# To tube or not to tube?



## wgmontgomery (Jun 9, 2011)

I am thinking of adding a tube preamp; I have never owned tube audio gear (I've ALWAYS used tube gear for played music-guitar amps, etc.) and wondered if anyone had some input; here's my plan:

I'd like to find a small, inexpensive tube preamp (a headphone amp/preamp would do) to use with my BM5As (powered Dynaudio monitors). I need 2 stereo RCA inputs and 1 or 2 stereo pre-outs (RCA or XLR).
I would run my main stereo source straight into the preamp (the other would be the main outs from my surround processor) and then to my powered sub/mains. I could enjoy pure tube sound for 2 channel, and still use the same speakers for HT. I'd just set the volume at ~9 o'clock and leave it there for surround; my processor would handle switching and volume for HT.

Any thoughts? Am I being dumb, or does this sound like a good idea? Any gear come to mind??

THANKS!!


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## tshifrin (Nov 24, 2011)

When I decided to venture into the tube world, I researched and ended up purchasing a Little Dot Mk III. It sounds fantastic and I've really enjoyed it. I bought it here: http://www.littledot.net/forum/index.php and was very pleased by the service I received. The model I bought only has one input, so I just switch plugs on the rare occasions I change sources, but if I remember correctly, they make a more versatile one.
I like the sound quality of the tubes (in my system), the build quality of the pre, and the flexibility to "tube roll" (which I'm still investigating). A good product at a reasonable price- I recommend it.

Tom


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## Jungle Jack (Jul 28, 2009)

Hello,
I am quite fond of Tube Gear. Preamps are a great idea as the Tubes last a long time compared to an Amplifier.
The great news is that there are a number of Companies that offer relatively low priced products. This is thanks to China and Russia both continuing to build them into modern times. I would check out Upscale Audio. They are a wonderful source for Tube Preamps and Amplifiers and Owner Kevin is a treasure of information and offers some very deals.
Cheers,
J


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## wgmontgomery (Jun 9, 2011)

Thanks; I've looked at some headphone amps that may do the trick. The biggest "problem" is that most of the inexpensive preamps/headphone amps that I've seen have only 1 input. I can Y the outs if needed, but I need 2 inputs.

I still think that this is well worth investigating. I'd have tube 2 channel and full 7.1 surround...sounds almost too good to be true.

I'll check out Upscale Audio; I've also seen some good reviews on some inexpensive SET gear out of China. Thanks


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## Jungle Jack (Jul 28, 2009)

Hello,
I really think you will like Upscale Audio. Their Website is quite well laid out and they also have a pretty large Used/Demo Area.
Cheers,
JJ


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## wgmontgomery (Jun 9, 2011)

Used/demo sounds really good; I don'y want to spend too much money. Thanks again!!


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## Jungle Jack (Jul 28, 2009)

No worries amigo. Brands like Jolida offer great value.


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## drchicago54 (Jun 5, 2012)

wgmontgomery said:


> I am thinking of adding a tube preamp; I have never owned tube audio gear (I've ALWAYS used tube gear for played music-guitar amps, etc.) and wondered if anyone had some input; here's my plan:
> 
> I'd like to find a small, inexpensive tube preamp (a headphone amp/preamp would do) to use with my BM5As (powered Dynaudio monitors). I need 2 stereo RCA inputs and 1 or 2 stereo pre-outs (RCA or XLR).
> I would run my main stereo source straight into the preamp (the other would be the main outs from my surround processor) and then to my powered sub/mains. I could enjoy pure tube sound for 2 channel, and still use the same speakers for HT. I'd just set the volume at ~9 o'clock and leave it there for surround; my processor would handle switching and volume for HT.
> ...


I am strictly a tube man myself and the best place to start is the used market. Rouge Audio builds some great inexpensive well built right here in America and I see their stuff for sale all the time. Remeber, tube equipment can be fussy but well worth it to me although most modern FET equipment has narrowed the gap between solid state and tubes


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## class a (Oct 22, 2010)

About a year ago I picked up a used Audio Research SP-16 for short money. Very happy w/it. Also has a HT pass through for my movies.:T


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## Jungle Jack (Jul 28, 2009)

drchicago54 said:


> I am strictly a tube man myself and the best place to start is the used market. Rouge Audio builds some great inexpensive well built right here in America and I see their stuff for sale all the time. Remeber, tube equipment can be fussy but well worth it to me although most modern FET equipment has narrowed the gap between solid state and tubes


Hello,
By little brother uses Rogue M-180 Monoblocks and a Rogue Preamplifier in his 2 Channel rig to excellent effect. However, compared to the Made in China Tube Equipment, it is decidedly more expensive. That being said, Rogue offers excellent build quality, resale value and customer service.

I am a big fan of Kevin over at Upscale Audio and think it is an excellent place to put together a Tube Based rig as I know of no other AV Store so into it. In addition they offer many used as well as new products.
Cheers,
JJ


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## class a (Oct 22, 2010)

If your going to check out Upscale Audio you might as well inquire about the Prima Luna line too. Excellent well built tube gear w/auto bias features that make tube rolling a breeze. Kevin Deal is the US distributor for the Prima Luna line. :T


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## wgmontgomery (Jun 9, 2011)

Since I am remaining in NC for the foreseeable future, I am back in the market for a tube preamp. I was holding-out since I didn't want to buy _another_ piece of equipment to pack and move. I'll be sure to check-out Upscale Audio!


