It is advised here and in original Hiraga artical to use massive power supply.
Regards
Sachin
Due to poor PSSR? Have any of you compared with smaller supply? What were the results?
Also, what is the voltage range that can be used with this amp. I see a 9-0-9vac transformer. Will it work using a 12-0-12vac transformer?
Thanks, Terry
Also, what is the voltage range that can be used with this amp. I see a 9-0-9vac transformer. Will it work using a 12-0-12vac transformer?
Thanks, Terry
It seems to have almost no PSRR which means that it needs ruler flat power rails. If you are running 96db sensitivity speakers even a single mV of ripple will be audible. I still have small issues with radiative inductance from my massive toroidal power supply. Its much harder to get quiet than any of the valve amps I have ever built.
Shoog
Shoog
Has anyone tried it with a capacitance multiplier, if so was it good sounding. Is there any PCB available for purchase ? I believe Juma had done a circuit for this but not sure if a PCB exist...???
When I start building mine, I will either try with a CLC filter or a capacitance multiplier.
Like Shoog, my speakers are also 96db...wish me luck...LOL
Rgds,
Eric
When I start building mine, I will either try with a CLC filter or a capacitance multiplier.
Like Shoog, my speakers are also 96db...wish me luck...LOL
Rgds,
Eric
I use a capacitance multiplier, with the big caps after it. The big caps dominate the sound which is fine. It works as designed - but correct layout and adequate distancing between the power transformer and the rest of the circuit is absolutely essential. The case I had means that the power transformer cannot be adequately isolated so my residual hum of about 1mV is from inductive pickup into the power supply lines.
Use a case which allows at least a few inches of clear space between the power transformer and the channels.
Shoog
Use a case which allows at least a few inches of clear space between the power transformer and the channels.
Shoog
These are very good advice. Not sure if it will help but my enclosure will be made of wood.
Could you share your schematic and is yours from a PCB or you used a perforated board ?
Couldn't find any capacitance multiplier PCB on e-bay...
Thanks,
Eric
Could you share your schematic and is yours from a PCB or you used a perforated board ?
Couldn't find any capacitance multiplier PCB on e-bay...
Thanks,
Eric
The cap multiplier is build straight onto a heatsink point to point - it very straightforward and based on the Elliot Sounds project. i think it has about 22Kuf before the CP and about 64KuF after.
The main circuit is built on perf boards and is specific to the output transistors I had at hand which are the big old Sankens which I had from a long dead Sony receiver.
Shoog
The main circuit is built on perf boards and is specific to the output transistors I had at hand which are the big old Sankens which I had from a long dead Sony receiver.
Shoog
Attachments
You need 10-0-10VAC min. transformer to get 12V rail.
You can use 12V to.
First time I built the Monster I used 9-0-9VAC 300Va transformer and I got around 11V rail under load.
If you want 9-10W some speaker need that if not sensitive enough, you can go 12AC with out problem.
Originally they chose the transformer to get 12V because they use car batteries to which is 12V.
Greetings
The 12-0-12vac transformer I have is 1200VA so it will hold about +-16Vdc rails. Jus wonder is this is too much.
Thanks, Terry
Thanks, Terry
You have to use a soft start on the transformer.
It would be more than enough 500VA but that is what you got use it.
I do not see why can not work.
The Jfet are cascaded. to the driver you can a flag style heat sink if is to hot.
The power transistors if got large enough heat sink they could handle even higher rail Voltage.
Please go for it.
Greetings
It would be more than enough 500VA but that is what you got use it.
I do not see why can not work.
The Jfet are cascaded. to the driver you can a flag style heat sink if is to hot.
The power transistors if got large enough heat sink they could handle even higher rail Voltage.
Please go for it.
Greetings
I want to use Onsemi outputs. I have MJL4281/4302, MJL21193/94, MJL3281/1302, NJW3281/1302, NJW0281/0302 & NJW21193/94. Which of any of these are suitable?
Thanks, Terry
Thanks, Terry
I think the MJW-s will be great.
