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Old 29th April 2008, 09:43 PM   #101
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Daniel, good to see you went ahead and are building the Hiraga. Sometimes photos are deceiving, but thar heatsink does look a bit small. I built my Hiragas as a pair of monoblocks, and gave each output transistor a huge heatsink and event then they ran on the hot side ( 60 deg. celcius on surface, to be exact). Take a look at the pic bellow to see what I mean. Also running 35V rails at 2A quiescent.

Anyway, great amp - loved the midrange and truthness of tone. Unfortunately it didn't drive my ATCs very well in the bass region, so I tore them apart and I'm building a design by a Scandinavian fellow named Nygaard.

Good luck on your project

J.Guilherme

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Old 29th April 2008, 09:49 PM   #102
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Oops...sorry - ok, here's the pic:

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Old 29th April 2008, 10:03 PM   #103
eduard is offline eduard  Netherlands
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Hello,
Guilherme you are absolutely right about the heatsink. The heatsink sold in Paris did have a thermal resisistance of 0,9 celsius/watt and there was just one transistor on each of the four of them. My last chassis did i did use for my 30 watt hiraga had a krell-like chassis using one heatsink for 2 transistors, But it was a massive heatsink ( more then 1 kilogram) but it still got hot. With metal prices going up it is getting difficult to get good heatsinks for this kind of amps for a reasonable price. Greetings, Eduard
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Old 30th April 2008, 04:04 AM   #104
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HI all!

thanks MJL21193,
Probably going to leave the caps blue or perhaps paint them red or something (unsure at the moment...) didnt think of polishing them...
I am jealous that you have the origional transistors! the original 2SA627/2SD188 are so hard to find now !
let me know if you have some more laying around !!!

currently I have origional spec 2SC1775A(E)/2SA872A(E) all hfe matched and 2SA634/2SC1096 (NEC) only my output stage is a little bit upgraded for higher power output.

u should build it ! I have only listened to one channel mono but its very promising....

Zen Mod,
If you do get the CD-ROMS i think you will be happy there is alot of good info and they are layed out very well in terms of finding info.

Guilherme,
Nice setup !!!
I agree with you about the heatsinks,
the heatsinks pictured are approx 75 x 300 x 35 ~0.37C/W (x4)
i have decided not to use these in the final chassis. I have some larger ones which i will probably use, I think i will end up with approx 34V rails and 1-2 A bias. and i would prefer not to burn people.!!

Interesting you found the bass response was lacking i have listened and measured and it seems good to me. then again 6 x 0.2F will help

-Dan
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Old 30th April 2008, 10:18 AM   #105
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u should build it ! I have only listened to one channel mono but its very promising....

One thing that I really liked about the Hiraga was the soundstage. I was very impressed with some recordings where the voice of the singer would come from the center in such a convincing manner that it was hard to believe there was nothing but air between those speakers. So hurry up building that second channel


