There s 2 versions /
HMA 7500
HMA 7500 MK2
GM is blatant (simplified) copy of the second one....
Attachments
that was the intention of the thread starter, who is long gone
we have been through this a hundred times
LO-D???
there you go with the LO-D!! what the hell is LO-D its Hitachi the same designer of your Goldmund device!!!! same company that makes the output devices for the GM!!! so the GM is LO-D too? what do you mean by LO-D? explain to me please?
there you go with the LO-D!! what the hell is LO-D its Hitachi the same designer of your Goldmund device!!!! same company that makes the output devices for the GM!!! so the GM is LO-D too? what do you mean by LO-D? explain to me please?
Wouldn't dream of it.
Sure, Mr Yvon knicked the basic outline straight from the Hitachi amp, too young at the time to have developed his own IP.
Still doesn't mean a stripped and tuned HMA will be an equivalent.
one of the nicest sounding amplifiers I have heard was designed by someone named "Bay" not too sure of spelling. but he was a japanese guy who had a workshop in a place near Cricklewood I seem to recall. was very good used 1 or 2 2SK135's that was it its entire semiconductor count. ran in class A on batteries only a few watts by modern standards this was around the end of the 80's. ran a business designing one off bespoke audio. good thread that may make. anyway
i at the request of a good friend ventured over to Cricklewood Electronics a short time ago coz he wanted to build his own amp for his recording studio monitoring. whilst there I purchased some components some carbon 3 and 5 watt resistors that I use in my own amps that I have not built for some years now but I can certainly build a "GM" with them I may look at some alternative semi's but have 100/200 BF469/470/471/472 etcvarious others for "front end" just not had the time to re-do the PCB as I cannoty find the old artworks but have a few PCB design progs to try ( I am more used to manual taping) so will knock up a few PCB's to make my non-inverted GM see what all the fuss is about. I do rather fancy using stabilised psu all rails throughout just need towork on the front end a little but should be really straightforward. not really into the hi-fi thing nowadays been there worn the T-shirt..... so will have to design some reference speakers too coz at present do not have any due to selling them all off but think I have a friend with some ATC 3 inch units I could beg or borrow as a basis for a design. also have some beautiful "Avell Linberg" TX's around 3Kva will give me close to 90v a few volts either way for each rail then I suppose put all of it up on here for all to see just not hear
i at the request of a good friend ventured over to Cricklewood Electronics a short time ago coz he wanted to build his own amp for his recording studio monitoring. whilst there I purchased some components some carbon 3 and 5 watt resistors that I use in my own amps that I have not built for some years now but I can certainly build a "GM" with them I may look at some alternative semi's but have 100/200 BF469/470/471/472 etcvarious others for "front end" just not had the time to re-do the PCB as I cannoty find the old artworks but have a few PCB design progs to try ( I am more used to manual taping) so will knock up a few PCB's to make my non-inverted GM see what all the fuss is about. I do rather fancy using stabilised psu all rails throughout just need towork on the front end a little but should be really straightforward. not really into the hi-fi thing nowadays been there worn the T-shirt..... so will have to design some reference speakers too coz at present do not have any due to selling them all off but think I have a friend with some ATC 3 inch units I could beg or borrow as a basis for a design. also have some beautiful "Avell Linberg" TX's around 3Kva will give me close to 90v a few volts either way for each rail then I suppose put all of it up on here for all to see just not hear
not so sure as to the "nicked" it bit after all it was originally an application suggestion by Hitachi in the notes for the new wonder device called a MOSFET.
a device I have seen more badly understood and used very badly by hundred or more bad designers or companies that made them
I am now 52, been in this art, or discipline of knowledge since age 7.
i remember hitachi's press releases and the amps they made all of them. it is entirely possible to make a Hitachi HMA amplifier become a GM clone with little or no difficulty at all the GM is a clone of it with mods!!!!
Charlie relax
The thread started by a guy who loved this amp so much he wanted to make it exactly the same, that's why its a clone. People bought into it and it became a group buy. You gotta remember that guys here make lots of amps, old ones new ones, simple ones complex ones. Its not a big deal if someone wants to make a goldmund clone is it?as for Andrew T (self appointed forum police?) I am and shall always remain an enigma. I do not publish my findings or make what I know public. sometimes it causes problems for others but only when it is their own doing in the first place.( but still sorry Mr Ken Dibble, but it was not in the agreed contract for disclosure so tough!!!) I am not an educator so choose not to do so. I did not find any conditions when I joined ie a sction that said justify yourself or did I miss it? I will however un-subscribe to the thread it no longer has interest for me or purpose as I am not a GM cloner. but thanx anyway for your courtesy of allowing me to participate
thanx which is what I said in the first place nearly missed this coz I normally login from e-mail. but yes the GM is a Hitachi or a variation on it as are countless other production amps that use or badly use this topology there was one quite well known "pro audio " outfit that had the gates tied together (no bias at all) sounded crap but it sold all the same coz of hype ...600 billion flies cannot be wrong sh** tastes good!
so wanna good looking GM mod a HMA 7500 MKII but now know that is not the goal here.
but just shows GM is a rip off in the first place of Hitachi so...start a new project clone the original????
Hi Jacco
except the capacitor, what is the other changes
i must do with this 2 x 45v transformer
- How big the Bias ?
- Any component changes ?
Thank you, best regards
Pocoyo
Read what Nagys answered me about lowering voltage: #1065.
Invodonchev have measured(simultation) whats happens at a lower voltage
in #1010.
By the way: Where are all the other Golmund clone builders. Listening results/measurement??
Nikosokey: Interesting picture, but components on both sides of the PCB confused me. What have you done (more than the 10 pF)??
Eivind Stillingen
Read what Nagys answered me about lowering voltage: #1065.
Invodonchev have measured(simultation) whats happens at a lower voltage
in #1010.
By the way: Where are all the other Golmund clone builders. Listening results/measurement??
Nikosokey: Interesting picture, but components on both sides of the PCB confused me. What have you done (more than the 10 pF)??
Eivind Stillingen
that was the intention of the thread starter, who is long gone
we have been through this a hundred times
yes YOU have not me! still now I know eh?
thank you liliya
as a matter a fact i didnt want to build another amplifier
since i got aussie nx150
i want to build this to use some Talema left
and want to know which one the best amp i ever heard
best regards
