Hayseed 30 Mod

Discussion in 'Amps and Cabs' started by The Pup, Dec 11, 2005.


  1. The Pup

    The Pup Supporting Member

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    UPDATE:

    Quote referenced from:

    http://vintageamps.com/plexiboard/viewtopic.php?p=391877#391877

    "tralfax wrote:
    Hi,
    That amp (as you can see in the pictures) has the Mercury Magnetic OT and choke. Although the choke does nothing to alter the tone, the Mercucy OUTPUT TRANSFORMER sounded better than the heyboer, due the the narrower frequency response. It made the amp sound more
    authentic than I thought it would ever be possible.
    Dont fret though, I am working on a simple mod for the heyboer equipped amps that gets the same results, i just need a couple of weeks to get the diagram together and do more testing to get it just right.
    the Mod kit will run $2,shipped.
    Rob"​

    I just completed the Heyboer to Mercury Magnetic Frequency Bandwidth Reduction Modification (aka the 250pf mod) a few hours ago. Here's my thoughts on the subject:

    When I first received the Hayseed I noticed it possessed prodigious bass content and phenomenal thump which was beyond any AC30 I have ever played. This is because the Heyboer transformers have a greater frequency range than the original AC30 Woden transformers. The Mercury Magnetics transformers are much closer to the original specification and do not have this rich extended bass characteristic (arguably undesirable to the AC30 purist).

    To compensate, Rob (Valvetech) designed a very simple mod to filter out the "undesirable" or extra bass and high treble frequencies...and it's very simple.

    Note: My circuit is somewhat unusual, meaning not your normal Hayseed; so it's best to contact Rob for instructions so your mod is representative of your Hayseed (ex. my tremolo intensity circuit was tied to the cut controls center tap and had to be moved).

    After completing the mod, I used a capacitance substitution box to dial in the best frequency response for the range and type of instruments I play and what best matched my speakers. I found that 285pf was the target sweet spot for me.

    According to Rob, the 250pf mod achieves the frequency characteristics of the Mercury Magnetics iron. You can easily save $150.00 by opting for the Heyboer transformer and installing the $0.35 (including tax) capacitor and 15 minutes of soldering. For future Hayseeders..I'm sure Rob will do this mod on all future Heyboer Hayseeds.

    I somewhat miss the thunderous bass content I had before the mod. I guess I'll install another little switch so I can have it both ways...traditional AC30 and original Hayseed with a capital "H".

    Recommendation: Get the Heyboer iron so you can dial in your own sweet spot. Its extended frequency range can be easily filtered to your desire...something you can't do with a lower frequency range source. For the beloved AC30 purist...grab the Mercury Magnetics iron and never look back.

    Bottom Line:

    For those of you with massive Heyboer iron...you can skip this mod for the rest of your life and not regret a thing. The amp sounded awesome before. However, for $0.35 and 15 minutes with a soldering iron, you can follow Rob's continuing pursuit of Hayseed 30 tone nirvana...an early '60's AC30.

    Reference: http://206.130.108.2/plexiboard/viewtopic.php?t=40793&postdays=0&postorder=asc&start=0
     
  2. The Pup

    The Pup Supporting Member

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    To help clarify:

     
  3. fullerplast

    fullerplast Senior Member

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    The guy in the referenced thread said: "it sounded too big in the bottom end, too hi-fi and unfiltered in its frequency response, and too hashy in overdrive".

    Something tells me there's more difference between output transformers than a 250pF cap can correct......:) If it were me and I were going for JMI AC30 tone, I'd go with the most accurate OT I could find rather than try and compensate via filtering. For a while, the Vox HW OT's were available, but I don't know if they still are in stock. I know Mitch worked on that one for a long time getting it right.
     
  4. bscepter

    bscepter Member

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    According to many Vox-heads, the Mercury Magnetics Woden clone is the bee's knees. I've got one in my Hayseed, and it sure sounds nice.
     
  5. fullerplast

    fullerplast Senior Member

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    Don't they also do an Albion clone? Anybody try that one?
     
  6. tralfax19645

    tralfax19645 Member

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    Hi,
    You will notice in the little mod picture that the CUT control was wired differently as well. The 250k resistence in the pot is wired between output caps of the PI. This is what rolls off the excess lows, and does it perfectly.If you have an amp with the single pot post PI master, really listen to it is you turn it down, it is not "linear"at all. It cuts the bass first, then the mids leaving only the highs at the very end, when it is turned almost all the way off. I simply set a Mercury transformer amp next to a heyboer amp, hooked up a pot between the output caps, and turned it down till it sounded the same (which it does) as the MM amp I did this test several times, each time with fresh ears and kept coming up with the same value, around 250k, which was cool, because then I only had to add 1 part.
    the 250 pf cap rolls off the highest highs, that are only really noticeable in higher gain settings. Just smooths the OD top, like the mercury.
    Rob
     
  7. Roe

    Roe Member

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    sounds great to me. If I'm going to buy a voxish amp, it'll be a Hayseed head.
     
