Hi, all. I enjoy this circuit too, it sounds really sweet. Due to loving it so much, then after several years diy life, I finally made it into PCB, to share it with some friends. In order to make it as an cute and sweet amp for my computer at home badroom or office purpose, it is biased to 3W for JLH1969 as BJT output stage and 15W as FET output stage.
It composed by 4 parts, power supplier board, Musical Fidelity A1 preamp board, and 2 switchable main power amp board by BJT or FET output stage as it similar but different.
Then finally my finished amp as following, only FET output stage board. But it is easy to switch to BJT board by a screwdriver, because all screw holes are exact at same positions.
Then here is the schematics for reference <--- click to open it.
It composed by 4 parts, power supplier board, Musical Fidelity A1 preamp board, and 2 switchable main power amp board by BJT or FET output stage as it similar but different.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Then finally my finished amp as following, only FET output stage board. But it is easy to switch to BJT board by a screwdriver, because all screw holes are exact at same positions.
An externally hosted image should be here but it was not working when we last tested it.
Then here is the schematics for reference <--- click to open it.
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Very professional job 🙂
I see you use an active volume control... interesting.
Do you find any subjective difference between the FET and BJT ?
It all looks very nicely put together... excellent.
I see you use an active volume control... interesting.
Do you find any subjective difference between the FET and BJT ?
It all looks very nicely put together... excellent.
good works!
seeing the cirsuit , some questions arise:
mu-fi a1 pre amp is prone to resistance noise , more simple and stable alternative considered?
tip41c is 65w max power dissipation , when temp arises it seems to reach near max
so voltage or current may need down regulated for safety margin. No problem in long term running? (and case to heatsjink thermal resistance of tip41c is not low)
cheers.
seeing the cirsuit , some questions arise:
mu-fi a1 pre amp is prone to resistance noise , more simple and stable alternative considered?
tip41c is 65w max power dissipation , when temp arises it seems to reach near max
so voltage or current may need down regulated for safety margin. No problem in long term running? (and case to heatsjink thermal resistance of tip41c is not low)
cheers.
Sure when you already got boards from Tea-Bag's GB. Someone did 2A positive side for a T-Amp already.
To Mooly: thank you. 🙂 yeah it is active volume control. Here I'd prefer to its function of buffer too. BJT version is more perfect in playing woman vocal. While tradiational BJT version sounds much more balance. And moreover, FET version is working at class AB situation, does not request a huge heat sink. It works fine in summer, if case is not sealed up. 
To shaan: thank you too. 🙂
To mindengine: thank you too. The preamp is use to be as an active volumn control but more important it has a buffer stage first. And for TIP41C in 3W design is supplied by voltage about DC14V totally which half voltage drop for each transistor is about DC7V only, it runs in safe area. But some friends intend to be higher power voltage or idle current, that's not a problem too, because the PCB has an alternative option to install TO-3P transistors such as 2sc5200, MJL21194 etc.
And yes it is runs long hours since first test PCBs in last September, which emulate PCBs hot tranfer printed, as following:
To shaan: thank you too. 🙂
To mindengine: thank you too. The preamp is use to be as an active volumn control but more important it has a buffer stage first. And for TIP41C in 3W design is supplied by voltage about DC14V totally which half voltage drop for each transistor is about DC7V only, it runs in safe area. But some friends intend to be higher power voltage or idle current, that's not a problem too, because the PCB has an alternative option to install TO-3P transistors such as 2sc5200, MJL21194 etc.
And yes it is runs long hours since first test PCBs in last September, which emulate PCBs hot tranfer printed, as following:
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
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Some may be interested in this:
http://www.diyaudio.com/forums/soli...stre-vs-parallel-jlh-class-9.html#post1988443
I should have posted it here in the first place!?
http://www.diyaudio.com/forums/soli...stre-vs-parallel-jlh-class-9.html#post1988443
I should have posted it here in the first place!?
hi jez. Nice to know you as a JLH lover in diyaudio. Maybe you posted it in the first place (earlier than i did). But please understand that my tests started from last year, as mentioned above, PCB design was finished in Jan of this year, latest PCBs were produced in July of this year.
