If the positive rail is disconnected out increases to 0.5V.
Negative rail disconnected output goes to V+ (±18V)
Removing one of the secondary fuses blows the other one.
So I'll leave the secondary fuses where they are and put 5 Amp fuses in both and I'll see what happens.
Thanks for your help Andrew.
Now I need to order a new box of fuses to replace the multiple 4 amp ones I've used up
Negative rail disconnected output goes to V+ (±18V)
Removing one of the secondary fuses blows the other one.
So I'll leave the secondary fuses where they are and put 5 Amp fuses in both and I'll see what happens.
Thanks for your help Andrew.
Now I need to order a new box of fuses to replace the multiple 4 amp ones I've used up
Hi Eric,
For the records and completeness (in case anyone is interested) from top left:
1) Soft power supply
This one has a number of problems. The 'push to make' contact didn't work reliably so I had to modify. There's also some problem with 'leakage' to the output terminals - i.e. when 'off' there's still some current flow to the capacitor bank. Soft start not necessary but I had it lying around and it had 2 by 75°C temperature 'cut outs' (connected to centres of heat sinks).
2) 15-0-15 160 VA transformer (Farnell)
3) Copper bus bar: Ground lift circuit ex ESP (can't find reference at the moment). 5 Amp AC fuses either side.
4) Jim's Audio 'MUR3020' rectifier/cap bank. Works well and construction is pretty good:
Bridge Rectification PSU PCB Using 4 Ultrafast Diodes Partial Kit | eBay
5) Alps log pot bought ex EBay. Needs replacing as the accuracy between the stereo tracks is very poor (suspect a 'knock-off')
6) Case ex Modushop:
Dissipante 02/300B 2U 10mm ARGENTO
Too small at 2U and 300mm depth - i.e. a little 'tight' to fit everything in.
I had someone drill the front panel for me. Think he held a rat and got it to gnaw the power switch and pot holes - will replace when next I order anything from Modushop.
Current set at 1.6 Amps per channel (otherwise the driver transistors get too hot - for my liking anyway - around 70°C or so). I fitted LED heat sinks to them (limited space for anything else). Not sure if these drivers should be attached to the main heat sinks?
The main heat sinks run at around 30 to 35°C above ambient when the amp is run for around an hour (without case top panel off).
Still to do:
1) Replace front panel.
2) Remove Alps pot and use external volume control. As the pot is too cramped and the lead wires too close to the cap banks (there is some hum pick up on the right channel).
The PCBs are placed for use of an integrated volume control. If I had known from the start I'd end up using an external volume control I'd have done the layout differently (Amps closer to the back).
Anyway, this is my first attempt at my own Amp. Been meaning to build the JLH since the original article came out. Probably find others might have a better idea of the layout.
Next in line is the Hiraga 30W Class A using a 4U Case ....
Hope this helps.
Cheers
For the records and completeness (in case anyone is interested) from top left:
1) Soft power supply
This one has a number of problems. The 'push to make' contact didn't work reliably so I had to modify. There's also some problem with 'leakage' to the output terminals - i.e. when 'off' there's still some current flow to the capacitor bank.
Soft start not necessary but I had it lying around and it had 2 by 75°C temperature 'cut outs' (connected to centres of heat sinks).2) 15-0-15 160 VA transformer (Farnell)
3) Copper bus bar: Ground lift circuit ex ESP (can't find reference at the moment). 5 Amp AC fuses either side.
4) Jim's Audio 'MUR3020' rectifier/cap bank. Works well and construction is pretty good:
Bridge Rectification PSU PCB Using 4 Ultrafast Diodes Partial Kit | eBay
5) Alps log pot bought ex EBay. Needs replacing as the accuracy between the stereo tracks is very poor (suspect a 'knock-off')
6) Case ex Modushop:
Dissipante 02/300B 2U 10mm ARGENTO
Too small at 2U and 300mm depth - i.e. a little 'tight' to fit everything in.
I had someone drill the front panel for me. Think he held a rat and got it to gnaw the power switch and pot holes - will replace when next I order anything from Modushop.
Current set at 1.6 Amps per channel (otherwise the driver transistors get too hot - for my liking anyway - around 70°C or so). I fitted LED heat sinks to them (limited space for anything else). Not sure if these drivers should be attached to the main heat sinks?
The main heat sinks run at around 30 to 35°C above ambient when the amp is run for around an hour (without case top panel off).
Still to do:
1) Replace front panel.
2) Remove Alps pot and use external volume control. As the pot is too cramped and the lead wires too close to the cap banks (there is some hum pick up on the right channel).
The PCBs are placed for use of an integrated volume control. If I had known from the start I'd end up using an external volume control I'd have done the layout differently (Amps closer to the back).
Anyway, this is my first attempt at my own Amp. Been meaning to build the JLH since the original article came out. Probably find others might have a better idea of the layout.
Next in line is the Hiraga 30W Class A using a 4U Case ....
Hope this helps.
Cheers
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Chassis grounded directly under the IEC power input socket - Roxburgh EMC RIR-022H-H. Green wire from the IEC input earth to the metal sub chassis (top right). The sub chassis is attached to the case by 4 S/S bolts.Nice amplifier..
No chassis grounding
The Roxburgh metal case is also part of the ground and connected via 2 bolts to the rear chassis panel - so basically 3 connections to earth.
A 'ground lift' is used for the audio earth connections (the copper bus bar top right).
Should be OK?
Hi Tony,
Sorry, I've been away for two weeks so only just saw your reply. Agreed, a very nice build. Know the feeling of too small a space. I still need to get my stuff assembled et al. Will post a picture when I get to a certain point in the build. I've opted for the capacitance multiplier board, as well as a decent reservoir cap bank, but I'll probably have to re-assess my PSU to make all things fit comfortably in the cases I have. Your comment about the "rat holes" I have side-stepped, by slowly building up my own small workshop. Took a damnably long time, but finally set to get my a**e in gear.
