Everyone who would like to be a part of the group buy, please go here http://www.diyaudio.com/forums/group-buys/175296-pcb-order-goldmun-clone.html#post2332200 and submit your order to bigpanda. The group buy is being put together right now.
The circuit and PCB board is 100% correct and ready for prime time!
The circuit and PCB board is 100% correct and ready for prime time!
Nagys:
Please build TWO before you make the group buy.
You build one and let someone with some experience build the other one.
SAVE the head ache and pocketbook ache of a rush to build, U don't know, what U don't know at this juncture.
Russian to build is a formula for WMD and MAD to paraphrase some COLD war rhetoric and mnemonics.
Please build TWO before you make the group buy.
You build one and let someone with some experience build the other one.
SAVE the head ache and pocketbook ache of a rush to build, U don't know, what U don't know at this juncture.
Russian to build is a formula for WMD and MAD to paraphrase some COLD war rhetoric and mnemonics.
Geez, where the heck is P-A??
He really freaked me out with his no-group-buy-without-prototyping-first stance. And heck, my board was as simple as it can get.
I don't know a jota of this thread, but I hope you're a really experienced fella that you try a group buy without a prototype. You better be
Have fun, Hannes
Hi All,
I've been reading this for the last two days trying to catch up. I've built a number of tube amps, preamps, and a couple of tube phono stages. I have a question. In the PDF reprint of Absolute Sound's review the author asked Reverchon to explain the performance of the amp. Reverchon says there are several other features, in fact, used by other amplifier designers, that contribute to overall performance. "There are no capacitors in the signal path and no electrolytics anywhere near the signal path." I've read all the posts from 1 to 450 but did not find the answer to this question. What distance is defined by the term "near the signal path". Thanks in advance!
I've been reading this for the last two days trying to catch up. I've built a number of tube amps, preamps, and a couple of tube phono stages. I have a question. In the PDF reprint of Absolute Sound's review the author asked Reverchon to explain the performance of the amp. Reverchon says there are several other features, in fact, used by other amplifier designers, that contribute to overall performance. "There are no capacitors in the signal path and no electrolytics anywhere near the signal path." I've read all the posts from 1 to 450 but did not find the answer to this question. What distance is defined by the term "near the signal path". Thanks in advance!
Dougie085 - Why does something have to be 100% perfect? Isn't this a DIY forum? I'm assuming that the potential builders will at least understand the fundamentals of electric circuits and be fairly handy? So lets say one might have to substitute a part, or make something fit better on the board by drilling additional holes, or omitting a part, or modifying the tracks slightly with jumpers, etc. This is all part of the fun and part of building any circuit. This is not meant to be a production PCB.
This is a fairly simple amplifier, with minimum amount of parts. The PCB will no doubt work properly. Everything else is up to each individual builder.
This is a fairly simple amplifier, with minimum amount of parts. The PCB will no doubt work properly. Everything else is up to each individual builder.
Yes order 2 boards first or etch them to test it.
You can divide the additional cost to the total order which won't add much if 100 boards or more are ordered
I think the concern for most people is that this is a wide bandwidth amplifier, so pcb layout becomes quite important for stability.
You can divide the additional cost to the total order which won't add much if 100 boards or more are ordered
I think the concern for most people is that this is a wide bandwidth amplifier, so pcb layout becomes quite important for stability.
buying the boards are not so much of a big issue
but its a lot of work for those who handle the GB
and a personal pain to them if something should have been corrected
and its a big issue for those who might be unlucky to burn it because of a simple stupid error
if you buy the boards, I suggest to at least wait with building it, until at least one brave member has done the first moves, and approved it to work properly
preferably with measurements
just my 2 cents
I would suggest a bit longer time limit on this GB
why the rush anyway
Im surpriced there havent been any demands for measurements
There usually always have been that, with other designs
but its a lot of work for those who handle the GB
and a personal pain to them if something should have been corrected
and its a big issue for those who might be unlucky to burn it because of a simple stupid error
if you buy the boards, I suggest to at least wait with building it, until at least one brave member has done the first moves, and approved it to work properly
preferably with measurements
just my 2 cents
I would suggest a bit longer time limit on this GB
why the rush anyway
Im surpriced there havent been any demands for measurements
There usually always have been that, with other designs
Well... The PCB has been checked over by many members against the original schematic, which is posted on page one of this thread. It's 100% identical. So if anything burns, it will be an error on the builder's part.
