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Chinese JL Hood 1969 Class A amplifier off Aliexpress

maty

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#21
Tell us what DIY speakers are to take a look at the impedance curves. The usual Class A prefer speakers with a minimum impedance > 6 Ohms as well as high sensitivity.

One of the keys of the class A is usually the harmonic profile -> euphonic sound. The problem with higher harmonic levels is with complex music like electronic or orchestral -> too much harmonics: cloudy sound.

You should read:

https://www.diyaudio.com/forums/solid-state/345345-akitika-kits.html

-> https://www.diyaudio.com/forums/solid-state/345345-akitika-kits-post5978478.html

-> https://www.diyaudio.com/forums/solid-state/345345-akitika-kits-3.html

BTW, how much money do you want to spend?
 
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#22
You mean THIS one ? Look no further.
Yes, this is the Nelson Pass Amp I was interested in. Do you think, this is superior to the Hood 1969 clone
LP Spirit T-01 for 134€?

Some Posts above there was a note that the Hood 1969 sounded slow and very laid back, maybe a bit tired?
Can you confirm that, Lorenzo?

By the way, I'm also using the FX Audio Tube 01 preamp (which I very like) + USB NON OS DAC.
 

solderdude

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#23
One of the keys of class-A is usually the absence of the horrible crossover distortion.
The other key is the large amount of dissipated heat in order to obtain a relatively small amount of speaker power.
The harmonic profile is not related to the output class, this has more to do with the used gain stage and feedback.

Both the ACA and JLH are not prime examples of class-A amps, they are prime examples of low gain and low feedback amps with a low part count that sound transparent enough at low output powers.
 

solderdude

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#25
Yes, this is the Nelson Pass Amp I was interested in. Do you think, this is superior to the Hood 1969 clone
LP Spirit T-01 for 134€?

Possibly the JLH measures a bit better, send it to Amir for scrutiny.
The ACA may be lower noise ?

Possibly about similar performance.
 
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maty

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#26
I was very interested in the new ALPHA 20 class A poweramp but my modded KEF Q100 with true 85 dB and 3.9 Ohms minimum are not negotiable (I LOVE them). And in summer they it would be like having a small stove on, something not very convenient with the usual heat on the Mediterranean coast (and more when it joins the humidity).

https://www.diyaudio.com/forums/solid-state/318102-aksa-lender-mos-hybrid-aleph-alpha-amplifier.html

Weeks ago, Hugh Dean (AKSA) with xrk971 and others are designing a variant with much greater efficiency, 43%, a very good value in class A! Maybe less heat but much more watts.

https://www.diyaudio.com/forums/solid-state/344540-alpha-nirvana-39w-8ohm-class-amp.html
 
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#27
Do you think there are better sounding amps with higher Output volume in the pricerange below 200€?

As I told, for me the sensitivity of my Speakers is o.k. for a low Output amp.
That shouldn't be the Problem.
 
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#28
Without entering the world of Chinese clones, just remind you that these class A amplifiers provide few watts, so they need high sensitive speakers.

https://www.doctorproaudio.com/content.php?2273-calculators-proaudio-sound-dmx&langid=1#calc_spl
My speakers :
Puissance admissible : 225 W RMS / 450 W max
Réponse en fréquence : 18Hz à 44 000 Hz
Sensibilité : 93 dB /1w/1m
Impédance nominale : 4-8 ohms
https://www.son-video.com/article/enceintes-colonne/magnat/monitor-supreme-2002-noir
 

maty

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#29
Yes. And chinese too but class AB and harmonics below -90 dB. About € 220 + shipping.
 
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#30
Could you Point me to the class AB for € 220 + shipping ?

By the way: A ready built and finished amp would be much more welcome than a DIY one
 

maty

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#31
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maty

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#33
Just now, a redesign of the ALPHA Nirvana for 20W//8R. Less heat than ALPHA 20 (19 watts at 8 Ohms).

https://www.diyaudio.com/forums/solid-state/344540-alpha-nirvana-39w-8ohm-class-amp-post5980699.html

[ This amp uses 20V rails, and performance is not as good as the 27V rails and about half the power. But it's essentially the same amplifier with very similar harmonic profile.

Interestingly at 20KHz and 12.5W//8R the H2 is at -45dB, which is almost identical to a tube like 6SL7 operating at B+ of 340V and 1.6mA plate current.

It clips at just under 21W, and quiescent is 1.32A. Front end is slightly changed; R4 could be a 2k pot to set offset. Quiescent is set by the two 0.27R resistors in the sources of the outputs, which each dissipate an easy 25.5W. This output stage is ideal for passive cooling, and total power for a stereo is 105W. With >94dB/metre/watt speakers this would be a killer amp. Max loop gain is 87dB at 510Hz. ]
 

maty

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#35
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#36
Yes, this is the Nelson Pass Amp I was interested in. Do you think, this is superior to the Hood 1969 clone
LP Spirit T-01 for 134€?

Some Posts above there was a note that the Hood 1969 sounded slow and very laid back, maybe a bit tired?
Can you confirm that, Lorenzo?

By the way, I'm also using the FX Audio Tube 01 preamp (which I very like) + USB NON OS DAC.
As for me not slow or not laid back , I would say sharp sound all along the spectrum whatever is the style of music .
Really present sound , never tired after hours and hours of listening , if you meant this by " tired".
Excellent scene/stage sound depending of course of quality sound of the recording.
I don't need to used a lot of power from the amp may be because of the DAC output :
Output level: 2 Vrms (RCA), 4 Vrms (XLR) (I use XLR connecters)
THD + N: 0.0003%
Dynamic range: 120 dB
SNR: 116 dB
amirm review https://www.audiosciencereview.com/forum/index.php?threads/smsl-su-8-version-2-balanced-dac.5433/
May be as well because of high response of my speakers, 93 dB/ watt/meter.
 

DownUnderGazza

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#37
I must admit that for a cheap albeit lower power amp I’ve been intrigued by the JLH1969 amp designs and variants on Aliexpress. I have several high efficiency loudspeaker designs with benign impedance curves that would go well with something ’cute’...
Would love to see how such amps stack up on the test bench
 

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