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A tale of two OT's / 5F2A

Discussion in 'Shock Brother's DIY Amps' started by HBamps, Aug 3, 2020.

  1. HBamps

    HBamps Tele-Meister

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    I recently built a 5F2A with a few tweaks for myself and found that it's a really great amp for home practice and low volume jams. SO much better than trying to control a big amp at home. I let a friend borrow it for a few days and he convinced me to make him one.

    Anyway, the original has a Weber Champ/Princeton OT (22905M). For my buddy's amp, I wanted to try the Classictone version (18030 I believe). The rest of the components on both amps are identical.

    While I know that every component has tolerance and the whole can vary in noticeable ways, these two amps are DRASTICALLY different. I looked over both amps for days trying to figure out why such a different response between the two. tone controls, partial shorts to ground, resistor values, tubes, caps, etc. When I couldn't find it, I decided to swap the Classictone for a Weber and BAM, the two were much more in line.

    Point it here is how drastic the tone and feel of an amp can change using different output transformers. I know they are important to the tone of an amp but never witnessed it first hand.
     
  2. D'tar

    D'tar Friend of Leo's

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    Mind posting the specs for each transformer. Some take a lot of liberties labeling their transformers for whichever circuit they wish.
     
  3. Wally

    Wally Telefied Ad Free Member

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    now, which OT do you like? What were the differences in the Sonics of each OT?
     
  4. Lowerleftcoast

    Lowerleftcoast Friend of Leo's

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    The classictone has a 5k and 8k primary. The weber primary is 7k. Which tap did you use on the classictone?
     
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  5. James Knox

    James Knox Tele-Holic Silver Supporter

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    Yes, which did you prefer and why?
     
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  6. HBamps

    HBamps Tele-Meister

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    I used the 8k on the classictone, switched to the 5k just to make sure the lead color wasn't messed up.

    To be fair, I really tuned the my circuit tweaks with the first amp with the Weber and hence the Weber sounds better to my ear with that particular circuit. But the differences are as follows.

    The Classictone seemed to have a fuller and looser low end and low mids and possibly slightly more very high end as well. More scooped I guess but felt less precise. The 5F2A is already pretty loose so I wasn't really a fan of this.

    The Weber is more mid-focused by comparison, just responds more evenly across the full frequency range. Cold just be because the less low end, but it feels more responsive with quicker attack.

    I am a fan of full bass but the Classictone made this amp seem and feel uneven and bloated. I really wanted the Classictone to sound great as it wasn't available at the time I built the first amp. Just not the case this time. No knock against them, and I would probably;y prefer the Classictone if I was to start with it first and tweak to it.
     
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  7. Treehouse

    Treehouse Tele-Meister

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    Hmm. Now I’m tempted to swap a Weber OT into my Classic 5 AliExpress special! Although it sure sounds very ok as it sits with a WGS G8C.

    I for one would love to see some pictures of your builds @HBamps!
     
  8. tubedood

    tubedood Tele-Holic

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    I do like Classictone.
    But I use the Allen TO11s. I wouldn't use any other in my experience.
     
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  9. tubedood

    tubedood Tele-Holic

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    OOps sorry didn't see the full context of your post HB on the screen I was using (although I still stick with that Allen transformer ha-haa). Maybe there is a better core gap between the 2 designs? Single ended transformers seem to at times make no sense in what sounds better. I have heard many an amp sound better with an old hi-fi or Baldwin organ transformer than the so called better quality iron sold for guitar amps.
     
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  10. HBamps

    HBamps Tele-Meister

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    Some pics attached, I think...
     

    Attached Files:

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  11. Treehouse

    Treehouse Tele-Meister

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    Dang @HBamps, those cabs are clean and pretty! What’s the third knob?

    Nice outdoor space too!
     
  12. HBamps

    HBamps Tele-Meister

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    Guitar Cabinets Direct. They do such a great job and are super nice folks.

    The circuit is a volume, Framus Mid control and a treble cut after the second gain stage.
     
  13. Nickfl

    Nickfl Friend of Leo's

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    Same speaker? Part of the difference could have been the speaker on the second amp being less broken in than the one on your first build.
     
  14. Commodore 64

    Commodore 64 Friend of Leo's

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    Need to know frequency response of both OTs. And then with some coupling/tone cap adjustments, I reckon you could get them sounding the same.
     
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