Filburt Posted May 8, 2008 Report Share Posted May 8, 2008 Current out DACs really want to see as close to a dead short on the output as you can get, sub 1 ohm. A resistor large enough to get the required output voltage isn't going to be close to that Most opamps can't get that low even with feedback and rise as freq. goes up because of feedback/group bandwidth. The THS403x was going to be my next choice for opamp to try, but I built a discrete current steering I/V which I love. No more opamps for me. I sort of regard passive i/v as the common fallacy of simple is better that seems to float around in audiophilia. No more complicated than necessary (standard razor principle) might make sense, but simplicity for simplicity's sake seems unwise to me. As you note, these chips are designed to have a near-zero impedance on their output. You're right that op-amps can't provide that into the MHz range; not even close. The feedback factor drops into oblivion by that point. Although, an old revision of the AD8055 used to have about 70dB of OLG to 2MHz (see - http://www.jancorver.org/info/atv/baseband/files/AD8055.pdf). Current steering i/v seems to be the way to go. luvdunhill - I can barely read the charts on that article. The distortion doesn't look particularly low to me, though. They also probably have to gain the signal quite a bit to get line-level output, which just means you throw in distortion from the VAS (in this case, resulting in what seems to be a lot of odd-order products). Might be worth trying to install a current steering i/v and see how you feel about it. Quote Link to comment Share on other sites More sharing options...
luvdunhill Posted May 8, 2008 Report Share Posted May 8, 2008 well, notice the 1.99vrms on the *balanced* output, so not as much gain is required as you might think. Quote Link to comment Share on other sites More sharing options...
Filburt Posted May 8, 2008 Report Share Posted May 8, 2008 PCM1704 is only +/- 1.2mA. If they aren't using much gain, they're using a relatively high value resistor, which would be even worse. Quote Link to comment Share on other sites More sharing options...
postjack Posted May 9, 2008 Author Report Share Posted May 9, 2008 yes is magicks Quote Link to comment Share on other sites More sharing options...
Pars Posted May 9, 2008 Report Share Posted May 9, 2008 nahhh, its FM fuckin majix Quote Link to comment Share on other sites More sharing options...
luvdunhill Posted May 9, 2008 Report Share Posted May 9, 2008 honestly, I don't care what the guy does... it's magickjzs alright. Quote Link to comment Share on other sites More sharing options...
postjack Posted May 9, 2008 Author Report Share Posted May 9, 2008 nahhh, its FM fuckin majix fukn madjix yes!! this topic is got way OT and and the unreasonable but dreamy and seductive part of me just wants an SCD-1 again. bah. Quote Link to comment Share on other sites More sharing options...
postjack Posted May 9, 2008 Author Report Share Posted May 9, 2008 i think you'll be disappointed if you get one. unless you mod it. bah! now i'm getting pressure via IRC to go for the krell. Quote Link to comment Share on other sites More sharing options...
justin Posted May 9, 2008 Report Share Posted May 9, 2008 I just bought one Don't get the Sony...don't make the same mistake I did. Although it was nice to try it Quote Link to comment Share on other sites More sharing options...
deepak Posted May 9, 2008 Report Share Posted May 9, 2008 I just bought one Don't get the Sony...don't make the same mistake I did. Although it was nice to try it God damn... Quote Link to comment Share on other sites More sharing options...
n_maher Posted May 9, 2008 Report Share Posted May 9, 2008 Don't get the Sony...don't make the same mistake I did. Although it was nice to try it No way, did it not survive the trip home? The thing worked flawlessly throughout the meet. Quote Link to comment Share on other sites More sharing options...
justin Posted May 9, 2008 Report Share Posted May 9, 2008 No way, did it not survive the trip home? The thing worked flawlessly throughout the meet. Actually, no it didn't. One of my SACDs wouldn't play in it, and 2 of the IsoMike's wouldn't either. Likely the majority of these players have the same problem, they just aren't used with a lot of SACDs. Mine is 17 for 20 in playing SACDs so far. Quote Link to comment Share on other sites More sharing options...
deepak Posted May 9, 2008 Report Share Posted May 9, 2008 Actually, no it didn't. One of my SACDs wouldn't play in it, and 2 of the IsoMike's wouldn't either. Likely the majority of these players have the same problem, they just aren't used with a lot of SACDs. Mine is 17 for 20 in playing SACDs so far. You probably don't want to mail it to Sony Quote Link to comment Share on other sites More sharing options...
luvdunhill Posted May 9, 2008 Report Share Posted May 9, 2008 Don't get the Sony...don't make the same mistake I did. Although it was nice to try it I know this place where I can get a pallet of those for like two dollars each... Quote Link to comment Share on other sites More sharing options...
