Top tips for buying a used tube amp?

Discussion in 'Audio Hardware' started by Shiver, May 7, 2015.

Thread Status:
Not open for further replies.
  1. Richard Austen

    Richard Austen Forum Resident

    Location:
    Hong Kong
    The OTO is fine with 91dB but your speakers present an interesting situation. They recommend 15 watts - but tha's really quite piddly difference from 10 watts of the OTO - 2dB. But the Spendor is 4 ohm - not a big deal the OTO has a 4 ohm tap. Still it's the kind of thing you'd want to try first. My gut tells me you might be better off with the SORO which is considerably more robust at 18 watts. Some people do like the SORO more than the OTO.

    Download an SPL ap for your smartphone (if you have one) - most are free. sit in your seat and play your hardest hitting album at the level you would play back at both what you would normally play and the stupid level you might occasionally play. Jot that number down and also take a measurement at 1 meter from the speakers. You may be quite surprised that 75dB in the listening chair is rather loud. But you want to know how many dB you lose going from 1 meter to your listening chair.

    A 91dB speaker will produce 91dB at just one watt of power at one meter away. The OTO with your speakers will get to 97dB without distortion and will max out around 101dB. Unless you're into GNR at concert levels the amp should be fine with the Spendors.
    1w=91dB
    2w=94dB
    4w=97dB
    8w=100dB
    16w=103dB
    32W=106dB
    64w=109dB
    128w=112dB
    256w=115dB

    But speakers typically have max power handling ratings which is usually under 200 watts thus going more than that isn't giving you anything.

    I typically try to get people to listen to SET amplifiers whenever possible - the OTO might be borderline with your speakers - My AN J/Spe not in corners is 89.5dB senstive and 92.5db Sensitive in corners and I can pelt the volume and the bass quite well - BUT it is a two way design and never drops below 5 ohms. The Spendor being 4 ohm dipping to 3.2 ohms will make the OTO work harder.

    If you are willing to go Chinese - have a look at the Line Magnetic 518Ia or the 218IA These are 845 SET amps of 22 watts and have transformers that seem to have endless reserves. But you have to bias the things - though they look cool.
    [​IMG]

    If SET isn't a big deal - you can look at Manley Labs (they were partnered with Spendors at a show I was at). And Rogue Audio has buckets of power but then to me doesn't have quite the tube sounding attributes - it's a little more SS sounding to me. Good mind you and affordable.

    The Manley Mahi is also an EL84 to keep tube prices down and it has 20 or 40 watts triode/UL mode
    [​IMG]
    http://www.manley.com/mahi.php

    Lastly - I'll throw one budget amp into the mix - the Line Magnetic 211IA - $1650US. This thing is basically a dead easy recommendation to anyone starting out into tubes - it sounds valve like - but has pretty good power 15 Triode and 32UL mode. EL34s are abundant. Build quality is high. It's not going to slam with the big boys but it does vocals really rather well - for people who are not crazy audiophiles you could live with this and under $2k this would be the amp I would buy. And it comes with it's own built in meter so you can bias the amp easier.

    [​IMG]
     
  2. Shiver

    Shiver Forum Resident Thread Starter

    Location:
    UK
    Yeah the ProAcs are apparently well suited to tube amps, thanks. I actually emailed them for any particular recommendations or rules-of-thumb for matching and got a nice but brief response saying yep pair well with tubes just make sure the amp drives 4 Ohm loads to be on the safe side. I'm really not looking for vintage now, but can see the appeal - want to play safe, percentages...
     
  3. Shiver

    Shiver Forum Resident Thread Starter

    Location:
    UK
    Aye, not looking vintage for those reasons, but thought worth ID-ing a local tech in case of any potential woes in a used piece... Thanks
     
  4. Shiver

    Shiver Forum Resident Thread Starter

    Location:
    UK
    Hadn't really thought of going down that line TBH. Interesting. Any default suggestions for a tube-pre/SS-power for c £1000? And probably a stupid question, but would this be the same design philosophy as a hybrid amp? (Rogue Sphinx being one I've had recommended). Must say I prefer the idea of one unit, but open minded at this stage. Thanks.
     
