How about this source
http://stores.ebay.ca/skipmalley?_trksid=p2047675.l2563
It is a pleasure working with silver plated teflon wire. No insulation melting while soldering.
I doubt that it will make signals sound better esp if you bundle them together. If so, we should be silver plating our pcbs too. do you not think conductor coupling would degrade any performance increase of silver plated copper? I know the silver plated RG-400/U we used was better at RF, for atten and return loss but we are talking ~400MHz not 20KHz
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OPA627's
Hi Eldam, OPA627... I use it like George does in a gain =2 situation. I reduced the gain at the Lundahl LL1690 by configuring it as a 2:1 ratio. OPA627 at unity gain (one)..... I have used it as a buffer in the past and found the DIP version to be dark sounding although high quality. In the gain =2, I find it to be completely neutral. Not bright nor dark. Simply accurate with excellent resolution. It is a datasheet build so it is as ideal as I can make the 2X gain circuit. If your looking for a more dynamic sound with drive the BUF03 has a warm class A type sound. Not nearly as open as a OPA627 in gain =2 situation. Truth is most of the sound quality is determined by the quality of the I/V stage. AD844 triple stack has a smooth quality that I have yet been unable to figure out why, it is pervasive. In other words the smooth quality is there regardless of the quality of the source. DDNF has more potential to provide resolution and I can tell which source is better. Likely the jitter is more obvious. Buffer for the DDNF circuit? That is an interesting question. If you match transistors so you have low offset and if you have a digital pot with high enough input impedance then likely you could make that work. Pedja set the stock circuit to 10 uF and 100K Ohm. With low offset you could omit the cap. I'd try not to reduce the output impedance much below say 100K Ohm. That may change the sound quality to much. Pedja's commercial dac... I have no idea what he used as a buffer in that. 🙂
Pedja Rogic DDNF circuit boards
Thanks for the wire tip. That would likely be excellent. DDNF... The shipping cost from the USA is obscene. So unless one of our Asian friends wants to take that on... I mean by making boards and shipping from Asia. I don't see another board offering. I have a few boards left that are unspoken for.
Wire
Nice! Previous searches didn't yield much. Thanks for the source. 😀 Yes. I like working with that wire too. Not sure if there is any quality difference. The Tin with Tefzel wire doesn't sound bad at all, still prefer better stuff. I will let you in on a secret... Best SPDIF cable is the Mil spec RG179U Silver Teflon FEP coax. I use Belden myself.
I like bare copper wire with teflon insulation but where to find? Silver plated wire is a bit difficult for system matching (may sound bright in some system). I had to buy some brand name bulk interconnect and cut it out to get the wire 🙁
Silver wire
I have had some interconnects that tended to sound bright in the past. I don't notice that with single Silver wires twisted or otherwise inside the dac. As you say it is a system matching deal. I have mostly Nordost older interconnects where I have installed new locking connectors. They just happen to be Silver as well. Look for PTFE or FEP tubing in very small gauge. Make your own wires as such. No one as far as I know makes a Copper Teflon insulated wire. Some wire manufacturers will make anything you want if the quantities are high enough. Likely not an option for hobby people.
Have you tried transformer winding wire, Seems to be a few people making intercionnects with it.
Never used it myself. I always use either Kimber cable (seven diff diameters copper sheathed in PTFE) or silver 99.99% from a jewellery wire supplier.
Russ Andrews used to sell the wire as well as made up speaker cables and interconnects.
I'm trying to find a way of making up a pair of interconnects for my turntable, also would like to try some digital cable. That RG179U Silver Teflon FEP seems impossible to source unless you want to buy a whole reel. The RG179U Silver has a copper plated steel core, is that right?
Never used it myself. I always use either Kimber cable (seven diff diameters copper sheathed in PTFE) or silver 99.99% from a jewellery wire supplier.
Russ Andrews used to sell the wire as well as made up speaker cables and interconnects.
I'm trying to find a way of making up a pair of interconnects for my turntable, also would like to try some digital cable. That RG179U Silver Teflon FEP seems impossible to source unless you want to buy a whole reel. The RG179U Silver has a copper plated steel core, is that right?
