Electro Voice Q1212 (Dynacord SL2400) pro amp impressions / insides

Discussion in 'Power Amps' started by Priidik, Jun 9, 2020.

  1. Priidik

    Priidik MOT: Estelon

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    For a while now, I have been looking for a beast amplifier to power multi way speakers bass section.
    Limited to 1..2 k$ max.
    There are many proven contenders that could have worked for me: Vidar, Crown CDi, used Krells to name the most relevant. I was close to get a mint MC2 T2000 and also considered used MC2 MC650, Crown Macro-Tech but in the end the eBay and other shady sources felt too much hassle.

    I was set to get something yet not discovered by trusted ears of SBAF.
    When no reliable impressions are accessible the next best thing is to investigate what the insides are and hope that the designer of the amp was not deluded and with decent ears.
    Luckily, Russians have yt vids of maintenance and teardowns of these sort of things.

    I had some goal points:
    - Class A-B (could be with switching rails Class H),
    - A robust linear psu,
    - Strong output stage (lots of parallel devices),
    - No digital trickery in the signal path.

    Voila:
    EV-Q1212_cr.jpg
    Solid ze German engineering. I have teared down lots of Dynacord amps myself and have never been disappointed.
    Lots of similarities in layout and even parts manufacturers to the Dynacord amps made in the early 80's.

    Success on the goal points:
    EV-Q1212-COLLAGE.jpg
    - Class H (A-B with switching rails) where probably for my normal use it rarely leaves the first voltage rail (there are 2), making it essentially regular Class A-B below few hundred watts
    - Massive tranny with Elna filter caps. The amp weighs nearly 18 kg (40lbs).
    - Signal route clean from garbage (digital, that is). There are some quite cheap opamps in the input area. I couldn't be bothered to reverse ngijneer what makes what. Given that everything else is expensive brand name stuff (Elna and Nichicon caps, Austrian Schrack relays, NJW1302/NJW3281 for OPT devs) I found it surprising. Perhaps the guys who tuned this thing thought the NE5532 sound better in this circuit than the modern better measuring opamps. There would have been easier places to cut costs.
    - output stage has 14 pcs 200W devices per channel. That should do.

    Usability:
    - It is air force cooled, so it will at some point get noisy. Good thing there are 3 levels to the fan output. It kind of bothers with some orchestral and jazz sometimes. Probably should add a couple of silent computer fans to the front.
    - Gain is 32 dB (40x) Ear against the tweeter I could hear tiny bit of hiss.
    - There are level adjustment knobs in the front. Real handy for bi-amping.
    - A ton of protection circuitry inside, no pop when switching it off, doesn't blow the breakers when turned on. Protection against shorts and overheating among the many.
    - Speakons. These felt so good, I decided to make all future amps and speakers with these.
    (even measured the Speakons to have lower resistance than screw terminal and tinned wire)


    Sound:
    I wish I had relevant known amplifiers to compare this to. In time I will update this section.
    RIght now I have two amps to use for mid-high while bass is fed by the EV Q1212 at all times.
    EC2A3 driving mid-tweeter without any padding or a JLHood doing the same.

    Caveat: I listen to speakers I made myself and the XO has not yet matured.
    Some of the characteristics I hear could be more attributed to the speakers rather than the amp.
    Dac for the tests is my trusty old diy Soekris.

    Only EVQ1212:

    - It was a surprise to find that the thing sounds normal. No grainy highs, no rough mids. It's smooth, airy, very neutral, perhaps slightly dark tilt to the sound. Yet importantly not d-e-a-d sounding. It might be one of the more neutral (good way) devices I have had in my system. I have tried pro amps before. That one does not sound like a typical pro amp from 10..20 years past. More like something found in pro studios.
    - It does BIG soundstage. Imaging is precise and granite stable. Width and depth projection size feels equally big. Sounds in synthetic music go behind me almost as far as to the front. Orchestra sounds grand in size, when the recording is worthy.
    However, depth projection feels quirky with some tracks. There might be some lack of cohesiveness from close to far between the sounds. A zone of emptiness. The images in space are super sharp, a bit like how Yggdrasil displays sounds. I wonder about the combo now, it could be unlistenable.
    - Macro dynamics are 10 out of 10. It's like driving a lightweight buggy with a superbike engine. Explosive&effortless. Breathes raw POWER to your face.
    - For describing bass I have forgotten the vocabulary, as I have been listening to HD800 and wanker studio monitors for too long. In short it's incredible. So much so that I get distracted of how good the other parts of the spectrum sound.
    - Tonal graduations, flavor. It's kind of average for a solid state A-B amp. On the stale side a bit.
    - Plankton matter. Again average or perhaps for a solid state amp above average.
    * It does have a 'thicc bass' button in the back

    JLHood on mids-highs and EV Q1212 on bass:
    - Noticeably warmer and mellower sound. A lot easier on ears with difficult recordings.
    - Noticeable lack of air and HF articulation.
    - Macrodynamics are slightly inferior in highs. A bit of veil to it.
    - Soundstage is much more closed in and imaging is not as precise. Soundstage far limts are blurry, not unlike JLHood driving HD800. However, there are no weird attributes, like with EV Q doing solo.
    - There is some seductive inner warmth that was completely missing with the EVQ1212 doing full range.
    - Tonal graduation / flavor: much more vivid, interesting. Acoustic instruments sound more pleasant and realistic.
    - Plankton matter: surprisingly close. Perhaps EV Q1212 by itself does a bit better.
    - Overall for half of my music collection I prefer this setup so far.

    Summary:
    For bass it's what the doctor ordered.
    Full range, a good sounding bonkers powerful amp to scratch that clean slam graving at 120+dB.
     
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    Last edited: Jun 29, 2020
  2. Poleepkwa

    Poleepkwa Friend

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    Nice write up. My beater Inter-M LW2400 does not use nearly as nice parts. Agree about the Speakon connectors - I guess the low mass helps
     
  3. dark_energy

    dark_energy Friend

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    Great amplifier. If you are weak, get lower power amp. This is heavy.
     

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