Wow Squalor, sure!
You know, it's so rare that people gets the link with Dune that somentimes I don't get it too...
Last edited:
I've been trying to learn about part choices. During your development of this PCB, Siva suggested making room at C3-C8 for larger smoothing caps. What benefit do 12,000uF and up caps bring to the sound ? or is it just the quality of the caps that matter.
In the BIG thread, Panelhead mentions 15.4V zeners but later it is said they trigger the spike protection. Have you tried slightly bigger like these 13 volt ones ?
I read C13 has the most effect on sound but C9 is important too. Is C9 the best place to experiment in order to tune the amp sound to my lowQ speakers ? How much room does Fremen eddition have around C9 ?
I read R12 has a big effect on sound. Would the Vishay TX2575 be good here ? Shinkoh ? If I used Takman REY would there be a benefit using 1/2W ? What about upping to 3K7 ?
What effect does a DCB1 have on sound ?
In the BIG thread, Panelhead mentions 15.4V zeners but later it is said they trigger the spike protection. Have you tried slightly bigger like these 13 volt ones ?
I read C13 has the most effect on sound but C9 is important too. Is C9 the best place to experiment in order to tune the amp sound to my lowQ speakers ? How much room does Fremen eddition have around C9 ?
I read R12 has a big effect on sound. Would the Vishay TX2575 be good here ? Shinkoh ? If I used Takman REY would there be a benefit using 1/2W ? What about upping to 3K7 ?
What effect does a DCB1 have on sound ?
Both
Thanks to a voltage limiter protection the Fremen Edition will use 14.6V
No, only a few cap in C9 just sound right (IMHO): BlackGate STD/FK, Elna Silmic (not II), Elna RJH.
In Fremen Edition there is space for 16mm caps so you can try whatever you want.
In C13, IMHO, the most transparent cap is Mundorf Zn.
Chepear good sounding alternatives (K73-16, Sonicap Gen-I, Mundorf MCAP) exist but none is as good as the Zn (IMHO).
I don't know, BTW in the Fremen Edition all through hole signal path resistors are 1/2W.
Big, actually.
Sorry but I must go back to the BOM... it's a long job, it will not be finished today... if you want an idea on costs use the Ultimate BOM.
Is lead-free required? What solder do they use for DIY these days?Why not?
Exact dimensions are 114.3 x 100.3 mm
2 mm FR4
0.7um copper
blue soldermask on both sides
silkscreen on both sides
with and without electric test
For 6 PCBs and 12 PCBs
Thanks
...
Part selection was thoroughly discussed in the New 'MyRef C' thread.
My final configuration is well documented there, but here is a brief response to your questions.
Of course C13 is the crucial element. The stock Kemet part is awful, and nothing else you do to the amp can make it sound good with that part in the circuit. There are plenty of good choices, depending on how much money you care to spend. Dario went with the Mundorf ZN; I tried that but prefer Sonicap Gen I. Whatever you do, avoid using a bypass here. One good cap is better than a piece of junk with a super bypass.
C9 should be a Blackgate. Sorry, that's the truth. Others do not sound as good.
R12 affects the sound, but less than those first two items. I tried Xicon metal film, PRP, Shinkoh tant, and finally the TX2575. The Shinkoh is the more musical choice; the TX2575 the more accurate, perhaps too much so. I might extract the TX2575 and go back to Shinkoh. Let me know if you'd be interested in trying them.
Peace,
Tom E
My final configuration is well documented there, but here is a brief response to your questions.
Of course C13 is the crucial element. The stock Kemet part is awful, and nothing else you do to the amp can make it sound good with that part in the circuit. There are plenty of good choices, depending on how much money you care to spend. Dario went with the Mundorf ZN; I tried that but prefer Sonicap Gen I. Whatever you do, avoid using a bypass here. One good cap is better than a piece of junk with a super bypass.
C9 should be a Blackgate. Sorry, that's the truth. Others do not sound as good.
R12 affects the sound, but less than those first two items. I tried Xicon metal film, PRP, Shinkoh tant, and finally the TX2575. The Shinkoh is the more musical choice; the TX2575 the more accurate, perhaps too much so. I might extract the TX2575 and go back to Shinkoh. Let me know if you'd be interested in trying them.