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## gmant123 (Jan 1, 2011)

You need found a preamp with low output impedance to drive better long/bad cables.

You can make a DIY pasive input selector easy, in diyaudio forum can help you......

Alberto.


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## rongon (Aug 23, 2012)

Are you handy with a soldering iron? What about a kit? 

Also, a question... Are you playing PC audio (FLAC, etc.), CD, DVD, SACD only? If so, all are designed to send out 2V rms from digital 0dB full scale (0dBFS). Most power amps are designed to go to full power with only about 1V rms (or often less) input. That means that any digital source can drive a power amp to full power, so you actually do not need a line amp ("preamp"). Just a selector switch and a volume control will do. 

Do you know offhand if your powered speakers require a +4dBm ("pro") level, or a -10dBV ("consumer") level at their inputs? Or maybe they have a switch so you can choose between the two? 

In hi-fi, one usually tries to reduce the distortion and noise to as low a level as possible. If you don't need the gain, adding any kind of preamp with gain will only increase distortion and noise. 

Do you want a tube amp for its sonic color? Or do you really need the gain to get your power amp to full volume? 

If your powered speakers need a +4dBm pro level input signal, then you might actually need a preamp with some gain. It should then be balanced, for sure. 

A really cool project might be a tube preamp with balanced (push-pull) outputs. SY, one of the moderators at diyAudio.com's Tubes forum, posted a design with a 6SN7 tube as a gain stage going into a 6DJ8 split-load phase splitter. So you get single-ended (RCA) inputs to balanced (XLR) outputs. The gain is about 15X. That would be more than enough (2V rms x 15 = 30V rms!). 

I generally don't like the Chinese do-it-yourself kits because they often have design mistakes. I don't know much about the commercial tube products coming from China. Some look nice, but I wonder if they're designed poorly. I'm sure there are some gems mixed in there, but I'd be careful. 

Just my $.02, FWIW.
--


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## rongon (Aug 23, 2012)

Sorry to double post... 

The design I was thinking of is the ImPasse Preamplifier by Stan Yaniger. His design has all sorts of cool tricks with transistors acting as loads for the tubes, and a regulated power supply. You could put together a simplified version to see how you like tubes in the signal chain. 

I can't post links yet, but if you look for The ImPasse Preamplifier, I think you'll find it. 
--


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## wgmontgomery (Jun 9, 2011)

Thanks, rongon! 

My speakers can handle either input; default is "pro" level, but there is a switch. 

I can solder and have an iron and silver-content solder. My main reason for wanting a tube preamp is for its "sonic color;" I've considered going DIY. A kit would be nice, and it would save me a lot of money!!


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## rongon (Aug 23, 2012)

wgmontgomery said:


> Thanks, rongon!
> 
> My speakers can handle either input; default is "pro" level, but there is a switch.
> 
> I can solder and have an iron and silver-content solder. My main reason for wanting a tube preamp is for its "sonic color;" I've considered going DIY. A kit would be nice, and it would save me a lot of money!!


I think the ImPasse or something like it would be the best choice. Mr. Yaniger knows what he's doing, for sure. It's a very good design. 

The 6SN7 is about the lowest distortion tube ever made. The ImPasse uses it for its voltage amplifier. It should have plenty of gain for your speakers' balanced inputs set to +4dBm ("pro" level). 

The 6DJ8 is used for the unity-gain phase splitter (aka "split-load phase inverter" or "cathodyne phase inverter"). The 6DJ8 is good for use at lower voltages, and has a relatively high transconductance characteristic, so will have a reasonably low output resistance. That means it should drive your cables well. 

The original design has an input transformer, which would be expensive. But you can do without that. Just use a selector switch to a good stereo volume control of some kind. Then take the outputs from the volume control (wiper) to the grids of the 6SN7 (inputs). 

I can't post schematics or links yet, but soon.

Oh yeah... What will you be feeding to the preamp? The output from a mixer? If so, balanced? Or just CD player, PC audio out, etc? (In other words, all unbalanced, consumer-level sources?) 


PS - CAUTION: If you've never built something with vacuum tubes before, please be warned that they work at high voltages (but relatively low current). An 'oops' can cause serious pain or injury, and if you're not careful, death. Any kit or DIY build using tubes is NOT to be taken lightly. Just need to be responsible about this... 

--


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## wgmontgomery (Jun 9, 2011)

I'll be using the tube preamp for stereo (actually 2.1) with a feed to a SSP for HT. Thanks; I'll check-out the equipment listed above.


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## rongon (Aug 23, 2012)

Let's see if I can send you links... 

Article from AudioXpress on building the preamp: http://syclotron.com/ImPassePreamplifier.pdf 

Site where you can buy bare pc boards for making it: http://www.tech-diy.com/Store/TubeStuff.htm
Impasse audio board is $8
Impasse Maida power supply board is $7

I hope that's helpful. 

--


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## wgmontgomery (Jun 9, 2011)

rongon said:


> Let's see if I can send you links...
> 
> Article from AudioXpress on building the preamp: http://syclotron.com/ImPassePreamplifier.pdf
> 
> ...


VERY helpful; thanks!! :hail:


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## wgmontgomery (Jun 9, 2011)

It looks like a great design; I glanced at the article/specs , and it appears to be a N. Pass design. :TT It's _true _dual mono; a big plus for SQ. I wonder how much _quality_ parts will cost? I'll look into this...thanks again!!


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