Regards, Kevin
Sorry, I've been away for two weeks so only just saw your reply. Agreed, a very nice build. Know the feeling of too small a space. I still need to get my stuff assembled et al. Will post a picture when I get to a certain point in the build. I've opted for the capacitance multiplier board, as well as a decent reservoir cap bank, but I'll probably have to re-assess my PSU to make all things fit comfortably in the cases I have. Your comment about the "rat holes" I have side-stepped, by slowly building up my own small workshop. Took a damnably long time, but finally set to get my a**e in gear.
Regards, Kevin
Hi Ferret,
Is that the cap multiplier ex Siliconray or another (I'd like to try one myself)?
Haven't been able to get onto siliconray's website for some time. Still seems to be down/hacked.
I have a small workshop too but only have a table top drilling machine (Makita). Not sure how well that would do for holes in 10mm Al front covers. I think one requires a milling machine for that purpose?
Otherwise if you need any details then please let me know.
Cheers
Is that the cap multiplier ex Siliconray or another (I'd like to try one myself)?
Haven't been able to get onto siliconray's website for some time. Still seems to be down/hacked.
I have a small workshop too but only have a table top drilling machine (Makita). Not sure how well that would do for holes in 10mm Al front covers. I think one requires a milling machine for that purpose?
Otherwise if you need any details then please let me know.
Cheers
Hi Tony,
Yes it is in fact SiliconRay's board. Looks their website is not going to be back anytime soon. The board never cost a farthing (well actually 1 cent each) it was just a few components I ordered too, and the postage from HK. I can scan the board and send it if you want. They did after all get it from a dude in Australia.
I also only have a table top drill press, but I got myself a stepped drill with 1mm increments, which has been quite invaluable for getting accurate holes in 10mm alu.
Thanks for the offer, I'll drop you a PM if necessary.
Ciao for now
Yes it is in fact SiliconRay's board. Looks their website is not going to be back anytime soon. The board never cost a farthing (well actually 1 cent each) it was just a few components I ordered too, and the postage from HK. I can scan the board and send it if you want. They did after all get it from a dude in Australia.
I also only have a table top drill press, but I got myself a stepped drill with 1mm increments, which has been quite invaluable for getting accurate holes in 10mm alu.
Thanks for the offer, I'll drop you a PM if necessary.
Ciao for now
Last edited:
e_fortier: Thanks for swift reply.
We've been trying different configs, trying to get rid of hum. Right now, i'm running bd139/140 and 2sc5200's. Psu consists of a 2x18V AC, 400VA transformer, both rails smoothed with 10KuF caps before 0V is joined. Then additional smoothing on the pcb's.
signal gnd, speaker gnd and 0V connected at star gnd, but tried different solutions here.
Just can't get rid of the hum. Not so much prob for me as i got 87db speakers, but friend enjoys louder hum
Even tried with 100K uF caps.
We've been trying different configs, trying to get rid of hum. Right now, i'm running bd139/140 and 2sc5200's. Psu consists of a 2x18V AC, 400VA transformer, both rails smoothed with 10KuF caps before 0V is joined. Then additional smoothing on the pcb's.
signal gnd, speaker gnd and 0V connected at star gnd, but tried different solutions here.
Just can't get rid of the hum. Not so much prob for me as i got 87db speakers, but friend enjoys louder hum
Even tried with 100K uF caps.
Mine is a lower power version at +/- 14Vdc which is basically like the JLH69 that works at 27Vdc but this one is a bipolar version, same output, i.e. 10Wrms. My bias is 1A.
10KuF per rail is not much for this amp, what is your bias ?
If I were you I would try the typical CRC filter; 33000uF, 0.2ohm, 33000uF per rail which is basically what's being use for a typical 25W F5 amp.
BR,
Eric
10KuF per rail is not much for this amp, what is your bias ?
If I were you I would try the typical CRC filter; 33000uF, 0.2ohm, 33000uF per rail which is basically what's being use for a typical 25W F5 amp.
BR,
Eric
e_fortier:
Ive tried from 450mV to 650mV across R10(?), but i am now running at 600mV/0.33ohm=1,8A bias.
Was a bit unclear in last post. I am NOW running 10K/rail (plus the onboard 5-10K, but i've tried with 2x Evox Eifa 100.000uF caps in there as well.
I think my main issue, is proper grounding. Grounding of signal gnd, speaker gnd, DC 0V and routing of the cables from mains, transformer, rectifiers, and to the pcb.
Am i correct if i am connecting signal gnd, speaker gnd and DC 0V, together at a star, as soon as they enter the chassis?
I did this once, but with some noise. Which got further reduced if i also connected a cable to the signal gnd input on the pcb, to the same star gnd. (hints of pcb traces with too much resistance in them?)
I'll upload a few pics and illustrations. unclear explanation this.
Ive tried from 450mV to 650mV across R10(?), but i am now running at 600mV/0.33ohm=1,8A bias.
Was a bit unclear in last post. I am NOW running 10K/rail (plus the onboard 5-10K, but i've tried with 2x Evox Eifa 100.000uF caps in there as well.
I think my main issue, is proper grounding. Grounding of signal gnd, speaker gnd, DC 0V and routing of the cables from mains, transformer, rectifiers, and to the pcb.
Am i correct if i am connecting signal gnd, speaker gnd and DC 0V, together at a star, as soon as they enter the chassis?
I did this once, but with some noise. Which got further reduced if i also connected a cable to the signal gnd input on the pcb, to the same star gnd. (hints of pcb traces with too much resistance in them?)
I'll upload a few pics and illustrations. unclear explanation this.
