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300B's vs. 2A3's

Discussion in 'Hi-Fi Stereo Systems & Separates' started by Paul Williams, Sep 25, 2005.

  1. Paul Williams

    Paul Williams
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    300B vs. 2A3’s

    OK as I’m hopelessly addicted to valves/tubes, now I’m looking at SE kits – fancy something a bit different, get some fun and experience with the soldering iron. As you can see from the title I’m thinking about these 2 classic output tubes, but I’ve never heard either. Being a kit amp I’m probably going to have to buy blind, but an initial trawl through cyberspace has elicited the following.

    300B’s have a top-to-bottom consistency which can be unrivalled, provide an expansive sound-stage/depth; however, they can be considered a bit to the clinical side of the centre.
    2A3’s have a (the best?) mid-band of any tube, but are uneven at the extremes, are (much) more to the musical/emotional side of the centre and lack the generous sound-stage.

    Now, the above are of course dependent on the tube implementation (and the tube manufacturer) and are relative to no specific benchmark other than these seem to be the statements that are commonly floating around the ether, when both are compared together. Does anyone have experience of both of these tubes and what are your thoughts?

    Why this type of kit? Well to be honest, they look simpler to build, and are less mainstream. I know whichever type of tube I settle on will produce minimal output (1 tube per channel) but that’s OK, I’m also thinking about trying out some full range single cone horns. ;)

    Like everything I do, I tend to take my time before I finally settle on a course of action, so I don’t expect to be placing and order for many months, so if anyone can point me in the direction of an interesting kit at about the £500 mark, please post the link. :smashin:

    Paul
     
  2. alexs2

    alexs2
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    Hi....I'm sure you know what sort of output you're looking at...2-3W/channle from 2A3s and up to 9W/channel from 300B's,both run as SETs.


    The various tubes do vary by quite an maount acroos the price range,and the TJ meshplate 2A3s and 300Bs seem to be the best price performance compromise currently,although this link may help you to decide.

    http://www.enjoythemusic.com/magazine/equipment/1201/300b/

    There are a few other very useful bits of info on that site as well.

    As to which kit....most will come in a bit above £500,although the Bottlehead amps from the US may just about fit in,as will the cheapest WAD 300B which comes in at £550 minus tubes.

    I doubt that you'd be displeased with either tube in terms of midband,treble or overall sound,although SETs can be very speaker sensitive,so your choice of horns may be best overall with respect to efficiency and load matching.
    Given that you're building kits,you also have the flexibility to build a relatively basic one now to save on costs,and upgrade things like the coupling caps,and internal wiring later as funds allow.
    Upgrading the caps on mine made a huge difference to what was already a good set of 300b amps.

    You could take a look at

    http://www.worldaudiodesign.com/wadproducts/kit300.html


    http://www.hificollective.co.uk/kits/300bseprice.html

    http://www.bottlehead.com/et/adobespc/Paramour/paramour.htm

    The Bottleheads have unusual names etc but are well regarded.

    Mine are a set of WAD 300B P/P amps and go very well with Quad ESLs,which is why I settled on PP rather than SET configurations.

    The Audionote kits are OK,but perhaps a bit high in price,and a bit lower on finish and help,whereas the Glasshouse and WAD kits,being UK based,have very good backup,especially WAD,which offer a build and repair service.

    Anything else....please ask
     
  3. Paul Williams

    Paul Williams
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    Hi alexs2

    Between 2 to 9W/channel seems fine and I suspect even with my current 89db/w speaker I use at present will work OK initially. Used to have 100w mono-block and 80db/w speakers and could never use their potential, now have a 35w amp with the current speakers and 10 o'clock on the volume control is too loud for my 18' x 11' room.

    At present the kit that is in top place is the Bottlehead Paramour. I recon these should come in at just under the £500 mark even with import duties. I like its non-traditional (Hi-Fi) looks and the flexibility for various finishing options and could always add a second pair for bi-amping the speakers. I did consider one of the cheaper WAD kits but really want to try something totally different from my current 6L6 PP amp and the Paramour is certainly that!

    Paul
     
  4. dynamic turtle

    dynamic turtle
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    Hey Paul,

    Long time no speak :)

    Getting bored with the Romulus and fancy a change then? 300B's is it? If you're on a tight budget, China is the place to look. Whilst I cannot vouch for the sonic & build quality of these amps, on the face of it, they are catastophically cheap for what they offer. I'm very tempted to purchase the Consonance M100S myself (300B integrated, push-pull), or the Reference 5.0 (9wpc SET 300B integrated). £700 & £650 respectively!

