McBride
Page 1 of 3 123 LastLast
Results 1 to 10 of 21

Thread: DIY low power Class A rackmount tube power amp?

  1. #1
    Join Date
    Jul 2010
    Location
    Calgary, Alberta
    Posts
    9
    Post Thanks / Like

    DIY low power Class A rackmount tube power amp?

    Hi all,

    I've been hunting for what seems like forever to find a decent low power (50 watts or less) 1u tube power amp that won't break the bank but have had limited success.

    Does anyone make a DIY kit for this? I was thinking a 20-30 watt power amp. Class A would be nice, but i could deal with AB.

    Tim

  2. #2
    Join Date
    Apr 2008
    Location
    Burlington, Ontario
    Posts
    4,241
    Post Thanks / Like
    Any home brew tube amp will cost you:

    Chassis + hardware + Power Transformer + Output Transformer + tube(s) support + tube(s)

    You will find the price nominally breaks down like this:

    ($25 to $200) + ($10 to $40) + ($30 to $250) + ($20 to $250) + ($10) + ($2 to $50)

    Now, you can do your own chassis for fairly cheep, 25 dollars or so, some sweating swearing and probably at least one metal cut thumb. Pre-purposed chassis can easily hit 100 and even 200 just for the piece of metal.

    If you do knobs and lights and power cord and fuse and switches on the super duper eBay cheep you can keep this closer to the 10 end, going with "name brand" parts you will easily go to 40 if not more.

    If you go with Antek and find a way around their 25 dollar shipping to Canada fee, they sell a $30 transformer suitable for a tube amp. Hammond is everyone's cats meow, and theirs is 250 dollars. There is a broad range between for pricing, but thats the high and low end of that.

    OT's on the low 10W end start at about 20 dollars. You can do two 10W channels and use 2 10W OT's for less than 1 20W OT depending on who you go with. Hammond again is the cats meow and again is the highest priced part there.

    No matter who you buy your tube sockets/resistors/caps from you will find that you will average 10 dollars per tube.

    If you get your tubes from the exUSSR you will be on the low end of the spectrum as low as 2 dollars for the bottle, and honestly tubes can go into prices so high that it no longer becomes a fun hobby. However, I think I see tube prices maxing around the 50 dollars each mark at L&M, me personally, I buy exUSSR.

  3. #3
    Join Date
    Jul 2010
    Location
    Calgary, Alberta
    Posts
    9
    Post Thanks / Like
    Right, so this could be done at a reasonable cost.

    Are there any DIY schematics or kits for a Class A amp?

  4. #4
    Join Date
    Apr 2008
    Location
    Burlington, Ontario
    Posts
    4,241
    Post Thanks / Like
    Made kits the lowest prices I think are here Tube Amplifiers Kits and Gear however these ones do not provide everything needed. I think they are all without chassis or tubes and some other bits and pieces.

    Next up is Trinity, there is a thread on a course we are trying to get people interested in jumping in on with both feet: http://www.guitarscanada.com/amp-bui...to-course.html and here is a look at what they have on their sale page Trinity Amps - Parts and Kits Not sure where they have the Tramp spec'd and sale'd. The better deal here is you do have everything you need to plug and play (other than tubes ... not sure).

    From these guys up, you will find that the next "lowest" priced kit is 450USD and I think the most expensive I have come across was in the low 1000's. There are a fair number of "kits" on eBay, but competition is pretty stiff if you have to bid on those and those prices can get out of hand fast.

  5. #5
    Join Date
    Jul 2007
    Location
    Kitchener, Ontario
    Posts
    7,260
    Post Thanks / Like
    Zilla...Welcome to the forum. Enjoy and post often !!

    I just want to clarify some things: you want only a power amp and you want it to be 1u in height ?
    (about how tall is 1u...1.5 inches or so?)

    You might be able to make this (physical) size of amp without tubes and with some type of low profile power transformer.
    It would be Class A , but might only produce up to 10 watts or so. I am thinking of a Hood amp.
    The Hood amp is ONLY a power amp and would need some type of preamp.

    BTW...I don't know of any kits for the Hood amp, but there are not many parts involved.

    I am somewhat of a beginner in amps & electronics as a hobby....I'm not a tech.

    Again, welcome to the forum.

    Cheers

    Dave
    Last edited by greco; 07-22-2010 at 01:59 PM.

    "Time on the instrument" Pierre Richard

  6. #6
    Join Date
    Jul 2010
    Location
    Calgary, Alberta
    Posts
    9
    Post Thanks / Like
    thanks for ht ewelcome.

    I was thinking something like this (physically)



    I'd prefer tube, otherwise a class D solid state amp.

  7. #7
    Join Date
    Apr 2007
    Location
    Bay Area, California
    Posts
    6,773
    Post Thanks / Like
    I'll go on record and say: there is no way you can build a one off, 1U tube power amp cheaper than you can buy one. Something like a Mesa 20/20 is already pretty value priced and even better on the used market around the $400 mark.

    Do this because you want the challenge (and it *will* be a challenge -- that is a tiny amount of space to build a power amplifier in to), not because you're looking to do it cheaper than you can buy it.

    It's rarely the case that building < buying in electronics.

  8. #8
    Join Date
    Jul 2010
    Location
    Calgary, Alberta
    Posts
    9
    Post Thanks / Like
    $400?

    Please tell me where you've seen one for $400 and I'll buy it right now :)

    every one that i've seen has gone for at least double that on ebay and CL.

  9. #9
    Join Date
    Apr 2008
    Location
    Espanola, On
    Posts
    2,882
    Post Thanks / Like
    Quote Originally Posted by zilla View Post
    $400?

    Please tell me where you've seen one for $400 and I'll buy it right now :)

    every one that i've seen has gone for at least double that on ebay and CL.
    They go for 500-550 USD on ebay (do a search of completed listings). 1U is pretty tight, the space for the transformer probably isnt there.

    The Lexicon Signature 284 is 2U and in the 450 USD range - but they're harder to find... It's a full featured mathcless style omap and stereo power sections. You can drive the output sections (about 3 watts each) via the fx loops though.

    Why do you need a tube power section? 1U solid state (often "tube emulated") power amps are cheap and plentiful, as are larger tube power amps like the Peavey 50/50.
    “My own view is that this planet is used as a penal colony, lunatic asylum and dumping ground by a superior civilization, to get rid of the undesirable and unfit. I can't prove it, but you can't disprove it either.”
    Christopher Hitchens, God Is Not Great: How Religion Poisons Everything

  10. #10
    Join Date
    Jul 2007
    Location
    Kitchener, Ontario
    Posts
    7,260
    Post Thanks / Like
    Quote Originally Posted by mrmatt1972 View Post
    1U is pretty tight, the space for the transformer probably isnt there.
    Do you think they use toroidal transformers for these 1U amps?

    The Hammond specs for the secondaries of torodial transformers don't seem to be conducive to use with tubes (given my limited knowledge and understanding of this type of thing).

    Cheers

    Dave

    "Time on the instrument" Pierre Richard

Page 1 of 3 123 LastLast

Tags for this Thread

Bookmarks

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •