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Perhaps the point is, a bog standard amp if the right bog standard amp, can indeed sound wonderful. Isn’t that also the point of the JLH too, a simple topology with unremarkable parts produces a great deal of satisfaction.
At the time, the Leak Point One Stereo 20 set a new standard for low distortion and sales took off quickly.
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As far back as 1937, the "ultralinear" design concept was patented by Alan Blumlein. Engineer/designers saw it as a big step forward for high fidelity sound but it was slow in reaching consumers. Music lovers seemed think it was an abomination, perhaps in the same way "blameless" solid state design principles are scorned by today's solid-state audiophiles.
In the case of the JLH amplifier, it is the relatively high level of 2nd harmonic distortion and absence of crossover distortion that makes it interesting and satisfying to many audiophiles and those who lean a little that way.
So, it's a "sweet sounding" amp. Being also simple and cheap to build is quite a bonus and that makes it irresistible as an intro to DIY and enjoying your music to heights we may never have even thought possible - all for a handful of cheap parts, a small case and transformer, power lead and connectors. How do you beat that?
In the case of the JLH amplifier, it is the relatively high level of 2nd harmonic distortion and absence of crossover distortion that makes it interesting and satisfying to many audiophiles and those who lean a little that way.
So, it's a "sweet sounding" amp. Being also simple and cheap to build is quite a bonus and that makes it irresistible as an intro to DIY and enjoying your music to heights we may never have even thought possible - all for a handful of cheap parts, a small case and transformer, power lead and connectors. How do you beat that?
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Lots of good info in this post, thanks.
I actually find the solution off too much bass. It was the preamplifier. I'm using a different one and I'm much happier with the sound now.
Stil, is very interesting to know where to fine tune the JLH. Thanks again.
Manel
Hello all
I have posted a pic of this before but didn't make any comment I think it's important that people don't waste their money and throw a very good (but full DIY) project in the bin, if you are contemplating buying this kit, please don't.
Buyer beware
Diy Kits 1pcs JLH 1969 class A amplifier Board high quality PCB MOT 2N3055
This is what is says on the eBay listing
This is the kit assembled
The little blue trimmers are; on the left to adjust the 1/2 Voltage and on the right to adjust the Quiescent Current. I got the 1/2V easily, I used a 12V smps brick just to try it. Connecting the 10 Amp readout on my cheapo digital multimeter and adjusting the other trimmer the most I could get out of it at zero ohms was 0.58 Amps. Ahhh I thought by limiting the output with the other resistor the trimmer will not burn out.
12V x 0.58 = 6.96 Watts this is the Quiescent Current on all the time. To work out the amplifier output, I took Mr Hoods 8 Ohm speakers recommended: 27V @ 1.2 Amps = 10 Watts, 27 x 1.2 = 32.4 Watts, 10 divided by 32.4 = 0.31.
Using that multiplier 6.96 x 0.31 = 2.16 Watts and if 24V was put into the circuit that would be about 4 Watts output and is the reason no wattage is mentioned in the eBay listing title, who would buy one if it was?
On to the mechanicals the board is very nice, but, the holes are very very small and would not take any veropins. The layout is for the components they supply and no others. On this thread I see lots of folks saying they've bought this and are going to modify it ...... and then nothing! Attempts at modification would result in a right old mess.
It is also my opinion that mounting the transistors on a piece of aluminium angle is a very poor idea especially as close as they are here, it wouldn't matter with just a few amps but huge ones would be needed to dissipate a large concentration of heat, assuming a bodged up modification . Mr Hood used direct mounting, one surface to another.
I would urge anyone not to buy this kit, I have also seen the two blue trimmers in ready made JLH amplifiers, with heatsinks that look far too small and the transistors too close together, now I know why.
Cheers
I have posted a pic of this before but didn't make any comment I think it's important that people don't waste their money and throw a very good (but full DIY) project in the bin, if you are contemplating buying this kit, please don't.
Buyer beware
Diy Kits 1pcs JLH 1969 class A amplifier Board high quality PCB MOT 2N3055
This is what is says on the eBay listing
This is the kit assembled
An externally hosted image should be here but it was not working when we last tested it.
The little blue trimmers are; on the left to adjust the 1/2 Voltage and on the right to adjust the Quiescent Current. I got the 1/2V easily, I used a 12V smps brick just to try it. Connecting the 10 Amp readout on my cheapo digital multimeter and adjusting the other trimmer the most I could get out of it at zero ohms was 0.58 Amps. Ahhh I thought by limiting the output with the other resistor the trimmer will not burn out.
