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Why doesn't anyone make a tube amp as follows?
Push pull
CLASS A
35 to 60 WPC
Under 1K
Maybe kit options
I have been searching for a tube amp /or kit amp. I don't want a 5 W SE that will force me to sell my Magnepans. However, everything else out there costs over 1K.
Do I have unreasonble expectations?
Thanks in advance
Push-Pull and Class A are mutually exclusive. An amp can be either one or the other, not both.
There are several manufacturers that advertise that their amps are push-pull AND class A. Ever hear of class A/AB? The amp is class A until it reaches a certain power output at which the amp turns into class AB. I have no idea how this type of biasing is arranged (one tube has a higher DC bias than the other?). I think that some manufacturers are biasing their amps class A/AB and advertising them as class A only. Slightly truthful advertising.My now unused sony receiver has a PP output stage but in the spec sheet it is listed as class A out to 15-20 watts. At that point it switches to class AB to 100 watts. It's highly probable that there are tube PP designs arranged in such a fashion. After all, both devices (tube & SS) are operating on the same principal: switches that have variable conductance/resistance which is controlled by an incoming signal on the grid/gate/base.
Have fun,
Tom S.
I'm simewhat confused ... are you looking for class A or push pull ? Or either of them ? GTA se-40 retails for slightly above 1K. Various jolida models come for under 1K. You can get either of them for about 500 used.
Why not build yourself a Blue Circle clone? One single ended triode driving a class A transistor output stage.No loop feedback.Cheap.Unlimited tube rolling platform.The Motorola MJ3281 has only 0.5%THD in class A/B and 0.05%THD in class A with NO feedback! Or how about an Atma-Sphere with the same output stage? If you look at the US patent for Atma-Sphere it shows a design for a hybrid.
Plus ruggedly built, weighing about 32 lbs., very good sound with Svetlana EL34's, simple external bias settings with a supplied plastic slot screwdriver, external resistance settings (4, 8, 16 ohms), and you can get good buys on used ones on the internet or ebay or get discounts directly from Sound Valves (www.soundvalves.com) on new cosmetically "blemished" amps, and, finally, made by a good company headed by the very solid and well respected John Peterson. Alternatively, if you need more but affordable power, there are often internet ads for used McCormack DNA 0.5 amps ($750-1,200) which also sound very good (some say like tubes) and mate well with tube preamps. Steve McCormack, from Mod Squad to McCormack fame, now has SMcAudio@aol.com (I think that's the address) and still modifies/repairs these amps. I believe he is also now affiliated with Conrad-Johnson. Good luck and happy listening.
Adam O
The Velleman K4040 sounded good when I auditioned it. It should sell as a kit for less than 1K, and Angela Instruments have it. Why don't you try a search on VElleman on the web and on the newsgroups. As I said in the header, its Class A (os says it is) for the 1st 15w.
Andre Jute also says a lot about it.
You have to decide if fits the bill, but was $1000 a pair. I do not know if they have any remaining. Tube changeout does significantly change the performance.
Thanks for all of your suggestions.
FYI, I am biamping with Maggie 2.5's (true ribbons) on top at 80 Hz. I am looking for the sweetest sound <1K out there. I was assuming class A tubes would do the best job. SE amps will not drive the Maggies. I need at least 35 W/c.
I have even thought about going to SS Class A but there is nothing under 1K there either.
Golden Tube audio se-40 is <$1000. It is not push-pull but it is class A.
The Welborne kit mentioned is no longer in production (I am greatly disappointed with this fact).:-(
Jolidas are push-pull but not class A. The 502B is <$1000 and is rated to deliver 60 watts. The 302B can be had for <$850 and is rated for 50 watts.
What kind of sound are you looking for?
I know that none of these suggestions meet your stringent criteria but for <$1000, you are asking too much for the money. Is there a reason why you want the costly and difficult combination of push-pull/Class A?
Tom S.
Yeah, I was afraid that the Welborne V-35 was no more. However, he could get a used ST-70 (or Mk.III for that matter) and use the Welborne mod kit that IS still available.
I'm not sure on prices here, but how about Jolida? Goldentube? Have you checked the used market?
Jack
Another one to consider is Audio Electronic's (the Cary subsudiary) AE-25. Granted, it's 25wpc instead of 35wpc but that difference is not really that large. Also, Welborne Labs had a really nice kit called the V-35. I'm not sure if it is still in production but it's definitely worth checking. Good luck.
I don't know if it is Class A, but it satisfies your remaining criteria. Go to www.sonicfrontiers.com and look under Parts Express.
Regards,
-ken
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