45 Sound out of a 300B? Or a more powerful 45 setup? Possible?

Discussion in 'Tube Audio' started by RichP4003, Sep 12, 2018 at 8:48 AM.

  1. RichP4003

    RichP4003 New Member

    Messages:
    47
    Location:
    Southport, CT
    I have found myself, like many, on an amplifier Everquest to match up to my Zu Audio Druid V. Some of the things I tried:

    - a "traditional" 300B (tube rectified, C3G driver, transformer coupled) and it sounded very nice, but a little syrupy, slow. Really nice but not quite what I was looking for.

    - a 2A3 amplifier (an earlier triode lab amplifier) and didn't really like it, although I was surprised with how sound 3.5W or so could produce.

    - A EL84 SEP amplifier (Decware Zen Taboo 3) wow this amplifier was impressive. It felt it was lacking power but the clarity and speed were very nice, and quite musical and great with voices.

    - A 45 amplifier: I was lucky to find a cosmetically damaged Yamamoto A-08 for a great deal. It sounds FANTASTIC. It is a very beautiful sound, yet quick and transparent. Voices are in the room not in the speaker. Bas isnt super strong but incredibly well defined. At less than 1.5W, even this sounds very powerful in the room (the amp is rated 2W but at 8 ohms, the Druids are 16ohm)

    If I ranked these, the 45 is the winner, with the EL84 second. Although the Zus are 101db, I still feel they need a bit more power. At louder listening levels the amp is just below/ starting to clip. I would love a solid bit of headroom..

    So given Im close to where I want to be, I have some options:

    - Build/acquire a PSET 45 amplifier.. with the issues that PSET brings. (4w)

    - Build a 45 amplifier that has 2 45 circuits bridged at the transformers, floating them from ground like Decware and Bottlehead accomplish their 45. They both claim this doesnt have the issues of PSET (smearing if the tubes are 100% matched throughout their lifetime) (again 4W)

    - Build an amplifier around the EML 45B tube. This tube can run like a regular 45, or up some numbers and run the right transformers and it can put out more power. if I went this route I would get the tubes first, try them in the Yamamoto and confirm they even sound like a true 45 (4-5W)

    The final bit is: Is there ANY 300B setup that sounds like a 45 tube? solid state rectification, a particular driver setup, a particular tube (its pricey but even like the ELROG 300B thing).

    Thanks everyone.. I feel like I am close to getting where I want to be (im honest in that in audio there is never a true "end-game")
     

     

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  2. Palustris

    Palustris Well-Known Member

    Messages:
    785
    It seems that choosing an amplifier that mates well with the Zu speakers is going to be a very personal decision for you and it might be impossible for someone to predict what you would prefer.

    That said, I would try the EML 45 in the Yamamoto; they both have great reputations. Notice that your Zu speakers will reflect a higher impedance to the 45 tube than an eight ohm speaker. That will slightly reduce the distortion and reduce the power slightly. I'm surprised the Yamamoto doesn't include a 16r tap, but the schematic doesn't show another tap.

    I don't see that you have included a direct coupled 300B (or 2A3) amplier with EML tubes. The "syrupy" sound of the amp you tried could be the result of the transformer coupling, the choice of 300B tube or both. I find that direct coupling gives tremendous speed and transfers the full rich harmonic content of the signal. Transformer coupling is bandwidth limiting and capacitor coupling can lead to "blocking distortion" when the cap charges negatively with the grid reducing bias and adding distortion.

    I would avoid "bridged" amplifiers to fully appreciate the SE topology.

    BTW: I use Zu Soul Superfly speakers in my system; also 101dB & 16r. My amplifier is a stereo SE EML 320B-XLS with Tamura 5002 output transformers. The EML 320 is driven by a direct coupled D3a, triode connected. The external power supply for both channels is capable of 550V @ 350mA and has <50 ohms DCR. You can't buy a setup like this; it needs to be engineered and built.
     
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  3. bean_counter

    bean_counter Active Member

    Messages:
    269
    Location:
    Oswego, IL
    I'm in the minority (and a small one at that), but I prefer class A push-pull DHT's. I think most of the "magic" comes from DHT vs SET, you don't give up much but you gain better control of the low end.

    Try a PP 45 with phase splitting transformer coupling; a 5842/417a is a good driver for a 2-stage amp (Amperex or WE, my experience is the Raytheon 5842 is quite inferior). No feedback.
     
  4. RichP4003

    RichP4003 New Member

    Messages:
    47
    Location:
    Southport, CT
    Ive considered it, but having two KT88 push pulls in the past (and an OTL SEPP), Ive been hesitant to revisit that topology. It is something worth revisiting if the DHT portion of it makes that much sense. (its too bad KT88 and 45/300B/etc are so far apart electronically because it would be great to be able to repurpose an amplifier I have)
     
  5. robert_kc

    robert_kc AK Subscriber Subscriber

    Messages:
    819
    Location:
    Midwest USA
    I agree with Palustris that this will be a personal decision. Nonetheless, I'll offer a few quick thoughts:

    Do you listen to LPs, or digital recordings? If digital, the Oppo universal players (e.g., UDP-205, BDP-105, BDP-95) feature "bass management" - i.e., a built-in configurable crossover, and a connection for a powered subwoofer. With Oppo's bass management, the low frequencies are off-loaded from the main amp and speakers, thereby facilitating greater overall dynamics. In other words, your tube amp's power will "go farther". (I sometimes connect tube power amps directly to my Oppo UDP-205 (i.e., no pre-amp), and use the Oppo's remote volume control.)