12V x 0.58 = 6.96 Watts this is the Quiescent Current on all the time. To work out the amplifier output, I took Mr Hoods 8 Ohm speakers recommended: 27V @ 1.2 Amps = 10 Watts, 27 x 1.2 = 32.4 Watts, 10 divided by 32.4 = 0.31.
Using that multiplier 6.96 x 0.31 = 2.16 Watts and if 24V was put into the circuit that would be about 4 Watts output and is the reason no wattage is mentioned in the eBay listing title, who would buy one if it was?
On to the mechanicals the board is very nice, but, the holes are very very small and would not take any veropins. The layout is for the components they supply and no others. On this thread I see lots of folks saying they've bought this and are going to modify it ...... and then nothing! Attempts at modification would result in a right old mess.
It is also my opinion that mounting the transistors on a piece of aluminium angle is a very poor idea especially as close as they are here, it wouldn't matter with just a few amps but huge ones would be needed to dissipate a large concentration of heat, assuming a bodged up modification . Mr Hood used direct mounting, one surface to another.
I would urge anyone not to buy this kit, I have also seen the two blue trimmers in ready made JLH amplifiers, with heatsinks that look far too small and the transistors too close together, now I know why.
Cheers
There have been many builders of similar looking kits to yours, including that helpful You-Tube guy, John Audiotech. Google his ID + JLH and see what you find. He seemed happy with his final effort, after he worked through the kit problems. Yes, he had problems too but nothing dramatic and nothing to do with parts ratings. The solutions were simple and most were down to supplier parts purchasing and a blunder or two. YouTube
Just sayin'... Veropins on kits of specific design amplifiers?.... That doesn't seem appropriate.
Just sayin'... Veropins on kits of specific design amplifiers?.... That doesn't seem appropriate.
Hello Ian,
I agree completely, the best way is to make everything you can yourself. Pithering about trying to alter kits is a waste of time. One has to use what they give you if that satisfies well OK, I like to make as much as I can myself. I wasted my money and my time on that kit, such is life.
Cheers
I agree completely, the best way is to make everything you can yourself. Pithering about trying to alter kits is a waste of time. One has to use what they give you if that satisfies well OK, I like to make as much as I can myself. I wasted my money and my time on that kit, such is life.
Cheers
Hello all,
This is the modified schematic I used;
I then looked closely at the photo of the circuit board Mr Hood used.
He used Lekrokit board, I was able to buy some Matrix board from Cricklewood Electronics very similar with single copper pads on the reverse side.
This is the Matrix board fully populated and ready to be installed, it's so easy to use and the components can be changed very easily they just slide out. I used U shaped pieces of wire to hold some parts down onto the board, soldered to the pads on the other side.
1/. I changed this resistor until I got the Amperage I wanted, using a cheapo digital multimeter, Pos lead to the supply Neg lead to the circuit. The resistor here has to be 1 Watt or as I have used 2 - 1/2 Watt ones in parallel. There are online calculators to do this, if like the above you use two the same value then halve the resistance. To work out the Wattage output multiply your chosen Voltage by your chosen Amperage and multiply that by 0.31.
2/. There are two veropins here connected under the board, these are to take Tr1 Collector, Tr2 Emitter, R1, C1 and the output.
3/. Return the -V from the loudspeaker here.
4/. Another veropin here this goes to the Star ground
5/. The lead on R5 is soldered to the base of Tr4 then under the board to the R5 trimmer, this sets the 1/2 supply voltage at 2.
6/. A veropin where the 39k resistor and the 100uf Capacitor meet, connected to the trimmer under the board, the centre lead of the trimmer is attached to the one of the outer leads.
The pic above is a 2D of a 3D object
To make it clear that the leads from C3 to R4 are just connected to each other.
If anyone does contemplate making the amp in this way I will be only too glad to provide some large printable images of the above, please send me a nice message.
Cheers
This is the modified schematic I used;
An externally hosted image should be here but it was not working when we last tested it.
I then looked closely at the photo of the circuit board Mr Hood used.
An externally hosted image should be here but it was not working when we last tested it.
He used Lekrokit board, I was able to buy some Matrix board from Cricklewood Electronics very similar with single copper pads on the reverse side.
This is the Matrix board fully populated and ready to be installed, it's so easy to use and the components can be changed very easily they just slide out. I used U shaped pieces of wire to hold some parts down onto the board, soldered to the pads on the other side.
An externally hosted image should be here but it was not working when we last tested it.
1/. I changed this resistor until I got the Amperage I wanted, using a cheapo digital multimeter, Pos lead to the supply Neg lead to the circuit. The resistor here has to be 1 Watt or as I have used 2 - 1/2 Watt ones in parallel. There are online calculators to do this, if like the above you use two the same value then halve the resistance. To work out the Wattage output multiply your chosen Voltage by your chosen Amperage and multiply that by 0.31.
