New pictures and construction info I am building 
Le monstre
Le monstre will be soon finished...
Please remind me of how to set the bias? Measuring the voltage accross 1K resistors and then what is the formula for calculating the current (silly Q.. but want to make sure)
Le monstre
Le monstre will be soon finished...
Please remind me of how to set the bias? Measuring the voltage accross 1K resistors and then what is the formula for calculating the current (silly Q.. but want to make sure)
Very handsome beast!
An externally hosted image should be here but it was not working when we last tested it.
a doubt
Hi all and neazoi,
This is really a fine job and an instructive forum.
There is only one thing that occurs strange to me : on the pcb which is on your site (Le monstre) drains of the fets are linked to the trim pot. IMHO on the original schematic (which is also on your site) they were to the bipolars, and the trim pot was the source resistor.
Is there a reason why, or forgive me if i'm saying something stupid ?
Kind Regards
Pierre-Yves
Hi all and neazoi,
This is really a fine job and an instructive forum.
There is only one thing that occurs strange to me : on the pcb which is on your site (Le monstre) drains of the fets are linked to the trim pot. IMHO on the original schematic (which is also on your site) they were to the bipolars, and the trim pot was the source resistor.
Is there a reason why, or forgive me if i'm saying something stupid ?
Kind Regards
Pierre-Yves
Hi All
Well going to have a run at this Le class a 20W from this eBay chap see schematic and parts list at bottom of page 2 X CLASS A POWER AMP KIT - BASED ON HIRAGA LE MONSTRE on eBay (end time 06-Sep-10 04:24:22 BST)
OK so my problem is sourcing the Transistors here in UK the following list is what I have sourced
2SC1775x2 In Stock
> 2SA872x2 In Stock
> 2SB716x2 replacing with 2SB647
> 2SD756x2 Replacing with 2SC2632
Can anyone confirm if these are ok? And will work plus if someone can recommend replacements for the 2N3055 /2N2955 as I find these sound woolly and grainy
Thank you for your help All
Colin
Well going to have a run at this Le class a 20W from this eBay chap see schematic and parts list at bottom of page 2 X CLASS A POWER AMP KIT - BASED ON HIRAGA LE MONSTRE on eBay (end time 06-Sep-10 04:24:22 BST)
OK so my problem is sourcing the Transistors here in UK the following list is what I have sourced
2SC1775x2 In Stock
> 2SA872x2 In Stock
> 2SB716x2 replacing with 2SB647
> 2SD756x2 Replacing with 2SC2632
Can anyone confirm if these are ok? And will work plus if someone can recommend replacements for the 2N3055 /2N2955 as I find these sound woolly and grainy
Thank you for your help All
Colin
Member
Joined 2009
Paid Member
For the output devices I like the 2SC5200 / 2SA1943 pairing.
You want to make sure to pay good attention to the heat-sinking and mounting of the output devices on the heatsink. Good luck - it's a design with an excellent reputation.
Hi Bigun
Thanks for the reply
And your recommendation on the output Trans so I can take it all the other transistors numbers I posted are ok as well then
Thanks
I used 2SC5200/2SA1943 also, and thought it sounded good. (Haven't listened to it in a while...) Bigun is right about the heatsinking, too.
Cheers
Nigel
Hi Nigel
Ok looks like the 2SC5200/2SA1943 then Still not sure which Version to Build the 12volt or the 22Volt as in the link I posted you views on which version I should build would be appreciated if you can point me in the right direction lads HO and is there a heat sink you recommend
Cheers
Ok looks like the 2SC5200/2SA1943 then Still not sure which Version to Build the 12volt or the 22Volt as in the link I posted you views on which version I should build would be appreciated if you can point me in the right direction lads HO and is there a heat sink you recommend
Cheers
Hi Colin,
Except for the output transistors, the version I built was the circuit from the Class A Amplifier Site, which has translations of the original L'Audiophile articles. (I was lucky to find the original driver transistors...) I've posted the schematic below for convenience, but you might want to take a look at the articles anyway. I can't remember who suggested 2SC5200/2SA1943 originally, but it may have been danieljw, who I know also used them, and may have further advice. The power supply was a cap multiplier from the ESP audio site, giving about +/- 19V.
