Good budget tube amp?


So, I've been wanting to upgrade to a good tube amp for a long time now. Currently, I've got a pair of Totem Rainmakers and an NAD C375BEE. I'm thinking about selling the NAD and getting a tube amp instead. My question--can I get something good for 1k or less? I've listened to a Rogue Audio amp that I loved and am trying to find something similar in quality. I've been told to look at Dynaco, but as I don't have much familiarity with them, I'm not sure exactly what to look for. If someone could point me in the right direction with some model names to look for, or even a good site that has information on Dynaco/other budget tube amps so I can learn a bit more about what's out there, that would be greatly appreciated. Thanks
rossbernstein

Showing 7 responses by seakayaker

Well, you have some pretty good suggestions above if you can find 'em; let's see what an "alternative" picture might look like. If you are buying new and are committed to retaining the Rainmakers, then have a look at Bob Latino's Dynaco-derived KT-120(easy)kit for KT-88's, et.al. Bob's eBay spots had a more useful one-shot presentation on this amp than the main website, the last time I looked. Documentation is said to be thorough for first-time builders, and options are set out clearly. Bob seems to have favored the Gold Lion Reissue KT-88's in this design for awhile, but there are other choices, both cheaper (some say the E-H KT-88's are fine), and dearer (Shuguang Treasure Series, et.al.). I'd opt for appropriate NOS tubes at the input, if not right away, then when you can: Bob, or someone like Jim McShane can surely guide you here (G**gle).

Some practical benefits of this choice: Work slowly, wire it with consistent, symmetrical, and "artistic" neatness; make the practical/premium choices in the "non-consumables" and input tubes; take photos as you go and record all the reasons YOUR build is "as good as you'll ever see"... and the inherent value, your retained value (for if and when you upgrade), will probably exceed comfortably your other options buying new. Your true cost -- that is, the real "price" -- is your total cost of ownership. Therefore, this might be your most economical choice, as well as potentially the best sounding. Of course, who can say what might show up in the listings here worth grabbing with little hesitation!

My personal choice might be for "[slowly] appreciating assets" among the vintage amp listings on eBay, and sometimes here: recognized "classics" like Pilot SA-232 and SA-260 (if bidding doesn't get overheated), and other broadly-respected units such as Eico HF-87 and Fisher SA-100. Also consider well-accepted models the whole crowd hasn't gotten hip to (i.e., bargains): various 7189/EL-84/6BQ5 Heathkits -- AA-151 is a good, low-cost choice (with some modding)-- Fisher SA-16, Stromberg-Carlson ASR 333/433, Sherwood S-5000 II and S-5500 --> version IV 7868 amps (stylish, if they're to your taste -- my late S-5500 IV is less rats-nest-y under the hood than earlier iterations, which = easier to work on); as well as the option of two decent integrateds to use as "monoblocks" (I picked up -- "submitted for your approval", as Rod Serling used to say -- in separate transactions, two VERY clean Heathkit AA-181's, ~23 watts/ch., with original tubes -- 7591's + the small tubes, worth approximately the cost of the amps themselves! -- for WELL under three hundred bucks). Figure $200 for refurb by a qualified person, maybe less, maybe a bit more... and you're there, depending on what sensible, straightforward mods may be advisable. Many know what to do here. In cases involving the integrateds especially, you'll probably want some wiring and control circuits up front bypassed, which is not a big deal; but read the vintage and DIY forums for guidance and caveats. You can also get an idea who can perform the work -- all of it, or some -- as you go along. Just G**gle.

For the latter choices, you'd want more sensitive and/or tube-friendly speakers, so it would be kind of a sea change for you. You didn't mention musical tastes, and that will have much to do with deciding which speakers would be suitable for the power on tap. I'm setting up a vintage-y system now myself (partly as a hedge against the economic effects of any more dubious four trillion dollar wars... or similar little faux pas -- seriously... I'm semi-retired and vulnerable). Through Audiogon, I have Silverline SR-15's & Minuets, plus Jordan wide-rangers to experiment with. There are the usual high sensitivity options (Tekton Lore [?], e.g.); also check out models that, at first glance, seem too "insensitive", because a few of these can surprise, if you have a small room or rarely CRANK it. Two examples I've seen vouched for in this regard -- though I cannot do so directly -- are the last iteration ACI Sapphires before the smaller Emeralds (by the designer); and the PSB Synchrony 1B's, if Andrew Marshall and 'Audio Ideas Guide' can be believed here (2A3's?!).

In sum, that's one sort of survey of the not too "specialized" tube universe from circa $1000, on "down". Have fun!
Trelja makes a fair point regarding the ST-70. Note that Mr. Latino can also supply an all new, "modernized" version of this that addresses these issues to a useful degree, and the Dynaco pedigree look is retained. Keep in mind that no matter how many raves you hear about this or that amplifier from the so-called "Golden Age", practically all of these were designed under serious cost constraints for a MASS MARKET. There was neither much of a "high end" as we know it today, nor a hardcore consumer subculture for extremely pricey solutions or boutique parts, status symbols not withstanding.

