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Teapo caps in Mytek Stereo96 ADC!?
Old 25th January 2009
  #1
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🎧 10 years
Teapo caps in Mytek Stereo96 ADC!?

Out of curiosity, I opened up my Mytek Stereo96 ADC, a supposedly high end converter, to take a look at the components inside. To my surprise, I saw two Teapo 4700uF 16V caps in the power supply. Here's a link to the user manual where you can see the component layout on page 6.

http://www.mytekdigital.com/download...al-v5-2005.pdf

The Teapo caps are C64 and C65. Now, according to the BadCaps.net forum, Teapo is a cheap Chinese brand that is one of the bad caps they found in motherboards.

Badcaps Forums - List of Bad Cap Manufacturers

So I'm wondering what these caps are doing in a well-renowned converter that cost me almost a thousand bucks. Surely Mytek could have used better quality caps for that price.

It may be that these caps don't really matter much in the circuit, but I'm not an electronics expert to judge that. I'm just a guy handy with a soldering iron who can do only simple component changes. So maybe I shouldn't worry about them as long as my unit is working, which it is. But in my noviceness I can't help thinking that replacing them with better quality caps would yield a noticeable improvement in performance or at least guard against the possibility of failure which seems likely considering the bad rep of Teapo caps. All of a sudden I'm getting the urge to replace these caps. What replacements would you suggest?

Your inputs would be greatly appreciated. Thanks in advance!
Old 22nd December 2011
  #2
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Convectuoso's Avatar
 
1 Review written
🎧 10 years
It's stuff like this that makes me really start to doubt my trust converter companies.

I'm really surprised no one replied to this.

What happened in the end?
Old 22nd December 2011
  #3
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🎧 10 years
In understand what goes into designing this equipment, marketing, etc. but point to point tube equipment costs what is does because of all the money in parts and labor. Converters use cheap parts and are mostly surface mount parts. I just don’t understand 1k for a single D/A, especially when they can’t even put decent capacitors in it.
Old 22nd December 2011
  #4
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lectric's Avatar
 
🎧 15 years
Good thread. I wait a good opinion.
Old 22nd December 2011
  #5
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Convectuoso's Avatar
 
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🎧 10 years
Yes, I'd really like to see the true cost of a lot of these converters.
Old 23rd December 2011
  #6
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🎧 10 years
what really gets me that there is no high end converters. to me bit dept is not there yet. I wish for a 128 bit 176khz converter.

some people improved the clock, but the chip manufactures do that. Maybe its board design, but that is usually a less than 5% margin when its digital. as the same 6 chips are used everywhere.

as the caps, they probably hand picked them (hopefully) but it means very little if they have made their voltage regulator on the aggressive side.

Surface mount technology as whole is not studio quality, and it does not hold up to on the road conditions either (I do feel sorry for those digital live mixing people as their units are short lived).

I don't like the new ways and stuff: I want a 2 inch machine again. and a 1 inch stereo
Old 23rd December 2011 | Show parent
  #7
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🎧 15 years
Quote:
Originally Posted by drtechno ➡️
what really gets me that there is no high end converters. to me bit dept is not there yet. I wish for a 128 bit 176khz converter.
128 bits! That's a lot.

19 real bits is a lot.


DC
Old 23rd December 2011
  #8
Gear Guru
I'd love to get a real 20 bits. Everything down there is just noise. I need more noise, it's so quiet here.

Maybe Michal wants the service end to pick up? Anyway, get a de-soldering tool and yank those bad boys out. Replace them with the Panasonic FR series and you wan't need to do that for another 40 odd years.
Old 24th December 2011 | Show parent
  #9
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🎧 15 years
Quote:
Originally Posted by Jim Williams ➡️
I'd love to get a real 20 bits. Everything down there is just noise. I need more noise, it's so quiet here.
Here's 1k at -120dBFS. We have been able to beat the limit-cycles and other noises into submission. IIrc, 4 averages applied. Maybe 8.

DC
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Teapo caps in Mytek Stereo96 ADC!?-1k-120.jpg  
Old 24th December 2011
  #10
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LeeYoo's Avatar
 
🎧 10 years
Going from the picture of the board layout, C64/65 are lineair supply mains filter caps.
They are working on 100/120herz.
Any old cap will work here with this frequency/current/ripple.
Also, 4700uF is overrated for this type of circuit. Surely, they are also bypassed with film, or ceramic caps.
Things like motherboards and switching power supplies work with high frequencies/currents. Special low ESR caps are required for that.
Leo..
Old 26th December 2011 | Show parent
  #11
Gear Guru
Quote:
Originally Posted by dcollins ➡️
Here's 1k at -120dBFS. We have been able to beat the limit-cycles and other noises into submission. IIrc, 4 averages applied. Maybe 8.

DC
Sure, you can beat a sign wave to go down there. Music is another story. Here I have problems with air at 70 degrees, it's too noisy and too much movement. The mics are less noise than the random air in the room. So are the preamps, etc. My problem is the air in the room is too noisy, the gear is fine. Recording at 32 degrees does help some but the players don't like that.

Maybe 128 bits will fix this? Global warming will make it worse.
Old 26th December 2011 | Show parent
  #12
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🎧 10 years
Quote:
Originally Posted by Jim Williams ➡️

Maybe 128 bits will fix this? Global warming will make it worse.
I hear that 'lectrics work real well at absolute zero. Maybe we need to stick the gear in the ice chest.

