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Post by jimwilliams on Apr 28, 2018 19:27:32 GMT -6
You don't need "headroom", you need dynamic range and a lot of it. -129.6 db EIN at 150 ohms is about the limit. At 50 ohms you can better that to -132 db EIN. That's a 72 db S/N ratio IF the mics are as quiet. Transformer coupled mic pre designs are limited to -128 db EIN at 150 ohms. Headroom is not an issue with modern ADC's or analog tape. Modern ADC's clip at around +20 dbu, far below the average balanced output levels of +27 dbu with standard + - 15 volt power supplies. Analog tape saturates at +13 dbu. Proper gain staging will avoid any issues with modern recording gear. No one needs +30 db audio levels unless you are driving a speaker. Gear with those elevated output levels can easily damage other gear that runs on standard voltage rails. There is no practical benefit to that sort of design unless it's a weiner measuring contest. Well whatever it’s called. Something that doesn’t saturate when pushed. That's called distortion. It can occur more at some frequencies before others. Usually an amplitude vs THD sweep will show lowering THD at 1k hz until right before it hits the power rails and then it clips. Most all modern opamp based gear will do that. If you change the test frequency to 10k hz usually you see rising THD above the 1k level as you approach clipping. Modern fast wide bandwidth opamps don't do that, THD is the same at all frequencies and levels. You get what you pay for. Then you have the effect of loading, plus several other distortion tests one can perform like IMD and FFT's. The basic THD+noise tests will usually catch the errors IF you test at all the audible frequencies, not just 1k. That's probably another reason pro audio manufacturers are afraid to show you that stuff.
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Post by jimwilliams on Apr 26, 2018 9:50:02 GMT -6
You don't need "headroom", you need dynamic range and a lot of it. -129.6 db EIN at 150 ohms is about the limit. At 50 ohms you can better that to -132 db EIN. That's a 72 db S/N ratio IF the mics are as quiet. Transformer coupled mic pre designs are limited to -128 db EIN at 150 ohms.
Headroom is not an issue with modern ADC's or analog tape. Modern ADC's clip at around +20 dbu, far below the average balanced output levels of +27 dbu with standard + - 15 volt power supplies. Analog tape saturates at +13 dbu.
Proper gain staging will avoid any issues with modern recording gear. No one needs +30 db audio levels unless you are driving a speaker. Gear with those elevated output levels can easily damage other gear that runs on standard voltage rails. There is no practical benefit to that sort of design unless it's a weiner measuring contest.
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Post by jimwilliams on Apr 25, 2018 12:12:04 GMT -6
The problem is vinyl. It's too soft and wears quickly. A new release sounds different on the second play. I used to give away records I did after one play because they never sounded as good the next time. Yes, it was played with good decks and carts.
I used to cut discs. They trained me well to find/locate the errors. That ruined my enjoyment of it because all I hear and focus on is the groove modulation, pops, crackles and inner groove distortions, etc. Plus the stereo crosstalk sucks next to my better DAC's.
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Post by jimwilliams on Apr 17, 2018 10:16:15 GMT -6
I sent out a pair of C-137 cards out yesterday. They were converted to mic preamps using the Jensen JT-13KC mic input transformer at 1/5 ratio. They have a 20~60 db gain range with a PEC conductive plastic pot.
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Post by jimwilliams on Apr 12, 2018 9:41:37 GMT -6
If people are buying it that must mean they like it.. so why not do it? Killing off the record biz should have been warning enough. Now these producers want to kill off the rest of your musical enjoyment. 20 years of mass compression ought to be enough, it has been for me.
Seems it's institutionalized now. Fashions eventually change, this has not. I recall asking folks in line at the old record store how they liked the sonics of the new releases. I got an earful every time. "Why does this music sound so irritating" was a common response.
They are no longer in line buying music. It's all free now because that's all it's worth.
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Post by jimwilliams on Apr 11, 2018 9:21:52 GMT -6
Without penalties nor enforcement mechanisms this is another meaningless paper decision without any teeth.
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Post by jimwilliams on Apr 10, 2018 19:23:55 GMT -6
In the shop use an Adcom GFA 545 power amp with a pair of $299 Emotiva B1 speakers. I added .1 and a .01 InfiniCap bypass caps to the mylar tweeter cap. It's a stunning sound with those AMT tweeters.
