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JLH 10 Watt class A amplifier
JLH 10 Watt class A amplifier
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Old 22nd April 2012, 08:58 PM   #2431
mikelm is offline mikelm  England
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Here it is again - this time each value of R doubling and shown only over the critical frequencies
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Last edited by mikelm; 22nd April 2012 at 09:11 PM.
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Old 23rd April 2012, 09:01 AM   #2432
AndrewT is offline AndrewT  Scotland
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I can see all 7 plots on both sides of the critical freq.
Thanks.
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regards Andrew T.
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Old 27th April 2012, 07:59 AM   #2433
mikelm is offline mikelm  England
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Quote:
Originally Posted by Lazy Cat View Post
Regarding simplicity measures, the TSSA basic is even simpler design and according to Sonnya measurements, and I believe they are correct, its results are even better than JLH 10 class A amplifier.
Just looked again at what I understand are real world fourier results for Pavel's JLH & Sonnys's TSSA and unless I am missing something I would say the JLH figures are more impressive - lower noise floor & total absence of higher order harmonics.

I'm curious to know why you thought the opposite - did I miss something ?

mike
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Old 27th April 2012, 08:09 AM   #2434
PMA is offline PMA  Europe
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I would like to add that JLH distortion results strongly depend on supply voltage and idle current, for the same load. Please note that most of my measurements are for single supply voltage of only +27V and idle current of "only" 1A. The dynamic range is also affected by a measurement method. One can clearly see effect of FFT resolution in the two attached images. One with resistor divider in front of the soundcard and the 2nd without the divider. Please note that lines around 15kHz and 19kHz are TV line freq. and FM radio pilot freq. induced to the high-sensitive setup. Frequencies at 25kHz and higher result from digital soundcard circuitry. Load and Vpp can be read from image file names.

I am very sorry I cannot follow the discussion now, as i am very busy with another project field.

Regards,
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Old 27th April 2012, 08:32 AM   #2435
Lazy Cat is offline Lazy Cat  Slovenia
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Quote:
Originally Posted by mikelm View Post
Just looked again at what I understand are real world fourier results for Pavel's JLH & Sonnys's TSSA and unless I am missing something I would say the JLH figures are more impressive - lower noise floor & total absence of higher order harmonics.

I'm curious to know why you thought the opposite - did I miss something ?

mike
From pics it is obvious that measuring "environment" of Sonnya's equipment has inherent noise floor at -100 dB, or it can be the noise floor of uncompensated, no low pass filter treated amp. That's really not so important, cause it's to low to affect real life performance. Also it can be mostly sorted out with good power supply etc.

What I was mainly concentrated were spectral components, ratio of higher order presence and their suppression. Measurement conditions were different so not so reliable comparison after all.

TSSA was without any reference point in the circuit (sch from the post#1 in TSSA thread), two simple CCSs added would rocketed performance surely.

Mike please don't misunderstand me, I'm very glad that we explore different amps and exchange our experiences, that's the most important thing.

P.S. Our DIY community here is so precious, cooperative, that I don't regret energy and any second spent on the forum, and there were quite amount of them spent here.

Last edited by Lazy Cat; 27th April 2012 at 08:40 AM.
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Old 27th April 2012, 12:42 PM   #2436
AudioLapDance is offline AudioLapDance  Canada
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Hey PMA,

Given the importance of the output coupling caps, I was just about to ask what you are using.

You mentioned the bypass was Roederstein MKT1813 3.3uF, I assume you mean the 63V part.

MKT1813533064 Vishay/Roederstein DC Link Film Capacitors

For my friendly Southern neighbours, look it up on the US mouser site. (Yes, that's how we spell "neighbours")

PMA, what electrolytic are you using?

I realize you're taking some time off, but I hope you stop by ...

(Maybe I'll check the pics at the beginning of the thread and see if I can read it)

Cheers,
Jeff
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Old 27th April 2012, 12:48 PM   #2437
PMA is offline PMA  Europe
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Nippon Chemi-Con 6800uF/50V SMH type.

The Roederstein is 250V type.
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Old 28th April 2012, 12:06 PM   #2438
mikelm is offline mikelm  England
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Quote:
Originally Posted by PMA View Post
Please note that lines around 15kHz and 19kHz are TV line freq. and FM radio pilot freq. induced to the high-sensitive setup. Frequencies at 25kHz and higher result from digital soundcard circuitry.
I always do fourier analysis in spice up to 20khz and I always have a high reading at 19khz.

Strange to see it there exactly the same in your real world analysis - so it may be something to do with using computers for analysis ? ? ?

I do not believe it is real

mike
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Old 29th April 2012, 05:53 PM   #2439
effebi is offline effebi  Italy
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Default PCB needed

I am ready now to start a new project.
I have long time dreamed to make a JLH, possibly the single power version, with TO3s.
I have most of thye components, so, since I do not intend to make changes to the classic circuit, I am looking for a ready - made PCB. Do you know a good source ?
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Old 10th May 2012, 08:16 AM   #2440
jacobthellamer is offline jacobthellamer  New Zealand
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My JLH is all cased up and running well



JLH 10 Watt class A amplifier-imgp8220-jpg
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