I think you'll find the KT-88/6550 version I mentioned with the beefier transformers more economical in the long run: the "supply side" constraint on resale prices and "appreciation" of the standard ST-70 and its many variants is pretty obvious. Then, too, your options for speaker choices (and speaker bargains!) are expanded. You can always use EL-34's or 6CA7's in the he-man version, if that better suits your taste in sonics. Also consider that triode mode switching and an input attenuator with gain/sensitivity options via tube choice are available, too. Work through the math, consider the market's alternatives... you'll see.
A few more things I should have mentioned regarding the "true blue" pop-classic: Proper NOS 7199's are a must -- they are generally considered pricey -- so carefully investigating the condition of these in any ST-70 you're considering is important. A minor mod to accept NOS 6GW8's (pricier)in this position is considered by some enthusiasts to be the high end way to go. Substituting a pair of top-shelf input loading resistors such as Caddock is dead simple and can clearly improve the sonics in a well sorted out tube amp for the price of a solo dinner at Appleby's. And don't think the kind of gold binding post mods you commonly see around are improving the sonics: more likely, the opposite, cable-fitting issues aside.

BTW, Trelja, do you think some folks in Kevin's network would want to take on some of the refurb work I alluded to in my initial post at a keen price for tube newbies? THAT would simplify this path greatly for Rossbernstein and others.
I very much take your point on the Concertina, Trelja, but here's the rub: the Concertina, or split-load style of phase splitter & driver, really is not properly used "naked" driving a Class AB output stage, or with any sort of output stage where you are going to be drawing much grid current. This is because the frequency balance between the two phases -- which interacts in various complex ways with other characteristics of performance -- depends crucially on the plate circuit and that of the cathode in the Concertina seeing EQUAL IMPEDANCES at all times.

Contrary to audiophile mythology, in a circuit where the two loads are effectively kept close in value and stable, the output impedances of the splitter, top & bottom, hence the "drive" characteristics of the two halves, are VIRTUALLY IDENTICAL. Not so in a Stereo 70 trying to push out nearly 35 watts into most real world speaker loads. How many "respectful" ST-70 mods retaining this splitter arrangement, but operating in pure Class A, where neither OP tube cuts off, have you seen -- preferably with grid chokes, etc, to handle the grid current? None, I bet. This is why D.T.N. Williamson added a LTP driver stage after the phase converter in his classic design... at the expense, because of multiple poles in the now more complex circuit, of marginal stability vis-a-vis the global loop feedback -- which itself interacts with complex, dynamically changing speaker loads. D.T.N. got it pretty much right -- others didn't.

Thus, some Williamson copycat amps of the '50's, being adulterated by cheaper, slightly wonky or inconsistent output transformers and such, could be -- and STILL ARE -- very dicey performers. The Heathkit W4-M is an example. It will work fine with a LTP converter and a simpler front end circuit.

Their are ways to stick some band-aids on these problems, but you know, why not get it right?

By contrast, a little EL-84/7189 amp with Concertina, running Class A or close, at 10-12 watts out, can sound excellent in ways a stock Stereo 70 never can. So, I have the doggone cutest little refurbished Fisher SA-16 on the way to me now to add a little reinforcement to my point! And I have, I guess, a very nice ST-70 refurb with the stock front end for sale (in theory).
BTW, thanks for your very gracious compliments! One more point: This audio business is a funny thing. Sometimes things that just "shouldn't" work manage to sound better than, as some say, "they have any right to". Other circuits and executions look like the bees' knees on paper or upon physical inspection, and for some reason you may never figure out, just sound like doggie-doo. Credit should also be given to those old-timey engineers, who because of their deep knowledge, had their ways to pull a rabbit out of the hat. The trick may not be evident to modern day analysts! This is what makes the hobby "fun"(?).
Sabocat59, I'd be curious to hear how this not-so-common (in contemporary gear) front end compares in sonic characteristics to those of today's more familiar circuit solutions. Can you compare pluses and minuses? And what tube complement did you choose to go with?
Ditto, Mezzanine, on the loudspeakers! As to these specific suggestions: If you get the ProAcs or Vandys at the right price, you shouldn't have any problem at all reselling, if for some reason they don't suit your own situation. For Zu, please do read the Audiogon forum responses thoroughly -- there are many close observations on their sonic characteristics, plus useful comparisons here.

You may also find that more sensitive, tube-friendly loudspeakers "wake up" at lower a volume and have a bit more life at civilized levels. For me personally, I tend to have little interest in models that won't show well with something like 9-10 watts Class A EL-84 power, even if you don't go there amp-wise for your own circumstances. There are exceptions, of course.

And don't overlook the fact that Paul Speltz's 'Zero Autoformers' will let you optimize the power output of tube amps of modest power, or the First Watt amps for that matter, into loudspeakers having an impedance minimum right there in the midrange where you may need EFFECTIVE power the most! They are not just for the OTL guys -- see Paul's website for plenty more on this. I keep a set of these around for exactly that reason. A First watt J2, being one example many may not have considered in this respect, should simply put more watts into typical examples of these loudspeakers, according to the math. This is because you are current limited -- it's similar with small tube amps which are not optimized for low-distortion power into low impedances, like some of the small Decware amps are. Nelson implies -- you may know how the Zenmaster operates with respect to pronouncements of opinion -- in a recent addition to the website something to this effect.