In the TV room it's the same S2 DAC feeding an Adcom GTP 400 preamp/GFA535 combo. The speakers are the $700 top rated Emotiva T1's with Kimber 8TC speaker cable. The sound is incredible on Blue Ray. Way better sound than any theater I've ever sat in including the special screening rooms at Warner's and Paramount Pictures in Hollywood.
Now I need a better TV, the sound is a cut above the video now. So far the only drawback is ugly records still sound ugly. This DAC is no make over expert. It will reveal warts.
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Post by jimwilliams on Apr 8, 2018 15:02:43 GMT -6
There are a bunch of these cheap DACs out now. The Project S2 is an all ESS design, ESS 9038 DAC chips, ESS 9311 voltage regulators, ESS 9602 output buffer/headphone amp. Those are some pretty good parts. I ended up buying a second one because it sounds so much better than anything else I have here. The clocking is doing something good, I'm hearing words much more clearly, guitars sound better in the mids, classical recordings like the Pony Canyon Classics (using Audio Upgrades mic pre's) grab you and pull you in. Todd Garfinkle's MA Recordings sound impressive too.
When a DAC makes a Rolling Stones record sound good, something good is going on.
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Post by jimwilliams on Apr 6, 2018 21:11:19 GMT -6
That's a short loaded version with a single ESS DAC chip, 5 rather than 7 filters, no MQA unfolding. The Pre Box S2 uses a pair of ESS DAC chips. I spent some time listening to mine and comparing it to some other DAC's here. It easily beats the Mytek/Levenson BurrBrown PCM1704 with THS 3061 opamps and the PCM1792 based RMA superbeast with ADA4898-2 opamps. It also bests the Schiit Modi II multibit with ADA4898-2 opamps.
In fact it beats everything I got here. Feeding the Adcom GFA 545 directly is a very pure sound. It's also great on DVD's and even TV playback. The low end is rather impressive and the low level details are easily heard.
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Post by jimwilliams on Apr 5, 2018 9:57:35 GMT -6
Use a 2k hz square wave. That's a standard frequency as used by Jensen and others. If you see a slope reduction on the rising edge that's the transients getting missed.
If 2k looks good then try 10k hz. Only a few will pass that unaffected.
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Post by jimwilliams on Mar 31, 2018 13:39:37 GMT -6
With over 3 volts RMS at full scale I don't know how much more gain someone would need from a DAC. Blast a modern rock CD with .000001 db dynamic range and you will be looking for an attenuator fast.
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Post by jimwilliams on Mar 29, 2018 11:10:15 GMT -6
Welcome to the SSL sound. It's a filter combined with a harmonic generator, a nice way of saying "fuzz tone". I recall one SSL I serviced 20 odd years ago. The owners were playing that Titanic song over the monitors. They had me mod one channel of the monitor path to "see" if it made any differences.
Then, all of a sudden a bell tree pops out of the modified channel. It was not there on the stock channel. The owner asks, "what's THAT"!
I told him that was the food your SSL has been chewing for you.
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Post by jimwilliams on Mar 29, 2018 11:03:48 GMT -6
This box uses the newest ESS 9038 DAC chipset. It is the low power version of that part. That way it could be powered by the USB cable. The S2 uses a pair of these stereo converter chips in a dual sine/cosign config. That does help improve the specs even more over using one chip.
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Post by jimwilliams on Mar 24, 2018 12:43:20 GMT -6
Simple noise tests would be easy to do and would be very informative. Everyone has different acceptable subjective opamp error rates but no one I've met ever liked noise.
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Post by jimwilliams on Mar 23, 2018 14:04:02 GMT -6
Brad McGowan just got his and says it sounds incredible. I'm still waiting here.
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Post by jimwilliams on Mar 23, 2018 14:01:46 GMT -6
I wish someone with more spare time than I would do some standard opamp tests on those things. Stuff like open-loop gain, bode plots, PSRR, CMRR, etc. Somehow subjective claims just don't do it for me.
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Post by jimwilliams on Mar 23, 2018 13:59:18 GMT -6
The AC polarity does affect noise fields some non-grounded gear. One of my bench headphone amps had a non-grounded AC cable. It generated a nice hum field my scope probes easily pick up if anywhere near by. Switch to a grounded AC cable with proper chassis grounds and that all goes away.