And I intend to reduce its output power to 3W on 8R speakers, in order to fit my purpose for computer of home badroom or office. Not like yours 25W/8R nor 12W/4R.
But anyway I don't think it is the point that how early we make it. Maybe there are some people did it much earlier than you or me. Just all of us love this great circuit, and like is fantasic sound. Could we are possible shake hands and enjoy it together?
And I intend to reduce its output power to 3W on 8R speakers, in order to fit my purpose for computer of home badroom or office. Not like yours 25W/8R nor 12W/4R.
But anyway I don't think it is the point that how early we make it. Maybe there are some people did it much earlier than you or me. Just all of us love this great circuit, and like is fantasic sound. Could we are possible shake hands and enjoy it together?
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I think you have misunderstood me La Mer! I am not saying I wish I had beat you to it or anything like that.... merely that maybe I should have posted to this thread rather than the JLH V Hiraga thread.
I am sure many did it back in 1969 so we have both been beat there!
It's a superb design and sounds great. Congratulations on the PCB design.
I am sure many did it back in 1969 so we have both been beat there!
It's a superb design and sounds great. Congratulations on the PCB design.
Thank you, jez, for all. I don't mean it misunderstanding too 🙂
Only because it is a great design, so that we can join together to enjoy this great design. PCB is only because more easy to install 🙂
BTW: your machine is great also 🙂 congratulation too. Because my apartment is not very large, so for my own purpose, I try it to be a smaller one. 🙂))
Only because it is a great design, so that we can join together to enjoy this great design. PCB is only because more easy to install 🙂
BTW: your machine is great also 🙂 congratulation too. Because my apartment is not very large, so for my own purpose, I try it to be a smaller one. 🙂))
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La Mer,
Fantastic work !
I am working on my first JLH, mostly trying to understand the design on paper first and hope to build it this winter. If I can make something that is even 50% as good as your amplifier I will be very pleased with myself.
I am aiming for 6W - not that this is an important number by itself, but to add my support to your idea that we don't need to make it too loud for our homes.
I haven't heard a JLH before so I'm keen to 'join the club'.
Fantastic work !
I am working on my first JLH, mostly trying to understand the design on paper first and hope to build it this winter. If I can make something that is even 50% as good as your amplifier I will be very pleased with myself.
I am aiming for 6W - not that this is an important number by itself, but to add my support to your idea that we don't need to make it too loud for our homes.
I haven't heard a JLH before so I'm keen to 'join the club'.
Bibun,
Thank you. And welcome join to enjoy JLH, it is quite simple but great.
And yes, I did this 3W design after original 10W circuit, like as follows that's my latest 10W JLH machine be built in end of last year. Just consider in my home a room with an computer, only 9 sqaure meters, 3W sounds loud enough and sweet soft at the same time, especially while it is whistling.
Wish you have fun on it.
La Mer
Thank you. And welcome join to enjoy JLH, it is quite simple but great.
And yes, I did this 3W design after original 10W circuit, like as follows that's my latest 10W JLH machine be built in end of last year. Just consider in my home a room with an computer, only 9 sqaure meters, 3W sounds loud enough and sweet soft at the same time, especially while it is whistling.
Wish you have fun on it.
La Mer
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
First JLH in costruction with my free PCB. Sorry is only italian language.
Max67
jlh
Max67
jlh
An externally hosted image should be here but it was not working when we last tested it.
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Joined 2009
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LaMer, that looks superb, very nice.
Is that the bridge rectifier I see hanging of the big capacitor though ? - I wonder if it wouldn't benefit from some heatsinking by bolting it to the chasis ?
My progress has been very poor - haven't managed to start yet. I am also getting distracted by trying to understand some more things about my version of the JLH which is pushing me off in different directions. I am now considering abandoning my alternative JLH design and actually try the original design - I have a bunch of RCA 3055 output devices recovered from some old regulated power supply units. But this may have to wait a bit longer before I work on it.
