Who says the fakes have to be lateral? You're giving the fakers a lot of credit there.Faking lateral mosfet? No way! Considering the small size of the market, anyone who fakes TO-3 lateral mosfet for a profit must be insane.
Just take a cheap vertical, relabel it as a lateral, sell a truckload of them and change your address. I think that's more like how the story goes.
Anyone who buys the stuff should be happy there's at least a piece of silicon in the package and it's some kind of fet. You're not always so lucky.
e.g. IIRC there was a Jfet group-buy in this forum a couple of years ago that turned sour because when the parts arrived (after being paid for), they turned out not to be Jfets.
Ah, you needed to remind me again that i returned the parts but haven't received the refund yet, along with 7 others.
Thanks, much appreciated.
http://www.diyaudio.com/forums/group-buys/110104-gb-2sk389-2sj109-77.html#post1705071
Thanks, much appreciated.
http://www.diyaudio.com/forums/group-buys/110104-gb-2sk389-2sj109-77.html#post1705071
Actually I have seen the inside of the original and the fake one, also the Exicon. The original Hitachi just well built (even compared to the Exicon).
Usually a fake transistor has a worse build quality. But for the lateral they look good so most probably it is a relabel of other well built transistor. But honestly I haven't seen a thick TO3 vertical...
Why are you saying that I'm giving the fakers a lot of credit? And sorry, you don't have to tell me about that group-buy, the organizer is very ignorant.
If you can't distinguish a vertical from a lateral from their characteristics, don't diy audio.
If you can buy a truckload of semicon, you surely know what's COD.
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bigpanda and everyone else who's part of the group buy: I would prefer if the circuit boards had no masking of any kind. Especially on the top, the "Ground Plane." There will be all sorts of things soldered to it and it makes it significantly easier to work with if the board is not masked. Goldmund does not solder mask their board at all, the top nor the bottom. So I would prefer it if the boards were completely unmasked. What is everyone's thoughts?
When I said "well laid out", I didn't mean it artistically but technically. It is coincident that Goldmund can do it artistically. The ground plane helps a lot to do it easily.
In the Goldmund you can see also that the feedback and signal path is very short. The vertical arrangement of the mosfets help a lot. Signals are kept away from power supply.
I build my amps point to point. The most difficult is to arrange the ground plane in three dimensional space, and to keep the signal away from the supply. And I hate the output zobel and inductor when it is mandatory!
We certainly mean the same thing. Maybe I did not use the correct word. Anyway, some of my layouts were technically different but as it showed up "not technically" enough... since they oscillated. ;-) My point is still that a 100% correct schematic, 100% transfered to a PCB might give you a 100% nice oscillator. ;-)
But you have to admit that:
If you lay out the schematic 100% technically, you will not get artistic looking PCB. In other word, if you apply even a slight "art" to your PCB, your lay out will not 100% correct.
A "flowing" layout is safe. But short path also give benefit to the sound. In order to get a short path we need also to know the effect of every detailed arrangement, which is still beyond me. For example, I'm afraid to make a crowded parts arrangement to get a compact size such as in the Goldmund pot. I also have never had a chance to hear the differences in layout arrangements. I only have the experience to hear that short path with firm connection (point-to-point) sounds better, and crowded part may lead to oscillation.
I also learn from many PCBs, especially those that is famous for it's oscillation statistics (such as Elektor's Crescendo) and those intended for high slew rate amp (such as the Stochino). BTW, Rod Elliot's P101 pcb is cool.
Maybe you are right. I made my layouts too artistically. But that was definetly not my intention. I had a 100% technical view. But as the good Homeros I may have slept... I am for the moment occupied by trying to transform my old layouts into a PDF file. It is not so easy as they were made in an old Cad program - Generic Cadd level 3. An ancient one and a bit hard to convert to more modern formats. But I will in time present some of my old layouts that was very critical and now and then made good oscillators. I might state at once that my intentions were:
1. High bandwidth before feedback. (100 - 300khz)
2. Low overall voltage and high Class A (0,6 - 1 A through end transistors)
By the way I tested many "Crescendolike" amps in those days. They had a bandwidth of 10 khz in open loop. And then a tremendous feedback giving them a RF bandwidth. I studied Otala and found out that if you have a low bandwidth in open loop you will not have satisfactory feedback in the upper frequence band and hence you will have this TIM distorsion. Well, there is much more to it and this will have do for the moment. And off course I am an amateur and by no means a professional electronic enginer. My methods were more like try and error than exact science. Anyway, to me, some of my designs sounded pretty good and were appreciated by many people. Right or wrong... ,-)
Goldmund was a strong believer in the theory that current caused vibration in electrical components and power supplies leads to 'dramatically deteriorated' sound quality.