    Also, Mei-Xing has very competitively priced 300B/845 monoblocks:

    http://www.meixingaudio.com/ENGLISH/products/mc-805a.htm £570 a pair

    http://www.meixingaudio.com/ENGLISH/products/mc-300c.htm £650 a pair

    http://www.meixingaudio.com/ENGLISH/products/mc845-c.htm £549 pair - apparently, these have "beautiful, vivid rythmiration"!!

    Are you still using the EE minimax as pre-amp?

    Rgds,

    DT
     
  5. Paul Williams

    Paul Williams
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    Hi DT

    Still happy with the Romulus and aim to keep it, yes still using the Minimax Pre (just gets better). The cost restriction is so as to ensure that I don't waste to much money if the Kit idea falls flat. As for Consonance, did you know they also do kits? 300B mono-blocks, or 2A3/45/300B convertable direct heated triode single input amp and EL34/KT88/6550 Push-Pull 2 input unit. Just fancy a project for those long winter evenings.

    Paul
     
  6. dynamic turtle

    dynamic turtle
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    Paul,

    I doubt very much of they do kits. You could of course buy a ready-made one, take it apart, then put it back together! Ideal for even longer winter evenings!

    Re kits, if it involves anything more than battery current, I steer well clear of it. Mains voltage isn't any fun, if you're the ditsy type like me ;)
     
  7. dynamic turtle

    dynamic turtle
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    I got some revolvers btw - the R16's. Luuuuuuuurvely speakers for the money. Smooth as a baby's and totally fatigue-free. Very happy with them.

    DT
     
  8. Paul Williams

    Paul Williams
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    Ah, but they do, but it almost seems that Consonance might be providing made versions of the kits! Bit chicken & egg.

    http://www.triode-systems.com/modules/wfsection/article.php?articleid=19

    Glad you like the Revolvers. Their new HC range looks even more interesting.

    Paul
     
  9. dynamic turtle

    dynamic turtle
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    ahhhhh, Interesting. I've heard nothing but positive reports about the LadyDay monos. Very good VFM byt the looks of it....
     
  10. Nic Rhodes

    Nic Rhodes
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    Goody goody, my sort of thread, pity I am off on my travels again. :(

    Sound quality wise I think the 2A3 is the better tube than the 300b (I use both) but I actually think a PX4 or PX25 are better again and worth considering (now also being remade). The 50 is another fine chouce but difficult to get now.

    There are good stuff for all of these now. NOS 300B are a no no (unless you buy the substandard Cetron) but others are still available like RCA 2A3 etc. Ther eis as with all these tubes quite a variation even with the same number. The TJ Meshplates Alexs recs aare the best of current production unless you can afford WE.

    Also have a think how you want to drive them. I woulkd look at transformer coupling with a choke input supply but most use 'Pi' supplies and are cap coupled. There is a HUGE difference. I like to keep it simple. The basic WE 91 amp is always an interesting one to make if you fancy tube rolling as it is quite versatile, try www.angela.com, for some down to earth stuff. Their 91a look alike I think used 6SJ7WGT but you could use the original, 6C6 etc etc, some great tubes at not silly money. Have 2a3 / 300b articles like the bendix if you are interested.
     
  11. Paul Williams

    Paul Williams
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    Hi Nic

    As I have no real technical knowledge in this area, I'll be getting a basic out of the box kit - the Bottlehead Paramour, seems most likely at this stage, even though they don't do a 230v transformer version. The idea is to build the basic unit, learn along the way and if I like the results, look into doing some changes/experiments.

    Paul
     
  12. Nic Rhodes

    Nic Rhodes
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    consonance seem pretty decent. AN kit work well but looks like a dogs dinner!! I like the idea of building an off the shelf kit using 6SL7GT / 6SN7GT / 300B personally but I am skint at the moment.
     
  13. Nic Rhodes

    Nic Rhodes
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    The welborne labs 300b is pretty innovative stuff.....
     
  14. Nic Rhodes

    Nic Rhodes
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    and looks great
     
  15. Paul Williams

    Paul Williams
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    But cost quite a bit!
     
  16. Nic Rhodes

    Nic Rhodes
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    look at the Angela designs then.....;)
     
  17. Paul Williams

    Paul Williams
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    Hi Nic

    I have been looking over the site and there are some tempting projects, but I'm not brave enough to do it from a parts list and schematic. I think I'm going to pay the premium for getting someone else to put everything in a box with instruction for the simpleton - "... see this blue thing, it's a *******, attach one end here the other there, but don't solder yet as you need the red thing to go there as well.." is what I'm going to be looking for! Maybe after this ones built and working I'll be looking for that 230v transformer conversion.

