Hiraga "Le Monstre"

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danieljw

danieljw

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Joined 2005
Paid Member
neazoi said:
I am glad you wish to make the battery version, that makes two of us :)

Before I print the PCBs I am trying to add the option to accept a precision trimmer for 1K too, in order to set the bias correctly. Audiomanics, if you could provide the pcb file it would be much easier than trying to edit the image.

http://www.eshops.gr/index.php?act=viewCat&catId=589
Click to expand...

I think that is a good idea at first to get the bias 100% right, then (if necessary) replace the trimmer(s) with fixed value. the only thing is the trimmers need to track exactly so both bias resistance values are equal.

-Dan
 
N

neazoi

Member
Joined 2007
qrp.gr
TzeYang,
Despite of it's simplicity, this can not be considered a cheap amplifier. Finding these odd transistors and FETs, aquiring the big heatsinc and capacitors used, even buying the batteries (if you select this mode), all these are expensive. The resuld with bad quality components may not be as good.

I suggest, If you need something cheap you may try some of these class AB kits available on commerce.
 
N

neazoi

Member
Joined 2007
qrp.gr
danieljw said:


I think that is a good idea at first to get the bias 100% right, then (if necessary) replace the trimmer(s) with fixed value. the only thing is the trimmers need to track exactly so both bias resistance values are equal.

-Dan
Click to expand...


You are right, modifying the PCB for that won't be necessary as you need dual gang pontentiometers, because the value must be equal on both 1k bias resistors in each channel. If you need you could just connect two wires and a dual gang pontentiometer at the place of 1Ks...
 
nelsonvandal

nelsonvandal

Member
Joined 2006
TzeYang said:
My friend wants me to build a relatively cheap speaker amplifier for his BR2 and I was wondering if the Hiraga Class A is up for the task.

It's 6 ohms and looks a bit demanding so to increase current output any changes such as paralleling output transistors I should consider?
Click to expand...
Why not hava a darlington output stage using SC4793/SA1837 as drivers and sc5200/SA1943 as output transistors? Just fire up LTSpice.
 
audiomanics

audiomanics

Member
Joined 2004
techgraphix.nl
neazoi said:
Audiomanics, if you could provide the pcb file it would be much easier than trying to edit the image.
Click to expand...
Yes, i could and i will.. But can you handle Malz++Kassner CAD6 files? As i draw the entire PCB by hand, all soldering-eyes, lines and components are drawn from scratch, so no "self-always-wrong-thinking" PCB program for me..
I tried to find a emailaddress on your site, but for me that's unreadable..

Kees
 
danieljw

danieljw

Member
Joined 2005
Paid Member
neazoi said:



You are right, modifying the PCB for that won't be necessary as you need dual gang pontentiometers, because the value must be equal on both 1k bias resistors in each channel. If you need you could just connect two wires and a dual gang pontentiometer at the place of 1Ks...
Click to expand...

previously i have started with the initial bias resistance value then soldered alligator clip leads to a dual gang pot to deacrease the resistance value... then turn the amp off remove pot/resistors measure and replace with fixed.... takes a little while but works well

-Dan
 
S

Stefano

Member
Joined 2002
Nelson Pass said:


In my experience the opposite is true. I have never had a FET amplifier
give me trouble with RF.

Le Monstre is a classic design, and there are several contemporary
pieces which are homages to it whether the designer knows it
or not.

I do think, however, that device technology has improved enough in
the last 26 years that it can be made better.

:cool:
Click to expand...


Nelson I would like very much if you give us your personal interpretation of Le Monstre!
 
L

Lumba Ogir

Banned
Joined 2005
Dan,
regarding transistor substitution, as for the J-FETS, only Toshiba has provided matched complementary pairs (it`s hard to do technically). Instead of 2SC1775, 2SC2362 or 2SC2240 would be suitable.
Some choices for the drivers:
From Sanyo
2SA3600/2SA1406
2SC2911/2SA1209
From Toshiba
2SC3423/2SA1360
From Hitachi
2SD1609/2SB1109
 
L

Lumba Ogir

Banned
Joined 2005
ericfe1975,
this could be something for you, no feedback (not quite true), giving a more natural sound.
 

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danieljw

danieljw

Member
Joined 2005
Paid Member
Lumba Ogir said:
Dan,
regarding transistor substitution, as for the J-FETS, only Toshiba has provided matched complementary pairs (it`s hard to do technically). Instead of 2SC1775, 2SC2362 or 2SC2240 would be suitable.
Some choices for the drivers:
From Sanyo
2SA3600/2SA1406
2SC2911/2SA1209
From Toshiba
2SC3423/2SA1360
From Hitachi
2SD1609/2SB1109
Click to expand...


thanks lumba i will look these up and see what they are like...
 
danieljw

danieljw

Member
Joined 2005
Paid Member
i have been doing some searchng for components to rival or preferably better the original Monstre output stage.... not alot of luck.... any ideas any one ?


so far i have ocme up with - 2SC5198/2SA1941 100W, Cob ~170pF, Ic 8A.... Ft 30MHz..

http://www.semicon.toshiba.co.jp/docs/datasheet/en/Transistor/2SC5198_en_datasheet_061110.pdf

or

so far i have ocme up with - 2SC5197/2SA1940 80W, Cob ~120/260pF, Ic 8A.... Ft 30MHz..

http://www.toshiba.com/taec/components2/Datasheet_Sync//66/7667.pdf

-Dan
 
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