  8. sundaypunch

    sundaypunch Member

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    I'm not sure what an accurate JMI transformer would be? Not to state the obvious but it would depend on which of the several JMI era transformers you were trying to duplicate. With AC30's there doesn't seem to be a consensus on a "best" version.
     
  9. fullerplast

    fullerplast Senior Member

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    Either Woden or Albion are generally considered to be the best JMI OT's. That's why I was asking if anybody had tried the MM Albion clone. They (MM) actually make several AC30 OT variations.
     
  10. tralfax19645

    tralfax19645 Member

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    Hi,
    They heyboer OT has the correct specs for funtion, like impedence matching power hanling and all that,no problem. They just missed the mark frequency response wise. My goal was to build an affordable AC 30 clone, heyboer has great prices. If I can get it to sound the virtually the same as a transformer thats cost 4 times as much, I will stick with the heyboers and give em a little tweak.
    If YOU were to build a VOX clone and want it as authentic as possible, and you dont want to tweak,buy the mercuries. These are as good as advertised.
    I would suspect this to be true to thier entire line, but I have only heard the VOX WOODEN clone of theirs.
    Rob
     
  11. bscepter

    bscepter Member

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    I was originally going for the MM Albion clone, then Paul at MM (and Jim at JMI Music) convinced me to go for the Woden. Also, Don "Toneman" Butler uses the MM Woden clone in his upgrade package for current Voxes, so I figured he'd know. MM also makes a Haddon clone, if that trips your trigger.

    In any case, as I said earlier, the amp sounds great, so I can't complain.
     
  12. AshlandBump

    AshlandBump Member

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    Not by much. It's difficult to benchmark an AC-30 -- there have been so many variations over time. To me, the benchmark is a Korg-reissue AC30TBX because I've never played a JMI. I have little or no "skills" when it comes to electronic wiring and repair so I don't have much interest in owning one either. The Hayseed is a lot closer to the AC30TBX tone than the AC30HW I used to own. It's a matter of taste as to what's "better." but the Hayboer iron in the Hayseed does not prevent the Hayseed from putting out a great Vox-ish chime.
     
  13. bluesbreaker59

    bluesbreaker59 Silver Supporting Member

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    Rob,

    Don't change a thing about your amps, they're glorious man, absolutely glorious. I miss my old Hayseed so bad, stinkin divorce... But soon, oh yes, SOON, I shall be on that list again, and some time next year, I'll own pound for pound the best amp on the market (IMHO). And its definitely the best amp for the rootsy rock stuff that I love to do with my Blackguard Tele and a hotcake. That is DEFINITELY a winning combo.
     
  14. gitt

    gitt Member

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    Did I already thank you for that??? :)

    Now you guys go play - you're making me nervous goin' 'my hayseed this', 'my hayseed that'....

    :D :D :D :D :D


    ...while I'm still wainting on mine :(

    Hey Rob, d'you have an estimated timeframe to cool me off?
    please please please please ;)
     
  15. tralfax19645

    tralfax19645 Member

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    Hi,
    You are comin up on the schedule.
    This is strange, the hayseed unmodded sounds a little too bassy for some, great for others. To me the rolled off lows that the mercury had sounded better,especially in the bypass/EF 86 normal positions. I think what I am going to do is of course keep the heyboers, voice the amp a little deeper than the mercury's, but not as deep as they are now.That should be the ticket.
    Rob
     
  16. gitt

    gitt Member

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    Good job, Rob :AOK
    I think you deserve a raise ;)

    That's one more example of the benefits of dealing with "small builders": instant reaction to customer feedback.
    Customers not only get a better product (and fast), but they also participate in the process - they feel and know they're a part of it.
    And I'm not even talking about prices...

    I guess that's just obvious and been said over and over, just not by me :D

    Hey Rob, I hope we don't put too heavy a burden on you and your family...
     
  17. The Pup

    The Pup Supporting Member

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    UPDATE:

    I received an e-mail from Rob (Valvetech) stating he has further refined the "mercury mod."

    From: Vtkamps@aol.com [mailto:Vtkamps@aol.com]
    Sent: Sunday, January 15, 2006 8:14 AM
    Subject: Re: Future Order

    Hi,
    Here is the last word on the "mercury mod" for the cut control.You can just clip a .0022 in parallel with the existing .0047 to get the same value. It works exactly like the MM ,only with more control. I prefer this set up more than the mercury transformer actually,after doing extensive side by side testing. The amp sounds fuller with this mod and the heyboer.You would remove the 250 PF cap.You can try it and see what you think.
    take care,
    rob

    [​IMG]

    I performed the mod and all is well as Rob stated. However, I dialed in a cap value that I preferred while sampling a few of my guitars. I settled on a .0080 mfd value. I found a .0070 cap which read .0081 with my capacitance meter (close enough).

