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Old 4th January 2013, 08:33 AM   #121
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Originally Posted by KSTR View Post
^ Yes, something similar to this. The xformer, rectifiers and main big reservoir can be shared while the sections after series resistors or other series elements (and in GND nets also) would be seperated between PCBs, being located on-board. Then a local GND bus connecting PCBs would establish a quiet and common GND. All this applies in case of mono PCBs (or multichannel >2CH), with stereo PCBs things would be rather simple; PSU (P2P or PCB), 3 wires, Amp-PCB.
I'm trying to "shrink" the simple version down to a size that would fit all on one board, but without omitting features.

I momentarily forgot what the series elements did. Fast is fast and dc is dc, and man I really forgot something. My DC (umbilical) power cable is 3-conductor, 20ga solid copper, insulated, twisted, and. . . with a knot in it. Well, that doesn't fit on 1-board compact builds and we wouldn't want to explain the knot. Assuming MBR1035 diode drops (instead of the cable) are the series elements at the output of the big power reservoir capacitance, I forgot the knot. Perhaps a very tiny ferrite bracelet on the leg of the MBR1035 can provide the same function as the knot?
FB43-226-RC J.W. Miller | Mouser
Eleven cents isn't a bad price for an audiophile part, and it is prettier than a knot.

And I forgot that the diodes had another job. The motivation to use them (or regulators) is that we could use large caps near the chip, without a dulling effect on audio. Panasonic Aluminum Electrolytic Capacitors - Snap In | Mouser Those large caps have very low ESR. Given the cable with knot or the diode with choke, is it then suitable to use a pair of these big caps instead of the multi-cap bank? High density capacitance would be so much easier to fit on a single board design.

It seems to be a bit difficult to make a 1-board design without compromising audio. The next step could be to get the bridge rectifiers on board in the fashion used for ham radio, tuners and integrated receivers. I've tried this with a real receiver at far fringe. MUR bridge rectifier utterly ruins the reception. KBPC1004's with approximately 3n3 polyester dip caps (lossy colorful bubble) parallel with each diode, didn't bother the reception. Am I on the right track?
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Last edited by danielwritesbac; 4th January 2013 at 08:51 AM.
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Old 4th January 2013, 10:28 AM   #122
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Originally Posted by gootee View Post
. . . PCB were used for only the chipamp circuit, that board could be mounted on short standoffs, OVER one end of the cap-array PCB. Then, the chipamp's power leads could go down through the small board and connect directly to the power planes.
This okay if amp front end is regulated. H o w e v e r . . .
We could try something without regulators, knowing that the omission needs a fix.

Problem:
If a simpler design is mounted direct to the power board, there's an omission. Usually an cable serves a filter function as an inductive resistor (filter) from amplifier enclosure to power enclosure. If that was omitted, it would be a downgrade to the typical sound of a chinese kit amp. This needs fixed.

Supplies:
If you remove regulators, diodes, and inductive cables from the list of possible series elements to use, that leaves: Resistor.

Fix?
When trying for a fix that doesn't involve a schottky diode, I ran for the bell wire, cat 5 cables, and ohmmeter. Short length 8" 20ga or 5" 24ga, got in the neighborhood of 0.12 ohms to 0.15ohms. That's got the resistor value of the cable, which is only one feature. Perhaps the RF filtering could be replaced with the little ferrite bead. So, the choked non-inductive resistor can replace the missing cable?
Question:
Quiet, non-inductive, and inexpensive. Will it do?
Perhaps it will be easier to measure than the audiophile play of selecting the perfect umbilical cable (filter) to connect amplifier enclosures to power enclosure?
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Last edited by danielwritesbac; 4th January 2013 at 10:35 AM.
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Old 4th January 2013, 12:50 PM   #123
redjr is offline redjr  United States
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Depending upon which we road the group takes here... If we want to experiment with the original amp PCB that both Bob and I used, I got a price/pair of $6.50USD from my vendor in China. I'm requesting a discounted price if we, say, order 20 pair - depending upon the level of interest. If we go with just the boards, we can further optimize performance using select components. I believe we could still make these PCB work with the PSU changes proposed in the earlier posts. I have not read Daniel's latest posts yet. However, if we want to go with a single, stereo PCB things obviously change.

Rick
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Old 4th January 2013, 01:13 PM   #124
KSTR is offline KSTR  Germany
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Quote:
Originally Posted by gootee View Post
For the reservoir caps, I would like to have consideration given to something similar to Terry Given's cap bank board. It uses a non-etched two-sided PCB. All you need is a drill. Use a slightly larger drill to remove copper from edges of holes for connections to bottom side. Cut cap leads, bend parallel to copper, and solder. Unless two PCBs were used, it would have to have all ground plane on one side and the power plane side would be split into two planes, for the power rails. The chipamp could be located over the line between the power planes. Check out the link and see what impedance Terry measured with his network analyzer!
That's a good an easy way to go. I have a scheme that is even more simple : Use a strip of double-sided blank PCB like 1" wide and 5" long and solder the caps directly along the two long edges,. This also is as low as it gets in term of inductance.

