Hi all,
I'm a brit that emigrated to Sing in March 2003 with my family.
In the last couple of years I've made my own phono stage which started as a Creek a like, and a dual mono power amp based on Randy Slone's Optimos, but now modified in a few areas. Very proud of both projects which sound fab - will post some pictures if anyone is curious.
I'm in the middle of archiving all my LPs onto my media server PC via a Midiman Audiophile 2496. I also have a modded xbox used for games and as a media centre.
Rest of the setup is Epos ES14 speakers, Linn Lp12, Origin Live modded Rega arm, Incognito arm wiring, tweaked Phiilips CD723 CD player, Pioneer 5.1 amp (using preamp out for L&R), Pioneer DVD & VCR player, NEC HT1000 projector, Yamaha Tape Deck, Home Theater Master MX-500 remote control which I haven't figured out how to use.
ttfn, Nick
I'm a brit that emigrated to Sing in March 2003 with my family.
In the last couple of years I've made my own phono stage which started as a Creek a like, and a dual mono power amp based on Randy Slone's Optimos, but now modified in a few areas. Very proud of both projects which sound fab - will post some pictures if anyone is curious.
I'm in the middle of archiving all my LPs onto my media server PC via a Midiman Audiophile 2496. I also have a modded xbox used for games and as a media centre.
Rest of the setup is Epos ES14 speakers, Linn Lp12, Origin Live modded Rega arm, Incognito arm wiring, tweaked Phiilips CD723 CD player, Pioneer 5.1 amp (using preamp out for L&R), Pioneer DVD & VCR player, NEC HT1000 projector, Yamaha Tape Deck, Home Theater Master MX-500 remote control which I haven't figured out how to use.
ttfn, Nick
Pictures.
Hi Nick.
Welcome to the fold.
It would be great to see your pics. Any details about your phono stage. I have just built a passive eq RIAA stage using opamps. Haven't tested it yet.
Are you processing the analog audio that you are storing on the server ? I mean applying noise reduction filters etc.
This must surely be a long process.
Cheers,
Ashok.
Hi Nick.
Welcome to the fold.
It would be great to see your pics. Any details about your phono stage. I have just built a passive eq RIAA stage using opamps. Haven't tested it yet.
Are you processing the analog audio that you are storing on the server ? I mean applying noise reduction filters etc.
This must surely be a long process.
Cheers,
Ashok.
Yep I live on the top floor of a condo and play stuff loud I haven't heard any complaints yet - maybe the volumes up too loud to notice!
It's taking ages to do my archiving, partly because I've been restarting everytime I improve the phonostage - but it's done to perfection (for me anyway) now so no more tweaking is required. I'm using cooledit and do a very gentle NR to take out some turntable rumble (which is low but visible) and then manually take out any big clicks. I'm also leaving things as 48Khz .Wavs at the moment because I have loads of disc space. So far I've done all my 7" and 12" singles and given them away to charity.
The basic design started off the same as in my creek 4140 integrated amp but with it's own dedicated psu, better components, a few circuit tweaks and shielding. It also uses opa2604 OpAmps whereas the Creek was NE5532. I put the design through Spice and using a made up inverted RIAA device I was able to get a near as damn it RIAA response. Noise is also very low. It's a two stage affair, the first is gain, then some RIAA correction in the coupling between the OpAmps, then final RIAA correction in the nfb loop of the second OpAmp.
It's taking ages to do my archiving, partly because I've been restarting everytime I improve the phonostage - but it's done to perfection (for me anyway) now so no more tweaking is required. I'm using cooledit and do a very gentle NR to take out some turntable rumble (which is low but visible) and then manually take out any big clicks. I'm also leaving things as 48Khz .Wavs at the moment because I have loads of disc space. So far I've done all my 7" and 12" singles and given them away to charity.
The basic design started off the same as in my creek 4140 integrated amp but with it's own dedicated psu, better components, a few circuit tweaks and shielding. It also uses opa2604 OpAmps whereas the Creek was NE5532. I put the design through Spice and using a made up inverted RIAA device I was able to get a near as damn it RIAA response. Noise is also very low. It's a two stage affair, the first is gain, then some RIAA correction in the coupling between the OpAmps, then final RIAA correction in the nfb loop of the second OpAmp.
welcome lah!
i miss singapore, having worked at jurong island for 4 years building oil and gas refineries.....
i miss sim lim square, funan center, where i spen weekends drooling over computer stuff!!!
hope to go there in the near future!!!
where are you staying, if you don't mind my asking...i stayed at clementi, west coast area....
