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PostPosted: 25 Oct 2020, 16:49 
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Joined: 13 Jan 2018, 21:33
Posts: 353
Location: australia
Back to future, have blown my 6as7 amplifer power and output transformer cash and bought a Thorens TD160 turntable expected to arrive today. It is old so I may need to do some work on it. This is to play just a handful of the hundreds of LPs I couldn't bring myself to part with in the early 90s. I may have to shelve my power amp building ambitions for a bit but not forever.

Now none of the three transistor amps I have or my tube amp have a phono stage with RIAA. I have been looking at the phono stage projects on this site, but thought I would ask people's views on a good tube phone stage in case other ideas have emerged lately. Looks like I will have about 4mv output from the turntable--yet to measure-- I am looking to bring the output up to line level for my 6sn7/300b SE which operates loudly enough from my iPad or CD player with the 250k pot hardly past 12 o'clock.

A miniature tube or tubes would be nice. A question to ask along the way too is - are tubes the way to go for a phono stage? I see Mark has been building a variety of transistor phono/mc stages. In the past my Quad amp had a phono stage and I used battery powered Naim unit to boost the MC output. I thought this sounded rather neutral but had never listened to a tube phono stage at that time.

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PostPosted: 25 Oct 2020, 21:15 
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Joined: 04 Jun 2008, 20:59
Posts: 4258
Location: Arizona, USA
Hi, A worthy endeavor....however you will find the SS phono preamps are a lot cheaper to build than tube ones. I have several of each type. The ones Mark is using (he is a long time audio buddy of mine ..about 12 years now) are the ones in the project I posted a while back. Check the thread on it in the forums. Surprisingly nice sounding and really quiet. They can run on batteries (drain is about 10ma) but I prefer AC. That explains the well regulated supply. It adds about $25-30 to the cost but I hate batteries as they always seem dead at inconvenient times. A handful of AA or a pair of 9 volt ones will give a goodly number of hours though and is a cheap solution. High quality tube phono preamps run the gamut of prices. I personally have not seen any much below $1000US that are really any good. Most below that range are actually hybrid with most of the gain from an IC and the the tube is often just a buffer. The project I posted is all tube and quite excellent. It will cost significantly more to build and does require skill in layout, construction and wiring. I don't consider it a good project for a first time tube build. Done correctly it is a killer. Done less well and it is a debacle..with a lot of hum issues.

Your TD160 is a worthy turntable and if you want to know how to maintain it check out vinylengine.com. That forum is friendly has a huge following and lots of knowledge. Great reference section as well.

Good listening
Bruce

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PostPosted: 25 Oct 2020, 21:34 
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Joined: 13 Jan 2018, 21:33
Posts: 353
Location: australia
Thanks Bruce. Much appreciated. Will study up on the circuits.

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