2/. There are two veropins here connected under the board, these are to take Tr1 Collector, Tr2 Emitter, R1, C1 and the output.
3/. Return the -V from the loudspeaker here.
4/. Another veropin here this goes to the Star ground
5/. The lead on R5 is soldered to the base of Tr4 then under the board to the R5 trimmer, this sets the 1/2 supply voltage at 2.
6/. A veropin where the 39k resistor and the 100uf Capacitor meet, connected to the trimmer under the board, the centre lead of the trimmer is attached to the one of the outer leads.
The pic above is a 2D of a 3D object
An externally hosted image should be here but it was not working when we last tested it.
To make it clear that the leads from C3 to R4 are just connected to each other.
If anyone does contemplate making the amp in this way I will be only too glad to provide some large printable images of the above, please send me a nice message.
Cheers
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Hi jemraid
I felt I needed to post a response to your post about the kit you built.
There is an excellent video on youtube From Astrolab's Electronics showing the construction and testing of a similar kit.
Your calculation about power output has missed the fact that the power output increases with the square of the voltage. This means doubling the the voltage will increase the power by a factor of 4 ie 24v will produce 8.6W.
You also made a comment about not liking the use of aluminium angle to mount the power transistors. This in not meant to be used as a heat sink alone but rather a heat transfer by fixing to a larger heat sink. The video clearly shows this.
I really think the kit is not as bad as you believe
It is interesting that you have gone back to the original layout and construction - I did a similar thing around 1970 when I constructed the amp.
Robert
I felt I needed to post a response to your post about the kit you built.
There is an excellent video on youtube From Astrolab's Electronics showing the construction and testing of a similar kit.
Your calculation about power output has missed the fact that the power output increases with the square of the voltage. This means doubling the the voltage will increase the power by a factor of 4 ie 24v will produce 8.6W.
You also made a comment about not liking the use of aluminium angle to mount the power transistors. This in not meant to be used as a heat sink alone but rather a heat transfer by fixing to a larger heat sink. The video clearly shows this.
I really think the kit is not as bad as you believe
It is interesting that you have gone back to the original layout and construction - I did a similar thing around 1970 when I constructed the amp.
Robert
To work out the power rating take the square root of the required power multiplied by the load to be driven then multiply this by root 2. That gives peak volts (in one direction) which has to be doubled for peak-to-peak swings.
Let us say 2W into 8R that is root 16 or 4 times 1.414 peak Voltage times 2 peak to peak equals 11.312V. When voltage drops across the power devices is considered a 12 volt supply is going to fall short of the target.
There are implications for stability when you reduce the supply voltage as well.
The kit design is OK and you should just build it according to the instructions - the flying leads to the alternative power devices are long and messy and the collector and emitter ones look skimpy if you want to run this at the recommended current level.
There is a reason why the pcb has been designed to be compact and to take 2N3055's. These don't turn off so these are like a non stop express in comparison to Class AB which has to stop and start every half cycle so a Tortoise can still beat a hare in a speed race.
Good morning gentlemen,
I take your points about the kit I was in error with my observations.
I would also point out that some of your assumptions are incorrect;
The leads I use to the TIP 3055's are no longer than the ones Mr Hood used, see the original article.
The leads will take 1,000V @ 1.8 Amps
There is no circuit diagram with the kit
There are no instructions with it either
As I can see that you feel strongly about the kit, perhaps you could put your heads together and produce the same as I have in my post. The kit would not suit me I use a pair of 4 Ohm speakers that need resistors and capacitor alterations. As per the table also in my post
An annotated image is worth a 1,000 words.
Cheers all
I take your points about the kit I was in error with my observations.
I would also point out that some of your assumptions are incorrect;
The leads I use to the TIP 3055's are no longer than the ones Mr Hood used, see the original article.
The leads will take 1,000V @ 1.8 Amps
There is no circuit diagram with the kit
There are no instructions with it either
As I can see that you feel strongly about the kit, perhaps you could put your heads together and produce the same as I have in my post. The kit would not suit me I use a pair of 4 Ohm speakers that need resistors and capacitor alterations. As per the table also in my post
An annotated image is worth a 1,000 words.
Cheers all
Tried to edit the above ... failed the 20 mins expired as I was doing it
[edit] Here's an interesting kit to have a look at: 2 X MINI JLH HOOD 1969 CLASS A 3W AUDIO POWER AMPLIFIER KIT
[edit] Here's an interesting kit to have a look at: 2 X MINI JLH HOOD 1969 CLASS A 3W AUDIO POWER AMPLIFIER KIT
Hello RobotC,
Thanks you for the information good of you to respond. I only bought one kit to try it out, I am not interested in pursuing it as a project. However if you would like to detail and provide images of a comprehensive project based on the kit then feel free to do so.