Cheers,
tony
i miss singapore, having worked at jurong island for 4 years building oil and gas refineries.....
i miss sim lim square, funan center, where i spen weekends drooling over computer stuff!!!
hope to go there in the near future!!!
where are you staying, if you don't mind my asking...i stayed at clementi, west coast area....
Cheers,
tony
I'm kept busy running regional IT & telecoms for a money broker. And I live in place called Queentown - awesome 15 minute commute time!
Singapore is a DIY audio nut heaven, we have Sim Lim Square which is basically 6 floors of computer & audio bits shops.
Sim Lim Tower across the road gets even closer to the metal as it were, with 4 floors of what seems like Ma & Pa bulk component sellers and DIY electronics parts shops.
Then if you like stuff already put together Funan is great for PC's. Across the road the Adelphi centre is full of high end & some quite looney HiFi equipment. I didn't realise but Asia has quite a fan base for expensive HiFi, mostly bought by classical music fans I think.
My job's great for travel and picking up bits e.g. I got my galactic remote control from Sydney and Akihabra in Tokyo is where I got my opa2604s which I strangely couldnt find in Sing (though I've since realised I can get them from Farnell). I also go to Hong Kong, but haven't yet found where to get stuff from, but I'm sure it's there somewhere.
Singapore is a DIY audio nut heaven, we have Sim Lim Square which is basically 6 floors of computer & audio bits shops.
Sim Lim Tower across the road gets even closer to the metal as it were, with 4 floors of what seems like Ma & Pa bulk component sellers and DIY electronics parts shops.
Then if you like stuff already put together Funan is great for PC's. Across the road the Adelphi centre is full of high end & some quite looney HiFi equipment. I didn't realise but Asia has quite a fan base for expensive HiFi, mostly bought by classical music fans I think.
My job's great for travel and picking up bits e.g. I got my galactic remote control from Sydney and Akihabra in Tokyo is where I got my opa2604s which I strangely couldnt find in Sing (though I've since realised I can get them from Farnell). I also go to Hong Kong, but haven't yet found where to get stuff from, but I'm sure it's there somewhere.
Hong Kong shops.
You can get components in Apliu street. I think that I got the name right. Better get all directions correct before you go there. Most locals cannot understand English.
This is near the Gloden Dragon Computer center in Sham Shui Po. Kowloon. My memory is rusty.
You get all the hard to get chips and hardware ( tools etc). I used to spend a lot of time there.
Try Wing Shing Computer Components Co. for Audio grade parts.
Ph 852-2387-4940. There are many other shops on that street.
Best way to get there is by subway.
Try to get a copy of their Audiotechnique audio magazine. It is full of colour ads, about one inch thick and heavy. It costs about HK$50/- ! It only in Chinese.
Very different from Western magazines. More like Japanese magazines.
Cheers,
Ashok.
You can get components in Apliu street. I think that I got the name right. Better get all directions correct before you go there. Most locals cannot understand English.
This is near the Gloden Dragon Computer center in Sham Shui Po. Kowloon. My memory is rusty.
You get all the hard to get chips and hardware ( tools etc). I used to spend a lot of time there.
Try Wing Shing Computer Components Co. for Audio grade parts.
Ph 852-2387-4940. There are many other shops on that street.
Best way to get there is by subway.
Try to get a copy of their Audiotechnique audio magazine. It is full of colour ads, about one inch thick and heavy. It costs about HK$50/- ! It only in Chinese.
Very different from Western magazines. More like Japanese magazines.
Cheers,
Ashok.
Nick Walker said:Hi all,
I'm a brit that emigrated to Sing in March 2003 with my family.
In the last couple of years I've made my own phono stage which started as a Creek a like, and a dual mono power amp based on Randy Slone's Optimos, but now modified in a few areas. Very proud of both projects which sound fab - will post some pictures if anyone is curious.
I'm in the middle of archiving all my LPs onto my media server PC via a Midiman Audiophile 2496. I also have a modded xbox used for games and as a media centre.
Rest of the setup is Epos ES14 speakers, Linn Lp12, Origin Live modded Rega arm, Incognito arm wiring, tweaked Phiilips CD723 CD player, Pioneer 5.1 amp (using preamp out for L&R), Pioneer DVD & VCR player, NEC HT1000 projector, Yamaha Tape Deck, Home Theater Master MX-500 remote control which I haven't figured out how to use.
ttfn, Nick
Hello,
Welcome to Singapore.
