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JLH 10 Watt class A amplifier
JLH 10 Watt class A amplifier
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Old 13th February 2018, 02:07 PM   #4451
marconi118 is offline marconi118  Germany
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can you post a link to elcheapo I can't fin it on Rod Elliott site
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Old 13th February 2018, 02:23 PM   #4452
huggygood is offline huggygood  France
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Old 13th February 2018, 04:44 PM   #4453
cumbb is offline cumbb
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Location: different/relative
;-)
Use in-different parts.
Use as few as possible parts - count pcb, solder joint, wire ... as part.
... to get in-different: clean, noiseless, homogenious sound.

Start with your speakers - lots lots lots to do. I know;-)
... not with any schemas;-)
Much more successful;-!
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Old 14th February 2018, 01:03 AM   #4454
still4given is offline still4given  United States
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JLH 10 Watt class A amplifier
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Originally Posted by marconi118 View Post
can you post a link to elcheapo I can't fin it on Rod Elliott site
Here you go.

Simple 40 Watt Power Amplifier
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Old 14th February 2018, 08:38 AM   #4455
nigel pearson is offline nigel pearson  United Kingdom
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El Cheapo

Simple 40 Watt Power Amplifier

The output darlingtons could be lateral MOS FET's like BUZ900/905. The bias could be class A. I doubt it really needs 68pf to Q2. Q1 is a buffer, it could be an op amp or preamp.
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Old 15th February 2018, 02:05 PM   #4456
Dudster is offline Dudster  Norway
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Default eBay JLH 1969 with 2SA1216...

Assembeld PNP A1216 JLH1969 single-ended class A power amp board R33 | eBay

Does anyone have experience or opinions about this version?
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Old 15th February 2018, 03:53 PM   #4457
cumbb is offline cumbb
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Location: different/relative
;-)
You should buy and try and tell;-)
And show the underside;-)
Tell about replacing of parts too. About solder joints. About removing of connectors. Of luster terminals.
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Old 15th February 2018, 04:01 PM   #4458
prasi is offline prasi  India
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JLH 10 Watt class A amplifier
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Originally Posted by Dudster View Post
Assembeld PNP A1216 JLH1969 single-ended class A power amp board R33 | eBay

Does anyone have experience or opinions about this version?
Dont know, but see if same deal is available on aliexpress. will be much cheaper.
Another option is to look for PCBs on ali or ebay (much cheaper)
and then order parts from a reliable source (mouser, farnell, rscomponents, digikey, etc) Measure the component package once you get hold of PCB and then order components.

regards
Prasi
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Old 15th February 2018, 05:42 PM   #4459
stevec67 is offline stevec67  United Kingdom
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Quote:
Originally Posted by Dudster View Post
Assembeld PNP A1216 JLH1969 single-ended class A power amp board R33 | eBay

Does anyone have experience or opinions about this version?
I have never seen that version, it looks quite a lot different from the NPN version that I'm building, I wanted to build the original first and then consider developments. I was advised to avoid the kits and readymades because of the risk of fake parts, so I bought some plain PCBs that look lovely. I'm assembling it now, it needs some skill to get some bits right. In particular I am unsure of how to arrange the 2N3055s, if the case is collector I will have to isolate them from the heat sink and then make up flying leads to the PCB. Knowing where is a challenge. Good project though.
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Old 15th February 2018, 11:33 PM   #4460
Ian Finch is offline Ian Finch  Australia
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Originally Posted by Dudster View Post
....Does anyone have experience or opinions about this version?
The kit has been around for more than a year in the PNP version, AFAIK. It seems a good idea to have the output transistors spread well apart and the PCBs mounted directly on a flat faced heatsink. Presumably, 2 heatsinks of around 0.5°C/watt rating will be used for sufficient heat dissipation for a stereo amp. The downside is that the PCB, components and connectors etc. will likely get baked on the heatsink and even if caps are rated 105C, constant heat is not good for DIY assemblies and the typical parts grades/brands we use.

I can't rate just a PCB assembly, since much of the performance is about the power supply and filtering. However, I have compared PNP and NPN versions of some other boards, using the same brand and type of regulated power supplies and a simple, unfiltered supply too. I can only say that when TO3 transistors with parts like 2N3906 with BD139-16 or their opposite genders) are used, the NPN versions seem to be a little better sounding to me. Any super-cheap kit that includes premium grade LAPT Sanken parts has to be suspect, even if they're not actually fake though.

I thought the kits similar to that shown, weren't particularly good sounding but I'm not sure whether that was due to the power transistors being fakes or just off-spec but genuine and still too good to sound right, if you understand me.

I've built and listened to the NPN version of this kit (it sure was cheap!) I'm not convinced there is any benefit from using high frequency, low distortion parts intended for class B, in this class A design though, where the extra distortion produced by the old power devices is actually what helps to make the sound quality what it is

It seems counter-productive to me, but if anyone seriously wanted to use premium parts because they assume the amplifier will sound better, MJ, MJL or NJW21194 and their PNP versions, bought from reputable agencies are a more reliable way to go.
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Last edited by Ian Finch; 15th February 2018 at 11:58 PM.
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