After all there must be lots of non-experts like me who would benefit from your expertise. It would be nice if you could start with the assumption that you are authoring for someone who know nothing about electronics and needs a very simple but comprehensive explanation.
As I am endeavouring to do. see below.
Cheers
Thanks you for the information good of you to respond. I only bought one kit to try it out, I am not interested in pursuing it as a project. However if you would like to detail and provide images of a comprehensive project based on the kit then feel free to do so.
After all there must be lots of non-experts like me who would benefit from your expertise. It would be nice if you could start with the assumption that you are authoring for someone who know nothing about electronics and needs a very simple but comprehensive explanation.
As I am endeavouring to do. see below.
Cheers
Hi
I just had a look at your blog. It seems you are progressing with the vero board version. I am not sure if the board is finished but the output you labelled as 2 looks like you mean to connect the speaker between the emitter and collector of the two transistors. These points should be connected and the output capacitor (C2) connected here
If you want to see a good explanation of the construction of a kit very like the one you bought watch the video I linked in Post 6611. I think it will answer a lot of your questions
I just had a look at your blog. It seems you are progressing with the vero board version. I am not sure if the board is finished but the output you labelled as 2 looks like you mean to connect the speaker between the emitter and collector of the two transistors. These points should be connected and the output capacitor (C2) connected here
If you want to see a good explanation of the construction of a kit very like the one you bought watch the video I linked in Post 6611. I think it will answer a lot of your questions
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Joined 2009
Paid Member
Jemraid, I think it's great that you are using something akin to veroboard. That's how I built my version. Not only did it feel to be in keeping with the sentiment of this project but it took me waaaay back to my youth when I tried building things on veroboard. Back in those days I was clueless and nothing actually worked but I had fun playing with the parts and smelling the flux. I feel interested in updating my JLH, it's not been used for years, the sound it not satisfying and I believe that is due to the compromises I made such as the use of some old power devices with particularly low ft performance (2N3055H). And with many devices in parallel the amp doesn't even make it all the way to 20kHz when I tested it on the bench. Anyhow, I feel as if it should be re-built using veroboard too. With a amp this simple I'd be reluctant to use a no-name kit.
p.s. looking at your blog I see you made a nice job of those speakers.
p.s. looking at your blog I see you made a nice job of those speakers.
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Hello Bigun,
Thanks for the message nice of you, thinking about the 3055's I recall either Nigel, Ian or John saying that they were very good components for the design, correct me if I recall incorrectly gentlemen, it being what the circuit was designed for.
I am very wary of so called 'comparisons' from memory and at the moment I am comparing the JLH to my 3886 over a 7 day period in the same fashion undertaken by Mr Hood, using a switch.
We love Herefordshire and have stayed, near Kington, near Hay on Wye and on Bircher Common. I did a photo essay on Bircher which was exhibited at the National Trust regional office. Odd place Bircher, I saw a programme about Morris Dancing and some dancers who went to a 'secret' location to dance as the sun rose on Midsummer's day, I knew that it was Bircher and exactly where and why, this will sound even odder but nevertheless in that spot I used to get a feeling of something infinite everytime I walked past. I also came across a bloke solo camping and asked him why there, he replied it just felt 'right', not creepy by any means if anything, 'joyful' and nothing at all to do with any 'belief' whatsoever.
Cheers
[edit] speelong
Thanks for the message nice of you, thinking about the 3055's I recall either Nigel, Ian or John saying that they were very good components for the design, correct me if I recall incorrectly gentlemen, it being what the circuit was designed for.
I am very wary of so called 'comparisons' from memory and at the moment I am comparing the JLH to my 3886 over a 7 day period in the same fashion undertaken by Mr Hood, using a switch.
We love Herefordshire and have stayed, near Kington, near Hay on Wye and on Bircher Common. I did a photo essay on Bircher which was exhibited at the National Trust regional office. Odd place Bircher, I saw a programme about Morris Dancing and some dancers who went to a 'secret' location to dance as the sun rose on Midsummer's day, I knew that it was Bircher and exactly where and why, this will sound even odder but nevertheless in that spot I used to get a feeling of something infinite everytime I walked past. I also came across a bloke solo camping and asked him why there, he replied it just felt 'right', not creepy by any means if anything, 'joyful' and nothing at all to do with any 'belief' whatsoever.
Cheers
[edit] speelong