Many forget to specify tolerance of the filter capacitors when specifying the impedance of the balanced connections.
the few times I have seen comment on capacitance tolerance there seems to be an acceptance of slightly wider tolerance compared to the resistances. Many suggest resistance tolerance should be 0.1% match or better to make balanced impedance worth the effort.
It seems that capacitance tolerance that matches this minimum standard should be around 1%.
It seems that 1% 100pF are easily available and should be good enough to maintain the HF balance.
Stray capacitances of cables and connectors does very occassionally get a mention. This Forum even discussed that recently.
The consensus is that the tolerance of cable and connector impedances is so small that they can be regarded as near ideal for most balanced topologies. But don't ignore them, bad cables will not be as good as good cables and that is down to cable tolerances. Some cables are specified as having welded insulation sleeves to help maintain the core to core spacing that is critical to the characteristic impedance/capacitance of the cable.
Hello, I am unable to edit the excel document but would love to contribute towards one of the SMD-assembled PCBs as well as a pair of the hypex regulators. This preamp should work wonderfully with another component originally detailed in Linear Audio, the Equal Opportunity phono preamp.
Watching this thread with anticipation.
Watching this thread with anticipation.
I've ordered a built SMD version with regulators and put myself on the list.
What are the modules?
btw, I live in the Hypex city in The Netherlands (Groningen), so could support where needed if there are shipment issues or anything.
What are the modules?
btw, I live in the Hypex city in The Netherlands (Groningen), so could support where needed if there are shipment issues or anything.
If you mean the Hypex Regulators then it is one each of these.
https://www.hypexshop.com/shop/shop.jsp?groupID=119
https://www.hypexshop.com/shop/shop.jsp?groupID=119
I understand that these are the regulators, but in the online excel file, there's also a column 'modules'. Next to this column is the one for the regulatos, so they seem to be different. Just not sure what and how...
Modules = fully built boards which I think has now been abondoned in favour of PCB's with soldered SMD components only.
Regulators as per post 368, though there are alternatives to the Hypex ones.
Regulators as per post 368, though there are alternatives to the Hypex ones.
I'm hoping to finalise in the next week or so.
I still need confirmation that the new BOM is OK - I'll check in case I missed something in the previous posts 🙂
Edit: What I might do is, with the approval of the mods, start a new, fresh thread which contains the current up-to-date information with the current offering and confirm pricing and availability.
We are nearing the 100 quantities. So even if we are not quite there, I'll go ahead rather than wait to hit 100 and then have a few people who will have missed out or those who will have lost interest!
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Hi Folks,
A basic question: Is the power supply also a part of the group by?
Put differently, do I only need to plugin in AC, connectors et all to the 'assembled PCB' OR do I have to assemble a separate power supply?
A basic question: Is the power supply also a part of the group by?
Put differently, do I only need to plugin in AC, connectors et all to the 'assembled PCB' OR do I have to assemble a separate power supply?
You need a seperate power supply. Just to clarify, as this has got confusing. The original discussion was over having either blank PCBs or fully assembled modules. As most can solder through hole it has now morphed into just SMD with the option of hypex regulators.
You have to procure and solder the through hole parts as well as build a PSU.
The PSU is built into the stereo PCB.
The power input is three wires (to J6) from a centre tapped transformer, or from a dual secondary converted to centre tapped.
The diode rectifiers and smoothing capacitors are on the PCB.
The regulators are on the PCB.
The smoothing capacitors and the regulators are through hole components and need to be acquired separately. The diode rectifiers are smd and should be ready assembled with the other smd components.
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Or alternatively and probably the easiest way, use two 18V DC Wall Suplies and connect them directly to J6 as -18V/0V/+18V.
The diodes on the PCB are a safeguard for preventing a wrong connection, so leave those in place.
It will also prevent any hum problems from radiating tranformers and/or induction from current peaks from the rectifier.
Feeding this preamp with DC gave a noticeable improvement in sound quality in my case.
The diodes on the PCB are a safeguard for preventing a wrong connection, so leave those in place.
It will also prevent any hum problems from radiating tranformers and/or induction from current peaks from the rectifier.
Feeding this preamp with DC gave a noticeable improvement in sound quality in my case.
I cannot recommend using smps to feed into this PCB.
One does not know the noise level from these DC wall supplies, unless one has access to sophisticated test gear and knowledge on how to use that gear to identify the quiet ones.
One does not know the noise level from these DC wall supplies, unless one has access to sophisticated test gear and knowledge on how to use that gear to identify the quiet ones.
All major SMPS suppliers specify the noise for their products, in this case mostly below 1% pp of output voltage, so 18V DC means roughly below 60mV RMS noise, way below the noise of an AC transformer being rectified.
Specified switching frequencies are always ultrasonic, far beyond hearing limit, so that information will do. All this noise will be perfectly suppressed by the Hypex regulators,
At the end it is only the quality of the sound reproduction that counts, and that is where the focus should be and not on technicalities.
So let everybody find out for themselves what should be the way to go .😀
Specified switching frequencies are always ultrasonic, far beyond hearing limit, so that information will do. All this noise will be perfectly suppressed by the Hypex regulators,
At the end it is only the quality of the sound reproduction that counts, and that is where the focus should be and not on technicalities.
So let everybody find out for themselves what should be the way to go .😀
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