Seems like you have found most of the local haunts. For computer stuffs, there's Sim Lim Square and Funan. Across the street from Funan, there's Adelphi, a building full of Hi-Fi shops. Across the pedestrian street from SLS, you will see Burlington Square. Well Audio Labs (www.wellaudiolab.com) and Martins Electronics are located within (level 1). They specialise in Tube audio.
Chinatown area has 3 shops where you can get your stuffs. Koba Electronics (level 3, People's Park Center) has lots of quality stuff cheap. (Got my Nichicon Muse and Panasonic FC caps there for below SGD2 each
) They got OSCONs and a large assortments of heatsinks there.To the basement of the same building, there's Larry's (www.tube-amp.com). Have yet to discover his shop..
Nearby in a row a shophouses, there's AHF Art Audio. (www.ahfartaudio.com) I have too, yet to find out where it is located, even if I follow the map.
Finally, here's a local forum for audiophiles. www.echoloft.com
Enjoy your stay in Singapore.
Hi,
Welcome to Singapore. That city is my wife and my all-time favourite city to relax in. (No, not for the shopping but just for the food courts and the laid-back mood.) I have two friends there, neither of whom, alas, is into DIY audio. And one of them actually has Bose Acoustimass speakers. He works in a multi-national bank and makes lots of money, so we must forgive him his bad taste.
I haven't had that good an experience finding things in S'pore. I found Sim Lim Tower most unimpressive, and the shopkeepers very bored, often not knowledgeable about things. I really had to hunt for metallised polypropylene caps. I guess you've seen this thread about component availability in S'pore?
Can you tell me a bit more of your Opti-MOS experience? I got the PCB track-side layout from Randy, and have built two PCBs. Am now taking a deep breath before jumping in. But I find the project a bit confusing, having just the PCB layout and the construction instructions to work with, not a full kit of parts. I'll list my questions:
Thanks in advance,
Tarun
Welcome to Singapore. That city is my wife and my all-time favourite city to relax in. (No, not for the shopping but just for the food courts and the laid-back mood.) I have two friends there, neither of whom, alas, is into DIY audio. And one of them actually has Bose Acoustimass speakers. He works in a multi-national bank and makes lots of money, so we must forgive him his bad taste.
I haven't had that good an experience finding things in S'pore. I found Sim Lim Tower most unimpressive, and the shopkeepers very bored, often not knowledgeable about things. I really had to hunt for metallised polypropylene caps. I guess you've seen this thread about component availability in S'pore?
Can you tell me a bit more of your Opti-MOS experience? I got the PCB track-side layout from Randy, and have built two PCBs. Am now taking a deep breath before jumping in. But I find the project a bit confusing, having just the PCB layout and the construction instructions to work with, not a full kit of parts. I'll list my questions:
- Were your PCBs double-sided or single-sided? Mine is single-sided. The documentation says that the PCB is available in both versions.
- How did you find out which pad was for which lead? (I'm referring to the pads for off-board leads.) Apart from the component pads, there are about half a dozen pads on the edges of the board. The silk-screen layout Randy's given me does not contain any legends marking those pads. So, I have to look at the circuit schematic, see the component connections and figure out... "Oh, this one seems to be ground." And so on. Seems strange to have these names omitted from the silk-screen layer. What makes it even more strange is that there are two pads about three inches apart on the same edge, on the same copper track. Both must go to ground, obviously. But why keep two pads so close to each other on a straight stretch of track? Won't that make a ground loop?
Another confusing thing is that there appears to be provision for only one star ground, not separate power and signal star ground points. I could've missed it in the docs, but that's what it seemed like to me. - Did you use his prescribed MPSA transistors for the small-signal portion? (He uses four of them... 8599/8099, I think.) Those are hard to get here, and Randy had once told me that many of his European readers had used other small-signal transistors, specially from the BC range, instead. He said that those transistors don't need to have high Vceo, unlike the rest of his circuit, so you can use pretty much any ordinary low-noise high-gain transistor pairs. I was wondering whether you had done any substitutions.
- Did you put the RL filter at the output? I was thinking of omitting it.
- What rating of power transformer and smoothing caps did you use?