Thank you all for your advice on hook up wire. I found two types that I can obtain
20awg tin plated ofc inteflon jacket
30awg pure silver OCC wire in teflon jacket made by neotech
both are solid single core
Already order the first one but the silver wire looks interesting too just a bit small.
20awg tin plated ofc inteflon jacket
30awg pure silver OCC wire in teflon jacket made by neotech
both are solid single core
Already order the first one but the silver wire looks interesting too just a bit small.
Attachments
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Transformer winding wire
A member in my audio club makes interconnects from magnet wire. They use them almost exclusively at the club events. They seem OK. I did hear the Nordost most expensive wire at an event. It probably is better then anything I have here. Trouble is the room at the club is tough to really make a reference system. We only hear that thing once a month at most. RG179U... True the core is steel. What you need to remember is the SPDIF is an RF signal so it rides on the outside of the cable via skin effect. So the signal really is in the Silver layer. Military cable is made to be robust and tough. I have bought the cable via the foot from Digi Key and maybe Mouser. 😉
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Thanks,
Just ordered a metre from ebay to try and compare it with my Audio Synthesis silver blue.
Interesting thread,
Lying around at my place are two non CDP units which are possible candidates, in both cases, immediately after the 1541, the usual de-emp circuit and 5th order sallen-key LPF operations exist, but share the same op amp. I think the de-emp circuit is the IV stage correct?
Anyway 844 is single channel. I discovered dual dip-8 equivalent of 844.
OPA2658 (datasheet) - whether the same topology with unique TZ pin, I'm unsure.
As long as the pins match to be able to drop this in is desirable but, either way mirror amps typically require pre-defined RF resistor for stability so re-arrangement is still in order...
Its then perhaps better to add new separate board as earlier suggested. Whether de-soldering existing opamps increases performance further I dunno... being live below added 844 board wouldn't this add noise?
Whats the 844 gurus take on the above?
Funny coincidence actually. One of the items is a Philips DFA888 amplifier with NOS 1541A inside.
Got it off ebay like this but it never materialized as a whole, only the DAC worked and only briefly too because I broke that in an attempt to diagnose a dodgy amp channel. After blowing up a regulator (for the illumination), I blew up the IV buffer amps for the TDA section due to improper re-connection of the inter-board cabling, funnily enough, only to learn about their inferiority in this application afterwards anyway!
How weird is that?!
The amp is in otherwise good cosmetic condition and I may pawn it to some DA member to have a look at and/or keep. Lots of space in it for transformers, tubes... MC/MM phono pre amp... any takers?
/end diary
Lying around at my place are two non CDP units which are possible candidates, in both cases, immediately after the 1541, the usual de-emp circuit and 5th order sallen-key LPF operations exist, but share the same op amp. I think the de-emp circuit is the IV stage correct?
Anyway 844 is single channel. I discovered dual dip-8 equivalent of 844.
OPA2658 (datasheet) - whether the same topology with unique TZ pin, I'm unsure.
As long as the pins match to be able to drop this in is desirable but, either way mirror amps typically require pre-defined RF resistor for stability so re-arrangement is still in order...
Its then perhaps better to add new separate board as earlier suggested. Whether de-soldering existing opamps increases performance further I dunno... being live below added 844 board wouldn't this add noise?
Whats the 844 gurus take on the above?
Funny coincidence actually. One of the items is a Philips DFA888 amplifier with NOS 1541A inside.
Got it off ebay like this but it never materialized as a whole, only the DAC worked and only briefly too because I broke that in an attempt to diagnose a dodgy amp channel. After blowing up a regulator (for the illumination), I blew up the IV buffer amps for the TDA section due to improper re-connection of the inter-board cabling, funnily enough, only to learn about their inferiority in this application afterwards anyway!
How weird is that?!
The amp is in otherwise good cosmetic condition and I may pawn it to some DA member to have a look at and/or keep. Lots of space in it for transformers, tubes... MC/MM phono pre amp... any takers?
