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Recommendation Request for Tube Power Amplifier

I have been using an all solid state system for many years. I hear so much about the "tube sound" experience. I'd like to check it out.The only experience with tube amps that I have comes from these two amps...

One is the Paragon System E Tube Preamp with phono. I bought this new about 1980. It uses six 12ax7 type tubes. I used it quite heavily for a few years. When it developed problems with the volume control, I replaced it with something I can't remember. In storage for a few decades, I pulled it out six months ago, cleaned all contacts, especially the volume pot. Still works!. I have measured this guy quite thoroughly. Phono gain is 43 dB. Distortion from Tape Out is below the noise floor at -95dB. Noise at 60 Hz and multiples is -60dB or better below 0dB recorded level.. Great numbers, even compared to modern preamps. I replaced the old 12AX7 tubes with six matched Genelex Gold Lion tubes.  I'm using this now as a phono preamp with the Koetsu RS and a step up transformer at 20x (Cinemag 1254). The table is a brand new Technics SL-1200G. I really like this sound.

But I'd like to try tube amplification again without spending a fortune.

What tube power amp would be a great match for this system? Years ago, I had a CJ MV75 power amp. I liked the sound, but hated the continual tweaking of the bias, even with brand new tubes. I sold it.

My budget is $3K or less.My system is not too efficient (86 dB sensitivity Revel 105 Bookshelf speakers and a self powered HSU sub, 100Hz xover), so I probably need more than the 3 watt/ch amps I see for some of the less expensive models. How much power do I need? I'm not sure. I've never heard any problems with the Levinson No. 27 or the present Bryston 2.5B cubed, but they both put out 100 W/ch or more. Balanced inputs would be great, but not absolutely necessary.

I consider my present system to sound quite neutral. I worked very hard to get it that way. I'm very pleased with the sound.

I want to exprience that warm tube sound if only to have a change of pace. Or maybe...

Thanks for your help!

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ltmandella's avatar
ltmandella
152 posts
 

I recommend Transcendent Sound OTL Tube amps.  Bruce engineers numerous OTL versions, using 300B or more affordable tubes.  And even a 50wpc into 2ohms "bruiser" (that one is not OTL).

They are all kits but for a reasonable fee there are customers on his forum which will assemble for you.

OTL has to be heard to be believed.  Those dern output trannies muck up the sound...

paradisecom
307 posts
 

Depending on the seating distance from the speakers and how loud you listen, I'd look for something that is at least 20wpc.

I have a little 5wpc tube amp and with my 91dB rated speakers at about 8' away and I get plenty of volume for my office system.

http://www.hometheaterengineering.com/splcalculator.html

bato1965
15 posts
 

Nice preamp. Try to invest in some Siemens or Tele ECC83, it should make it a bit better, and if NOS should last forever. Also a very good match for RWS (I do have it too). I'd just try some other SUTs, but that is more of the personal preference, or acquired taste. Like herbs and spices, like Syrah vs Shiraz...

Your speakers have a low sensitivity, but also unkind impedance curve, which makes for a legitimate double whammy... If you want to drive them properly, something based on KT120 - better yet, KT150 - and at least 100 wpch, would work for sure. ARC is good, but that will costs much more than your budget dictates. Heck, retubing them big monoblocks might cost as much...

I tried to drive Dynaudio S40 with Audiomat, which is 30 wpch and amp known for great current. However, it was not enough to control LF. When pushed, amp lose the control over the LF drivers and they would start farting... If pushed just a bit more, drivers would bottom out and fart out their last fart. Lil' Bel Canto S300iU I had handy sounded "better" than Audiomat... Now, if hooked up to higher sensitivity speakers with tame impedance curve, Audiomat far surpasses Bel Canto. 
Simply, EL34, 6L6, KT60, KT77, even KT88 - based designs are not enough for your speakers. 

When amp and speakers are not properly matched, that distortion is always present. Most of the time, people who are listening at low levels would not even know that something is wrong. However, if they would change the amp, suddenly a mediocre SS would sound noticeably better than a great tube amp... And they would blame the tubes. 

If you want to experience the tubes, I would suggest buying a nice used tube amp and above mentioned (also used) Tannoys - if you can find 15" dual concentric, thats where the magic happens. Then hook up both speakers, changing back and forth for some time. Give the tubes / Tannoys some time before you decide what is better. 

Did I say you have a very nice cartridge?

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