AliExpress / eBay JL Hood 1969 Class A Amp

IMPRESSIONS

As promised, impressions (with the above red caps in place). I didn't listen to the stock amp too long, but I will comment on it a bit later. I will refer to this updated JL Hood 1969 amp as the JLH69.

The greatest strength about the JLH69 is that it doesn't draw attention to itself. I've been able to listen to hours and hours, and feel just as engaged and immersed in the music as when I just turned the thing on. The tonal balance and timbre are superb. Very smooth with no solid state nasties. Slightly warm, an emphasis in the lower mids really, with just the right amount of body, but not excessively so. Again, this amp doesn't scream "see how wonderful I am in presenting an oversaturated color or artsy sepia-tone rendering". Nor does it scream "I'm a lean mean detailed machine". The presentation is very natural, not organic natural, but just normal natural. The timbre and harmonic textures are spot on. Voices and natural instruments are a joy to hear!

Compared to the Hegel H2 and especially the Pioneer M-22, the JLH69 does not reproduce micro-detail as well. There's just that last bit of plankton missing, probably because of the big cap at the output. However, micro-dynamics are superb. The JLH69 convincingly renders small contrasts in volume with what it has available to work with. It's definitely an engaging listen. The Pioneer M-22's and JLH69's overall presentation are actually quite similar with the exception that the M-22 is a little more "magical" sounding than this amp; it does draw a bit more attention to itself. It would be interesting to see the distortion profiles.

The Hegel H2 is definitely the attention getter, slightly bright in the treble (in a good way), robust explosive (when called for) articulate bass, crisper more incisive transients, and soundstage the size of an IMAX screen with you sitting in row 30. This amp and the M-22's soundstage is a closer and smaller than the H2's. But we still have row 12 seats. No slouch at all for folks who prefer a deeper soundstage, and pretty much as good as it gets with solid-state amps. (The H2 seems to be an exception to this).

I do feel that the JLH69 pulls off the microdynamics trick a tiny bit better than the H2. And in terms of clarity, it meets the H2, which is no slouch in this department, but both are ultimately beaten by the M-22. The H2 still has that last bit of MOSFET mist. The JLH69 has a big electrolytic cap (bypassing with higher quality smaller caps can only do so much) in the way. The M-22 has caps in the signal path too, but they are small sizes. In all fairness, we are really comparing apples to oranges because the Hegel H2 should really be powering low-efficiency planar or traditional 58 piece crossover multi-way speakers. Still, I feel that providing a reference is useful.

Here are some handy links for reference to the other amps mentioned:

http://www.superbestaudiofriends.org/index.php?threads/hegel-h2-power-amp-mini-review.3791/
http://www.superbestaudiofriends.or...er-amp-epic-japanese-gear-from-the-past.4177/

Same Altec 511B horns with Altec compression drivers and 12" Beymas (in slightly undersized boxes) and source (tweaked Gungnir Multibit / Freya) was used in the M-22 evaluation.

P.S. The JLH69 needs at least a few minutes warm up. 30 minutes to an hour is best. Probably something to do with bias stabilizing and chassis reaching optimum temperature given lack of parts in the design. Audyn Red 10uF cap bypass on the big electrolytic caps increased plankton and lifted veil slightly, improved dynamics and bass extension quite a bit, and resulted in less required warm up time. The amp when cold has a tonal balance akin to the Jotuenheim with some glare and grain, but only at about a third to that extent. Once fully warmed up, the amp's tonal signature shifts to the impressions above.

 

ADDITIONAL NOTES AND THOUGHTS:

1. Gain is lower than Hegel H2 or even M-22. This is good for anyone running 100db horn compression drivers and 95db woofers, especially from a tube preamp (Freya) that adds a decent amount of gain.
2. The JLH69 is better than the Vincent SP-331 in every way, assuming you don't need the SP-331's power or aren't especially attached with the SP-331's tube bloom.
3. This should go on the loaner program.
4. Because of the low gain, I am going to wire up some adapters (or wait until @brencho returns mine) to test as a headphone amplifier.
5. Measurements on the way. Very curious how this amp measures in terms of distortion.

 

Most of the cost goes into heatsinking / chassis (material). A big electrolytic at the output isn't the end of the world. The smaller film bypass cap does help (but in all honesty, it only goes so far). The big cap is a tradeoff to allow a SE design with only three transistors in the signal path. Not the last word in resolution, slightly better clarity can be obtained, but there is some serious righteousness with the sound of this amp.

 

I am not sure if I can totally recommend the JLH69 as a headphone amp because the gain is too high. The volume knob is not even at the 9 o'clock position (using Gungnir Multibit as the source) for HD800s and HD650s. There is a faint buzz (it's faint enough to be buried if there is background noise like a fan running) on the left channel, but I think this has to do with the 120V ACmains wiring running up to the switch on the left side near the left channel board. This actually might be fixable. Just need smarter routing of the wires. The gain can probably be reduced too by increasing feedback. Knowledgeable users can probably tweak the amp to work with headphones. I know most regular uses won't want to mess with stuff like rerouting wires or soldering resistors, so this is why I can't make a general recommendation.



Compared to the Jotunheim, the JLH69 isn't quite as resolving, isn't as full in the bass, and has a slight veil (this veil is probably still less than that of the Valhalla 2). However the JLH69 has a more spacious and deeper stage, better microdynamics, and possesses none of the hard edge of the Jotunheim.

Other than the barely audible buzz and excess gain, the JLH69 actually worked well with both HD650K and HD800V (modded) headphones. Obviously the HD800V had a bit more hardness and glare at top with certain recordings, but this is about as good as it gets in balancing treble smoothness with crisp transients.

If I can get rid of the buzzing, I'd easily take the JLH69. Despite its failings in resolution and ultimate clarity, the music just speaks to me more. Other people may have different preferences. The amp does get super HOT though.

 

I'd say more like the Magni 2 Uber, more but smoother with even better rendering of textures, timbres, and significantly better in microdynamics.

Capacitor veil is kind of different from the MOSFET haze and warmth of the Asgard 2.

 

Check continuity with a multimeter. E / F are continuous. Both of those black EPCOS caps are paralleled and should be as considered larger one cap the sum of their values.

Points C / D are continuous. What I did was solder one end of the cap on E / F (also continuos), and screw the other end on either A or B (this is the one point I am not sure about). Either point A or B should be continuous with points C / D. If it's not A, then it should be B. The only reason I screwed down on the terminals is the cap I used was physically too large to bend the lead down to C / D.

 

On the A or B, one of them sound be ground / common. So should be continuous with the one on the other side or on the black speaker post. What you want to hit is a point continuous with the red speaker post and points E / F.