With a tube-based preamp in place, I am somewhat tentatively taking a look at some tubed power amplifiers to go with it.  I’m nowhere near a buying phase yet (unless an incredible deal comes along), but it helps to get familar with brands, models and price ranges for completed sales, to have a point of reference.

The tubes have a specific lifespan, so that is the first consideration.  How many output tubes will the amp have, how hard are they to find, and what do they cost?   Are they common tubes, or something unusual (which can be both good and bad)?  The small signal tubes have a longer lifespan but there, too, eventual replacement will be lurking in the future.

Next, what about power consumption?  At idle, tube amps can use a lot of power.  Some days if I am working from my home office, I may have the power amp running twelve hours per day.  If it is idling at 500 watts, that is quite a substantial amount of power…and heat.

Finally, to get a hefty amount of output power, will I need to find a larger stereo amp, or switch over to monoblocks?

As for brands, there are a lot of choices. Given my experience with Conrad-Johnson, I may want to stick with their products.  I passed up the MV60SE that the seller of my preamp had, but I didn’t feel 60 watts per channel was adequate for electrostatics.  It still might be a good entry point.  The Classic Sixty is another, similar model that would fit the same bill.  I really like the Premier 140, or even a Premier 11, the latter being around 70 watts per channel and the former being around 140/channel.

VTL (Vacuum Tube Logic) is another manufacturer I’ve kept an eye on.  I had to pass by a ST-150 that was several years old, yet was hardly used.  One neat feature about many of VTL’s amps is that you can use the amp in two different modes–an ultralinear tetrode mode that is faster and more accurate, or the triode mode which has the “tubey” characteristics that many like, albeit at half the output power.  A rear panel switch changes modes.

One other interesting option is a VTA M125 monoblock–it is a kit-built amp based on the old Dynaco circuitry, yet greatly enhanced.  It, too, has a dual-mode switch, and it can also run in a half-power mode with only two output tubes vs. four.  The only drawback is that these are built on a raw chassis and have no cages, something I would prefer to have with an amp.  I tend to buy most of my equipment second hand, and pricing these out, the cost is about the same as some of the other amps I have mentioned above.

Given the few drawbacks of tube amps, I sometimes wonder if sticking with a better solid state amp might be a better choice.  My current amp needs some new capacitors and a couple of small modifications which would make it into a top notch amp.  Likewise, I can get ahold of a Conrad-Johnson MF-2300 that gives me about the same amount of power I have now, but would maybe be a better match to my C-J preamp.

It only took me 34 years, but I finally have a new (to me) preamp in the system, and I am finally a member of the “valve audio” club.  The PV-14L arrived two weeks ago, and I have been getting familiar with it.  My unit has had the “S2” upgrade, which features improved caps, Vishay resistors, etc., and a new spec for the tubes.

Having only seen photos of the front panel, I was afraid it was going to be silver.  Instead, it is a pale gold color, which looks nice with the engraved front panel.  Operation is by pushbutton, with most features available via the remote.  Switching and volume are done internally, so worries about oxidizing potentiometers is eliminated.

The tubes were changed out at some point, as the factory spec Mullard M8080s were replaced with the Philips ECG 6C4WAs. For a quick replacement, I ordered in a pair of Tung-Sol 6C4s which were marked for FAA use.  I have the M8080s shipping from the UK, as they are reportedly less microphonic than these 6C4s are.  The Tung-Sols do sound nice in the system, slightly less bright or “etched” sounding than the Philips pair.

One thing I have noticed with this preamp is that the imaging is rock solid.  Instruments are more clearly placed left to right in the soundstage, and vocals are spookily centered between the speakers.  Clearly my speakers are the weak point (for that “last mile” of improvement), yet I can still hear the differences.  One critique of this preamp was weak bass (boooo….), but the S2 upgrade cured that.  The bass is definitely weighty in the improved version.

It also appears to be a good match to the Nelson Pass-designed Stasis amp (Nakamichi PA-7).

The only thing it does not have is a phono stage.  But, that issue has been solved as well…

I will be back with a long-term update, as well as an update once I get the Cardas interconnects built.

I’ve lived with my Silver Sonic cables for several months, which I wrote about this past April.  While they are a clean sounding cable, I am finding the sound to be somewhat thinned out.  Perhaps the silver in the mix is not to my liking.

I have decided to embark on another cable project and make up a few sets of interconnects usinc Cardas 2×21 interconnect wiring.

This particular Cardas cable uses a “golden ratio” of conductors in an arrangement where the inner strands are smaller than the outer.  More notable is that Cardas produces these using litz wire, where each individual strand is insulated with a clear lacquer coating, similar to how windings in a transformer are insulated.  I won’t go into the technical and electrical advantages, but others who have heard Cardas cables mention that they are less bright (some even say they are dark) while the sound is more full-bodied.

This cable is not so expensive that I need to worry about buying enough to make the interconnects.  With that in mind, I am going to go with the Cardas 2×21 and, again, the Neutrik ProFi RCA plugs.  I had considered the Cardas Silver RCA plugs (their lowest cost plug), but it still uses a similar brass core that the Neutrik uses.  Since my RCA jacks on the new preamp (you’ll find out more in a few days 😉 ) will be gold plated, having gold on both the plug and jack will prevent metal mismatches.

Since it has the separate shield, again I will use the floating shield method of building the cables; my Silver Sonic cables remain dead quiet even today.

What’s nice is that I can mix and match these different sets of cables as needed.  If the phono playback is too dull, I can swap in one of the Silver Sonic cables.  If digital is too bright, I’ll stick with the Cardas over the Silver Sonic.