The heatsinks I used were improvised from a burned-out power module from a car audio repair shop. The thing looked huge, and weighed a ton, but cut into two and used as the two sides of the chassis it wasn't really enough. (Stable operating temp was close to 60 deg. Celsius) If I were building this again I would use something about the same size as I used on the F5 that replaced it - if you look on the big F5 thread on the Pass Labs forum there are loads of posts about what would be suitable. Alternatively, you can check out the heatsinks I used online - they were two 10" lengths of CPP 5179 from Franab - their site is
FRANAB - Industria Metalúrgica Ltda
They gave excellent service, for the record, but I imagine shipping to Scotland would be pretty expensive and I'm sure you can source something more locally.
Best of luck
Cheers
Nigel
Except for the output transistors, the version I built was the circuit from the Class A Amplifier Site, which has translations of the original L'Audiophile articles. (I was lucky to find the original driver transistors...) I've posted the schematic below for convenience, but you might want to take a look at the articles anyway. I can't remember who suggested 2SC5200/2SA1943 originally, but it may have been danieljw, who I know also used them, and may have further advice. The power supply was a cap multiplier from the ESP audio site, giving about +/- 19V.
The heatsinks I used were improvised from a burned-out power module from a car audio repair shop. The thing looked huge, and weighed a ton, but cut into two and used as the two sides of the chassis it wasn't really enough. (Stable operating temp was close to 60 deg. Celsius) If I were building this again I would use something about the same size as I used on the F5 that replaced it - if you look on the big F5 thread on the Pass Labs forum there are loads of posts about what would be suitable. Alternatively, you can check out the heatsinks I used online - they were two 10" lengths of CPP 5179 from Franab - their site is
FRANAB - Industria Metalúrgica Ltda
They gave excellent service, for the record, but I imagine shipping to Scotland would be pretty expensive and I'm sure you can source something more locally.
Best of luck
Cheers
Nigel
Member
Joined 2009
Paid Member
Hi All
Yep I have a 300VA 0-18 0-18volt I am hoping to use and a Capacitance of about 88.000uf to start with
Member
Joined 2009
Paid Member
When you first turn this on the transformer and rectifier have to charge up a lot of capacitance. I don't know if this is a problem or not, but splitting up the capacitance to create a RCRC kind of filter after the rectifier might be worth considering. It increases the impedance of the supply for transients that are large enough to suck all the power out of the 'last capacitor' but otherwise the benefit is reduced peak charging currents through the rectifier and greater ripple reduction - which your Hiraga amp will appreciate. The resistors could be of order 0R5 where you an readily get inexpensive power resistors. Leave space to add more capacitors just in case.
Anyhow, this is what I did when I had a stab at Class A SS amps.
Ha Williams/Bigun
As I am just a beginner in this amp building game apart from a pre amp or two a valve Phono stage and Valve Headphone Amp so I will be asking lots of questions? Likely
At the moment I’m just gathering the Hiraga amp parts as this will be a winter project Bigun when you Say RCRC How about a RCLCRC as in a Valve Amp PSU just a thought what do you think
As I am just a beginner in this amp building game apart from a pre amp or two a valve Phono stage and Valve Headphone Amp so I will be asking lots of questions? Likely
At the moment I’m just gathering the Hiraga amp parts as this will be a winter project Bigun when you Say RCRC How about a RCLCRC as in a Valve Amp PSU just a thought what do you think
Member
Joined 2009
Paid Member
Hi Colin,
Yes, putting an 'L' in there is good. In general, the 'R' is just a poor mans 'L'. The inductor provides an impedance that increases with frequency and in theory a good one can have a low impedance at dc which is ideal for a power supply.