Peace,
Tom E
Apart the solder we use the problem is that is illegal in Europe to import electronic goods that are not ROHS compliant... so yes: lead-free is required
Got the estimate for non ROSH compliant, so I should get new estimates tomorrow. Looks like the price for would not be much different, but shipping would be a difference. Should be less since we won't be going half way around the world twice. What I can remember from shipping drivers to Germany and GB, my shipping was less than half of what they quoted to ship back to me.
The China supplier offered Chemical Gold at the same price of ROHS HASL, if so get the quote for Chemical Gold.
DIY and many special cases do not have to use lead free solders.
Leaded solders generally perform better than any of the lead free.
Buy a eutectic solder. The cheapest and most generally available is 63/37.
Buy it by the half kilo, in various diameters, before it becomes too expensive or too difficult to source.
Leaded solders generally perform better than any of the lead free.
Buy a eutectic solder. The cheapest and most generally available is 63/37.
Buy it by the half kilo, in various diameters, before it becomes too expensive or too difficult to source.
Hi Andrew,
I use leaded solder (WBT), actually.
I'm not suggesting to use lead free solder but PCBs should be lead-free to avoid Customs problems.
I think the prototype boards are not going to come out too different. Unless the China supplier is new to you, I think going with them probably is lower risk. The factory of here is a two person operation, not sure what their quality is, just that I know some people have small quantities made there. The main difference between them and larger company is when it comes to small lots of orders.
That was what I was wondering when looking at the equivalent schematic in the data sheets.
Well, for 15 boards, lord knows why they quoted me that way, it equates to 39 Euros per two channels. Production minimum order is 150 boards. The price difference between lead free, chemical gold etc. would be different only in production. The owner mentioned that usually people are going to use solder anyway, so it might no make sense to use chemical gold on those solder points, which seems to make sense to me not to add another layer of different material. Gold plating is used where you really need that extra corrosion resistance, and is done on the full traces.
At the risk of sounding super silly - since the boards will be sold and used in pairs, would there be an advantage/possibility to create "mirrored pairs" for the sake of consistency in internal wiring and board placement options. Don't know if this has ever been done but I have seen it used on 2 channel single boards designs.
makepcb is much cheaper... 67€ for 6 boards excluding shipping (31€ via express courier or 13€ via air mail).
I don't know if it make sense but to me the red pcbs from the Ultimate GB seems to sound slightly better than green ones from the previous.
The only difference, apart color, is the gold plating.
It would be nice but production costs will double.
For sure the prototyping phase is not the right one but maybe we can consider it if and when a group buy is started (but at least 200 boards, 100 right and 100 left are necessary to be convenient, IMHO)
I've some news...
While making the BOM I've had to change some things on the PCB since some components are no available with the needed values or in the planned format so the PCB is going to have 1206 format resistors pads (which could accomodate also MELFs) and R11 is again a through-hole part.
I've upgraded to Eagle 6.0 and it was a great mistake!
Eagle 6 have several problems (some serious) and the 0.9.7 version is now only Eagle 6 compatible so I'll have to redesign it in Eagle 5, it will take a day or two more...
Last edited:
Dario,
Need to take into consideration shipping to others around the world. So if they ship to to, then you ship to other destinations. So what does that shipping include? If we get it shipped to us. I think it's good. BTW, maybe some gold plated and some not. I would not mind getting a set of each.
Need to take into consideration shipping to others around the world. So if they ship to to, then you ship to other destinations. So what does that shipping include? If we get it shipped to us. I think it's good. BTW, maybe some gold plated and some not. I would not mind getting a set of each.
Sorry, I can't understand well...
I don't know if the PCB factory ships individually but I don't think so. Not without a surcharge.
In every GB, from what I know, there's a single person who receive all PCBs and then package and ships them individually.
Making some PCBs with HASL and some with Chemical Gold would increase cost since the price goes lower with higher numbers...
BTW this sort of things should be discussed while organizing the GB, in this moment we're only trying to prototype the amp...
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.