By that I think JP means less heat if the SMPS is not excessively large, because loss of efficiency manifests as heat. Power supplies in PC's are frequently oversized by large margins and I've never come across or heard of any problems due to too large PSU's.
GASCo, I don't think you have to worry about a 30W SMPS being too large. You just have a big safety margin. 🙂
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I have tried both SMPS and Class 2 transformers with the preamp. The Class 2 linear tend to be quieter. They don’t have the high frequency fuzz that can leak through. If you can find a used 800mA to 1000mA 12VDC wallwart - the type used for routers, those are ideal as a supply.
I'm piecing together the 0805/1206 SMD BOM. It looks like the BC860C (Q1,Q2), is hard to come by. Would a BC857C (BC857C-7-F Diodes Incorporated | Mouser) be a good alternative? They look very similarly spec'ed but the BC860C is the lower noise version? Any other good replacements or critical specs that should be matched?
It also looks like the "BC860CW,115" variant is available: BC860CW,115 Nexperia | Mouser. SOT-323-3 instead of SOT-23-3.
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I thought the 4 spaces to the left were inputs and the last to the right output. It's funny why the 4th space is offset, but I thought it was a layout constraint.
You may be right. It never occurred to me that the spacing might be irregular.
I thought that the two sets of RCA connectors on the right are outputs.
I thought that the two sets of RCA connectors on the right are outputs.
The fourth's also connects to the switch, like the 3 first ones while the fifth connects to the center connector. I believe to be an output, the traces must come from the center connector without passing through the switch
Thanks for that, GASCo. The spacing really threw me off. I'll be connecting the RCA's to the RCA/switch PCB via 2.54mm header connectors and short leads. That means I'll be able to rearrange the RCA's in a more logical manner.
That's a good transformer - although why did you remove it from its protective plastic case? Now you have to deal with line voltages, a wall plug, requisite earth grounding for electrical code, etc, and it is no longer a Class 2 (safe double insulated and essentially no risk of mains electrocution danger) transformer.
I guess if you planned on putting mains into an IEC receptacle on the case anyway, this is one way to go.
Visually an IEC connection is much more pleasant, in my (and my wife's for sure) opinion.
I'm working on the AKSA pre and 4 ACAs and I'm putting all PSUs inside the chassis. I just hope noise won't be a problem..
I'm working on the AKSA pre and 4 ACAs and I'm putting all PSUs inside the chassis. I just hope noise won't be a problem..
Gee GASCo, you're a busy man. A Lender, 4 ACAs, FHXLs, home renovations and a wife - giving X a go for multi-tasking!
PS: don't forget to feed the dog...
Hahaha. That's easy, Twocents, the dog will bark when hungry!! lol
Really, everything is halfway done, I hate that. Missing little parts here and there (all my fault when ordering stuff).
I didn't have any space in my garage to do woodwork until this last weekend, but the FHXLs are turning pretty nice at least! 🙂
Really, everything is halfway done, I hate that. Missing little parts here and there (all my fault when ordering stuff).
I didn't have any space in my garage to do woodwork until this last weekend, but the FHXLs are turning pretty nice at least! 🙂
I hear you, X. Thanks for the advice. I'll be careful with the line voltages and will provide the necessary grounding, etc. I have some experience with line voltages.
I would certainly have kept the transformer inside the plastic case if I could, but the PSU is too big to fit in the preamp case with the grid/mains pins attached. The plan is to test the preamp with the transformer inside the case. If it turns out to be too noisy, I'll move it out of the preamp case and use another similar PSU that's still in the plastic case.
I've been planning for a while now to have an IEC receptacle and mains switch on the rear panel. I'm sort of practicing for the M2 that's my next project.
Here is the LTSpice schematic for the Aksa Lender preamp with the BSP129 model included as directive. You will need the Cordel models txt file to run (you can get that from his website).
