OK, here's the background:
I'm an EE working mainly in microwave/RF so professionally anything below about 1 MHz is just DC.
I used to be a hi-fi DIY-er, having built speakers and a turntable about 20 years ago, but for the past 10+ years I have been listening to a mostly Linn system, which on the whole I am reasonably happy with. (This can tend to polarize some people's views). Recently, though I have begun to feel that I could do better than simply shelling out tons of $$ to upgrade the sound, and I have browsed a few of the forums (fora?) here and picked up quite a few tips. Built a Class A headphone amp last year (no headphone jack on the Linns) which sounds OK apart from what sounds like some RFI.
Here are a few of my first thoughts and questions:
1. Interesting threads on new analogue ICs, mainly from AD. Is the AD797 still the IC of choice for a phono amplifier? I didn't notice any comments on the AD275: is this because no-one has tried it or it has been found wanting in some way?
2. Is there an article clearly describing linear PSU constuction in a hi-fi context: grounding paths, signal and mains grounds, analogue and digital grounds, ground lift resistors and chokes, what and where to 'star', caps and decoupling, layout issues, is the type of wire important...?
3. ...and regulation. Apologies if there's already a thread on this. I've used the LM317/337 in the past without much thought except that it seems like 'a good thing' to do. Recent reviews in the magazines of Tom Evans' "the Groove" preamps have highlighted teh importance of good PS regulation. Good in this context meaning low noise, wide bandwidth, rapid recovery time (slew rate I guess) as well as voltage stability. Any regulator experts out there who can comment, and maybe come up with a real hi-fi linear regulator design?
4. I have a LP12/Valhalla+RegaRB300/Asaka, and looking for a reasonable upgrade. Options that I can think of (not all mutually exclusive) are:
Build a 2-phase power supply for the ac motor;
Put in a dc motor (maxon?), and build a supply - feedback or not?
Rewire the RB300 with cardas (Incognito kit) and fit Origin Live counterweight, or
replace the Rega with an Ekos.
That's all for now from Wine Country, just wish we could get good English beer here.
I'm an EE working mainly in microwave/RF so professionally anything below about 1 MHz is just DC.
I used to be a hi-fi DIY-er, having built speakers and a turntable about 20 years ago, but for the past 10+ years I have been listening to a mostly Linn system, which on the whole I am reasonably happy with. (This can tend to polarize some people's views). Recently, though I have begun to feel that I could do better than simply shelling out tons of $$ to upgrade the sound, and I have browsed a few of the forums (fora?) here and picked up quite a few tips. Built a Class A headphone amp last year (no headphone jack on the Linns) which sounds OK apart from what sounds like some RFI.
Here are a few of my first thoughts and questions:
1. Interesting threads on new analogue ICs, mainly from AD. Is the AD797 still the IC of choice for a phono amplifier? I didn't notice any comments on the AD275: is this because no-one has tried it or it has been found wanting in some way?
2. Is there an article clearly describing linear PSU constuction in a hi-fi context: grounding paths, signal and mains grounds, analogue and digital grounds, ground lift resistors and chokes, what and where to 'star', caps and decoupling, layout issues, is the type of wire important...?
3. ...and regulation. Apologies if there's already a thread on this. I've used the LM317/337 in the past without much thought except that it seems like 'a good thing' to do. Recent reviews in the magazines of Tom Evans' "the Groove" preamps have highlighted teh importance of good PS regulation. Good in this context meaning low noise, wide bandwidth, rapid recovery time (slew rate I guess) as well as voltage stability. Any regulator experts out there who can comment, and maybe come up with a real hi-fi linear regulator design?
4. I have a LP12/Valhalla+RegaRB300/Asaka, and looking for a reasonable upgrade. Options that I can think of (not all mutually exclusive) are:
Build a 2-phase power supply for the ac motor;
Put in a dc motor (maxon?), and build a supply - feedback or not?
Rewire the RB300 with cardas (Incognito kit) and fit Origin Live counterweight, or
replace the Rega with an Ekos.
That's all for now from Wine Country, just wish we could get good English beer here.
Welcome aboard. My history is similar to yours - being out for about 20 years and looking to get back in. Not a whole lot has changed, actually. Learn the different forums and ask your questions or make your comments there. You should get plenty of comments for interesting questions.
JohnW said:
Welcome back to brewing your own (and you could do that too).
There are various writings on PSU layout. Doug Self analyses PSUs in his "Audio Power Amplifier" book. Fundamentally, it comes down to thinking about where the currents go, and assuming that all wires have a non-zero impedance.
Steve Harris wrote a very good paper in the AES about digital and analogue grounds which is probably available at the Crystal Semiconductor site.
Bill Whitlock wrote an AES paper about grounds, balanced working etc, which is probably available at the Jensen Transformer site.
With your grounding in RF, you shouldn't have any problems...
Hi, Thanks for the feedback.
Re the grounding tutorial - I have Doug Self's (first) book, and what he says about grounding makes alot of sense. I also looked at Ben Duncan's articles in HiFi news (Pre-amp design, early '80s) and he also has some interesting comments, particularly about ground-lifting.
I downloaded Bill Whitlock's app-notes from the Jensen site - thanks for the tip.
I noticed that there is also a new-ish thread about transformers and grounding with some useful tips too.
Maxon Motor - I didn't know about the Mars Rover! I had read about the Maxon motors being used in some high end T/T (Teres, I think). I heard some negative comments about this DC motor in terms of acoustic noise - whirring of the motor - anyone have any personal experience or comments?
J
Re the grounding tutorial - I have Doug Self's (first) book, and what he says about grounding makes alot of sense. I also looked at Ben Duncan's articles in HiFi news (Pre-amp design, early '80s) and he also has some interesting comments, particularly about ground-lifting.
I downloaded Bill Whitlock's app-notes from the Jensen site - thanks for the tip.
I noticed that there is also a new-ish thread about transformers and grounding with some useful tips too.
Maxon Motor - I didn't know about the Mars Rover! I had read about the Maxon motors being used in some high end T/T (Teres, I think). I heard some negative comments about this DC motor in terms of acoustic noise - whirring of the motor - anyone have any personal experience or comments?
J
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