- Did you use his suggested back-to-back tantalum caps at the input, or did you replace them with a metallised polyprop or something?
- How sensitive is the amp's performance to the quiescent current setting? Randy, unlike Rod Elliott, uses a cheap single-turn preset to set this current. (Rod uses neat little vertical multi-turns.) I was wondering whether you faced any difficulties on this front.
- Does one have to be careful handling MOSFETs? I've never used them.
- How do they sound? Any comparisons with any other amps?
Thanks in advance,
Tarun
Nick Walker said:
There's a shop called Kaichin at lvl 3 of Sim Lim Tower. There's 2 of this, the one which looks 'junkier' actually has more treasures within. You can spend hours in the shop just looking at strange and funny things you never thought it existed. The huge electrolytic caps (Good for Aleph i think) are all at the outside of the shop in a tray.
Enjoy your shopping trips.
I actually love shopping in SLT, I spend hours there hunting for things! Quite often just as I'm about to give up I find what I'm looking for, e.g. MPS8099/8599 - just one shop had these.
tcpip I'll be happy to help with your build.
I etched my own PCB based on the book design. I don't think it is essential to buy his pcb, however if you do it's a nicer dual sided layout and a bit more compact. Probably better resistance against Mosfet oscillation. I've also paid for the ESP P101 board which has a nice pcb layout on it for practically the same Output Stage and novel mounting idea - so I might redo things again.
For your PCB, which I don't have, you'll have to compare with the schematic, it shouldnt be hard. I imagine each gnd point requires a connection to a star ground. You wont get ground loops from a short parallel tracks, you're probably thinking of inductive coupling, which is also going to be unlikely. I actualy used a slightly thinner gauge wire for my signal grounds and thick gauge for power grounds, all going to a single star ground. It worked for me, alternatively your signal ground could be an inch or so upstream of the power ground.
I had some problems with oscillation and hum and chopped and changed quite a bit of Randy's design. But now everything is working and the amp is awesome. I've not yet heard anything better sounding.
From memory, the changes I made were higher input resistance, less gain, increased the input stage Zener currents slightly, stablised the cascode in the VA stage with 6.2V zeners instead of his soft clipping potential divider idea, and removed the protection circuits - which should probably be put back in. I have 220pf for the miller CC2 not 300pF. For the nfb capacitor I used 1000uF.
I built a dual mono design with two 500 VA 50-0-50 torordial, using a single Bridge rectifier per channel and 20,000uf on each rail (total 80,000 in the amp). Bypassed each cap with 0.1uf and also the BR terminals and have an X2 across the mains input IEC. If I had more room in the case I would use four BRs. I also have a soft start circuit because without it I trigger the household circuit breakers everytime!
For grounding I have one star ground per channel, the grounds meet at the RCA inputs, my mains earth goes to the chassis and also to the RCA inputs which are not isolated from the case. I might change this and use a group loop breaker, however I don't suffer from hum.
I found the MPS8099/8599 in SLT at $2.50 each, new ones from On Semiconductor. But you could use the same 2n5401/5551 devices to get you up and running with a slight noise penalty.
I used the RL network on the output.
I have back to back tantulums, but may change this at some point, that was partly my motivation for raising the input resistance.
I used a 200ohm multi turn trimpot for bias adjustment.
You need to be carefully handling the Mosfets. I also raised the gate resistor on the upper nchannel pairs to 1k to stop oscillations, however I think an alternative way is to solder a small cap between the gate and source. I'm not sure which is the better approach. I also used lower 0.22 ohm source resistors.
Ask away with any further questions, when I get back from my business trip I'll post some pictures, however the internals aren't going to win any beauty prizes!
tcpip I'll be happy to help with your build.
I etched my own PCB based on the book design. I don't think it is essential to buy his pcb, however if you do it's a nicer dual sided layout and a bit more compact. Probably better resistance against Mosfet oscillation. I've also paid for the ESP P101 board which has a nice pcb layout on it for practically the same Output Stage and novel mounting idea - so I might redo things again.
For your PCB, which I don't have, you'll have to compare with the schematic, it shouldnt be hard. I imagine each gnd point requires a connection to a star ground. You wont get ground loops from a short parallel tracks, you're probably thinking of inductive coupling, which is also going to be unlikely. I actualy used a slightly thinner gauge wire for my signal grounds and thick gauge for power grounds, all going to a single star ground. It worked for me, alternatively your signal ground could be an inch or so upstream of the power ground.
