SET Asylum

Posted by Mike C (A) on April 02, 2007 at 12:23:27

I have not posted for quite a while as I've been busy on other things, and enjoying lots of music when I've had time to. Lucky!

Anyway, I have a nice self built 300B SET (called Valentine); driven by a 6SL7/E83F mu stage with its own PSU; fixed bias; AC heated 300Bs. I have recently changed from TJ 300Bs to recent WE's and wow, what an upgrade that is!

OPTs are Lundahl LL1620s and they can't be bad as this amp is the most musical I've ever heard. However, a friend (and Asylum member) whose opinions I respect a lot suggests that a change of OPT will give far better tonality and better sound generally.

So I'm tempted to try something else. I'm into accoustic music; classical, folk, some rock with a special liking for female vocals.

I've done lots of research here, diyaudio and google which brought up lots of oriental sites. My short list so far is:
Hashimoto H-20-3.5U
Hashimoto H-30-3.5S
Tamura F7002
Tango FC-30-3.5S (very similar to older XE-60-3.5S)
Cost is not a major issue if I get a 'result'. As I'm in the UK I looked at the Audionote site but prices seemed excessive to me.

I tend to rule out the Tamura F5 series as it seems to lack some bass; while I'm not a bass freak, I like that of the WE300Bs and Lundahl OPTs and don't want to lose this.

Any comments or recommendations welcomed.
Any help to choose from within my short list is specially valuable.
Thanks in advance.

• Re: Output Transformer Choice for 300B - haukito 22:32:06 04/03/07 (0)
  In Reply to: Output Transformer Choice for 300B posted by Mike C on April 2, 2007 at 12:23:27:

  Hi,
  you could also use the Lundahl LL1664 80mA or 100mA.
  This one is not expensive. I like it a lot!

  Kind Regards

  Barossi
  

  • LL1664   (Open in New Window)

  
  

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• Re: Output Transformer Choice for 300B - SteveBrown 07:28:09 04/03/07 (1)
  In Reply to: Output Transformer Choice for 300B posted by Mike C on April 2, 2007 at 12:23:27:

  Well, if cost isn't a big concern... may I suggest parafeed using MQ iron? I tried this for the first time on a 45 amp, used some Robin Hoods that included some nickle, and I forgot the choke part number, but it was MQ. The sound is fantastic. This is a synergy thing, of course, and it all has to work together, but I'm impressed that the bass is much more articulate and overall music more satisfying than any 300B I've made using air gapped TFRs (I've used OPT from Audio Note, Bartolucci, James, ElectraPrint).
  
  

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  • Re: Output Transformer Choice for 300B - Mike C 00:55:40 04/04/07 (0)
    In Reply to: Re: Output Transformer Choice for 300B posted by SteveBrown on April 3, 2007 at 07:28:09:

    Hi Steve,
    Very good suggestion - but not as a mod for this amp as it's tightly packed in.
    It's on the list for my next amp though. I wonder if Hashimoto iron would work well ... perhaps by the time of my next build we might know!
    My next full DIY build will be another phono stage as I've done two decent ones but not quite hit the target. It's a challenge! Anyway, a simple OPT upgrade of the power amp will suit me pretty well for the moment.
    Regards, Mike
    
    

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• Re: Output Transformer Choice for 300B - drummerwill 05:35:00 04/03/07 (0)
  In Reply to: Output Transformer Choice for 300B posted by Mike C on April 2, 2007 at 12:23:27:

  
  Pick a good manufactor Electra-Print, Magnaquest, Tamura, Hashimoto
  Silk, James, any of them. But have the secondsaries wound in Silver.
  Silver prices are much higher than they were 4 and 5 years ago when
  I had mine made. But I would do it again, sacrficing some other
  project. If you ever heard the sound of silver OPT's, it will
  definitly make you think about it.
  have fun
  Willie
  
  

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• Re: Output Transformer Choice for 300B - lurcher 23:56:25 04/02/07 (2)
  In Reply to: Output Transformer Choice for 300B posted by Mike C on April 2, 2007 at 12:23:27:

  Hi,

  Given that you are in the UK, the obvious suggestions (listed in order of delivery time)

  Sowter
  SJS
  AE
  Tribute

  The latter two will do you a nice amorphous core.
  
  

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  • Plitron - bouncy ball 06:35:44 04/03/07 (0)
    In Reply to: Re: Output Transformer Choice for 300B posted by lurcher on April 2, 2007 at 23:56:25:

    Is what I am using, excellent sound with superb bench measurement.
    Picking good OPT is like looking for good coffee, everyone has his own favourite. Be careful with amorphous, silver and other exotic material, all have their own character.
    
    

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  • Re: Output Transformer Choice for 300B - Mike C 00:33:09 04/03/07 (0)
    In Reply to: Re: Output Transformer Choice for 300B posted by lurcher on April 2, 2007 at 23:56:25:

    Hi,
    Reports of direct comparisons suggest that Sowter are not up to the standard of sound quality of the best Japanese. I use their PSU tx's and chokes though.
    SJS is a thought - this amp uses his power TX's and they are fine. But I think he's now based in the US?
    I'll have another look into AE, but I believe Tribute take about a year!
    Thanks for good ideas.
    