  5. Shiver

    Shiver Forum Resident Thread Starter

    Location:
    UK
    Cheers Bill. Another brand/amp I've been looking in to. Seem well liked and reviewed. There's a dealer not too far away in Manchester (actually a car audio place...!) - maybe a good place to start. Thanks.
     
  6. Keim

    Keim Hangin' here from the start

    Location:
    Moscow
    If op is really interested in learning about tube amps they could buy a kit and build their own amp. Save money and learn a lot. Not difficult. My Bottlehead amps sound great.
     
    timind and Shiver like this.
  7. Shiver

    Shiver Forum Resident Thread Starter

    Location:
    UK
    More options! Thanks, really. Appreciate the dB info too, and will try that out this weekend. SET is the thing that (at least some) tubests seem to find the most magic; but with obvious speaker requirements... Would be keen to hear what it's all about. With these and the other recommendations above I probably just need to start hearing some.

    (And just for clarification my speakers are ProAcs not Spendors... :) ).
     
  8. TarnishedEars

    TarnishedEars Forum Resident

    Location:
    The Seattle area
    It can be a similar philosophy to a hybrid, depending upon the hybrid. Some hybrids use a reverse model with a SS front-end and a tube output stage. I'm recommending a tube preamp with a SS amp which would be comparable to a hybrid with a tube front-end combined with a SS Output stage.

    I'm a lot less familiar with the tube gear which is easily found in Europe. But if you can find either a CJ PV6 or a CJ PV2AR, or an ARC SP-6 for a good price, then those would be some excellent options. Although all of these would require recapping at this point, so they might not be as cheap as one might hope.
     
    Shiver likes this.
  9. Keim

    Keim Hangin' here from the start

    Location:
    Moscow
    This would be an easy and cheap project that would dip your toe into the tube world:
    http://bottlehead.com/product/quickie-1-1-battery-powered-directly-heated-tube-preamplifier-kit/
     
    Shiver likes this.
  10. You really can't go wrong with the Line Magnetic stuff. Rock solid and sounds fantastic. PrimaLuna is another great one. I love mine. They're making good stuff in China these days for sure (at least these two brands).
     
    Shiver likes this.
  11. Shiver

    Shiver Forum Resident Thread Starter

    Location:
    UK
    Keim likes this.
  12. Shiver

    Shiver Forum Resident Thread Starter

    Location:
    UK
    Well, maybe call me hasty, but I’ve just gone ahead and ordered a PrimaLuna Prologue II!

    Given all the considerations, research, and not least the advice from members here it seemed to stand out as a particularly good way to enter the world of tubes. Main points that stood out were:
    - Power: no question over whether it would be sufficient to drive my speakers to reasonable levels
    - Adaptive auto bias: the point of biasing seemed a key issue, and from what I’ve read and understand, the PrimaLuna approach seems to make it about as compromise- and maintenance-free as it can get, especially for a tube-newby. Again, I do want to develop a good technical understanding and working knowledge of this stuff, but don’t want to have to think too much from the outset
    - General reports (including user ones) of build quality, reliability, and moreover, sound quality

    I wasn’t dead-set on the PPII by any means, and was fully prepared to spend a few months or whatever trying different options where possible (even though this would have been pretty difficult – especially if not buying new and being able to demo them), but when I saw this ex-demo PPII for sale with three-month guarantee (and seven-day no-quibble return policy) and managed to negotiate a good price, I just thought ah what the heck. Buying without having listened to a few other options first is the last thing I’d advise, but it seemed a really safe bet. Especially as buying a used tube amp without any return option seemed increasingly not without its potential hazardous and costs.

    The main remaining question in my mind is would it be better going down the SET route? Questions over power sufficiency and cost of some of the suggested options meant I wasn’t able to go down that line now without trialling and saving. This is still something I can explore over time though, whilst as least having had some real-world tube experience for reference.

    The amp arrives Thursday and I’ll play around over the weekend and write up a report of initial findings and impressions. Can’t wait.

    Thanks again all for your advice and input – really is appreciated and a great help. :righton:
    Rob
     
    action pact likes this.
  13. VinylRob

    VinylRob Forum Resident

    This represents a huge step toward enlightenment, and possibly turning your back (forever) on the dark side.

    It would be prudent to make sure that when you decide to bring home a piece, loaded with a great set of tubes, that you have researched to the best of your abilities that she should be expected to play nice and be reasonably compatible with the woofs & tweets in your world...

    Be prepared (if there is such a thing) for musical ecstasy... not mere infatuation.

    Happy thermionic listening!
     
    Last edited: May 11, 2015
    Shiver and jupiterboy like this.
  14. Shiver

    Shiver Forum Resident Thread Starter

    Location:
    UK
    Thanks! Funny. Yeah from what I gather I'm pretty confident that it should drive the speakers well enough - but proof will be in the pudding.

    The Cambridge (840A v2) has performed well on every objective level and never felt anywhere near the limit of its power, so IMO sets a good benchmark to compare with. It'll be really interesting to hear the differences.
     
  15. Shiver

    Shiver Forum Resident Thread Starter

    Location:
    UK
    Cheers Brian. Good to hear. A few PrimaLuna reviews I came across basically say one look at this and you can forget any blanket prejudices one might have around Chinese manufactoring... Not that I had any as such
     
  16. conjotter

    conjotter Forum Resident

    I recently passed on buying a used Decware Torii Mk 3 - sight unseen off of a website - because I would have been the fourth owner of the unit. Nothing against the seller, but the unit has changed hands too many times for me.
    Buying used is always a risk, but with tubes I would imagine the risks are magnified, especially when you have no idea about the life of the tubes.
    The answer for me is to save up for new or to buy used from a dealer, so at least there would be some warranty protection.
    Just have to be a little more patient.
     
  17. Shiver

    Shiver Forum Resident Thread Starter

    Location:
    UK
    Understood. This particular unit is an ex-demo from a dealer apparently, and, as mentioned above, either way comes with a good return policy/warranty. Bit of a punt, but if I have any doubts or see bad signs about it from the outset it'll go straight back.
     
  18. Keim

    Keim Hangin' here from the start

    Location:
    Moscow
    Very solid choice from the reviews I have read.
     
    Shiver likes this.
  19. Jeffczar

    Jeffczar Well-Known Member

    Location:
    Milwaukee, WI
    If going vintage you need to find someone who is familiar with basic tube amp restoration. When properly restored the sound is difficult to match with any modern amp, period. They absolutely need to be gone through properly and completely. I was a young audiophile in the 80s and quickly discovered that vintage tube amps got me sound almost unobtainable with modern equipment of the era. So at 13 I bought and restored my first amp, a Heathkit AA111. At that time you could get vintage amps for next to nothing. I quickly learned nearly everything about tube amp design and became proficient with a soldering iron. It has been a life long love ever since and I currently own over 30 vintage amps all completely restored (well, there are a few that I still need to get to !). That could be another option for you. Get a decent Stereo 70 and and an assembly manual. There is a lot of online resources now where almost any question you have can be answered. The results will be well worth the effort. I routinely bring my Heathkit W5s or Scott 299 to audio type gatherings and let them go head to head with Audio Research, Comrad Johnson, and various others and they never fail to drop jaws. I have converted many an audioohile to vintage. If that isn't an option for you then definitely find someone who can do the job properly for you. I have restored a few vintage amps for said converted friends and if the job is done thourally, the amp will function for many years without needing any further service other than tube changes. I did a Stereo 70 for a friend of mine 10 years ago who drives Martin Logan electrostatics with it and it still runs perfectly to this day. He was running a rather expensive Krell until one day I brought a Stereo 70 over just to see how it would compare on a difficult to drive speaker. The Krell was embarrassed. If you do decide to get a vintage unit to restore or be restored, be sure to avoid anything that has had the circuitry "modified" or "improved" by the owner. The more stock and original the better. There has been much written on "improving" vintage amps. Ignore all of it. Almost without exception it is misguided and falls under the category of a little knowledge is dangerous. In automotive lingo, it is like stuffing a Dodge engine into a Jaguar XKE. Buying new tube gear is expensive and sonicly the best it can do against a better vintage amp is a draw. Tube rolling is highly subjective and highly dependent on the amp design. It can be fun and there is no harm in it. However, there are some vintage amps which are designed around up rated tubes such as 7189, EL37s and the like that one should be careful with rolling any old thing in and out. I did recently hear a budget tube amp that I thought sounded pretty impressive for the money and that was the little Jolida FX10 at around 500 dollars. You could always try something like that and if you really like it, start researching vintage amp restoration, or possibly borrow one from a friend to try in your system to see if it's to your taste. Good luck and I hope you are able to give vintage a whirl. A good Scott 222 or 299, Fisher X100/101, Dynaco 35 or 70 would give you a good taste of what it's all about. I warn you though, once your ears are opened, you can't unhear, you be addicted !
     