/end diary
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Re the OPA2658 being a dual op-amp it hasn't got the separate pin for Tz connection.
Ah right, thanks
So the 844 is the only one with this unique pin a la Gilbert topology... It really should be named after the designer eh?
Moving on, checked mouser via 'sort by' for 2 channel 8dip not alot of alternatives. Not that a separate patch board is a problem but keeping the original functionality intact would've been neat... in some superfluous way. Don't even know if that word is appropriate in that context, seems fitting enough.
But aye, with the philips amp, I offer it in here seeing as the buffers are all fried lol. I guess an agreement can be made to 'pawn' it for a while, dunno, few years.. I may never buy it back of course.. It's just lying around, work-able and it has black gates. Did I mention that it has black gates...?
So the 844 is the only one with this unique pin a la Gilbert topology... It really should be named after the designer eh?
Moving on, checked mouser via 'sort by' for 2 channel 8dip not alot of alternatives. Not that a separate patch board is a problem but keeping the original functionality intact would've been neat... in some superfluous way. Don't even know if that word is appropriate in that context, seems fitting enough.
But aye, with the philips amp, I offer it in here seeing as the buffers are all fried lol. I guess an agreement can be made to 'pawn' it for a while, dunno, few years.. I may never buy it back of course.. It's just lying around, work-able and it has black gates. Did I mention that it has black gates...?
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Just to double check.
Other than the useful tZ pin for use with for different outboard buffers and voltage select and excluding the 797, could other mirror feedback amps still be suitable as a buffer? Anyone tried?
Other than the useful tZ pin for use with for different outboard buffers and voltage select and excluding the 797, could other mirror feedback amps still be suitable as a buffer? Anyone tried?
Yes but they all need feedback around them, the 844 doesn't, this is why I believe it sounds so good as a I/V, as it may be more stable to the very HF noise and glitches that come from dacs, maybe super stable because of the zero feedback loop, who knows.
We all know that power amps become more stable and more stable the less and less feedback is applied why not an opamp as well??? Especially in an I/V stage were it get's all those hf/glitch horrors inputted from the dac.
Cheers George
It doesn't seem to me the issue is about the stability of the feedback loop.
I have tried passive filtering (LC, 2nd order) prior to my active I/V which does have (current) feedback and didn't notice any difference in SQ. So if glitches are a problem (they may indeed be) it would depend on the architecture of the analog stage to what degree they're an issue. The advantage of using feedback (the primary reason I am using it) is to get the input impedance down. Open loop the AD844 has about 50ohms Zin, my discrete circuit with feedback gets the input resistance below 1ohm.
I have tried passive filtering (LC, 2nd order) prior to my active I/V which does have (current) feedback and didn't notice any difference in SQ. So if glitches are a problem (they may indeed be) it would depend on the architecture of the analog stage to what degree they're an issue. The advantage of using feedback (the primary reason I am using it) is to get the input impedance down. Open loop the AD844 has about 50ohms Zin, my discrete circuit with feedback gets the input resistance below 1ohm.
So the 844 passes TDA current to this pin and should one choose to bypass the 844s buffer... what would the mirror stage do differently to tapping from TDA directly?
Not experimented yet, but I'm also in favor of the feedback atm, apparently these specify an exact resistor value to use closed-loop for optimum results, for desired bandwidth. Foremost, I seen this type mentioned here on DA, did more research and ultimately found this thread.
I'm sure the 844 sounds great but It's not obvious just yet what it does differently other than, passing on current.
IF the buffer was used then yea, I guess you get control over how much HF images the buffer see's. I think..
Not experimented yet, but I'm also in favor of the feedback atm, apparently these specify an exact resistor value to use closed-loop for optimum results, for desired bandwidth. Foremost, I seen this type mentioned here on DA, did more research and ultimately found this thread.
I'm sure the 844 sounds great but It's not obvious just yet what it does differently other than, passing on current.
IF the buffer was used then yea, I guess you get control over how much HF images the buffer see's. I think..
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