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DLH Amplifier: The trilogy with PLH and JLH amps
DLH Amplifier: The trilogy with PLH and JLH amps
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Old 26th August 2017, 02:40 AM   #1
diegomj1973 is offline diegomj1973  Argentina
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This very simple design has all the ingredients to satisfy even the most demanding DIYers. The output power in pure class A operation is 15.52 W at 2 ohms and 1 KHz, or 7.76 W at 4 ohms and 1 KHz, or 3.88 W at 8 ohms and 1 KHz. THD is only 0.025 % at 15.52 W and 1 KHz (2 ohms). THD is only 0.0024 % at 7.76 W and 1 KHz (4 ohms). THD is only 0.00091 % at 3.88 W and 1 KHz (8 ohms). Voltage gain = 8,9 dB.

Only two stages. Four transistors. Very few components. Its performance is surprisingly good, despite its total simplicity.

High bandwidth. Ultra low distortion. Input in single ended configuration. Output in single ended or push pull configuration, entirely adjustable by the position of a trimpot. PSRR: 61 dB across the entire audio bandwidth.

I want to hear comments from those who intend to build this simple amplifier.

regards

Here are the first dirty tests. The microphone does not reveal all its high quality. The tests were between 1A and 1.3A of bias current, levels at which the amplifier should give lower quality than stipulated. The loudspeaker impedance tests = 4 ohms:

Amplificador HDC 20W (Clase A) Parte 4 - YouTube
Amplificador HDC 20W (Clase A) Parte 5 - YouTube
Amplificador HDC 20W (Clase A) Parte 3 - YouTube
Amplificador HDC 20W (Clase A) Parte 2 - YouTube
Amplificador HDC 20W (Clase A) - YouTube
Attached Images
File Type: jpg DLH Amplifier.jpg (119.7 KB, 4140 views)
File Type: png Fourier Analysis at 1W 8 ohms.png (29.5 KB, 4066 views)
File Type: jpg Transient Analysis.jpg (275.7 KB, 4148 views)
File Type: jpg THD vs Frecuency.jpg (135.6 KB, 3996 views)
File Type: jpg THD vs Output Power.jpg (142.0 KB, 3952 views)
File Type: jpg PSRR vs Frecuency.jpg (248.4 KB, 3810 views)
File Type: jpg IMD at 2 ohms.jpg (462.5 KB, 3798 views)
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Old 27th August 2017, 04:24 AM   #2
Jonathan Bright is offline Jonathan Bright  Australia
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Thank you. I have a 1969 JLH. Interested in Mosfet alternatives.
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Old 27th August 2017, 10:13 AM   #3
Bonsai is offline Bonsai  Europe
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Wow - very nice simple circuit Diego with great performance!

What's the DC stability like - both Iq and output voltage?
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Old 27th August 2017, 12:34 PM   #4
Ketje is offline Ketje  Belgium
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Looks interresting but 60W in for only 16W out (said the tube lover )
You could try this, just an idea
The diodes are for zero-out temp.compensation.
Mona
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File Type: jpg dLHAmp.jpg (52.3 KB, 802 views)
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Old 27th August 2017, 01:25 PM   #5
diegomj1973 is offline diegomj1973  Argentina
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Many thanks Jonathan Bright, Bonsai and Ketje.

In relation to compensation, I had thought something like this:
Posible esquema para la compensación del offset de salida con la temperatura.png

I have not tried this same subcircuit, although in simulations it shows perfect compensation with temperature.

The circuit of the first post is a basic circuit. As it is shown in the first post has been tested in the videos. Everything can be improved, although as well as it is performs in impressive form.

Regards

Last edited by diegomj1973; 27th August 2017 at 01:45 PM.
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Old 27th August 2017, 02:00 PM   #6
diegomj1973 is offline diegomj1973  Argentina
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One possibility to attempt to partially compensate for a variation of the output offset with the variation of the supply voltage could be as follows:
Posible esquema de autopolarización.png

While that resistance could increase Johnson's noise in a sensitive part of the circuit, it would also increase the input impedance of the circuit by a ratio of 6 to 8 times the current values.

This resistance could be between 150 K and 180 K approx.

This has also not been tested, although in simulations reduces variations by a factor of around 2, relative to the first circuit.

Regards

Last edited by diegomj1973; 27th August 2017 at 02:21 PM.
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Old 27th August 2017, 05:50 PM   #7
diegomj1973 is offline diegomj1973  Argentina
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This version has not been tested, yet.

Regards
Attached Images
File Type: jpg DC Output Offset vs Temperature.jpg (547.2 KB, 1545 views)
File Type: jpg DLH Amplifier (version 2).jpg (125.5 KB, 1490 views)
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Old 27th August 2017, 06:34 PM   #8
diegomj1973 is offline diegomj1973  Argentina
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This version has not been tested, yet.

Regards
Attached Images
File Type: jpg DC Output Offset vs Temperature (version 3).jpg (503.4 KB, 1476 views)
File Type: jpg DLH Amplifier (version 3).jpg (154.4 KB, 1467 views)
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Old 27th August 2017, 07:58 PM   #9
Ketje is offline Ketje  Belgium
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Last schematic makes no sense.Redraw it for a more usual look.
Mona
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Old 27th August 2017, 09:17 PM   #10
diegomj1973 is offline diegomj1973  Argentina
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Quote:
Originally Posted by Ketje View Post
Last schematic makes no sense.Redraw it for a more usual look.
Mona
Excuse me, but your subcircuit is not like the one I posted . Check it out, since it's not like mine . In your schematic you are connecting - V with ground, among other things ---> Booooommmmm !!! .

Anyway, this subcircuit could be arranged visually so that everyone can understand it better .

Regards

Last edited by diegomj1973; 27th August 2017 at 09:39 PM.
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