wahab - That's a review for Mimesis 9. Not a 9.2. Mimesis 9 is a stereo amplifier, where as the Mimesis 9.2 is a monoblock. A pair of Mimesis 9.2s are significantly more expensive.
Well, in that case, i can only encourage people to build it,
at least, they won t be defrauded of some huge $ amounts...
at least, they won t be defrauded of some huge $ amounts...
If to obtain the targeted sound quality such mechanical work should be done as described in attached Mimesis3 jpg document I will not be able to build this amp, the metal is out of my reach!
I attach also the complete ABS review of Mimesis9 in pdf file. Excerpts of this review was already given by the link included in c2cthomas previous post.
I attach also the complete ABS review of Mimesis9 in pdf file. Excerpts of this review was already given by the link included in c2cthomas previous post.
Attachments
Is OP amp module same as A1?
Nagys Audio - Products - Provider of High End Audio Interconnect Cables
Attachments
Look at the warranty. Ten years parts AND labor. I know of no other warranty that nice except Bryston. Several bad design issues and you are out of business.
We need to go ahead with this pcb thing. There are many hungry soldering irons on the workbench at DIY audio.
Has anyone every experienced the transitor vibration issues stated in the Goldmund writeup. Supposedly the reason for potting the input stage.
Tad
We need to go ahead with this pcb thing. There are many hungry soldering irons on the workbench at DIY audio.
Has anyone every experienced the transitor vibration issues stated in the Goldmund writeup. Supposedly the reason for potting the input stage.
Tad
NVD33 - perhaps this is issue of mechanical vibration not a show stopper. There are devices around that can mechanically isolate things such as PC hard drives. There is also a great deal of technology and tricks that we can borrow from TT mechanical isolation. Do not despair or give up just yet - for all we know this is just sales brochure cow manure - or perhaps something not of importance at lower wattage levels. Buuuuuuut perhaps Goldmund is onto something here! After all if you put a transformer under increasing heavy load you can feel the mechanical vibration increase with load and often times hear the sound of the transformer increase with load. Such vibration of the transformers windings if often experienced with poorly made or badly aged xformers. I think that by using quality parts and some rubber isolators (or whatever) the problem could be licked - perhaps even made better.
AND - - - - it could be a valuable lesson for other amplifier mods as well!!!! Papa and ZM would sxxx their paints if they found out that such a consideration to design could result in measurable improvement!!! 😀
Last edited:
I wonder about a statement like There are many user who have broken Goldmund equipment.....
Nagys Audio - Products - Provider of High End Audio Interconnect Cables
and I wonder about the use of both a zobel and output series inductor
Nagys Audio - Products - Provider of High End Audio Interconnect Cables
and I wonder about the use of both a zobel and output series inductor
apexaudio - Yes, the Goldmund A1 module is the same as the OP amp module in my schematic.
Guys, I wouldn't worry about the mechanical issue. Yes, it helps. Yes, Goldmund uses it, because they can and they charge lots of money. Yes, it does make a sonic difference. But it has nothing what so ever to do with the amplifier working properly, or not. It's the same as putting hard metal cones under the heatsink, or where the output transistors are located, only that Goldmund incorporated it into the entire design. Please do not make this into something it's not.
Guys, I wouldn't worry about the mechanical issue. Yes, it helps. Yes, Goldmund uses it, because they can and they charge lots of money. Yes, it does make a sonic difference. But it has nothing what so ever to do with the amplifier working properly, or not. It's the same as putting hard metal cones under the heatsink, or where the output transistors are located, only that Goldmund incorporated it into the entire design. Please do not make this into something it's not.
Last edited:
tryonziess - There are 47pF X 5 capacitors in the schematic in the input stage to prevent the amp from oscillating. This is exactly what you are asking for I think.
tinitus - There are just as many audiophiles with broken equipment as there are with Bryston, or Ayre, or Levinson, or Boulder, and the list goes on. The Zobel and the series inductor are both necessary because this is a wide bandwidth amplifier, it might oscillate without them. Not a bid deal at all.
apexaudio - I do. Do you really want it? It's kind of useless IMO. If it senses DC on the output, the relays disconnect the speakers. It was always finicky and the problem of a lot of Goldmund amps, I'm not a big fan of it.
