Looking to get a budget 300B SET Integrated Amp

Discussion in 'Audio Hardware' started by axnyslie, May 29, 2008.

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  1. axnyslie

    axnyslie Active Member Thread Starter

    I know the title is a bit of an oxymoron, but there are a few on my range of $1k to $1.5k if used. I'll be driving 97db Klipsch speakers with it. Here's what I'm considering

    Antique Sound Lab AQ 1005 DT
    Omaha Audio OD-300B
    Bewitch King 300B
    Jolida JD 300B

    I was also considering push pull amps with SET sonics like the Jolida JD 707a or the Consonance Cyber 100S but I would prefer triode over push pull.

    any other models I should consider? I am way too mechanically declined to go the DIY route. I'd probably electrocute myself.
  2. 51nocaster

    51nocaster Forum Resident

    Cayin was making a 300b integrated amp that looked promising. I never encountered anyone here or elsewhere who had one and many here seem to shy away from Chinese electronics. Does anyone here have any experience with the unit?
  3. axnyslie

    axnyslie Active Member Thread Starter

    The Omaha Audio OD-300B is US made so that's a top contender for me. Jolida and Bewitch are Chinese manufactured but designed and tested in the US & UK. I'm not sure about Antique Sound Lab I believe they are all US made.
  4. Green Tea

    Green Tea Sweet Soulful Sounds

    The Omaha Audio OD-300B SET integrated amplifier (Retail: $1400)
    got a good review on positive-feedback:


    (I've not heard the SET above; I've got Quicksilver mid-mono amps).

    TONEPUB Forum Resident

    Portland, Oregon
    Actually, they are made in china, but the importer in in California....

    If you are handy with a soldering iron, consider the Bottlehead monoblocks.
    I've had both their 300B amps and their 2A3 and they offer up a lot of sound for not much money. You can always go back in and add better caps, resistors, etc should you be so inclined. The 300B circuit is pretty simple, so it's a great way to get into DIY, again if you feel the urge.

    Woops, I missed that part of your post about DIY, sorry.

    There are always a bunch of used Bottleheads floating around that are already built,
    might be an option.

    All four of the ones you are suggsting are pretty much equally good. Go for the best deal
    and if you can, spend the rest on some better tubes!
  6. mcow1

    mcow1 Sommelier Gort

    Orange County, CA
    All I can say is I really like my Jolida 502B
  7. TimB

    TimB Tube be or not Tube be?

    Galion, Ohio USA
    I have a Dared 300B!

    They run around $650 minus tubes. Mine is running and sounding great after 5 years.

  8. Paul Chang

    Paul Chang Forum Old Boy, Former Senior Member Has-Been

    I came across this very negative review of the Omaha 300B Stereo Integrated Tube Amplifier. I don't know how credible Stereomojo is.

  9. Chad Etchison

    Chad Etchison New Member

    Atlanta, GA
    I second this good advice. Look for a used Bottlehead or similar design on ebay or over at Audiogon. Building an amp is a lot easier than a phono stage or other projects, especially if it is a kit.

    The Bottlehead amp will probably be parafeed and will have SS rectification which some like, some don't, it will sound darn good though.

    Anytime you are using a 2a3/45 or 300b amp it is a triode amp regardless of topology. These tubes are triodes, so that doesn't change. Some like push-pull over SET and vice versa. For purity and simplicity, SET is the way but there are many great push pull designs too, just ask Lynn Olson. I like SET because of the smaller parts count and simplicity, I built what is called a direct-reactance amp which is direct-coupled (no caps in the signal path). Refer to Jeremy Epstein's Free Lunch circuit for more info on that one.

    You can also have a Bottlehead kit built for you, I don't know if he does it or not but you could ask forum member Wardsweb, he's built some nice looking bottlehead amps.

    Over at Bottlehead the cost of finished mono blocks that they will build for you is $1700. For around $2000 or so, you could have the amps and a pre that would be pretty awesome.

    Food for thought...


    TONEPUB Forum Resident

    Portland, Oregon
    Having read the stereomojo review and reading about the problem they had, I suspect that one of the 300B's was inserted in the socket wrong.

    I had this happen to me ONCE a long time ago when I wasn't paying attention. Fired it up, in about 30 seconds it went BOOM. Sent it in for repair and the mfr said "did you double check the pin orientation?"