J.Guilherme
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Old 30th April 2008, 10:34 AM   #106
eduard is offline eduard  Netherlands
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Hello Daniel,
I did take a closer look at your pictures and i think it will be difficult to incorporate these chokes somewhere. Because my job is about making holes in metal sheets i know the trouble you have been through???
If your chassis layout is close to the one used by the original hiraga. You could try mounting the choke under the first capacitor with some long-sized stand-offs . If they are potted and to high you can make a rectangular or square hole in the bottomplate. This way you can gain some soace if the feed you are using are a few centimeters high. The amp once completely finished will get quiet hot. On the cd-rom you can read that they did spend a lot of time to improve heat circulation in the chassis. Mounting the heatsinks with their '' backs '' against the sides of the chassis will cool them down but will make life hard for the capacitors. Mounting them with sturdy stand-offs about 15 mm long will create a kind of chimney effect so air can rise on all sides of the heat sink. I remember Hiraga did talk about this before making the chassis that was widely known as le classe A.
The replcement for the original power transistors were considered better by the magazine and all the people that did build these monsters. Maybe some french internet sites have more updates on the hiraga amps. BUT this amp was described as a perfect marriage of design and choice of components. Why not use a regulated power supply?
The 8 watt hiraga which did get his name le monstre from a stax 8 watt amplifier using a 1200 va power transformer has been elaborated using more capacitors, car batteries, supercapa. Hiraga then did write that regulated power supplies did have advantages but sonically using no active components was the way to go.
I think if 30 watt power output will not be enough then 35 watt will not be enough either. I think you will need a big choke to make it work like a choke input. Using 200mhenry there would probably give the the voltage a huge swing when switching on. It used to be easy to get 20 henry tango chokes suitable for choke-input tube designs. They were not exactly cheap ( even when bought in Japan) but i did buy eight at once after having tried one. Using a choke-input for a hiraga amp will make the voltage drop close to the original ones. I do have some chokes 100mh 1,3 ohm 1,3A potted and 400mh 4,2 ohm 2A not potted. The ones in the hiraga were 200mh not potted. I remember switching to a choke-input with my tube amps ( which also meant using another power transformer ( same VA) to compensate the voltage drop did give it more authority. If one day i will switch to bi-amping and using solid state for the bass i would surely get myself a choke input power supply. They will be at least 10 cubic centimeters make it 15 to be sure but it will be more beneficial than doubling the va of the power transformer.
If you would be in europe i would lend you a pair to give it a try. But now i realize you use the same powersupply for both channels so the 100mh will be tortured to much. Allthough it is a professional part ( made by bourdeau something like French Emt ) it will probably have a short life or the induction will drop to much.
Greetings, Eduard
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Old 30th April 2008, 10:39 AM   #107
eduard is offline eduard  Netherlands
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Hello,
I remember reading a german review where the writer did get a kind of strange sensation because of this holographic imaging. He did ask if somebody did put a kind of drug in his coffee.
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Old 1st May 2008, 02:13 AM   #108
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Quote:
Originally posted by eduard
Hello Daniel,
I did take a closer look at your pictures and i think it will be difficult to incorporate these chokes somewhere. Because my job is about making holes in metal sheets i know the trouble you have been through???
If your chassis layout is close to the one used by the original hiraga. You could try mounting the choke under the first capacitor with some long-sized stand-offs . If they are potted and to high you can make a rectangular or square hole in the bottomplate. This way you can gain some soace if the feed you are using are a few centimeters high. The amp once completely finished will get quiet hot. On the cd-rom you can read that they did spend a lot of time to improve heat circulation in the chassis. Mounting the heatsinks with their '' backs '' against the sides of the chassis will cool them down but will make life hard for the capacitors. Mounting them with sturdy stand-offs about 15 mm long will create a kind of chimney effect so air can rise on all sides of the heat sink. I remember Hiraga did talk about this before making the chassis that was widely known as le classe A.
The replcement for the original power transistors were considered better by the magazine and all the people that did build these monsters. Maybe some french internet sites have more updates on the hiraga amps. BUT this amp was described as a perfect marriage of design and choice of components. Why not use a regulated power supply?
The 8 watt hiraga which did get his name le monstre from a stax 8 watt amplifier using a 1200 va power transformer has been elaborated using more capacitors, car batteries, supercapa. Hiraga then did write that regulated power supplies did have advantages but sonically using no active components was the way to go.
I think if 30 watt power output will not be enough then 35 watt will not be enough either. I think you will need a big choke to make it work like a choke input. Using 200mhenry there would probably give the the voltage a huge swing when switching on. It used to be easy to get 20 henry tango chokes suitable for choke-input tube designs. They were not exactly cheap ( even when bought in Japan) but i did buy eight at once after having tried one. Using a choke-input for a hiraga amp will make the voltage drop close to the original ones. I do have some chokes 100mh 1,3 ohm 1,3A potted and 400mh 4,2 ohm 2A not potted. The ones in the hiraga were 200mh not potted. I remember switching to a choke-input with my tube amps ( which also meant using another power transformer ( same VA) to compensate the voltage drop did give it more authority. If one day i will switch to bi-amping and using solid state for the bass i would surely get myself a choke input power supply. They will be at least 10 cubic centimeters make it 15 to be sure but it will be more beneficial than doubling the va of the power transformer.
If you would be in europe i would lend you a pair to give it a try. But now i realize you use the same powersupply for both channels so the 100mh will be tortured to much. Allthough it is a professional part ( made by bourdeau something like French Emt ) it will probably have a short life or the induction will drop to much.
Greetings, Eduard
I have used choke input supplies with tube amps before & I tend to agree it improves the supply quality alot.
If i do use a choke I will probably mount it inside the case near the capacitor terminals.
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Old 1st May 2008, 02:17 AM   #109
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Quote:
Originally posted by eduard
Hello,
I remember reading a german review where the writer did get a kind of strange sensation because of this holographic imaging. He did ask if somebody did put a kind of drug in his coffee.

Did you see my little version of "Le monstre" ?

the link on my signature line below,

this particular amp had the imaging effect you mentioned and i am building the "Le class A" to achieve similar sonics with a little more power. ~30-50W

Interestingly the "le monstre" I built barely made 8W however sounds alot more powerful.

-Dan
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Old 1st May 2008, 11:02 AM   #110
eduard is offline eduard  Netherlands
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Hello Daniel,
I did see your monster. It is a baby monster. The people in France did use high efficiency loudspeakers to compare electronics. I did build the 30 watt because at that time i did have low eff. transmission lines.
L'' audiophile did sell the fostex 103 ( low eff but difficult to drive) triangle tqwt 95 db, onken bass cabinets around 99, altec vots bass cabinets 103 db, tad 2001 with sandfilled horns 109 db. The 8 watt offered by the monster equipped with a huge power supply will make you shiver.
In the eighties i did built the hiraga mc amplifier called le pre pre. Using lead batteries, 470000MF caps. The author ( called Chretien) did explain the reason for using the caps by saying that these caps have a much lower esr and batteries also make noise because of the chemical process. Because of the very small signals generated by the cartridge this noise will mask some of the music so it should be reduced as much as possible. Chretien did compare it to a balance to weigh very light objects. It has to be heavy as hell to do so.
Musical signals related to recreate ambiance are said to be extremely small so if there are signals coming from the power supply overruling these even smaller signals the holographic image will be gone.
Number 36 of l'audiophile did describe le monstre using 2 12 volts 40ah car batteries in 1985!! Completely charged it will give you about 3 and a half hour of listening pleasure. Giving each channel their own batteries will double this. Maybe modern technology batteries have a bigger ah for the same price and or volume.
I remember my PREPRE was allways in charging mode except during listening sessions but it did use sealed batteries not the kind used in cars.
Greetings, eduard
P.s get these cd-roms and be amazed
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