The only caveat with Cardas litz wire is that it requires special preparation–a rosin flux, and tinning.  I may not invest in a solder pot for this project, but the flux is a necessity to flow the solder and melt the lacquer insulation.  (I need to use a heat sink to prevent melting the insulation further up the wire.)

I was without the 17D3 for a couple of months, as I had returned it for a minor warranty issue.  With no new stock forthcoming, the distributor got in touch and offered me an upgrade to the XX2 Mk. II.  It would be factory rebuilt, and I could either borrow it long-term until the 17D3 came in, or keep it if I liked it; the cart would go into their demo stock for use in trade shows.

Turns out I’ve kept the XX2.  Given that I can now actually see the cantilever, it is juuuust a little bit easier to align. From what I can tell, it uses the same basic cartridge body as the 20X2.  Yet the motor and everything else is improved.

As with the 17D3, the XX2 outtracks that piece of shit Ortofon 2M Black I formerly owned.  I will say that from first impressions, I still think I prefer the sound of the 17D3–it is more neutrally balanced.  Granted, the XX2 has not broken in yet, and I have also not been able to further adjust the cartridge loading in the pre-preamp.  I find it to have a slightly “peaky” sound, almost as though I can hear the resonance of the aluminum body manifesting itself in the music.  Not that it is a glaring problem–it’s subtle. And it very well may go away once it breaks in.

After a few months and a more careful alignment, I will have more impressions on this fine cartridge.

After 33-1/3 years (give or take a couple of weeks…seriously!), I finally refreshed the capacitors in the DH-101.  A year or two ago, I swapped out the DH-110 for a handful of reasons.  First, I always thought it was a little “softer” sounding, maybe even mushy.  Second, I bought it used, and the front panel and knobs tend to chip off.  Third, I hated the stepped volume control with a passion–at lower volumes, it was impossible to set to the desired level.  Fourth, the switches and potentiometers were quite noisy, and got noisy faster after a good cleaning.

That drove me to put the DH-101 back into the system.  I’d read comments from some owners preferring the 101’s sound over the 110, the background being “blacker.”  And upon hooking it back up, I noticed it was not only quiet, but sounded a touch more precise.  Faster, maybe?  At any rate, the 101, and the 110 for that matter, were both overdue for a refresh.  Time for some new capacitors in the 101!

Rather than buy them individually, I wound up buying a complete capacitor kit.  I might have preferred caps that were a little more high-end, but the advantage here was that these were electrically paired and matched for a much closer tolerance than what I could have bought on my own.  All of the electrolytics are now Nichicon.

The kit was only for PC4, the main audio board.  It did not include power supply caps.  No problem, as I had other plans.  The process went rather well, I’m happy to say, and it did not take long to replace everything.  A couple of days later, I was finally able to give it a listen.

Was there a huge difference?  No.  But I did notice the sound was cleaner and clearer than before, and the tonal balance was subtly better.  It also seems the highs lost a slight bit of roughness.  It did come out quieter than before, although I was also battling some substandard Audioquest cables at the time.

The power supply caps I ordered from Mouser.  The 101 originally had capacitors before and after the 7818/7918 voltage regulators.  Before the regulators were 1000µF 35 volt capacitors, and after were 100µF 35 volt.

Or, so I thought.  Many years ago, I had a similar problem where the power was intermittent, the preamp would only turn halfway on–the sound was distorted, and the LED was dimly lit.  Back then, I had replaced the caps on one side of the power supply.  That fixed it, for a while.

Only after I took the caps out did I realize I’d replaced the originals with 25 volt capacitors.  Which might explain why they failed again!

We’re good now, though.  The new caps are 50 volts vs. 35 (or, oops, 25).  I also read that increasing the value could help the sound, so I bumped them up–the 1000µF are now 3300µF, and the 100µF are 330µF.  What are the advantages?  Better filtering (lower noise), and more importantly, increased storage capacity, as that is one function that capacitors provide.  Luckily I found capacitors with the same lead spacing and diameter, as it’s a tight fit.

So, what happened to the sound?  The noise level is very slightly better, to the point of almost not noticing it (as it is already very quiet).  But the drive…the bass is subtly stronger and clearer now that the voltage does not sag.  Very nice!  The heft of the bass improved with the Nak PA-7 in the system (which has, I think, about 132,000µF total capacitance in its power supply), and this helped it along even more.  It’s subtle again, but the preamp has an even more effortless quality than it did before.  I can turn it up and hear no straining whatsoever.

I bypassed the external processor loop.  Doing so freed up a set of RCA jacks.  I have long wanted to have an attenuated output, so I could regain more of the volume control’s range.  One output is still full power, while on the other, I have two resistors per channel (33k, and 8.2k) in an L-pad configuration, giving me ~12dB-15dB attenuation.  Due to the power output of the preamp, I went with 1-watt resistors.

I will likely not take modifications much further, beyond some mechanical changes.  I may change to a star grounding arrangement to get rid of some stray EMI/RFI.  I might rewire it with premium wiring (even though I did a nice job of routing it when I originally built it up) from DH Labs.

Most notoriously are the horrid RCA jacks on the back.  Made of aluminum, the are quiet dull, and they are also loose to the point of rattling.  I need 22 panel mount gold-plated RCA jacks to make a change here, not so much for sound, but to prevent future problems.  All of my cables are now gold plated, so there will be no metal mismatch.

Despite its age, the little DH-101 still holds its own, and is refreshed for another couple of decades.  I am leaning towards a tubed preamp, but this 101 will not leave my possession.  I might match it back up with the M-500t, or I may find a Hafler DH-220 power amp to pair it with.  That would make for a nice-sounding system.