Pars Posted May 9, 2008 Report Share Posted May 9, 2008 I know this place where I can get a pallet of those for like two dollars each... Pallet of what? SCD-1s? Or Krells? Quote Link to comment Share on other sites More sharing options...
postjack Posted May 9, 2008 Author Report Share Posted May 9, 2008 I just bought one Don't get the Sony...don't make the same mistake I did. Although it was nice to try it congrats! poking around the internet, the krell of course has had its share of transport issues, up through the MKII version. MKIII everything seems to be fine, since they are using a completely different transport. Everyone seems to love the sound though. Quote Link to comment Share on other sites More sharing options...
postjack Posted May 9, 2008 Author Report Share Posted May 9, 2008 well, the question i would ask is how expensive would it be to get the transport issue fixed if you get one of the Standards and it gets bad. thats a fine question to ask. i'll commence the research. there is one on audiogon write now for $1600 with just shy of the full warranty left. seller says he'll help the buyer send it in if there are any issues, but who knows where the seller will be in a year when the transport kaputs. it seems like the best you can get service wise on SACD players are from the likes of John Tucker and Dan Wright. Quote Link to comment Share on other sites More sharing options...
purk Posted May 9, 2008 Report Share Posted May 9, 2008 Actually, no it didn't. One of my SACDs wouldn't play in it, and 2 of the IsoMike's wouldn't either. Likely the majority of these players have the same problem, they just aren't used with a lot of SACDs. Mine is 17 for 20 in playing SACDs so far. Time to replace the laser and lube the gear and trasport. My modded SCD-777ES has been working flawlessly for over 2 years now. I had three or four discs that won't read properly, but the success rate is over 95% so far. Knock on wood! T The ealier versions (pre-2001) of those units are not that reliable, however, they are supposed to be pretty reliable for 2001, 2002. The optical laser is only $140, so the part is not so bad. However, shipping cost will get expensive when the SCD-1/SCD-777ES have problems. My modded SCD-777ES is a 1999 model and I believe that the previous owner have replaced the laser once. I will stock up on laser for both since I have SCD-1 & SCD-777ES. Quote Link to comment Share on other sites More sharing options...
purk Posted May 9, 2008 Report Share Posted May 9, 2008 is it just SACDs the Sonys have trouble reading? a 98% success rate would have me tearing my hair out. Based on my experience with these Sony SCD units (SCD-C333ES, C555ES, 555ES, SCD-777ES, and SCD-1), the problems usually start with SACDs first, following by CD-Rs, and Redbook CDs last when the laser starts to go bad. The good thing is parts are still available and it doesn't cost arm and leg to repair these units. However, expect to pay around $100 shipping each way if you want to send the SCD-777ES/SCD-1 in for mods or repair as they both are over 55lb. Once the unit is repaired, the unit should last for 3 or 4 more years. I will start stocking up on lasers b/c I really like these units. Quote Link to comment Share on other sites More sharing options...
Pars Posted May 9, 2008 Report Share Posted May 9, 2008 Time to replace the laser and lube the gear and trasport. My modded SCD-777ES has been working flawlessly for over 2 years now. I had three or four discs that won't read properly, but the success rate is over 95% so far. Knock on wood! T The ealier versions (pre-2001) of those units are not that reliable, however, they are supposed to be pretty reliable for 2001, 2002. The optical laser is only $140, so the part is not so bad. However, shipping cost will get expensive when the SCD-1/SCD-777ES have problems. My modded SCD-777ES is a 1999 model and I believe that the previous owner have replaced the laser once. I will stock up on laser for both since I have SCD-1 & SCD-777ES. What laser do these use, and how involved is it to change them? I have done the Philips CDM4 in my Rotel once and have two spares, as these are pretty much unobtainable anymore, and that was pretty much drop a new one in For those thinking about the Krell, my advice would be to find out what mechanism they use and see how much they are and how available they are (and whether it seems like supply is drying up). If you pick up a spare or two, that would last you along time... probably longer than many of you keep your gear around here Quote Link to comment Share on other sites More sharing options...
tkam Posted May 9, 2008 Report Share Posted May 9, 2008 so the lasers typically go bad in those players every 3-4 years? that seems like a pretty short time to me. Quote Link to comment Share on other sites More sharing options...
Pars Posted May 9, 2008 Report Share Posted May 9, 2008 I'd agree. The laser in my Rotel went 15+ years at least, and is still probably good (was getting a few disc errors, but those may be from a couple of caps I need to change). Quote Link to comment Share on other sites More sharing options...
purk Posted May 9, 2008 Report Share Posted May 9, 2008 so the lasers typically go bad in those players every 3-4 years? that seems like a pretty short time to me. I'm not really sure to be honest, b/c I didn't buy them new. Most my Sony SCD machines were bought used. The only unit that had to replace the laser thus far was the SACDmods C555ES, and a three months after that I sold the unit. $300 to $400 repair bill every 4 years doesn't sound so bad to be honest. They do sound really great and for how much I bought the unit for, I won't be able to buy anything that as good for the same price. The folks at RAM also think that the SCD-777ES/SCD-1 stock are still one of the best sounding units out there at this price point. Quote Link to comment Share on other sites More sharing options...
justin Posted May 9, 2008 Report Share Posted May 9, 2008 congrats! poking around the internet, the krell of course has had its share of transport issues, up through the MKII version. MKIII everything seems to be fine, since they are using a completely different transport. Everyone seems to love the sound though. It doesn't seem nearly as bad as SCD-1 problems. Also, the retail price for MKIII went up from 4k to 6k, and I think the MKIII are too new to find used. You'd probably pay 5k at a dealer after bargaining it down -- more than 3x what I paid for a used MKII. Quote Link to comment Share on other sites More sharing options...
Pars Posted May 9, 2008 Report Share Posted May 9, 2008 Yeah, its too bad that someone can't step up and build a really good transport mech that is capable of both CD reads and DVD type reads (for hi def) that is reliable, easily repairable, etc. Maybe something along the Philips line but better made, and actually supported The recycled DVD mechs that seem to be used these days just don't cut it. How has the reliability on that TEAC drive (VRDS or something like that) been? Quote Link to comment Share on other sites More sharing options...
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