Oh Sh#7! Eddie Current Studio B

Discussion in 'Headphone Amplifiers and Combo (DAC/Amp) Units' started by purr1n, Aug 15, 2020.

  1. wbass

    wbass Almost "Made"

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    Thanks, Marv. Always appreciated.
     
  2. Elnrik

    Elnrik Super Friendly

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    Transformers are internal then?
     
  3. purr1n

    purr1n Building Magnis part time because it's peaceful.

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    Yup. The OPTs are under where the red spots are indicated.
    Untitled.jpg

    I believe that it will be a limited run. He had two dozen transformers left which means a dozen amps. 300B only because he needs to make them without the hassle of variations and finally close down the lab (this is why he had to get rid to the Ultralinear amp quickly).

    It's the same as the Studio Junior except in BA chassis. This amp is the Studio B. The difference between the SJR and AF is the the SJR uses 300B and a different custom made output transformer. The AF used the Cinemag. The Cinemag were dryer and cleaner sounding. The SJR custom are richer and more mellow. Like the AF, there's a tertiary winding for a few db of feedback. If one has a SJR, there is no need to get this other than for aesthetics (really reminds me of the old Moth stuff with the switches). This is the reason I am getting one, and also because it will be his last non-custom release.

    The circuit is extremely simple. I will document AF, SJR, SB, etc. after EC formally closes. Craig said he will still be supporting people who bought amps from him.
     
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  4. gixxerwimp

    gixxerwimp Professional tricycle rider

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    Sorry for OT, carry on ...
     
  5. ald0s

    ald0s Acquaintance

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    Are there impressions from the Studio Junior anywhere on SBAF for speaker use? I have searched the original thread to no avail but feel like I'm missing a repository of information somewhere, I remember reading about Marv's preference for 2a3 vs 300b but can't find it again.

    I've always wanted to own an EC amp but can't really justify it for solely headphone use. Currently running old Omegas but looking at the super alnico's.
     
  6. purr1n

    purr1n Building Magnis part time because it's peaceful.

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    300B is fine. I had a SJR proto (no feedback) on my big JBLs (4-ohm woofer, 8-ohm rest). Without feedback, the 300B takes over with bloomy lower mids, soft bass, rolled highs.

    The feedback (production) version is glorious. Gets plenty loud. But we are talking 99db SPL sensitivity on the JBLs. I imagine the Omegas will work great. The thing is that SET is SET. There will always be weaknesses with SET, a rounder sound. If you want tight zippy clean lines, SET won't sound like that. However if you want nuance, layers, expressiveness, expansiveness, nothing beats SET.

    Note that on my old Oris horn setup, I still ran solid-state on the woofers. The SET amp ran the top end and also the input to a solid-state amp that powered the woofers. I didn't split early with a preamp. I felt the distortion characteristics of the SET amp were best transmitted to the solid-state amp for best integration. Opposite approach to HT.
     
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    Last edited: Aug 17, 2020
  7. Hyperkin

    Hyperkin Rando

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    Very interesting.

    Always wondering how big of a different there is between the Studio and Studio jr.
     
  8. Ruined

    Ruined HD700 ruined my ear holes

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    Would studio B power these well?


    two-way, reflex-loaded, stand-mounted loudspeaker. Drive-units: 0.75" (19mm), ferrofluid-cooled, aluminum-dome tweeter, 6.5" (162.5mm) polypropylene-cone woofer. Crossover frequency: 2.2kHz. Crossover slopes: 24dB/octave Linkwitz-Riley. Frequency response: 55Hz-20kHz ±1.5dB, 50Hz-21kHz ±3dB. Sensitivity: 86dB/W/m anechoic (2.83V). Nominal impedance: 4 ohms. Amplifier requirements: 15-200W.
     
  9. ogodei

    ogodei Headphone Heaven Gatekeeper

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    No. From EC site: "Will drive 4,8 ohm speakers to 4 watts."
     
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  10. Ruined

    Ruined HD700 ruined my ear holes

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    Oh well always wanted an EC amp and was trying to justify this with a pair of nice spare speakers I need an amp for
     
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  11. Cakecake

    Cakecake Guest

    No
     
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  12. batriq

    batriq Probably has made you smarter

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    I don't know what to say folks. I never owned an EC amp. This was my last chance to do so. It's not cheap, but I'm not getting any younger, and I don't want to finally own an end-game amp when my hearing cannot fully appreciate it. It's being fed by BF2 and I'm listening through HD650 (ireland version, or whatever we're calling them, balanced). Plankton, well-defined bass, amazing layering/separation, black background. I listen mostly to speakers, and this is the first time I get the same level of enjoyment and engagement listening to headphones. Tubes I'm using are Mullard GZ34 (f32, not metal base with pixy dust), Gold Lion 300B (basically EH tubes), and the 5670 tube that came with the amp (Jan GE).
     
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  13. Prtuc2

    Prtuc2 Rando

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    Does anyone know if the Studio B or the previous Studio Jr. pair well with the Schiit Yggdrasil DAC? Thanks.
     