In the brochure that was posted earlier, they claim to have been befuddled as to why the high current version of the Mimesis sounded poorer and it was when they used the mechanical grounding the magic came back. They did things like heavily potting the torroids to reduce vibration, coupling the torriods and output stage directly to the anti virbation feet. The chassis was decoupled from the vibration feet via teflon insulators.
Then there is the issue of the input stage. Nagys seems to think the input stage was on it's own board and potted to keep it secret. But according to Goldmund, the input stage is very sensitive to microphony effects and was deliberately decoupled from the rest of the curcuit and outpage stage vibrations. Nagys could be right, but Goldmunds own literature regards this as an important part of the mechanical grounding implementation, and the picture of the newer Telos amplifiers shows the same exact same thing, an input stage on it's own board. (but with no potting)
All taken with salt of course...
In the brochure that was posted earlier, they claim to have been befuddled as to why the high current version of the Mimesis sounded poorer and it was when they used the mechanical grounding the magic came back. They did things like heavily potting the torroids to reduce vibration, coupling the torriods and output stage directly to the anti virbation feet. The chassis was decoupled from the vibration feet via teflon insulators.
Then there is the issue of the input stage. Nagys seems to think the input stage was on it's own board and potted to keep it secret. But according to Goldmund, the input stage is very sensitive to microphony effects and was deliberately decoupled from the rest of the curcuit and outpage stage vibrations. Nagys could be right, but Goldmunds own literature regards this as an important part of the mechanical grounding implementation, and the picture of the newer Telos amplifiers shows the same exact same thing, an input stage on it's own board. (but with no potting)
All taken with salt of course...
When I designed my amps back in the 90-s I did not regard them as some kind of "springreverbs" like the ones you use i guitar amps. Maybe that was a big mistake. It probably is of significance! But back then I was more concerned about noise from the net, passing through transformers etc and interfering with the audio signal. This, I was certain created IMD. badly decreasing sound quality. So apart from using separate power sources for the input and output stages I put a lot of time in developing "complicated" LC circuits and filters to clean up the power. An attempt to get it more "batterylike". This I still think is a very important matter. We have here in Sweden mr Svalander who gave this some hell of an effort 1980 - 1990. But it was not he who "woke" me up. It was a certain mr Jan Stridbeck, designer of some of Swedens best loudspeakers. Even now I regard the power source as the most important part when you are hunting that magic sound. You can use the best circuits and components in the world. But they all get ruined if you do not feed them well and ground them properly. I would say that this kind of IMD is far mor important than all other forms of distortions. Within descent limits off course.
A visit to any professional recording studio will show you just how important clean power and earthing circuits are - including the use of a "technical ground" that is a separate ground from the AC power panel and is used only with regard to grounding signal shields, signal grounds, etc. We used this scheme working around space based telecommunication gear.
fuse
Hi there,
First thank you for launching such a exciting project. As I would like to participate to this GB, I will do my homework comparing schematics vs PB.
I've had just a quick look, the fuse on the PCB is ON FRONT of the big cap (4.700uF) (not between C31 and C32) - on switch-on it could burn - unless a "slow" type used (?)
I will try to pass through it this afternoon...
Hi there,
First thank you for launching such a exciting project. As I would like to participate to this GB, I will do my homework comparing schematics vs PB.
I've had just a quick look, the fuse on the PCB is ON FRONT of the big cap (4.700uF) (not between C31 and C32) - on switch-on it could burn - unless a "slow" type used (?)
I will try to pass through it this afternoon...
Looks really good Alex! Can you please update the protection circuit and use this relay (Panasonic JTN1AS-PA-F-DC24V): http://pewa.panasonic.com/assets/pcsd/catalog/jtn-catalog.pdf
Please make sure that the circuit traces will work with this relay's legs/pin-out. This is a current Panasonic relay and a replacement for the old Panasonic relay that Goldmund used. This relay is inexpensive and is available everywhere, so a great choice to use.
Thank you again for very quick work. Please contact Bigpanda so that he can receive your new files.
Please make sure that the circuit traces will work with this relay's legs/pin-out. This is a current Panasonic relay and a replacement for the old Panasonic relay that Goldmund used. This relay is inexpensive and is available everywhere, so a great choice to use.
Thank you again for very quick work. Please contact Bigpanda so that he can receive your new files.
Anyone who is interested in participating in the group buy, please go here and follow post #6: http://www.diyaudio.com/forums/group-buys/175296-pcb-order-goldmun-clone.html
We are getting close to the final version of the board now. Only a few minor changes remain.
We are getting close to the final version of the board now. Only a few minor changes remain.