I hate The Absolute Sound mag. They sent me a comp scrip and I keep buying stuff. Emotiva speakers, Schiit boxes, Pro-Ject DAC's, etc. Not everything in there costs $25,000.
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Post by jimwilliams on Mar 21, 2018 11:13:08 GMT -6
Try the Gibson L6-S wiring. That is a 6 way rotary switch that does all the combinations.
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Post by jimwilliams on Mar 21, 2018 11:09:57 GMT -6
Soundcraft Delta monitor section. It has re-biased transistors and great opamps. The resistors are either Vishay S-102's or Dale CMF/PTF types. The coupling caps are also gone.
I also use a custom job built with LME49713 CFA's, also direct coupled with DC offset trimpots. That is 2kv/us slew rate and very low THD+noise. It's fed BurrBrown and ESS DAC's.
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Post by jimwilliams on Mar 21, 2018 11:04:15 GMT -6
I still use and love mine. It is never out of date. Jack in ESS or BurrBrown conversion and it's as good as that stuff is. I find it very fast and intuitive when running an analog studio. Live it always impresses.
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Post by jimwilliams on Mar 17, 2018 18:21:29 GMT -6
It doesn't power through the 5 volts of a USB connector, it uses a wall wort. No power switch though. ADC's are for a small crowd of recorders, the forgotten man. Those too will come down in cost, some day. The fact that low cost first rate RCA connected playback gear is now cheap is a gift to us. It's not hard to wire up a XLR to RCA plug. DAC's put out a lot of voltage at +20 dbu single ended. It's not the old Tascam -10dbv RCA days.
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Post by jimwilliams on Mar 17, 2018 15:10:18 GMT -6
One could feed the AES/EBU to the coax input or re-route to USB and use the transport functions and or MQA and other features. This is only 400 bucks and tiny so most high end mastering houses would probably hide it behind another box to impress clients.
ESS also makes a new high end 8 channel DAC chip. The high end/low cost multi-channel DAC's for recording can't be far off now. Glad I kept my Alesis HD24XR, it works with these too.
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Post by jimwilliams on Mar 17, 2018 14:01:45 GMT -6
I found a new new 32 bit DAC design made in Germany. It's made by Pro-Ject and called the Pre Box S2 Digital. This puppy uses the newest ESS 32 bit Sabre DAC chips, a pair in dual cosine. These are the same chipsets used in the $5000 Mytek Manhattan II.
It is small but has all the inputs, coax, optical and USB. It will do several rates of DSD and up to 760k 32 bit. The USB input provides 16 core asynchronous USB transfer for MQA rendering, a unique/expensive feature catching on in the high end consumer market. It also does remote control of transport functions to your computer.
The $40 a piece ESS 9038 DAC chips are the current best in market. This has a pair of them. It also uses the new ESS 9602 headphone/output buffer for -120 db THD+noise. The power supply uses the new ESS 9311 low dropout voltage regulators, designed for high end DAC power supplies.
The clock design is excellent, only 100 femtoseconds of jitter, better than most high end clock generators. It has 7 selectable digital filters and uses organic polymer capacitors for the power supplies. The layout and design is excellent with a 4 layer gold pcb. There are pics of the innards with descriptions on their web site.
This may be a new game changer as it is far beyond the capabilities of nearly all the pro-audio DAC's out there. This is some real engineering folks.
By now you probably want to know how it sounds. I don't know, I'm waiting for it. It did win the EU audio shootouts but is new here in the States.
You probably want to know how much it costs? It could be $4000. It could be $2000 and a deal. It actually costs $399 shipped to your door. I don't know how it can be made that cheap with those expensive chipsets.
www.project-audio.com
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Post by jimwilliams on Mar 17, 2018 13:39:01 GMT -6
Add some higher output piezo's and use the Jim Cunningham gain reset designs and you can lower the EMT return noise to -100 dbu.
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Post by jimwilliams on Mar 9, 2018 21:40:37 GMT -6
I have a 5 way 4 deck switch in my Tele Thinline. I got it from All parts. It adds the series position along with an out of phase position besides the regular 3 pickup choices. The out of phase is super funky and nasal. All Parts has the 4 way switch too. www.allparts.com
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