    Any of you that are 300B owners know how easy it would be to insert that tube wrong if one wasn't paying attention and knowing what we do about Chinese assembly, it wouldn't surprise me at all if a worker had ten amps lined up and ten tubes lined up where they just dropped them in wrong.

    I've even seen Wavac ship an amp with the tubes inserted wrong. It's a very simple mistake to make.

    The 300B amplifier is a very simple circuit, so perhaps they missed it at SM, especially considering the guys at Positive Feedback didn't have a problem.
  11. Nope. Chinese. You might be confusing them with Audio Electronic Supply, which is made by Cary in the US.

    TONEPUB Forum Resident

    Portland, Oregon
    The Audio Electronic Supply 300B amp is also pretty darn good.

    Again that circuit is pretty simple, it's hard to get a bad one.
    The more expensive ones are a bit more neutral and extended
    at the frequency extremes, but they are all pretty friendly.

    Depending on the sound you prefer, they respond very well to
    different types of 300B tubes and you can go from the 75 dollar
    chinese tube to the $400 apiece Western Electric 300B.

    When I was in the SET mode and had about 10 different sets
    of tubes, I was always surprised at how much different/better
    even the inexpensive amps could sound with a pair of WE 300B's,
    so keep that in mind too....

    A 300B amp can really be a lot of fun, very musical!
  13. axnyslie

    axnyslie Active Member Thread Starter

    That's an incentive for the Bewitch model because it comes stock with Russian Electro-Harmonix 300Bs. So I'd just need to roll the input tubes to something better so they don't act like firecrackers as Steve would put it. I've read the Sophia mesh plate 300B's are also really good and close to the premium WE 300B's.

    If a SET amp has 6N9P & 6N8P for input tubes can they be swapped with 12AX7 and 12UA7? My current phono stage and amp has JJ & Tung-Sol in them and I'm please with the sound I get from them.

    Another factor is most models don't have EZ-bias or auto bias. How tedious is it to bias the amps? What is exactly involve with the process?
  14. axnyslie

    axnyslie Active Member Thread Starter

    I got the Omaha OD-300B which arrived today and I'm not happy. I'm barely getting any output signal and the sound distorts badly at max volume. My Klipsch F-3 speakers are supposedly rated at 97db according to their web site but now I don't think that's true. They sound just as week as my 91db Infinity speakers. The 300B tube barely glow at all. Is that how they are supposed to look?

    I purchased it used on Audiogon so no chance of a return. I hope I didn't just lose a lot of money for nothing. I am at fault for not auditioning it first but no one locally sells tube amps like these. :(
  15. Rick58

    Rick58 Forum Resident

    Tracy, CA, USA
    I am pretty sure the Klipsch speakers are not 'underrated'; I bet something is wrong with the amp. The 300B tubes may not even look like they are on - you may just see a little glow on some of the wires inside. I only know my Bottlehead 300B amps are on by looking at the driver tubes!

    I would say if there is no recourse with the seller, take the amp to an electronics tech for evaluation. Ask around here & elsewhere to find someone knowledgeable. Good luck!
  16. BigE

    BigE Well-Known Member

    So you're saying that you cannot contact the seller and see what he might have done to it before shipping it? (like tried to clean it up and maybe reinstalled the tubes wrong?) I would at least let him/her know you're having trouble and see what response you get.

  17. axnyslie

    axnyslie Active Member Thread Starter

    *SIGH* well I'm embarrassed to admit this but I did exactly what TONEPUB warned against...I inserted the 300B tubes in backwards! :sigh: Fortunately I caught my error before I blew it up. Now it plays really loud! A fantastic wide 3D sound stage with lots of air and clarity! The singer is right there in the room with me. Nice!

    There is one other problem though, a real nasty ground loop hum. It's there in my system even when the Omaha amp is not connected to anything. The hum starts the moment I insert the Omaha plug into the wall socket or into my Belkin Power Conditioner. Even with another amp connected to the system instead, it picks up the hum loudly. I used one of those AC 3-Prong grounding plug adapters and that got rid of it, but I don't know how safe that is. I've have another ground problem like that with my Jolida JD-9 phono stage but it's not nearly as loud of a hum as the Omaha puts out.
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