  14. purr1n

    purr1n Building Magnis part time because it's peaceful.

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    Depends upon taste and your headphones. Generally, I would prefer more neutral or forward sounding DACs. I use Gungnir MB with my custom 45 (same output transformers as the Studio B/Jr). Headphones range from Grado (TTVJ pads), HD650, Verite Closed, etc.
     
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    Last edited: Oct 22, 2020
  15. Prtuc2

    Prtuc2 Rando

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    Thanks purr1n, I am primarily using the HD650 and HD800 headphone.
     
  16. purr1n

    purr1n Building Magnis part time because it's peaceful.

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    Posting these questions here on behalf of @m17xr2b because he's too afraid to ask here on SBAF. LOL. Seriously, this is an open forum. If you have questions please ask. Even if you think this amp sounds like shit, it wouldn't hurt my feelings.

    In regards to your "the puny power supply compared to the original, this is not the place to make cuts" assertion, I think you shouldn't judge a book by it's cover (or size of chassis). Here are the differences (with BA PS chassis internals photo below):
    1. The Studio B power supply uses a single EI transformer supplied from a California company. The EI has two secondary windings for B+ and the filament heaters. The BA used two separate chinese toroids. EI power transformers will be more compact. As to the sound and sizing requirements of EIs and donuts, that's up for debate. Some audio designers prefer EI, and others prefer big donuts.
    2. Since the discontinuation of the BA, the high-frequency heater boards were miniaturized and placed instead inside the amp chassis, where the output leads are closer to the output tube filaments, instead of inside the power supply chassis (note green board bottom left in photo)
    3. The Studio B uses a single 5AR4 which has more current capability compared to dual teeny 6X4 (meant for preamp duties). The reason is that the BA was meant purely as a headphone amp. The Studio B can power high-efficiency speakers with impedance as low as 4-ohms.
    4. The Studio B incorporates a choke in the power supply. The BA did not have a choke.
    5. The Studio B B+ voltage is higher than the BA. I can't recall the exact numbers.

    BA Power Supply
    upload_2020-10-22_10-6-48.png

    All in all, your assertion that the Studio B's power supply is puny compared to the original and a result of cost cutting is premature, based on looking at the size of the chassis, and at worst misinformation.

    I have a huge stash of 6SN7s that I have purchased over the years. It is unfortunate for me that the Studio B doesn't use these grand sounding octals, but instead the WE396A, 5670, 2C51. The reason is that 6SN7s don't have much gain. While this is suitable for headphones of an era prior, it may not be so suitable now. Also consider that the Studio B does have speaker taps. Speakers, even high efficiency ones, will need a bit more gain than the 6SN7. Finally, at the end of the day the WE396A, 5670, 2C51 is a really good sounding tube. There's a reason why I bought the huge cache of the WE396As fr om eBay when people had no idea what they were. The only other 9-pin small tube that I really like is the WE417. The rest are OK. I don't even know why you are harping on no 6SN7 since you own a Stellaris. That doesn't come with a 6SN7 octal either but a 9-pin 6N1P.

    There is a lack an output heater voltage adjustment because this is 300B amp. The filament requires 5V. The output transformers are spec'd for the 300B. The BA had a voltage adjustment because it was meant to run either PX4 or 300B tubes. FYI, many a folks destroyed their 4V $$$$ KR PX4 tubes because they forgot to dial back the voltage back to 4V when rolling from 5V 300B to PX4. The switch on the back of the BA was not for voltage adjustment. It was for bias. Optimum bias for PX4 and 300B were different. Excessive tube rollers are the bane of tube amp manufacturers.

    I can't find internals of the Studio B power supply, but here is a DIY / proto version (don't laugh) of it. The final is mostly the same with few minor extra parts. The circuit is simple after the rectifier. CLC. Again, the high-frequency heater boards were moved to inside the amp chassis. The EI has two secondary windows (B+ and heater). It really doesn't get any simpler than this nor does it need to be. Chokes for the win.[​IMG]

    Also here is some perspective on the 6X4 tubes in the BA (left) - compared to a common rectifier tube 5UG4 (right)
    DSC04140.JPG


    Again, all you had to do was ask here if you had questions or wanted measurements. I simply posted this as public service for the EC fanboys with zero intention of writing a review or mentioning anything about improvements. (It kind of peeves me off that you represented me otherwise or hinting malicious intent "intentionally vague"). One reason for this is that I'm rather burned out from the Aficionado bullshit where one-half of people liked the no-feedback version and the other half liked the feedback version. The other reason is that Craig is semi-retired and not in a rush to build them nor may he be able to source all the parts to make them should a flood of orders come in.

    In the meantime, I'll ask Craig for a Studio B so I can take measurements. I'm sort of curious how a higher-end tube amp would compare to a lower end one like the Woo WA6 SE in terms of measurements.
     
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    Last edited: Oct 22, 2020
  17. purr1n

    purr1n Building Magnis part time because it's peaceful.

