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!

128x128Ag insider logo xs@2xkevemaher

I too have used solid state amps for nearly four decades, staying away because of the same reasons you state. In retrospect I am sorry that I wasted so much time. My tube amps have autobiasing and slow warm ups to increase tube life. Although in retrospect, biasing is really not that big a deal and need not be done often. I really would not make it a requirement.

 

I am running my speakers (90db efficient) with 70wpc and they will play louder than I can stand without reduced dynamics. Tube amp power is very different from solid state. Because ss are so fast you typically need a lot more power. On the other hand your speakers are not very efficient.

 

I am sure there are folks that will be able to recommend a budget amp for you. But remember… in this price range there are going to be some compromises. How much power do you need? I am not sure… 50wpc?

In the old days tube amps tended to be syrupy and really warm with attenuated detail. So, the word tuby came about. Todays tube amps have converged on detail and are in no longer syrupy. But they have highly detailed bass, great midrange bloom, and have a realism that seldom can be matched in solid state. What you loose is some stirility and slam. The bass with tubes is far more detailed and realistic, but does not tend to give you the exaggerated bass slap that ss amps do.

You might consider used and get a bit higher quality / sounding amp. I think you are in for a treat.

@ghdprentice Thanks. I am certainly considering used amps. I've seen a used Rogue 100 here on Audiogon that seems to fit. So far, I've seen great reviews, especially from 10 Audio.

I should add that I'm thinking that this amp will be for my phono system only. I've got the Bryston for the rest..

     Nothing (AT ALL) wrong with the above, but: here's another tack, you might consider.

     You already have two excellent amps, that are a better match to your less-than-efficient speakers, than tube power would be.   Even with the powered sub.

      Either would easily prove transparent enough to convey whatever improvements made, in your preamp.

       The Paragon System E (NICE pre, btw) was built with MOSTLY Metalized Mylar caps, which are good (basically) for ever.

       The external power supply is a huge plus, far as noise reduction.

       BUT: if yours has the two, light blue, electrolytic caps; they are over forty years old and could (probably) use replacement.    As well as any electrolytics in the PS.

       Older components can still sound good with aged/weakened electrolytic caps, but: much better, if refreshed.

        Whether you choose to address those or not: why not explore the world of 12AX7s extant, to shape your system's sound, to better suit your aural palette?

        Were you to purchase just one pair of NOS 12AX7/ECC83/5751s: there are three positions per channel, in which you could try them. (great flexibility).

                                                        ie:

         For a warmer presentation: British tubes (ie: Mullard or Brimar).

         Clear as crystal: Telefunken or Seimens.

         Somewhere between those: Bugle Boy, Amperex and some USA (RCA, Sylvania).

         Of course, you'd want to be certain; given their intended purpose (your pre/phono), they were tested for the lowest noise possible.

          Brent Jessee* would be my go-to, far as MY preferential/most trusted source.

          Here's a bit of wisdom, from a popular 6SN7 comparison, that's applicable to any tube circuitry, using multiples of the same tube:

          "One thing became clear based on customer feedback, combining 6SN7 types seems to work better than using all 6SN7s of the same type.

           With so many preamps and amps using this tube, you can end up with
Six 6SN7s per channel.

            It appears combining tubes like the VT-231s as voltage amplifiers and 6SN7Ws or 6SNGTA/GTBs as driver tubes you gain the strengths of all.  Using one type seems to accentuate the tube’s weaknesses."

                           *http://www.audiotubes.com/12ax7.htm

                                (Brent's on vacation until Aug 6)

                                 Have fun and happy listening!

           

 

            

           

           

 

 

@rodman99999 Thanks for the great advice.

Yes, I have looked at the caps in the PSU and the unit. I normally replace all caps in a vintage audio product. I've done it for all the tuners that have come this way and lately for the two APT model preamps and a couple of turntables. I've been putting it off out of laziness.

Thanks for the tip on the electros that may be in the unit. I will need to look to see if I have any.

I have already noticed a difference in sound compared to the Musical Surroundings phono pre I have. Sound is smoother, flows easier it seems. But not the big, enveloping warmth that people glow about. Maybe I'll find it with the power amp.

Yes, lower powered tube amps are problematical with the speakers I have. I probably need more than 50 W/ch.

I sincerely appreciate the time and effort you spent on your post.