    Shiver and Keim like this.
  20. jawaka1000

    jawaka1000 Forum Resident

    Location:
    Netherlands
    Prima Luna is not Chinese!
     
  21. chervokas

    chervokas Senior Member

    Dutch company, but the gear does seem to be Chinese-made. From the company's own "about" page:

    In the early 2000s, van den Dungen recognized a growing interest in affordable tube equipment, however the existing gear often faced reliability problems and consumers new to hi-fi hesitated to buy. The 56-year old entrepreneur wanted to bring those prospective customers into the fold with a product that would also stimulate the European market. In 2003, he assembled a team to create the PrimaLuna ProLogue line that would fill the need, and in several months they had created a high-quality, dependable product. However, to make it affordable it would have to be manufactured outside of Europe - in China.
    Now, I'm not saying because the gear is manufactured in China, it's no good. There's obviously a lot of crappy, cheaply and indifferently built, with poor QC, Chinese-made products on the US market at the moment across all kinds of product categories...but I'm sure there are Chinese factories perfectly capable of turning out high quality stuff too. I have no personal experience with the PrimaLuna stuff so I have no opinion of it, but it is apparently Chinese-made.
     
  22. johnt23

    johnt23 Forum Resident

    Location:
    Oregon
    Decware offers a lifetime warranty, transferable (for a nominal charge) to the next owner if purchased used.
    Takes all the worry out of the equation.
     
  23. Shiver

    Shiver Forum Resident Thread Starter

    Location:
    UK
    Thorough and interesting - thank you. To reiterate, I've now gone and bought a Prologue Two amp (see inititial impressions in another thread) so am not considering any other options at present. But it's fair to say I'm sold on the world of tubes, and it'll certainly be interesting to hear some vintage options when possible!
     
  24. Shiver

    Shiver Forum Resident Thread Starter

    Location:
    UK
    It is. And the build quality and finish (of the Prologue Two at least) is stunning. On first impressions you wouldn't question it being made at some high-end set up from UK, Germany, North America, or whatever... I say first impressions as I've yet to run it long-term; but, overall, user reviews seem to credit their reliability.
     
  25. Larry I

    Larry I Senior Member

    Location:
    Washington, D.C.
    The Prologue two is a good choice, as would be a number of suggestions given above. I like Proac speakers and I have heard them work well with solid state and tube gear, although I have mostly heard their speakers with pushpull amps. There are lots of factors that come into play when trying to determine if a SET amp is suitable, so as a starting point, it probably makes sense to go with moderate power pushpull.

    The Prologue two will give you PLENTY of opportunity to experiment with the other "joy" (or neurotic obscession) of tube ownership--trying different tubes. For practical reasons, a manufactuer will install tubes that are cheap and plentiful. It does not really make sense to source more expensive tubes when the "best sounding" tubes are a matter of personal taste and system matching. That leaves the decision to experiment with alternatives up to the owner. The Prologue two is particularly flexible because it is designed to work with a wide range of alternative output tubes. The KT-88 delivers a lot of power, but, I am certainly not alone in preferring alternatives. I would suggest trying KT-66, EL34 and 6L6 (my particular favorite in this family). Actually, it makes sense to start your experiments off with the small signal tubes. These are cheaper and often make a more dramatic difference in the sound and tend to be a better upgrade investment because they last longer. There are plenty of alternative 12AX7s, both current production and old tubes out there to sample.
     
    Shiver likes this.
Thread Status:
Not open for further replies.

Share This Page

molar-endocrine