The original Goldmund schematic that I have is in such a bad shape that I'll have to either draw it in Photoshop, or by hand. So it might take some time.
The original Goldmund schematic that I have is in such a bad shape that I'll have to either draw it in Photoshop, or by hand. So it might take some time.
Doesn't the Zobel work better when mounted to the back wall of the chassis?
Leach decided this was an issue in the Super Leach amplifier. Catch the high frequency critters before they infect the board.
Which particular Goldmund amp is this pcb being designed for. Is it a current production model or something a little bit older?
And yes Nags the caps you mentioned are what I was concerned with, thanks.
We rarely get to visit the ultra high end arena in DIY and this is, money wise, the ultra high end, excluding tube amps.
Since I am not familiar with the European Audiophile amp offerings is Goldmund a fixture for the super rich?
TAd
c
Leach decided this was an issue in the Super Leach amplifier. Catch the high frequency critters before they infect the board.
Which particular Goldmund amp is this pcb being designed for. Is it a current production model or something a little bit older?
And yes Nags the caps you mentioned are what I was concerned with, thanks.
We rarely get to visit the ultra high end arena in DIY and this is, money wise, the ultra high end, excluding tube amps.
Since I am not familiar with the European Audiophile amp offerings is Goldmund a fixture for the super rich?
TAd
c
I already have all in my production, I don't like use protection with relay in high-end amps (post #43 http://www.diyaudio.com/forums/solid-state/173462-studio-reference-amplifier-5.html)... You don't use protection circuit and evan fuses are drop. Do you want protect your expensive speaker of DC?
Last edited:
Kind of...
I often go to Switzerland ( it s 25KM from my home)
and i can aknowledge that it s a very very original
country with some very original guys as well...
http://www.goldmund.com/products
Last edited:
tryonziess - Having Zobel on the board is no problem at all. As a matter of fact, all Goldmund amps have the Zobel on the circuit board.
This particular PCB is for a Goldmund Mimesis 9.2 mono block. It's not a current production. This amp was in production during the 90s.
Goldmund overall probably makes the most luxurious and expensive equipment in the world. Their speakers cost $250,000 and up. Their home theater room costs millions. Every component from current production is made out of precision machined metal in the same Swiss factory that only has 2 other customers, Rolex and Patek Philippe. So yeah, they are extreme. But their components also sound incredible.
This particular PCB is for a Goldmund Mimesis 9.2 mono block. It's not a current production. This amp was in production during the 90s.
Goldmund overall probably makes the most luxurious and expensive equipment in the world. Their speakers cost $250,000 and up. Their home theater room costs millions. Every component from current production is made out of precision machined metal in the same Swiss factory that only has 2 other customers, Rolex and Patek Philippe. So yeah, they are extreme. But their components also sound incredible.
Just a further note. All Goldmund Mimesis amplifiers used the same exact schematic. Only difference is in the number of output transistors. Mimesis 9 and 9.2 used 3 pairs, while Mimesis 6 and 3 used 2 pairs.
I see some small issues with board layout
only 2 mounting holes
transistor legs solder points seems a bit far from heatsink
it cannot be mounted horisontal without mounting angle
parts of supply rail line seems smallish
many paralel copper lines
ofcourse I dont know, but it seems to me you may find it better to have supply and groundplane closer to the middle of board
if boards a professionally done, it would be natural to use double sided boards
but ofcourse that would make a DIY copy difficult
only 2 mounting holes
transistor legs solder points seems a bit far from heatsink
it cannot be mounted horisontal without mounting angle
parts of supply rail line seems smallish
many paralel copper lines
ofcourse I dont know, but it seems to me you may find it better to have supply and groundplane closer to the middle of board
if boards a professionally done, it would be natural to use double sided boards
but ofcourse that would make a DIY copy difficult