scope, it scopes very good as well, I am happy. It even drives 8 ohm speakers, if you don't draw much power. But to listen in normal room loudness, it will work on 8 ohm, serious.

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Greetings from Holland, Ben

My DIY Audio Projects:
- Single-Ended 12B4A tube amp with ECC802S driver
- DIY Push-Pull KT88 tube amp (OddWatt amp from scratch)
- 832 / GU32 tube push-pull amplifier project


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PostPosted: 30 May 2010, 10:52 
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Joined: 28 Oct 2009, 02:34
Posts: 501
Location: Utrecht Nederland
Hy guys,

I got the enclosure almost finished, waiting for the last coat of clear paint to dry, looking good so far. it will be very simpl, 2 RCA's as input and a 3,5 mm headphone jack for the headphones, a power switch, finished. Pictures will come soon.

I wanna bypass the tubes and listen to the op amp alone, see how much of the sound really comes from those tubes. Did anybody else try that?

_________________
Greetings from Holland, Ben

My DIY Audio Projects:
- Single-Ended 12B4A tube amp with ECC802S driver
- DIY Push-Pull KT88 tube amp (OddWatt amp from scratch)
- 832 / GU32 tube push-pull amplifier project


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PostPosted: 30 May 2010, 13:31 
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Joined: 15 Dec 2009, 17:28
Posts: 70
Location: Netherlands
I haven't tried it but take note that the opamp runs at a gain of 1 (unity gain). Output may be very low.


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PostPosted: 30 May 2010, 16:19 
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Location: Australia
Beftus wrote:
I haven't tried it but take note that the opamp runs at a gain of 1 (unity gain). Output may be very low.

There is good gain in the front (tube) end. The OPAMP is there just as a buffer/driver. There is plenty of gain.

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Projects:"Zeus" - Holton inspired 300W AB amp | "Pass F5 trubo” - dual mono high-end amp | “MWH” - 1920s UX-171A preamp | ”Image” - Low Profile 100W Class D amp |


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PostPosted: 30 May 2010, 16:48 
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mwhouston wrote:
Beftus wrote:
I haven't tried it but take note that the opamp runs at a gain of 1 (unity gain). Output may be very low.

There is good gain in the front (tube) end. The OPAMP is there just as a buffer/driver. There is plenty of gain.


But not if you, like Benny wants to try, bypass the tubes.
BTW, I just finished another hybrid today, a Starving Student Hybrid headphone amp. Sounds absolutely wonderful.


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PostPosted: 30 May 2010, 16:51 
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Location: Australia
Beftus wrote:
mwhouston wrote:
Beftus wrote:
I haven't tried it but take note that the opamp runs at a gain of 1 (unity gain). Output may be very low.

There is good gain in the front (tube) end. The OPAMP is there just as a buffer/driver. There is plenty of gain.


But not if you, like Benny wants to try, bypass the tubes.
BTW, I just finished another hybrid today, a Starving Student Hybrid headphone. Sounds absolutely wonderful.

I missed that bit.

Yes agree no gain just buffering.

_________________
Projects:"Zeus" - Holton inspired 300W AB amp | "Pass F5 trubo” - dual mono high-end amp | “MWH” - 1920s UX-171A preamp | ”Image” - Low Profile 100W Class D amp |


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PostPosted: 30 May 2010, 16:58 
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Location: Utrecht Nederland
Hi everybody,

no I was just curious, that thing don't hiss and impresses me quite a bit I have to admit. I just had it connected to my RIAA pre amp, listening to records with headphones, also very nice, no hiss. It's got a new home now, an old cigar box, nicely finished, pictures will follow tomorrow. Not much, 2 RCAS's for the input, of course gold, a switch and a 3,5 mm jack for the headphones, not more, All wires are shielded, input and output, and yes, it's got a stereo poti, too, that was it. The box is small, it all fits just in there nicely, so it is very portable. I don't know why this one don't hiss, maybe the better shielding, I really am so happy it doesn't hiss, I don't want to cause it to hiss. :D

The input caps I could bridge, I suppose, all my sources are dc free.

Thanks Mark for everything.

_________________
Greetings from Holland, Ben

My DIY Audio Projects:
- Single-Ended 12B4A tube amp with ECC802S driver
- DIY Push-Pull KT88 tube amp (OddWatt amp from scratch)
- 832 / GU32 tube push-pull amplifier project


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 Profile  
 
PostPosted: 30 May 2010, 20:21 
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Joined: 28 May 2010, 20:42
Posts: 20
Beftus wrote:
BTW, I just finished another hybrid today, a Starving Student Hybrid headphone amp. Sounds absolutely wonderful.

So far I had completed CMOY, Sijosae's hybrid amp and also building the yet to come 6418 amp. The next one I am considering is the Millett Hybrid MiniMAX. Wondering how much different in term of sound as compare to those I had build? Maybe you could advise since you just completed your Starving Student Hybrid headphone amp. Thanks.


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PostPosted: 31 May 2010, 03:21 
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Joined: 06 Jun 2008, 18:23
Posts: 5226
Location: Australia
Bennybuis wrote:
no I was just curious, that thing don't hiss and impresses me quite a bit I have to admit. I just had it connected to my RIAA pre amp, listening to records with headphones, also very nice, no hiss. It's got a new home now, an old cigar box, nicely finished, pictures will follow tomorrow. Not much, 2 RCAS's for the input, of course gold, a switch and a 3,5 mm jack for the headphones, not more, All wires are shielded, input and output, and yes, it's got a stereo poti, too, that was it. The box is small, it all fits just in there nicely, so it is very portable. I don't know why this one don't hiss, maybe the better shielding, I really am so happy it doesn't hiss, I don't want to cause it to hiss. :D

The input caps I could bridge, I suppose, all my sources are dc free.

Post some images. A picture is worth a thousand words. Like to see the box.

_________________
Projects:"Zeus" - Holton inspired 300W AB amp | "Pass F5 trubo” - dual mono high-end amp | “MWH” - 1920s UX-171A preamp | ”Image” - Low Profile 100W Class D amp |


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