Nice pcb's !
Max 67 - Wow, a great mix of British design and Italian style - I can not ask for more than that.
Is that the bridge rectifier I see hanging of the big capacitor though ? - I wonder if it wouldn't benefit from some heatsinking by bolting it to the chasis ?
My progress has been very poor - haven't managed to start yet. I am also getting distracted by trying to understand some more things about my version of the JLH which is pushing me off in different directions. I am now considering abandoning my alternative JLH design and actually try the original design - I have a bunch of RCA 3055 output devices recovered from some old regulated power supply units. But this may have to wait a bit longer before I work on it.
Nice pcb's !
Max 67 - Wow, a great mix of British design and Italian style - I can not ask for more than that.
my JLH1969 prototype.
work in progress the new one based on the original schematic and protoboard build .
the 2 black tubes are elko siemens 68000uf.
work in progress the new one based on the original schematic and protoboard build .
the 2 black tubes are elko siemens 68000uf.
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Hi, Bigun, sorry later reply.
Yes bridge rectifier is hanging of the big capacitor, because I'm lazzy on it and ran out of pcb board. 😀
Last photos are for the original JLH1969 design. It sounds very nice too. But at my room, 3W output power sounds enough for me.
Hello,
I build the updated version of JLH amp last week. I build only one channel for experimental reasons and i want to ask a little thing about driver transistors then i'll build the second one.
My speakers are 6 ohm rated. 10W output power will be adequate for me.
I'm using BC309C on input transistor, two BC560C's on output DC offset transistors, BC560C and BD140 on quiescent current control, two MJ15003's on output. I have an option for driver transistors as:
1-2N1711, measured hFe with multimeter=150
2-2SC3421, measured hFe with multimeter=180
3-BD139-16, measured hFe with multimeter=230
which one between them will be more suitable? At the schematic, 2SC3421's are shown as preferred ones but in design notes, it's written as highest gained transistor for driving low gain output transistors(like MJ15003's)should be used for minimal distortion.
And, for 10W output power at 6 ohm (i'm using capacitance multiplier for supply), a 150VA transformer will suffice?
Thank you
Onur
I build the updated version of JLH amp last week. I build only one channel for experimental reasons and i want to ask a little thing about driver transistors then i'll build the second one.
My speakers are 6 ohm rated. 10W output power will be adequate for me.
I'm using BC309C on input transistor, two BC560C's on output DC offset transistors, BC560C and BD140 on quiescent current control, two MJ15003's on output. I have an option for driver transistors as:
1-2N1711, measured hFe with multimeter=150
2-2SC3421, measured hFe with multimeter=180
3-BD139-16, measured hFe with multimeter=230
which one between them will be more suitable? At the schematic, 2SC3421's are shown as preferred ones but in design notes, it's written as highest gained transistor for driving low gain output transistors(like MJ15003's)should be used for minimal distortion.
And, for 10W output power at 6 ohm (i'm using capacitance multiplier for supply), a 150VA transformer will suffice?
Thank you
Onur
I am about to order populated pcb of JLH 1969 amp from one of our sponsors, Nutsaudio.com. Does anyone have any experience with this?
Doug
Doug
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Joined 2009
Paid Member
hfe = current gain. I don't even like the idea that a transistor has current gain, in my view it should be thought of as an input impedance because I don't subscribe to the idea that a transistor is a current device - in my view it is a voltage controlled device. A higher hfe implies a higher input impedance and this is mostly a good thing so I would agree with selecting the higher hfe part.
Hiraga's advice was to select devices and operating points so that the dc operating current occurred at the peak of the current gain so that the drop in hfe with the signal swing would be symmetrical. To determine this you need to look at the spec. sheet. For the BD139 I believe you need 10'smA of dc current to put this device into that kind of optimal operating point.
My own JLH is stuck - my heatsinks are inadequate so I have to sort this out before I can progress.
Similar to my simplistic way of interpreting what I have garnered.
I see a BJT as a voltage to current device.
delta Vbe gives delta Ic.