As a side note to the noise issue... as one who has recently left a studio and will eventually attempt to record some things here at home... oh my, why is the world so loud?
Old 26th December 2011 | Show parent
  #13
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🎧 15 years
Quote:
Originally Posted by Jim Williams ➡️
Sure, you can beat a sign wave to go down there. Music is another story.
Can you do that with your D/A converters? Personally, the other systems I've looked at always show either harmonically related spurs or ones generated by limit-cycles at those levels.

Quote:
Maybe 128 bits will fix this? Global warming will make it worse.
These are the type of questions that you and Drtechno should begin to address immediately.

The world is waiting.


DC
Old 27th December 2011 | Show parent
  #14
Gear Guru
Quote:
Originally Posted by dcollins ➡️
Can you do that with your D/A converters? Personally, the other systems I've looked at always show either harmonically related spurs or ones generated by limit-cycles at those levels.
DC
DAC's arn't the problem, it's air noise. I use a PCM/DSD1792A that uses an ADA4898-1 I/V stage and 2 pole MFB filters using LME49713 CFA's. That system does -129 db with the last 9 db being noise. There is no audio in those bits, the ADC's didn't encode it as their resolulution is less.

It's not about sine waves, mastering other's stuff and AP's, here it's about capturing live music performances without noise with gear that is already beyond the random air movement noise in a 70 degree room.

That's what I mean when anything beyond 20 bits is noise. It's not something to be very concerned with if your masters are done with less than 3 db's of dynamic range applied as is done with most releases today.

Meanwhile, if those failure prone ******** caps have you bummed out, a pair of Panasonic FR's will work great and will last 40+ years.
Old 27th December 2011 | Show parent
  #15
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🎧 15 years
Quote:
Originally Posted by Jim Williams ➡️
DAC's arn't the problem, it's air noise. I use a PCM/DSD1792A that uses an ADA4898-1 I/V stage and 2 pole MFB filters using LME49713 CFA's. That system does -129 db with the last 9 db being noise. There is no audio in those bits, the ADC's didn't encode it as their resolulution is less.
I'm not talking about air, mastering, temperature, or current-feedback. Just actual analog performance.

I'd just be curious to see an FFT of 1k @ -120dBFS.


DC
Old 28th December 2011
  #16
Gear Guru
It's up on their data sheets, look up the BB PCM1792A. The FFT's are there for you. If you use 2 of them in a sine/cosign configuration, they will do -132 db dynamic range. There is no audio in those last bits, it's just noise.

Analog, Embedded Processing, Semiconductor Company, Texas Instruments
Old 28th December 2011 | Show parent
  #17
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dcollins's Avatar
 
🎧 15 years
Quote:
Originally Posted by Jim Williams ➡️
It's up on their data sheets, look up the BB PCM1792A. The FFT's are there for you. If you use 2 of them in a sine/cosign configuration, they will do -132 db dynamic range. There is no audio in those last bits, it's just noise.
Your actual analog performance of a -120dBFS sine at 1kHz is what I'm talking about.


DC
Old 30th December 2011
  #18
Gear Guru
Let me think.... Well, the signal at -120 db is pretty low, it's not going to have any audio or guitar, just random air movement when the rig is off. Otherwise, I have very good reproduction of the residual hiss and hum off that guitar amp, but it's a really quiet amp compared to others. Once it's mixed to CD prep, there's nothing encoded down there anyway. 16 bits is a sort of gate.

With acoustic sources, it's all air movement noise, not electronic hiss which is now below the acoustic air noise. It's there at 24 bits but most is not encoded to CD's, not enough dynamic range to reproduce it. The preamps are -136 db EIN, the mics are 5 db self noise, there is just acoustic air noise down there now, nothing I'm too concerned about.

I use a PCM/DSD4222 ADC with custom analog front end. It does around -120 db. Good enough to encode natural air in the room. The rest really doesn't matter here, what the ants are doing in the corner of the room doesn't really concern me. I'm not a sort that does fashionista mastering, I love the CD dynamic range and I use as much as I can. 120 db doesn't seem to be needed nor desirable with today's 2 db dynamic range, it's a fun exersize but when that guy comes into your place and demands you make HIS record louder than the rest, this all is meaningless. Fortunately, I don't do mastering for a living so I don't ever need to do that. I like to be able to listen to my stuff.
Old 30th December 2011 | Show parent
  #19
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dcollins's Avatar
 
🎧 15 years
Quote:
Originally Posted by Jim Williams ➡️
Let me think.... Well, the signal at -120 db is pretty low, it's not going to have any audio or guitar, just random air movement when the rig is off. Otherwise, I have very good reproduction of the residual hiss and hum off that guitar amp, but it's a really quiet amp compared to others. Once it's mixed to CD prep, there's nothing encoded down there anyway. 16 bits is a sort of gate.
Siily me, I should have known better than to expect any sort of objective measurements here. It's better to say "those resistors are awesome!"

Someone mentioned that they wanted 128 bit D/A conversion, and I showed an actual circuit that can approach 20. In a real-world measurement.

Quote:
120 db doesn't seem to be needed nor desirable with today's 2 db dynamic range, it's a fun exersize but when that guy comes into your place and demands you make HIS record louder than the rest, this all is meaningless. Fortunately, I don't do mastering for a living so I don't ever need to do that. I like to be able to listen to my stuff.
It's true that while I have dabbled in electronic design, my "real" job is as a professional listener.

Some clients want it loud, some don't.


DC
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