    Great appreciation and thanks to Rob for the simple tweaks. What a cool amp...vintage AC30 with some very serious balls!

    There just isn't a bad sound in this amp. I'll leave it this way until the next mod comes out. 8)
     
  18. The Pup

    The Pup Supporting Member

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    UPDATE:

    For those of you who would like to have your EF86 and reverb too (or whatever effect you like)...here's how to get a great sound out of your line-level effects loop with your line-level effects (drawing courtesy of Rob [Valvetech]):

    [​IMG]

    In my case, I'm using an Alesis Quadraverb 20K (ROM upgraded to "plus") and some bits and pieces I found in my scrounge (obviously Rob's layout is much cleaner...I just used what I had on hand to make it work):

    [​IMG]

    [​IMG]

    This setup is virtually dead quiet and the added spaciousness of a little reverb with the huge EF86 grind sounds great. You will still have commanding control of your gain (tube preamp saturation) with your guitar's volume knob just as before. Very cool!

    I also made this by-pass switchable. I can easily go from:

    1) 12AX7 with tube reverb/tremolo.
    2) 12AX7 with tube reverb/tremolo and Quadraverb reverb/delay...etc.
    3) EF86 with tube tremolo and Quadraverb reverb/delay...etc.

    I got the Quadraverb for real cheap on ebay...I'm sure there are better units, but this really does the trick. No perceived tone sucking!!!

    Note: I've only used the reverb and delay so far...I doubt I will use it for anything else. One cool patch I like allows me to get some nice percussive delay...hey, sometimes I like to get a little spacey.

    Whirlwind Little IMP:
    http://www.whirlwindusa.com/spcint.html

    [​IMG]
     
  19. The Pup

    The Pup Supporting Member

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    Update:
    Rob, the ever mad scientist, has a new cut control mod/variation to further explore the Heyboer equipped Hayseed's tonal possibilities. The mod sounds great and helps to better replicate the early '60's vintage sound...taming the Heyboer's prodigious bass and beyond vintage bandwidth (which is very cool in its own right).
    [​IMG]
    This is a cool one! Let's call it: the "Cut Super Mod!" ...for now. :wink:
    With all of these mods, I've got $4.00 in parts and 20 minutes of my time invested. This amp is so easy to mod and it's a blast shaping the tone of my amp to that of my desire.
    As you can see...just remove a few screws and you can play around to your heart's content.

    Note: None of these mods are necessary or essential...I'm just having fun and making the amp extremely versatile for my growing stable of guitars. What a beautiful sounding amp!

    Tonight was the Jazzmaster, Duo Jet and the ES-335 with the amp set at:

    MV: 1/3 (2/3 attenuated)
    Power Sw: 1/2 (15w mode)
    Filter SW: 16uf
    Mode SW: EF86 Bright (TB)
    Reverb: 1/3
    TB Gain: 11:30
    HI: 12:00
    LO: 12:00
    Cut: Full CCW
    Tremolo: Speed 10:00, Depth: 11:30

    Very lush and inviting...impossible to stop and say goodnight.

    Earlier today, with the SG and the EF86 gain full on (Cut set at 12:00), I was able to get a phenomenal distortion sound using this cheap Svetlana tube EF86:
    [​IMG]
    It really hit the spot. Very tasty indeed!
     
  20. The Pup

    The Pup Supporting Member

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    Did another EF86 Tube taste test this weekend with the following tubes from my home spares stash (pulled used, but all very good and all completely non-microphonic):

    [​IMG]

    [​IMG]

    Amperex, Mullard (a few different types), TFKN, Valvo and Svetlana Winged "C."

    Each tube has its merits and I must admit you really cannot go wrong with any of them. If I could have a lifetime supply of just one of the above, it would be the Valvo by a thin margin over the rest (although I found it almost impossible to keep them straight in my head after a few swaps back and forth). Dimed, the Valvo even beat my current favorite: the Svetlana Winged "C."

    The Valvo had a nice breathing/squishy crunch that was quite surprisingly pleasant even with my highest output humbuckers. I also found the Amperex and the black labeled Mullard similar but not as much grind at full throttle. The TFKN was quite sweet at 1:00 (gain setting), but lost a small degree of focus at full CW gain. The Svetlana was not as sweet and focused at moderate gain settings but really shined full-on.

    Disclaimer: I am not an EF86 expert by any measure, so I wouldn't be surprised if a few of these tubes were manufactured at the same plant and relabeled for sale.

    Note: Obviously tested with the Hayseed (EF86 Normal and Brilliant selected). If you want a good sounding EF86 for cheap (as of today), get some of those Svetlana Winged "C" tubes (no longer in production but plentiful).
     

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