[lee730]

  select all frequencies at 0

 
You must have done something right. He loves it with no eq and at eq -9.

 

[Migou67]

@Burnway I have changed last evening back to 0, too much bass and lost clarity !
I just wanted to have more volume control for my sensitif IEM, finaly is not a problem.
 
@Alphaman I will take the risk, the sound is too good, thank you for the explanation.
@Lee You are no more my friend  

 
 
Edit : For the popping noise, it just append one time at power on, I must get used to plug my IEM after.

 

[alphaman]

  @Alphaman I will take the risk, the sound is too good, thank you for the explanation.

Now that I think about it, most modern DAPs and smartphones and iPads, etc. do not have output protection. A few years ago, home components (CD/DVD players, etc) had output protection transistors (and a lot of DIYers removed them for improved sound). I think output protection is old-school thinking ... back when something blowing was more likely and would cause DC on the output (e.g., tube stuff) Today, QC and component reliability has gotten good enough that we can bypass old-school protection topologies. You'll probably get a new DAP way, way before the remote 0.1% possibility of a screw up. Still, you've got nice higher-end IEMs and the louder TeKMOD power-on thump is a little scary -- I've frankly never felt comfortable with the STOCK thump of T51. If you have DMM, connect some probes to T51 output and set it to DC in millivolts. Keep a sharp eye on it when you power it on. Write that transient value down and report back ... if you have the time  
P.S. Transient may be very quick, so video-capture with your iPhone and examine the values in slo-mo playback.

 

[Migou67]

I unfortunately have no volt meter to do that, but for me the easy way is to plug the IEM after, I power on the T51 one time a day in morning and I stop it in evening at home, I use USB to keep the charge during the day at my desk.
 
PS: I dont have an Iphone but a Note2

 

[burnwaygta4]

  Now that I think about it, most modern DAPs and smartphones and iPads, etc. do not have output protection. A few years ago, home components (CD/DVD players, etc) had output protection transistors (and a lot of DIYers removed them for improved sound). I think output protection is old-school thinking ... back when something blowing was more likely and would cause DC on the output (e.g., tube stuff) Today, QC and component reliability has gotten good enough that we can bypass old-school protection topologies. You'll probably get a new DAP way, way before the remote 0.1% possibility of a screw up. Still, you've got nice higher-end IEMs and the louder TeKMOD power-on thump is a little scary -- I've frankly never felt comfortable with the STOCK thump of T51. If you have DMM, connect some probes to T51 output and set it to DC in millivolts. Keep a sharp eye on it when you power it on. Write that transient value down and report back ... if you have the time  
P.S. Transient may be very quick, so video-capture with your iPhone and examine the values in slo-mo playback.

I use resistors of 1% of accuracy, on an output of an ushnik it is no more 10mV than DC. No protective transistors are present in stock T51, and they aren't necessary there - short circuit protection is in THS4222. If you haven't enough knowledge - will suffice to talk nonsense.

 

[alphaman]

  I unfortunately have no volt meter to do that, but for me the easy way is to plug the IEM after, I power on the T51 one time a day in morning and I stop it in evening at home, I use USB to keep the charge during the day at my desk.
 

That's a lot of effort ... and now, the TekMOD produces even greater transients?!! Well, we all NOW know what the risks are ... so those that may be affected have been properly warned

 

[burnwaygta4]

  That's a lot of effort ... and now, the TekMOD produces even greater transients?!! Well, we all NOW know what the risks are ... so those that may be affected have been properly warned

Dangerous to earphones of transient phenomena there is in tekmod, as well as no risk.
I will repeat: If you haven't enough knowledge - will suffice to talk nonsense.

 

[Migou67]

Is just a popping noise, nothing to worry about.

 

[alphaman]

  Is just a popping noise, nothing to worry about.

Not saying you will ever encounter the worst-case scenario but in the case of DC, it's not what you HEAR that will kill your IEMs

burnwaygta4 wrote:
 
 ...they aren't necessary there - short circuit protection is in THS4222

Is this what you're using for the TekMOD HO and/or LO opamps?
Why not use purpose-built headphone amp ... also from TI? E.g., TPA6133A2. I think your customers would like this, but you'll have to solder at SOP level. Or you may also try a class-D amp for experiment.

 

[burnwaygta4]

  Not saying you will ever encounter the worst-case scenario but in the case of DC, it's not what you HEAR that will kill your IEMs
Is this what you're using for the TekMOD HO and/or LO opamps?
Why not use purpose-built headphone amp ... also from TI? E.g., TPA6133A2. I think your customers would like this, but you'll have to solder at SOP level. Or you may also try a class-D amp for experiment.

THS4222 has a large quiescent current, body msop8, excellent data on the level of distortion and range of distortion.
I collected the amplifier on tpa6120 - it concedes noticeably to the amplifier on THS4222. Or you think, what if "vendor" assigned a chip as the naushnikovy amplifier, it because of it will be the best? It is simply ridiculous such to read.

 

[burnwaygta4]

  Not saying you will ever encounter the worst-case scenario but in the case of DC, it's not what you HEAR that will kill your IEMs

it won't destroy anything, at worst T51 can give out at most ~3.6 volt of DC, any earphones won't die of it, is checked. Already the third time I tell, stop to talk nonsense and to mislead readers of a forum, go be collected knowledge, them you have no times.

 

[alphaman]

  THS4222 has a large quiescent current, body msop8, excellent data on the level of distortion and range of distortion.
I collected the amplifier on tpa6120 - it concedes noticeably to the amplifier on THS4222. Or you think, what if "vendor" assigned a chip as the naushnikovy amplifier, it because of it will be the best? It is simply ridiculous such to read.

The THS4222 may have "excellent data" (PUBLISHED specs) but  ...(a) those are specs done by the manuf. (or did you personally bench spec them, burnwaygta?); and (B), in any case, good specs do not always equal better sound. A good example of this is vacuum tubes vs. solid state.
I have compared the THS4222 to the TPA6120 and much prefer the latter. I design by ear and  manuf. specs and my own oscilloscope measurements.
 
The manuf. datasheets of opamps publish full and complete schematics of high-performance (suggested) circuits, like TPA6120. These are circuits designed and tested by TI.com, so the have a lot of expertise backing them up. 
burnwaygta: I suggest you post your full schematic here, in this thread, so you can get better feedback in this forum.

 

[T.R.A.N.C.E.]

Hi everyone
 
burnwaygta4, how much does the mod cost?

 

[burnwaygta4]

  Hi everyone
 
burnwaygta4, how much does the mod cost?

Hi T.R.A.N.C.E., mod cost is $130 + expenditures on player transportation

 

[burnwaygta4]

  The THS4222 may have "excellent data" (PUBLISHED specs) but  ...(a) those are specs done by the manuf. (or did you personally bench spec them, burnwaygta?); and (B), in any case, good specs do not always equal better sound. A good example of this is vacuum tubes vs. solid state.
I have compared the THS4222 to the TPA6120 and much prefer the latter. I design by ear and  manuf. specs and my own oscilloscope measurements.
 
The manuf. datasheets of opamps publish full and complete schematics of high-performance (suggested) circuits, like TPA6120. These are circuits designed and tested by TI.com, so the have a lot of expertise backing them up. 
burnwaygta: I suggest you post your full schematic here, in this thread, so you can get better feedback in this forum.

Listen to tpa6120, your business
Here only in case of a supply +-4V tpa6120 won't work in T51

, and ths4222 works perfectly (and as has the output cascade Rail-to-Rail that is very important for low supply voltages).
I am not going to publish all details about the modification, it isn't necessary for me.