JLH 10 Watt class A amplifier

[grunf]

this is with extra capacitors

 

[cumbb]

My plan is to make another pair of regulators so that I can separate the power for both channels. I think that will be the final step for this amplifier and I think then I might experience sound enlightenment.

Channel-separate-psus? Do not;-) It is a mistake of the inexperienced;-)-;

 

[bogdan_borko]

Channel-separate-psus? Do not;-) It is a mistake of the inexperienced;-)-;

And why is that a mistake??

 

[grunf]

I replaced NE5534 with AD825, there is a difference on the oscilloscope. The AD825 cleared the audio image a bit more. I think whether to replace them with the AD817 because I had the best results with it in Jung's regulators. There is an audible difference between the AD825 and AD817 in W. Jung's shunt regulator.

 

[cumbb]

And why is that a mistake??

;-?

 

[cumbb]

AD825 or AD817 - I would just try ... to get the best audio-performance;-)

I would replace all WIMAs. Would use the big caps only.
Coupling caps too. Any older electrolytics: do sound very very well. The WIMA MKP screeched and ripped and warped only. The MKS do sound gray and grainy.

 

[grunf]

AD825 or AD817 - I would just try ... to get the best audio-performance;-)

I would replace all WIMAs. Would use the big caps only.
Coupling caps too. Any older electrolytics: do sound very very well. The WIMA MKP screeched and ripped and warped only. The MKS do sound gray and grainy.

The WIMA MKP10 is quite OK for the price / quality ratio, as far as audio signals are concerned, I have never used MKS for an audio signal, they are for decoupling.

I'm not a fan of old capacitors, especially electrolytes.

 

[vizion]

Hi Guys,

I'm planning to build a 3-watt amplifier. Which is better ? A 3w Zen or 3w JLH ?

Thanks.

 

[cumbb]

... for an audio signal, they are for decoupling.

Everything within and outside the box "amp" is "audio signal"-)

A 3w Zen or 3w JLH

I would prefer the Zen.
Or would slim the JLH: No bootstrap, no Tr4 (see below: schemata)
Both with output-cap, no "complementary-psu" (+ and -)-!

... and no WIMAs;-)

 

[grunf]

A few days ago I put the CRCRC filter back in power supply before the regulators, I lost another 2V on it and 3V on the regulator so now I have +/- 19V to power the JLH69.
The JLH69 sounds better again, so this combination definitely stays in the amp.

 

[Cerniu]

A few days ago I put the CRCRC filter back in power supply before the regulators, I lost another 2V on it and 3V on the regulator so now I have +/- 19V to power the JLH69.
The JLH69 sounds better again, so this combination definitely stays in the amp.

I see you have output transistors on separate heatsinks. Are they connected in some way that is not visible in the photo, or is it not a problem if they are on separate unconnected heatsinks?

 

[grunf]

I see you have output transistors on separate heatsinks. Are they connected in some way that is not visible in the photo, or is it not a problem if they are on separate unconnected heatsinks?

It doesn't matter because both transistors have the same dissipation, so they heat equally.

 

[Mooly]

Duffo adele, your post has not been approved as you have been repeatedly told to post in English.

From the rules:

Not allowed

6: Posting in a language other than English without a translation.

 

[Duffo adele]

hello to all I am french and the translations being very bad, my knowledge in very limited electronics I do not understand all.Est what one of you could give me the schema leads jlh2003 with the list of components and the rule of the current of rest for a power supply of + - 30 vd advance a big thank you to you

 

[Duffo adele]

Hello to all i am french the traductions being very bab, but knowledge in very limited electronics i have a lot of trouble understanding you. Is that one of toi cloud give me the définitive schema of jlh 2003 with the list of the components and setting the quiescent current for a + -30v Feed in advance a big thank you to you

 

[prasi]

Hello Adele,
Have a read at the site here...
The Class-A Amplifier Site

Also I have posted PCB design for 2 pair output device 2003 version.
Please see here...

JLH 10 Watt class A amplifier

 

[Duffo adele]

Français
Anglais


Hello message to huggygoud I already explained on the forum that I don't understand anything about translations.is what we could match by email or phone. I want to assemble a jlh2003 and I have a great need for advice. But in good French. Thank you
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[nigelwright7557]

Thanks every one... I know the 2n3055 are old and considered not suiteble for quality audio.. I also read that in D.Self's book.. so I would like to switch to the MJ15003's.. I just need to find them first

greetings,
Thijs

I use the MJ15003/4 in an update of the 1980's Maplin disco amplifier.
They work very well.
I get mine from CPC, Farnell and RS Components with no problems.

 

[Rallyfinnen]

Hello!

Looking for advice/suggestions on JLH projects here.. I bought a pair of the chinese JLH kits (white PCB 1pc JLH 1969 Class A Verstarker Board Hifi hochwertiger PCB mot/2n3055 Do it yourself Kits | eBay)
and a pair of 'JLH2003' boards with dual supply and double outputs 2 PCs Hood jlh2003 Class A Single-Ended Power Amplifier PCB 2 Kanal 22w+22w | eBay


The white boards I have been thinking of modifying to 'sublimed' ( sublimed JLH1969 )
Or, should I just keep it as is, or maybe replace just outputs?

The dual supply/dual output boards need populating.. any recommendations on what good and easy to find transistors I should use? Possible improvements?

 

[Rallyfinnen]

I see now that the dual supply version is the same as the 'Higher power circuit' here: The Class-A Amplifier Site - JLH Class-A Update


I found the following transistors locally:

Q1, Q2 MJ15003
Q3 BD139-16
Q4 BC560c
Q5 BC560c
Q6 BC560c
Q7 BC560c
Q8 BD140-16

Is this a good substitution, or are there better alternatives? The 2sa/sc (toshiba?) are not available.