    

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• Re: Output Transformer Choice for 300B - HebrewHills 20:12:06 04/02/07 (0)
  In Reply to: Output Transformer Choice for 300B posted by Mike C on April 2, 2007 at 12:23:27:

  The Hashimoto would be an excellent choice I would think.
  Elecktra Print is pretty fair game to from a sonic standpoint.
  
  

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• Try Tweeking The Driver Stage First - ben 19:07:29 04/02/07 (3)
  In Reply to: Output Transformer Choice for 300B posted by Mike C on April 2, 2007 at 12:23:27:

  Try the Kimmel Choke coupled MUstage with a O-Netics or a Tribute interstage transformer.Their will be no coupling caps in the signal path.
  
  

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  • Re: Try Tweeking The Driver Stage First - danlaudionut 05:20:35 04/04/07 (1)
    In Reply to: Try Tweeking The Driver Stage First posted by ben on April 2, 2007 at 19:07:29:

    Ben

    How do you use a choke coupled mu stage
    with an interstage without a coupling cap?

    DanL
    
    
    
    

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    • Search The Welborne Forum For "twystd" - Ben 20:46:49 04/06/07 (0)
      In Reply to: Re: Try Tweeking The Driver Stage First posted by danlaudionut on April 4, 2007 at 05:20:35:

      If you search Welborne forum for "twystd" it will tell you all about it including some Reviews of the Mod.
      
      

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  • Re: Try Tweeking The Driver Stage First - Mike C 00:14:15 04/03/07 (0)
    In Reply to: Try Tweeking The Driver Stage First posted by ben on April 2, 2007 at 19:07:29:

    Good thoughts, but I'll save that for my next project.
    The main point about that will be better 2 pi PSUs and that won't fit on the existing chassis.
    Once I design a new chassis I'll consider ITs or grid chokes etc etc ...
    
    

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• Re: Output Transformer Choice for 300B - Paul Joppa 16:55:46 04/02/07 (1)
  In Reply to: Output Transformer Choice for 300B posted by Mike C on April 2, 2007 at 12:23:27:

  To keep the bass, you'll want to be sure that the inductance and maximum DC current rating of a replacement transformer are not compromised. These numbers are often hard to find, especially if you insist on them being measured in the same way so that a comparison is valid ... :^)

  According to the data sheet, the LL1620 has quite a high inductance.
  
  

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  • I second Paul's comments... - Thomas Martens 16:56:48 04/03/07 (0)
    In Reply to: Re: Output Transformer Choice for 300B posted by Paul Joppa on April 2, 2007 at 16:55:46:

    particulary pertaining to the importance of having a high primary
    inductance and current handling ability. If you want your SET amp to
    sound "BIG", then you actually need a pretty BIG piece of iron to
    accomplish this. Size does indeed matter here --even at 6-10 watts
    output.

    Good luck,-

    T.M.
    
    

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• Re: amp is the most musical I've ever heard - danlaudionut 15:31:45 04/02/07 (0)
  In Reply to: Output Transformer Choice for 300B posted by Mike C on April 2, 2007 at 12:23:27:

  Mike

  Since you like the sound of the Lundahl LL1620,
  why not try the LL1620AM (amorphous core).
  Same musicality but more detail.

  DanL

  
  
  
  

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• Re: Output Transformer Choice for 300B - Ian L 15:17:10 04/02/07 (1)
  In Reply to: Output Transformer Choice for 300B posted by Mike C on April 2, 2007 at 12:23:27:

  I strongly recommend two things .

  1) Add Magnequest to your short list. They make an extremely reasonably priced SE Output Transformer (TFA-204) that was originally designed specifically for the WE 300B when run at 8 Watts out or less - and they have other SE Output Transformers rated for higher power. Though my opinion is biased in that I love their stuff they are certainly at least as good as the other big names.

  2)
  You say the amp is the most musical you've heard and I take that to mean you're enjoying the sound with the Lundahls. Well, this is pure opinion and waxing philosophical but IMHO . . .
  Isn't it a mistake to change something while you still really like the sound of what you have? - It could well be that a future you will value a different amp more - but enjoyment doesn't come cheap (Look how much everybody is spending to try and get it!!`,;^)and it's good to appreciate what you like while you can. Especially as this amp is your own creation you have an interest in hearing deep into the sound, getting to know the sound intimately.
  Of course, nothing is perfect and eventually the things that you want to change will surface in your own mind before they do in anyone else's.
  
  There are so many uneasy, 'concerned' guys who spend all their time modding (or thinking about it) because they once made the choice to ignore what they liked and now have to wander the land of everybody else's recommendations trying to find it again.
  
  

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  • Re: Output Transformer Choice for 300B - Mike C 05:57:40 04/03/07 (0)
    In Reply to: Re: Output Transformer Choice for 300B posted by Ian L on April 2, 2007 at 15:17:10:

    Hi Ian, I really like your post!

    Re the uneasy, concerned guys wandering trying to find what they like; I was perhaps a bit like that (not as bad as most of my friends). But the situation changed totally once I changed over to valves. :-)

    I still change things, but I tend to have a backout plan (easily reversible changes). DIY helps enormously with this. And of course in this case I can always swap back to Lundahls, but somehow I doubt if I will need to. Anyway, that's how I address your highly valid point of why change when I really like the sound of what I have.

    And .... other people's recommendations on several Asylums have proved exceptionally reliable; more so than dealer or magazine advice (in the distant past, before I discovered these Asylums, valves, DIY ...).
    
    

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