Thought I might as well post a picture of the power supply (I probably posted it earlier too). Not living-room friendly. Transformer primaries are in series, secondaries in parallel after rectification with a small amount of resistance to balance the load a bit.
Caps are 68000 uF each.
Caps are 68000 uF each.
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Paulb,
Thanks you for the info. Wow, the caps for your PSU are quite huge. I was planning to use 6 x 12000 uf per channel only, looks like I better get bigger cans.
Regards
Hi, John
How are you? How is your amp runnng? Care to comment on the sound? I am still collecting parts for mine. Take care.
Regards
Hey Lo_Tse,
I am putting my Hi Power JLH for ESL to good use...just finished my ESL's last night - need to build the Bass Panels, but I really like the amp / speaker combo on 250hz and higher....
http://www.diyaudio.com/forums/planars-exotics/203993-martin-logan-cls-power-supply-4.html#post2889499
I am putting my Hi Power JLH for ESL to good use...just finished my ESL's last night - need to build the Bass Panels, but I really like the amp / speaker combo on 250hz and higher....
http://www.diyaudio.com/forums/planars-exotics/203993-martin-logan-cls-power-supply-4.html#post2889499
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Hi, John,
The ESL panels look really sharp. Did you actually fabricate them or you assembled them from purchased parts? Was that a pair Magnepan behind the ESL panels? My current main speakers are a pair Eminent Tech planar magnetic panels too. Hey, the JLH amp fit right in with the rest of your gear!!
Regards
The ESL panels look really sharp. Did you actually fabricate them or you assembled them from purchased parts? Was that a pair Magnepan behind the ESL panels? My current main speakers are a pair Eminent Tech planar magnetic panels too. Hey, the JLH amp fit right in with the rest of your gear!!
Regards
Hey Lo (??),
Yes, the speakers in back are my Magnepan Tympani IVa. Ones in front are the ESLs - Martin Logan CLS Panels (I bought off a member here), with new home built Bias/stepup transformer...
I have to say the ESLs sound very nice with the High Power JLH from 250hz and up. Vocal, guitar, percussion clarity is amazing. I am using the Tympani Bass Panels with the ML CLS and they mesh perfectly...even the wife was amazed (and that never, ever happens).
Your ETs should sound nice. If, per chance, your not happy, try the JLH on your ET's from 250hz and up, and make up the low end with another speaker/amp, and you should be more happy...
Yes, the speakers in back are my Magnepan Tympani IVa. Ones in front are the ESLs - Martin Logan CLS Panels (I bought off a member here), with new home built Bias/stepup transformer...
I have to say the ESLs sound very nice with the High Power JLH from 250hz and up. Vocal, guitar, percussion clarity is amazing. I am using the Tympani Bass Panels with the ML CLS and they mesh perfectly...even the wife was amazed (and that never, ever happens).
Your ETs should sound nice. If, per chance, your not happy, try the JLH on your ET's from 250hz and up, and make up the low end with another speaker/amp, and you should be more happy...
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Initial impression- The sound is not as good as the BJT version.
Recently I built another JLH with lateral FETs. This time with single supply, capacitor coupled output and bootstrap current source. Thus ending up with a truly simpler circuit than before with excellent results.
1. Silent turn-on and turn-off.
2. Iq rises quickly to preset value and decreases about 100mA after warm-up(at 1.7A).
3. Mild hum at speaker with Iq less than 800mA, no hum with Iq more than 1A. (!?)
4. No noise or any audible artifacts.
5. Drives my 4ohm sub with ease, bass is superb.(with 100uF feedback cap)
6. Sounds open and clean, but different than my BJT JLH. Vocals and highs are clean and brighter even at high volume, unlike a BJT JLH. Sounds less "warm" than the original JLH and more "crispy", like a symmetrical amplifier, but in no way boring or tiring, no fatigue after 4-5 hours of listening. Also, response to volume knob turning seems more accurate.
7. Love its music, a new JLH with a new sonic signature!
P.S.: R8 seems unnecessary but adding it resulted in increased linearity as the output approaches positive rail and better positive clipping. I noticed considerable reduction in even harmonics after adding it to the circuit. Calculated distortion is 0.2% without R8 and 0.08% with R8 at 12VPP into 8.2ohm load. Of course R4 needs to be doubled when R8 is removed, in order to maintain the same Iq.
P.P.S: I'm discovering a new JLH almost every month! Let's see what's next.
P.P.P.S: Circuit is powered from a 160VA transformer with simple 35A bridge followed by 15000uF+1ohm+15000uF in pi config.
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Member
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Sit on board and pass some current.
Nothin' else for me. You are The expert, I ask you the same.what does R8 do?
Oh come on don't believe simulations that much. R8 just lowers THD a little, says my ears. Thats tested. Everything else is just numbers.
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With 1.5A Iq, THD is lowest when R3=R8/2. Especially the even order harmonics. This does NOT happen when I remove R8.
This even harmonic cancellation mechanism is unknown to me. I wonder If some kind soul will teach me. I played with the values of these resistors and observed the results, built the circuit, played some music and it sounded like an amp with dominant odd harmonics. To me it sounds very good but also very different from the '69 or '96 JLH.
This even harmonic cancellation mechanism is unknown to me. I wonder If some kind soul will teach me. I played with the values of these resistors and observed the results, built the circuit, played some music and it sounded like an amp with dominant odd harmonics. To me it sounds very good but also very different from the '69 or '96 JLH.
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When R8 is a shunt regulator that enforces the rule of equal and
opposite output currents, R8 is always whatever it needs to be.
R3 is still essential to keep Q4 turned on somewhat at all times.
In class A configuration, the purpose of these resistors is not to
turn off Q2 and Q3. OK maybe with a MOSFET for Q3 it is... BJT
for Q3 would not care, so with BJT it is only for Q4's happiness.
Even with a shunt, sometimes you want real resistor R8 in parallel.
A shunt reg for R8 could turn off in extreme case of hard clipping.
And then, what is to turn off the top transistor??? So if you are
not using any sort of clip management, you probably need an R8
and Zener if MOSFET too... 40V+40V pullup hazard on that gate.
opposite output currents, R8 is always whatever it needs to be.
R3 is still essential to keep Q4 turned on somewhat at all times.
In class A configuration, the purpose of these resistors is not to
turn off Q2 and Q3. OK maybe with a MOSFET for Q3 it is... BJT
for Q3 would not care, so with BJT it is only for Q4's happiness.
Even with a shunt, sometimes you want real resistor R8 in parallel.
A shunt reg for R8 could turn off in extreme case of hard clipping.
And then, what is to turn off the top transistor??? So if you are
not using any sort of clip management, you probably need an R8
and Zener if MOSFET too... 40V+40V pullup hazard on that gate.
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