    Paul
     
  18. alexs2

    alexs2
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    One reason why I didnt mention them,although as Nic says,a lot of the design ideas are innovative,and very clever in keeping the component count down to an absolute minimum.

    The AN stuff,as Nic has said,can look like a dogs dinner,although the actual components can be as good as any around(although the alternatives,such as Jensen and Jupiter caps etc) are at least as good,and in some cases have been rebadged as AN gear in any case.

    The 2A3 is widely held to be better overall than the 300B,but has the problem of lower power output,but in your case that may not be as much of a consideration as I found it,and a number of recent reviews have placed the meshplates pretty much alongside the WE 300B's,although I havent heard the WE originals(I'm very happy with the TJ meshplates,price and performance wise).
     
  19. dynamic turtle

    dynamic turtle
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    I'm not familiar with the 2A3. You say it has a power output of 2-3 watts in SET mode? Is this tube really useful with anything other than horns?

    DT
     
  20. Paul Williams

    Paul Williams
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    Don't know until I try - but because of a couple of things I been told from sources I trust I'm interested enough to give it a go. I never listen to music that loud & I'm given to understand that SET's and in particular this type of tube based amp can work very well at low levels, of course in this instance, chances are I'll be using the most (if not all) of the output capabilities of the amp.

    The other thing that came to light a few years ago in discussion with an amplifier manufacturer (about amps that have a few watts in class A, then switch to AB) was that most people only use the first 2 or 3 percent of their amps output capabilities anyway and never find the sweet/dynamic/controlled area that comes in later - hence the class 'A' for the first few watts, the bit most people use. Bit like keeping your car in the power band when driving to ensure optimum acceleration and control.

    35 watt amp at 9 o'clock (that about 1/6th of the usable travel on the pot) how many watts exactly is it outputting?

    Well does that all sound rubbish, I guess some more technically advanced people will chip in if they feel it is :D
     
  21. alexs2

    alexs2
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    A lot of what you say makes very good sense,but the major limitation of a 2A3 based SET is it's lack of headroom when used with anything but the most sensitive speakers(doesnt NEED to be horns,but it does help).

    The point about amps with some initial Class A bias,is a bit back to front,as most amps will actually perform better in that region(more linear etc) than in Class AB,and a good,well engineered Class A power amp can sound superb,but has the problems of PSU design and heat dissipation,unless a sliding bias system is used a la Krell and Levinson etc.

    You will also find that a 100W amp with speakers of average efficiency,is outputting a couple of watts most of the time,until a loud transient appears,and then it may have to deliver near its maximum ouput...e.g....music with a dynamic range of only 20dB will take you from 1W to 100W quite easily.

    Your other possibility is finding a parallel single ended design,and getting a few more watts if thats a consideration,and do also remember that all SETs are very sensitive to speaker impedance and reactivity,and anything other than a simple load(horns/efficient speakers with simple x-overs again) can significantly alter the frequency response and power output.
     
  22. Paul Williams

    Paul Williams
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    Hi alexs2

    Surprised you didn't mention that more speakers are damaged by low power amps going into clipping than high power amps over-driving them. If I go ahead and build these (by mo means certain) I would initially try them with my 89db/w speakers, but then would have the choice of building a second set - would perhaps look quite nice with all four lined up in a row - or go for a more efficient set of speakers.

    For a home building a horn loaded design (or in this case a "back loaded horn + bass reflex hybrid) initial thoughts are based around a Fostex FE126E 93db/w unit. I would estimate the total build cost at a minimum of £120 for a pair in, shall we say "development" level of finish. If I liked the "horn" sound then it would be time to re-build with better cabinet finish or go to a higher quality unit.

    The choice of the Fostex 126 is based on cost, a cost (minimum) efficiency (highest for lowest cost) and impedance curve (flatest for lowest cost) & on axis frequency response. To move 1db/w higher, but with a less benign impedance curve, but flatter response would add £36, for 3 extra db/w, very benign impedance curve and less flat response would add £74. In each instance as the driver size increases so will the cabinet size and also up the cost - not really a fully fledged cost benefit analysis, more a "lets not spend to much on this" and see what I can get. The cabinet design will be the one provided by Fostex.

    However, all this may now have to put on hold as it look as though a house move is now on the cards!

    Paul
     
  23. alexs2

    alexs2
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    Thats obviously true,but I rather assumed you were aware of that,which your post above bears out.

    At 89dB/W,your speakers are quite sensitive as modern designs go,although not in the horn league!....you may also be able to find designs for the Lowther range of drive units,although they would be more expensive.

    Best of luck with the house move!
     

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