They can be bulky and expensive and like power transformers they can leak magnetic flux which can induce 'hum' (i.e. currents) in nearby circuitry (I had this problem recently with my tube amp).
In a tube amp you're usually looking at 10's mA for the psu current draw but for a SS amp like yours the current is measured in Amps and this is going to saturate the kind of inductors popular in the power supply of tube amps.
The compromise is to to use a common mode choke, one where an inductor on the + rail shares it's core with an inductor on the - rail. Then the magnetic fields generated by the dc current flow going out the + rail and back the - rail cancel out and you don't saturate the core of the inductor. These kind of inductors won't have nearly as much inductance as those used on tube amps so they don't do so much to reduce mains ripple - which is why you need CRC. But they do cut out the higher frequency trash produced by the rectifier and other stuff that gets through on the AC mains.
Yes, putting an 'L' in there is good. In general, the 'R' is just a poor mans 'L'. The inductor provides an impedance that increases with frequency and in theory a good one can have a low impedance at dc which is ideal for a power supply.
They can be bulky and expensive and like power transformers they can leak magnetic flux which can induce 'hum' (i.e. currents) in nearby circuitry (I had this problem recently with my tube amp).
In a tube amp you're usually looking at 10's mA for the psu current draw but for a SS amp like yours the current is measured in Amps and this is going to saturate the kind of inductors popular in the power supply of tube amps.
The compromise is to to use a common mode choke, one where an inductor on the + rail shares it's core with an inductor on the - rail. Then the magnetic fields generated by the dc current flow going out the + rail and back the - rail cancel out and you don't saturate the core of the inductor. These kind of inductors won't have nearly as much inductance as those used on tube amps so they don't do so much to reduce mains ripple - which is why you need CRC. But they do cut out the higher frequency trash produced by the rectifier and other stuff that gets through on the AC mains.
Hi All
Yep I Just have the HK Hiraga "le monster PCBS so only have the Schematic and parts list only I don’t have any notes for this 22volt version as I said I an beginner at this so would appreciate your guidance on what current this amp should be set at and sorry to be so basic but if possible a step by step guide on how-to do this i.e. like where do you connect the MM to set the current for the amp
Yep I Just have the HK Hiraga "le monster PCBS so only have the Schematic and parts list only I don’t have any notes for this 22volt version as I said I an beginner at this so would appreciate your guidance on what current this amp should be set at and sorry to be so basic but if possible a step by step guide on how-to do this i.e. like where do you connect the MM to set the current for the amp
hi colin,
do not worry too much !!!!!!!
assembly the pcbs and use a good pwr transformer min 300va
build a large capacitors bank, it takes a lot of current, i am using a total of 0.6 farad.
a +/- 22vdc pwr supply is not a problem, just be aware of the heat sinks, they must be big, large, good coupling to the pwr transistors.
the aluminum bracket for the pwr transistors supplied with the kit is not very good, take care and adjust the pot for dc offset at the output;
first with out a load,
then connect a load similar to the spk and readjust it.
repeat the adjusting procedure several times during amp heating
then you are dc off set adjusted and ready to hook it to your system
the dc current is automatically set, you do not deal with it.
best luck,
Williams
do not worry too much !!!!!!!
assembly the pcbs and use a good pwr transformer min 300va
build a large capacitors bank, it takes a lot of current, i am using a total of 0.6 farad.
a +/- 22vdc pwr supply is not a problem, just be aware of the heat sinks, they must be big, large, good coupling to the pwr transistors.
the aluminum bracket for the pwr transistors supplied with the kit is not very good, take care and adjust the pot for dc offset at the output;
first with out a load,
then connect a load similar to the spk and readjust it.
repeat the adjusting procedure several times during amp heating
then you are dc off set adjusted and ready to hook it to your system
the dc current is automatically set, you do not deal with it.
best luck,
Williams