Hiraga "le monstre"

[Ragnwald]

Originally posted by neazoi

I have found a series of audio note tantalums and I was wondering if they have better musical properties than the Shinkoh ones.

resistor comparsion

[neazoi]

Does anyone know where to find some non inductive 1 Ohm 5W resistors for this amplifier? Metal film Carbon film Metal oxide or better tantalum will do.

I have found some 3W metal oxide resistors. Will they do or they have to be 5W?
Thanks

[Salas]

Why not making a 6W MOX by parallel combination?

[neazoi]

What do you mean by MOX please? They have only 1 ohm ons not 2 ohm so I can parallel them. wuou mean series parallel combination? wont is add more noise than a single resistor?

[SQLGuy]

MOX = Metal OXide

Of course, you would need two 2 Ohm 3W to parallel into one effective 1 Ohm 6W.

Or you could just buy some 1 Ohm 5W metal oxides from Mouser... they're about $1 each.... but shipping to Greece might be impractical unless you need a bunch of other parts at the same time.

Maybe dalbani.co.uk?

[ericfe1975]

hello,

after reading about this nice amp "monster" , i have a few questions...

about stability: is there serious stabilities issues? i have read about how critical are the 1 ohm resistors and the layout, is there a big risk of oscilation?

does the monster with the new transistors , tip 30555 or 2sa1943, have the same warm sound ? ( like in the "modern schematic in this page : http://www.kk-pcb.com/hiraga.html )
how does the monster react when the output is shortcircuited?

i am asking because i can't decide if i should build a jlh or a monster.

help is apreciated.

[danieljw]

Hello Ericfe1975,

I have built and listened to a Le Monstre and a JLH Class A (1996 version) Perhaps I can help you out:

KK-PCB has the old JLH capacitor coupled version & Le monstre tip3055 version. In my opinion both of these designs are flawed but that is no reason not to use their pcbs if you select the correct components a - friend of mine in Melbourne has purchased Le Monstre PCBs from KK-PCB and they are of high standard.

JLH made a 1996 version which is has a output stage which is "DC coupled" offering much better performance than the original version per the man himself the first version was limited by the output cap.

Hiraga went to great lengths to select transistors which have the appropriate characteristics to achieve the high performance obtained by this amplifier. TIP3055 is simply not fast enough to achieve the performance of the original.

I would suggest if you have high efficiency speakers >90dB1W/1m more like 95-100dB 1W/1m then the Hiraga is excellent amplifier at 6-10W rms.

If you have moderately efficient speakers then the 1996 JLH with 22V and 2A bias will make slightly over 30W class A.

In terms of stability problems - In practice I found both amplifiers stable once the bias was setup and the amps was left to reach thermal equilibrium. I fact i had no stability issues at all.

*however i used matched transistors (and jfets for the le monstre)
and its best to select good quality potentiometers suitable for the the bias circuitry............

Either amp you build - JLH class A 1996 version or Le Monstre should not disappoint.

one thing i would like to note is on the Hiraga Le monstre the bias resistors are quite critical in terms of value (JLH has a pot) - for example i started with the initial value and them soldered different values after calculation twice to get the desired bias point.

PS: the thermal coefficient or "drift" of the resistors makes a difference in bias of these simple amplifiers which is one of the reasons Shinkoh Tantalums were used in the original Le monstre at something like @ ±50PPM°C. (excellent thermal spec) you can achieve similar results by increasing to slightly larger power rating resistors as the resistor will not heat up as much. ie thermal lag is greater with a higher power resistor in the same given circuit.

I wont comment on resistor sound or transient performance or magnetic end caps !!!

too much text already !!!!

Hopefully this helps and does not add to the confusion !

-Dan

[neazoi]

>and its best to select good quality potentiometers suitable for the >the bias circuitry............

To talk about specific items, how about these trimmers?

http://cgi.ebay.com/75H-100R-TRIMMER...arms=72%3A1205|66%3A2|65%3A12|39%3A1|240%3A1318|301%3A1|293%3A1| 294%3A50

http://cgi.ebay.com/3386F-1-101-TRIM...arms=72%3A1205|66%3A2|65%3A12|39%3A1|240%3A1318|301%3A0|293%3A1| 294%3A50

And how about the precision ones?

http://cgi.ebay.com/10pcs-3296-101-1...arms=72%3A1205|66%3A2|65%3A12|39%3A1|240%3A1318|301%3A1|293%3A1| 294%3A50



>*however i used matched transistors (and jfets for the le monstre)

Tantalums of 1-2% should be pretty matched already, shouldn't they? I have bought 0.5W audio note tantalums but I am not fully aware of their performance, although they should be much better than the metal film ones..?

Soon I will have 100 resistors of 1 ohm 5W metal oxide 5% so I can match them. The problem is when they heat up their values could change differently, couldnt they?



Will it be so much problem if the input fets are not matched? I am not aware if a disaster in sound could occur by using not matched fets, any thoughts?

[audiomanics]

Is a Cermet trimmer preferred above a Carbon?

Soon i will adapt the PCB a bit, so various types of trimmers can be mounted. I wil post it ASAP..
Wat is the length and diameter of the MOX-resistors? Maybe i can adapt the PCB for that too.
Further recommandations are welcome ofcourse..

BTW if someone is willing to make me two of these PCB's, i would be delighted..

Kees

[neazoi]

As long as I have the MOX resistors I will let you know. Some could do a bit of hack to connect different types of pontentiometers and resistors, it is not too difficult i think.
I usualy tend to alter a bit the pcbs to match the component sizes that I have available anyway.
I am going to make the pcbs at some time in the next months so if you are interested I can make you a copy.
Right now I am making a solid thick aluminum box.

I have also checked your PCB the components placement and the transistors placement and is seems ok, so I think I will go for it as I like the layoyt. At audio frequencies the layout should not be too much of a problem especially for these little pcbs and I see you are trying to keep in ming the star topology. I will try to make them when I have all the parts.

The question now is, what are good types of pontentiometers to use for the bias? Are Multi-turn trimmers fine? I think multi turn trimmers are not inductive like the multi turn pontentiometers. Anyway are there any suggestions for a good type of trimmer to use in the bias?