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    The Yggdrasil A2 is organic sounding and my preference is to use speakers or headphones with tight or lean bass with the Yggdrasil. It's hard to say because I do not know your preferences. My concern is that it would be too fat sounding. The Studio B isn't anywhere as "300B" (organic, low-mids bloom, rolled highs) as typical 300B amps because of the feedback. But still... there's 300B in there. Also the output transformers are richer sounding.

    Note that I do not consider HD650 or even HD800 to have tight or lean bass. The HD800 is OK, pretty good. The HD650...

    Instead of Yggdrasil A2 (organic), maybe the Yggdrasil GS (not so organic)?

    There are a lot of other DACs around too. Burl B2 comes to mind. I'm quite smitten by it for a different kind of sound. The warmth can be dialed in or out via the gain on the B2 DAC.
     
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    Last edited: Oct 22, 2020
  18. capt_wacky

    capt_wacky Rando

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    My Studio B arrived a few weeks ago, and I've been pretty glued to it ever since.

    Here are some images:
    https://imgur.com/a/PIZZb0j

    I emailed Eddie Current back in early October when I first read about the Studio B, and Judi graciously invited me to come meet Craig in Calabasas and listen to his new amp. Craig impressed me as both a gentleman and a genius in my brief time with him. I tested the amp on my HD800S and Auteur, as well as Craig’s LCD-2, and then I placed an order.

    The Studio B makes an immediate impression before you even plug in your headphones. It’s very large and imposing. Even the power supply is bigger than some tube amps I’ve heard before. You feel like you’re in the cockpit of a steampunk spaceship. All switches are huge and give a pleasurable thunk, and the volume knob is very satisfying. I know we’re supposed to ignore these intangibles and focus on the sound, but in real world you can’t really take these touches out of the experience. I think that EC and DNA amps are works of physical art, and it’s a pleasure to sit in front of them for your music ritual.

    On the amp I tested in his office, I’m pretty sure he had a pair of new production Shuguang Treasures 300Bs, and they sounded great. I am starting with a cheaper option, the Genalex Gold Lion PX 300Bs. I don’t feel the need to roll or upgrade for now, and I don't think I'll ever pay the rates of the WE 300Bs.

    Sound — Headphones

    I’m not as talented as many of you at describing sound, but I’ll attempt to do it anyway.

    For the past couple weeks, my source iMac > Schiit Bifrost 2. I tested the headphone amp with my HD 800S, HD 600, Auteur, Ananda, and Sundara, though I just sold the HiFIMans to help pay for this amp.

    The sound is very dynamic and packs a punch. It’s authoritative and powerful. The bass digs deep and there seems to be no loss of detail or rounded edges or sense of gooeyness like you sometimes hear on a tube amp. Microdynamics are very articulate and exciting, especially for a tube amp. It's the audio equivalent of a high-end OLED that has been perfectly tuned -- the blacks are inky and the whites pop. The midrange is smooth, and vocals are intimate, lively, and emotionally engaging. I should try this with more DACs and report back, but what I love the most about the amp is that I don’t spend a lot of time trying to analyze the sound, because I’m just caught up in the music. My favorite headphone pairing in the Auteur, which gives it just the right touch of fun and squeezes out those few drops of wetness. I would imagine that Verites with these would be heaven. The Sennheisers also loved the Studio B, but the HiFiMans didn’t seem to scale as much to my ears. The LCD-2 I heard at Craig’s office was also a good pairing, though I didn’t spend as much time with it.

    The noise floor is pitch black, I have heard zero microphonics from the tubes after powering on the amp. The large volume attenuator has no channel imbalance all the way down to the lowest level. I noticed no lack of power in SE, though I listened primarily with the balanced output.

    Sound — Speakers

    The amp can also drive some very sensitive speakers at 4 watts, so I purchased a couple of SpeakOn connectors and plugged these into my old Klipsch Heresys. The Heresys are a little bass shy in general, and they were perhaps a hair more shy here, given the modest power of the amp. That said, the midrange was lovely, and vocals sounded great. It gives a pleasant way to listen in my small office.

    Closing Thoughts

    I love the Studio B. The sound is wonderful, the experience of operating it is special, and it’s a piece of audio art made by a small business in my native state. Though expensive, I consider it to be a good value for the quality of what you're getting.
     
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    Last edited: Dec 2, 2020
  19. Mystic

    Mystic Mystique's Spiritual Advisor

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    Can the lineouts be used to connect a sub? My Rythmik L12 has rca inputs. Is this an optimal way to connect the sub in my system with a possible Studio B powering my Klipsch speakers?

    @purr1n
    I've owned a few different Eddie Current and DNA amps and wouldn't be able to pick a favorite between them. As your probably the only person in the world who has heard both, Studio B or Stratus? One 2A3 with no feedback. One 300B with feedback plus speaker amp.
     
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  20. purr1n

    purr1n Building Magnis part time because it's peaceful.

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    Different sound. DNA is more slightly more tubey, more bloom, more lush. Studio B is more tubey than typical EC amps on the account that it's 300B. From a technicalities POV, I think Studio B is a bit better of account on the transformers.
     
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    Last edited: Dec 3, 2020

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