I had some problems with oscillation and hum and chopped and changed quite a bit of Randy's design. But now everything is working and the amp is awesome. I've not yet heard anything better sounding.
From memory, the changes I made were higher input resistance, less gain, increased the input stage Zener currents slightly, stablised the cascode in the VA stage with 6.2V zeners instead of his soft clipping potential divider idea, and removed the protection circuits - which should probably be put back in. I have 220pf for the miller CC2 not 300pF. For the nfb capacitor I used 1000uF.
I built a dual mono design with two 500 VA 50-0-50 torordial, using a single Bridge rectifier per channel and 20,000uf on each rail (total 80,000 in the amp). Bypassed each cap with 0.1uf and also the BR terminals and have an X2 across the mains input IEC. If I had more room in the case I would use four BRs. I also have a soft start circuit because without it I trigger the household circuit breakers everytime!
For grounding I have one star ground per channel, the grounds meet at the RCA inputs, my mains earth goes to the chassis and also to the RCA inputs which are not isolated from the case. I might change this and use a group loop breaker, however I don't suffer from hum.
I found the MPS8099/8599 in SLT at $2.50 each, new ones from On Semiconductor. But you could use the same 2n5401/5551 devices to get you up and running with a slight noise penalty.
I used the RL network on the output.
I have back to back tantulums, but may change this at some point, that was partly my motivation for raising the input resistance.
I used a 200ohm multi turn trimpot for bias adjustment.
You need to be carefully handling the Mosfets. I also raised the gate resistor on the upper nchannel pairs to 1k to stop oscillations, however I think an alternative way is to solder a small cap between the gate and source. I'm not sure which is the better approach. I also used lower 0.22 ohm source resistors.
Ask away with any further questions, when I get back from my business trip I'll post some pictures, however the internals aren't going to win any beauty prizes!
Thanks
Thanks, Nick, for a very patient and prompt response. I'll probably bother you once again as soon as I get all the parts together and start construction. You've given me confidence. I'm thinking of becoming a bit daring and replacing the MPS transistors with some pin-compatible ones from the BCxxx range. And I may or may not retain the output RL. My friend Angshu (on this forum) does not think it's always needed, and I intend to drive a relatively simple load anyway.... I'm planning to use active xo, and directly couple the amp to one or more drivers.
Thanks again,
Tarun
Thanks, Nick, for a very patient and prompt response. I'll probably bother you once again as soon as I get all the parts together and start construction.
You've given me confidence. I'm thinking of becoming a bit daring and replacing the MPS transistors with some pin-compatible ones from the BCxxx range. And I may or may not retain the output RL. My friend Angshu (on this forum) does not think it's always needed, and I intend to drive a relatively simple load anyway.... I'm planning to use active xo, and directly couple the amp to one or more drivers.Thanks again,
Tarun
Hi Nick,
just saw this thread, welcome to SIN city ;-) The more DIYers here, the merrier!
Just my 2 cents about SLT - buyer beware. I am getting quite frustrated after a couple years using components I bought there. It looks good, but the quality, just awful sometimes. It doesn't take long in humid SG for "gold" plated connectors to rust through... or for even resistor leads to start rusting (!!!).
Basically, it's great for cheap enclosures, transistors, IC's and basic supplies, and yes you find almost everything except toroidal transformers, BUT almost nothing that is reliably good quality. Do not trust anyhting. Especially not pots and any kind of connectors. Those I order from RS, free shipping >100 SGD (sadly they just changed their website to a new look and it's very unreliable - lots of server timeouts etc).
And I'm not especially picky, I just don't want to rebuild everything twice.
MBK
just saw this thread, welcome to SIN city ;-) The more DIYers here, the merrier!
Just my 2 cents about SLT - buyer beware. I am getting quite frustrated after a couple years using components I bought there. It looks good, but the quality, just awful sometimes. It doesn't take long in humid SG for "gold" plated connectors to rust through... or for even resistor leads to start rusting (!!!).
Basically, it's great for cheap enclosures, transistors, IC's and basic supplies, and yes you find almost everything except toroidal transformers, BUT almost nothing that is reliably good quality. Do not trust anyhting. Especially not pots and any kind of connectors. Those I order from RS, free shipping >100 SGD (sadly they just changed their website to a new look and it's very unreliable - lots of server timeouts etc).
And I'm not especially picky, I just don't want to rebuild everything twice.
MBK
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