A network analyser is the weapon of choice to make a PSU that has low and consistant impedance, now that I have my own I learned so much about this in only a few weeks.... For example : an array of some 30 pieces of 47uF/50V of a moderate ESL type (Pana FC) with smallest lead spacing gives a completely flat profile up to 20MHz. No way I could achieve that with a couple of low ESR bigger caps with paralleled film caps, it always looked more ragged albeit a bit lower impedance in general.

---------:---------

As for the questions of etched PCBs or not, a well designed PCB always can cope with any other type of contruction and has the advantage that it is easy to recreate the original results for any builder even at low skill level. Also, cost is moderate if a batch of a dozen or so is made and if we don't use fancy options. The success of the MyRef FE is a good example, wiring up that thing on perfboard or P2P would be a hassle and problematic.
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Old 4th January 2013, 01:22 PM   #125
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My vote is for both directions. The cost/scope creep reality, if fully adopted, will not work for some budgets (and some with self control and common sense ) and limit their participation. The kit, current PCB, is remarkable even in a stock build and IMHO, deserves as much attention/improvement as it can attract. That may be all some builders need or want. Those board prices look very attractive an would encourage me to participate in a ground-up revision of the components.

Let me suggest the possibility of a split - two separate threads if the interest and need develops.
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Old 4th January 2013, 01:37 PM   #126
redjr is offline redjr  United States
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Originally Posted by bcmbob View Post
My vote is for both directions. The cost/scope creep reality, if fully adopted, will not work for some budgets (and some with self control and common sense ) and limit their participation. The kit, current PCB, is remarkable even in a stock build and IMHO, deserves as much attention/improvement as it can attract. That may be all some builders need or want. Those board prices look very attractive an would encourage me to participate in a ground-up revision of the components.

Let me suggest the possibility of a split - two separate threads if the interest and need develops.
Sounds like a wise approach to me. Even when doing a new PCB layout, the designer needs to account for the size of the components, if not the exact ones he or she recommends. Though the external components are few, it's still something that whomever does the layout needs to be aware of. If we can use the stock PCBs and populate with better components then it seems to me a very viable approach with a minimum of risk and additional time involved with a new PCB layout, prototyping, fabrication, etc from the ground up. But I'm just one member speaking.

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Old 4th January 2013, 01:47 PM   #127
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It is shame to waste KSTR experience and instruments in a P2P project, even on a perf, unless for components selection. PCBs, if a GB is setup, will not cost a fortune.
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Old 4th January 2013, 01:48 PM   #128
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Quote:
Originally Posted by bcmbob
The kit, current PCB, is remarkable even in a stock build and IMHO, deserves as much attention/improvement as it can attract. That may be all some builders need or want. Those board prices look very attractive an would encourage me to participate in a ground-up revision of the components.
Bob, I think you can determine whether the kit boards will do or not, after you try some small signal options on the amp boards and also some power board options.

At some point, hardship in component selection might indicate that upgrading to excellent design onto a dual layer PCB with an excellent layout is both a better quality and a considerably less expensive way to go.
Quote:
Originally Posted by KSTR
A network analyser is the weapon of choice to make a PSU that has low and consistant impedance, now that I have my own I learned so much about this in only a few weeks.... For example : an array of some 30 pieces of 47uF/50V of a moderate ESL type (Pana FC) with smallest lead spacing gives a completely flat profile up to 20MHz. No way I could achieve that with a couple of low ESR bigger caps with paralleled film caps, it always looked more ragged albeit a bit lower impedance in general.
Separate power board it is then. Thank you! That answered my capacitor question thoroughly.
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Last edited by danielwritesbac; 4th January 2013 at 01:51 PM.
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Old 4th January 2013, 01:57 PM   #129
redjr is offline redjr  United States
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Update!!! I can get 20 pairs of stock PCB for $4USD/pair with postage of $8USD. Maybe even a lower unit price if we order more than 20. That's an incredibly good price for 2 PCBs! Food for thought.

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Old 4th January 2013, 02:11 PM   #130
KSTR is offline KSTR  Germany
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Let me suggest the possibility of a split - two separate threads if the interest and need develops.
Agreed, the thread here should stick to this stock PCB/kit in question, which I think is quite a good layout for a single-sided design.

After finishing a 2p2/deadbug proto, I'll open a new thread on my take of a simple but excellent 7294 (stereo) amp which will have some design features that are not seen typically. Since double-sided PCBs are only a few % higher price (if at all) than single-sided, single-sided design makes no sense to me. Further, with double-sided the integration of the PSU section(s) is far easier.
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