    I own an Inspire “Fire Bottle” SE Stereo Tube Amplifier HO (in addition to 23 PP tube amps). My speakers in this system are RF-7II (101dB), which I love. This amp supports significant latitude in tube rolling, allowing you to tailor the sound to your speakers and your tastes. My Fire Bottle sounds great with my RF-7II, except not quite enough power to deliver the dynamic impact of large scale orchestral music (e.g., Mahler Symphony 2). OTOH, for a string quartet, or big band (e.g., Count Basie), or Eva Cassidy – i.e., genre with little dynamic range - my Fire Bottle sounds great.

    Here’s the output tubes that I’ve tried:
    • Zenith 6V6G (vintage)
    • Sylvania 6L6GA (vintage)
    • Sylvania 7408 (vintage, 6V6 variant)
    • Mullard EL34
    • Bugle Boy EL34 (vintage)
    • Russian 6P3S-E (Russian military surplus 1980s 6L6GC equivalent)
    • Groove Tube Gold Series GT6L6GE (6L6GC)
    • McIntosh branded GE 6L6GC (vintage)
    • GE 6L6GC (vintage)
    • Tung-Sol 7581A (6L6GC variant)
    • Tung-Sol 6L6G (6L6GC in a big bottle)
    • Gold Lion KT88
    • Tung-Sol KT150
    • Gold Lion KT66
    • Sylvania 5881

    Rectifiers that I’ve tried: 5Y3, 5U4, 5U4GB, 5V4, 5V4GA, 5AR4 (multiple manufacturers of each)

    Front-end (9 pin miniature socket) tubes that I’ve tried: 6CG7, 6N1P-EB, 6DJ8, 6N2P-EV, E88CC

    My favorite combination: 6L6GC / 5V4G / 6DJ8.

    I have no experience with 45 or 300B, so I can't comment on how the Inspire “Fire Bottle” SE Stereo Tube Amplifier HO would compare. My only point is that this SEP amp allows hundreds of tube combinations.

    Dennis Had, the designer and builder of the Inspire amps, currently has a 45 based SET amp on eBay: 153175011655 (I have no affiliation.) Dennis designs and builds several different types of single-ended amps. Here's an interview:



    FWIW - my favorite amp is a pair of McIntosh MC30s. If that's too warm sounding for you, then MC225. These both have enough "oomph" for large scale classical music with my Klipsch RF-7II, and Klipsch Palladium - particularly with a powered subwoofer.
     

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  6. bean_counter

    bean_counter Active Member

    Messages:
    269
    Location:
    Oswego, IL
    I can understand that. Feedback amps aren't my cop o' tea, either.

    A KT88 amp might not be so bad to convert, depending on the amp, add a choke input to the power supply and it brings the B+ down to something suitable for fixed bias 2A3 or 6B4G. Maybe tall enough for a cathode bias 45, since the current draw is less IIRC. You could always play around with a small poly cap before the input choke to dial in the B+. Work it out on PSUD II and see what you get.

    I converted a pair of Dynaco MkII's to PP 6B4G, tho there's not much left of the Dynaco beyond the power trans, the crappy little choke (2nd choke in LCLC ), and the bias scheme.
     

     

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  7. analog addict

    analog addict Glory or Death!

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  8. RichP4003

    RichP4003 New Member

    Messages:
    47
    Location:
    Southport, CT
    99% digital, using a Luxman DA06 and Luxman C600F ahead of the amplifiers. I appreciate the thorough writeup! I *think* I am pretty set on 45. I love this Yamamoto.. just want more of what its doing.

    Right now I have 2 pairs: the luxman MB3045s and a pair of luxman MB88u. The latter are a more classic Williamson circuit.

    DUUUUUDDDEEEEE..... PSE is a contentious issue.. what do you think considering you had a single 45 amplifier before?
     
  9. bean_counter

    bean_counter Active Member

    Messages:
    269
    Location:
    Oswego, IL
    Hmmmm... I don't think I would be ripping up any Luxman tube amp, except to mod the ones with that funky unobtainium output tube. Better off selling them and buying/building.
     
  10. RichP4003

    RichP4003 New Member

    Messages:
    47
    Location:
    Southport, CT
    Ha! You mean the MB3045s.. which have already been converted to KT88 in the pursuit of keeping them usable.
     
  11. bean_counter

    bean_counter Active Member

    Messages:
    269
    Location:
    Oswego, IL
    I didn't recall which had the odd tubes. A year or two ago somebody local had them on C-list for weeks at a decent price, nobody bit (likely because of the tubes). I should have grabbed it, but too many projects, and I really didn't want it for my system anyway. Then it would have been me flogging it for weeks.
     

     

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  12. analog addict

    analog addict Glory or Death!

    Messages:
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    Location:
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    More power, dynamic headroom, and driver control, same rich 45 SET sound.
     
  13. for_p1

    for_p1 Addicted Member

    Messages:
    5,468
    Location:
    North TX
    You forgot to try SET amplifier with 845 tube. Most models with that tube will LOVE 16 ohms load giving you low distortion. Even cheapest amplifier will provide 10-12 REAL watts, so power will not be am issue.

    Here would be a good example to try: https://www.line-magnetic.eu/en/pro...icateur-intégré-single-ended-845-2x22w-detail
     

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