Once we all get the PCBs, I have no problem being the first one to attempt a build.
Once we all get the PCBs, I have no problem being the first one to attempt a build.
My concern is how many times in this thread have we read where the boards were said to be good to go than someone caught a problem, like the extra resistor just a few post back. Not trying to stir anything but I leaned a long time ago when something is rushed it usually doesn't turn out right.
Brad
Brad
Input stage bottom : 6V zener and 3K, is 1mA through each JFET.
Input stage top : 1mA and 3K, is 3V drop.
Vas : 3V -0.6V, 2.4V drop.
2.4V divided 375R equivalent emitter resistor, 6.4mA Vas bias current.
Makes ~1.73V across the bases of the drivers.
Read the Id-Vgs curve in the datasheets and calculate the quiescent current yourself.
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I'm all in already sent email to tony. I build things off of gut and this or the F5 will be my first intro to a solid state amp build. Having followed the thread since the beginning problems have been found with the original schematics by you , we can't check that since we don't have the amp. Hopefully all is good on that front now.
Sorry that with my non experience with SS amps I don't have much to offer.
Brad
R20 is a fixed bias resistor. It's not adjustable. Goldmund adjusts the bias at the factory with a variable resistor, measures the resistance, and then solders in a fixed resistor. Depending on which output MMOSFETS you decide to use, R20 will be between 270ohm-330ohm. Goldmund Mimesis 3 and Mimesis 6 (the amplifiers that I have) use 2 pairs of MOSFETS and their bias resistor is 330ohm. Goldmund Mimesis 9.2 (schematic from page one) uses 3 pairs of MOSFETS and the bias resistor is 270ohm.
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I need a relay expert!!! bigpanda and Alex, maybe you can help chose the protection circuit relay?
Goldmund Mimesis 9.2 (schematic posted on page one) specs for a Panasonic JN1A-TMP-DC24, this relay is out of production and is no longer available.
Alex has created the PCB for the group buy (as I requested) with this original relay and its pin configuration/layout. Here's a picture:
The Goldmund Mimesis 3 and Mimesis 6 that I own, has a SDS Relais (Panasonic) S4-24V. Please see the picture below:
Unfortunately, this relay is also out of production. But it's easier to find. Here's a picture of its leg layout/configuration, please see upper left corner:
Both relays are approximately 20-30A, high frequency, fast switching, 24VDC. I'm not sure which relay to spec. This has been bothering me and before the group buy gets their boards, I would like the relay used to be readily available. And Alex's PCB have the correct pin/leg layout.
Can anyone recommend a new, in production, high quality relay that could be used in this circuit?
Here's the protection circuit's schematic:
Goldmund Mimesis 9.2 (schematic posted on page one) specs for a Panasonic JN1A-TMP-DC24, this relay is out of production and is no longer available.
Alex has created the PCB for the group buy (as I requested) with this original relay and its pin configuration/layout. Here's a picture:
An externally hosted image should be here but it was not working when we last tested it.
The Goldmund Mimesis 3 and Mimesis 6 that I own, has a SDS Relais (Panasonic) S4-24V. Please see the picture below:
An externally hosted image should be here but it was not working when we last tested it.
Unfortunately, this relay is also out of production. But it's easier to find. Here's a picture of its leg layout/configuration, please see upper left corner:
An externally hosted image should be here but it was not working when we last tested it.
Both relays are approximately 20-30A, high frequency, fast switching, 24VDC. I'm not sure which relay to spec. This has been bothering me and before the group buy gets their boards, I would like the relay used to be readily available. And Alex's PCB have the correct pin/leg layout.
Can anyone recommend a new, in production, high quality relay that could be used in this circuit?
Here's the protection circuit's schematic:
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Then woudn't the one change from the original schematic possibly be a variable resistor here if alex can make it work. Is the option not too because it is 3 watts?
Brad