I do like the MJL4281/4302 but those may oscillate in these circuit.
Greetings
I do like the MJL4281/4302 but those may oscillate in these circuit.
Greetings
Your charging spikes will be significant and this will create radio frequency noise which can effect all other components. I had a similar problem with my 300VA transformer and in the end I had to put resistance in the secondaries to slow things down and reduce the buzz I was getting from my speakers.
Despite what most people may imagine a to large transformer is not an advantage in creating a quiet amplifier. I would personally opt for something in the range of 120VA if I was building mine again. At this level the slight transformer resistances act as a choke to transformer noise.
Shoog
Hi,
I use 300VA transformer to give about +/- 20Vdc, however my output current is about 800mA, my heatsink is able to carry the heat dissipated by my output transistors, no problem there.
I use 300VA transformer to give about +/- 20Vdc, however my output current is about 800mA, my heatsink is able to carry the heat dissipated by my output transistors, no problem there.
It's mainly the voltage I an concerned about. My transformer has four secondary windings I can output va in 300va increments. As long as+-16v is OK I can make it.
Hy gaborbela. About power transistor, what do you think about the use of mj15003-mj15004? I have some spare and i'd like to try.🙂
Thank you!
I had 9-0-9VAC transformer from Plitron.
After the amp did warm up the transformer was about 45C or more at summer.
OK the total bias per channel was a bit over 1.2A after full warm up.
I think for 2 channel 300VA req. for long term.
You can separate your transformer (shield it) if is not shielded already.
Or use separate enclosure for the PS or just for the transformer. Lot s off option to try..
If you use large caps CRC or CLC mode and your grounding is up to the task I do not see problem why you can not use that.
OK in these case bigger is not better but if you already got that transformer just use it.
After the amp did warm up the transformer was about 45C or more at summer.
OK the total bias per channel was a bit over 1.2A after full warm up.
I think for 2 channel 300VA req. for long term.
You can separate your transformer (shield it) if is not shielded already.
Or use separate enclosure for the PS or just for the transformer. Lot s off option to try..
If you use large caps CRC or CLC mode and your grounding is up to the task I do not see problem why you can not use that.
OK in these case bigger is not better but if you already got that transformer just use it.
Thats not really the main issue here - its the DC resistance of the primary which allows the huge charging spikes. in order to supply a 1200VA transformer the wire resistance will be virtually zero which will mean that the transformer will be able to charge the caps very very quickly with currents in the 10's of Amps. this makes for very short and very sharp charging spikes and when the diodes switch off the back EMF of the3 collapsing field of the transformer creates an even larger voltage spike with the transformer acting as a perfect radio antenna to dissipate the energy.
If it can be significant with a 300VA transformer it will be more than twice as significant with a 1200VA transformer. Coupled to this will be the significant stress this will place on your capacitors in dealing with such massive inrush currents.
Its just not a very sensible idea - consider placing some resistance in series with your primaries and/or secondaries (which negates any advantage of have such a big transformer) or better still use a smaller transformer.
Many years ago I built a Zen V3 amplifier and I used a puny underspec'ed transformer. it got very hot - but the amp ran with little hum and had a nice smooth sound. I upgraded the transformer to a more in spec one and I got hum and a harsher sound for my trouble (in fact I replaced it with the transformer I am currently using in my Le Monstre).
I would also choose an EI transformer over a toroidal in this application - because they suppress line hash which has to be dealt with through additional components with toroidals. I once used a similar sized toroidal transformer to yours and it used to dim the lights on power up.
Just sharing my own personal build experience.
Shoog
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16V is fine!
Just pay att. to the bias at start up, I would use 1K multi turn trimmers to the cascade to set up the right bias and after replace that with normal resistors.
Just pay att. to the bias at start up, I would use 1K multi turn trimmers to the cascade to set up the right bias and after replace that with normal resistors.
I would be fairly comfortable with running any well built transformer at 50 Centigrade. All my valve amps run their power transformers at about that temp mainly because I use far bigger caps in my power supplies than most people choose to.
Shoog