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PostPosted: 30 Mar 2019, 18:43 
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Location: Australia
Yet another tube phono pre only this time a different schematic and kit. This is based on the Esoteric 834p phono preamp which has excellent reviews from around 2005. All high end parts and the first time I have seen Vishay caps. Chassis has been drilled and sprayed. This time I mounted the components on the back to allow the tubes to pop up. Time for assembly.
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Projects:”Calibre 834” - tube phono MM preamp | ”najah” - Raw 180W Tripath Class D power amp | "Icon" - Shuguang CV-181Z preamp | "Njira" - 180W Tripath Class D power amp


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PostPosted: 31 Mar 2019, 06:03 
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Finished the phono stage “Calibre 834”. The external PS I was using for my current tube phono pre needed a simple mod to work with three tubes now and not two. Sounds excellent.

Tubes are to short plate (very important) Sovteks 12AX7 and a GE 12AU7 driver.
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Projects:”Calibre 834” - tube phono MM preamp | ”najah” - Raw 180W Tripath Class D power amp | "Icon" - Shuguang CV-181Z preamp | "Njira" - 180W Tripath Class D power amp


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PostPosted: 01 Apr 2019, 15:48 
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Some will have picked up that the title should be EAR not EAT. EAT supply me the Class D amp modules. Guess I got a bit mixed up.

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Projects:”Calibre 834” - tube phono MM preamp | ”najah” - Raw 180W Tripath Class D power amp | "Icon" - Shuguang CV-181Z preamp | "Njira" - 180W Tripath Class D power amp


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PostPosted: 24 Apr 2019, 19:20 
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I just read where Jim Austin of Stereophile uses a EAR834p tube phono stage. When he has reviewed dozens of tube phono stages yet has stayed with almost a vintage phono stage. He must like the sound. So do I.

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PostPosted: 25 Apr 2019, 11:28 
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Joined: 29 Jun 2016, 15:59
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mwhouston,

Hi. I am interested in building this phone preamp.
Questions:
Where did you buy the kit from?
What do you mean by "Tubes are to short plate (very important)"?
Any noticeable noise/hum?

Please, let me know. Thanks,

Danny


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PostPosted: 25 Apr 2019, 16:58 
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Danny

There are a few on eBay. I chose without tubes because I have way to many very good new 12AX7s. The parts which came with mine are very high quality. This is what you need for a phono stage.


https://www.ebay.com/p/E834-RIAA-Mm-Tube-Phono-Amplifier-Kit-Turntable-Preamp-Base-on-Ear834-Circuit/13021134092?iid=322544889064

I have a low hum and buzz at the mo. This is due to my earthing arrangements and where my preamps floats. Still working on the issue. But you have to get right down at the speaker to hear either. At my listening distance some 5 to 6 meters back, nothing.

All tubes are microphonic to some point, some far more than others. Most short plate tubes should be less microphonic than long plate. In 12AX7s you can get both short and long plates. I chose short plates. I had a couple of pairs of both but went for the short plates. Bruce of oddwatt fame said he thought the long plates sound better. Up to you try both.

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PostPosted: 28 Apr 2019, 06:42 
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Mwhouston,

Thanks.


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PostPosted: 07 May 2019, 13:43 
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Joined: 19 Oct 2018, 15:30
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Location: Montréal, Québec
Some people argue (like Paul McGowan from ps audio) that microphonics might be what causes the "tube sound". Without any facts backing up is statement, Paul thinks that the sound coming out of the speakers might get picked up by the tube, creating some sort of "reverb". Don’t know if it’s true, but if it is, getting rid of microphonics would also mean getting rid of the tube sound. That might also explain why Bruce likes the sound of the long plates.

Anyway, I think that people should listen to what sounds right to them.

I was interested in those kit, but never bought one because of the lack of reviews. I might give it a try ! Do you know anything about the other version of the same circuit ? There is at least one or two other versions with different looking pcbs !


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PostPosted: 07 May 2019, 16:31 
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Location: Montréal, Québec
Just to add to what I said before : in my universal 4S preamp my favorite tube is a RCA clear top 12AU7A, wich is a long plate tube. I actually use a GE ECC82 in the cathode follower buffer stage, wich is a short plate. I prefer this combination to all the other 12AU7 I have in my stack ! Two GE ecc82 was great, but darker than the RCA clear top.


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PostPosted: 07 May 2019, 17:35 
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Joined: 04 Jun 2008, 20:59
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Location: Arizona, USA
Hi, Not to open a can of worms......I prefer long plate JJs for ECC803S (12AX7), ECC802S(12AU7) and several brands for the 12AT7s all of which are short plates. In the things I use them in the long plate ones seem to have more detail and a smoother sound. For each their own though that is what diy audio is all about.

Good listening
Bruce

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