[adydula]

Listening to Love and Happiness (Emmylou Harris and Mark Knofler - All the Roadrunning)...

The sound and presentation with the T2 here is absolutely superb!
Excellent soundstage, tonality, no distortion etc that I can hear.

Using Beyer T90's at the moment, Jriver Flacs CD redbook etc...from Schitt Bifrost MB dac.
The T90;s by many are very bright and if I cant hear distortion or wonky treble with these on this amp
then to me its just not there for my ears!!

Going back to back with the Burson Fun with Sparkos SS3601 discrete op amps and the Burson wins out by a small
edge in overall presentation, but its not that different.

Alex

 

[tomchr]

I forgot to measure the thump that occurs when the T2 is turned off. That's hereby rectified. I'll add this to the review.


Keep in mind that the line output on the T2 is the same as the signal provided to the headphones. Thus, the line out will exhibit the same turn-on/turn-off thump as shown above. I will definitely caution those who plan to use the T2 as a preamp to develop a strong habit of turning the power amplifier on last and off first. That's a good habit to get into anyway. If you turn the T2 off first, your speaker cones will be in for quite a ride.

Tom

 

[gaz2613]

Like many, I was intrigued by simplicity in design of the T2 and when offered to borrow one so I could measure it and have a listen, I jumped at the opportunity. It turned out to be about a week's worth of measurements, listening, and exploration of the ins and outs of the T2, which has led to one of my most thorough reviews. You can find my review (and measurements) here: DIY Audio T2 Headphone Amplifier Review and Measurements.

Tom

I just bought one of these boards but now I feel like I dont want to waste the money getting the components to build it. I like precise amps too. I currently have the Whammy and the NuHybrid which I built both myself and I am really happy with those. Just dont want to waste money if they will not sound as good. Thank you for the measurements and the detailed write up.

 

[gaz2613]

I forgot to measure the thump that occurs when the T2 is turned off. That's hereby rectified. I'll add this to the review.


Keep in mind that the line output on the T2 is the same as the signal provided to the headphones. Thus, the line out will exhibit the same turn-on/turn-off thump as shown above. I will definitely caution those who plan to use the T2 as a preamp to develop a strong habit of turning the power amplifier on last and off first. That's a good habit to get into anyway. If you turn the T2 off first, your speaker cones will be in for quite a ride.

Tom

The thump also puts me off, how could the designer make such an oversight to not include a muting circuit. Even cheap chinese boards have muting circuits.

 

[adydula]

Hey guys....dont let this report stand in the way of building this amp.

I respect Tom and what he does and belive the measurements are what they are.

That said I have the amp and use it and it sounds very good to me....yes there are better but this amp still works well
sonically.

The original Schitt Asgard had a turn on thump issue, it doesnt bother me at all...I ususally turn the amp on and them insert the headphone...no
real problem other than its a DIY thing here.

Hope you still try and build it, its a really great little amp that work well sonically..

Alex

 

[tomchr]

Thank you for the measurements and the detailed write up.

You're very welcome. I firmly believe that informed consumers will be able to make the best purchasing decisions.

The thump also puts me off, how could the designer make such an oversight to not include a muting circuit.

Especially in an amp that runs from a single power supply rail. The thumb is from the output capacitor charging. The only way for the charging current to flow is through the headphones, hence, the thump. Thankfully, the circuit designer included 470 Ω in parallel with the output, so you do have the option of just plugging your 'phones in after a delay, and unplugging them before you turn off the amp.

That said I have the amp and use it and it sounds very good to me....yes there are better but this amp still works well
sonically.

Have you compared it to anything serious, like the Benchmark HPA-4, or just to the stack of DIY amps you showed earlier? I'm not knocking any of the DIY amps, but I doubt any of those in the stack reach the precision the HPA-4 and similar precision amps do.

The original Schitt Asgard had a turn on thump issue, it doesnt bother me at all...I ususally turn the amp on and them insert the headphone...no
real problem other than its a DIY thing here.

And lots of people expressed concern about that thump in the Asgard. Subsequent revisions of the circuit had a muting circuit built-in.

Maybe I misunderstood your statement above, but the notion that turn-on thumps are OK because it's "a DIY thing" doesn't sit well with me. I think DIY kit developers have a responsibility to ensure that their circuits are safe for use and well tested. DIY headphone amp kits should not produce turn on/off thumps that put the builder's headphones at risk.

How would you feel if someone had their $3k Focal Utopia destroyed by the turn-on thump? Would you offer to buy them a new pair? Do you think the designer of the T2 would? As a circuit designer, that's the kind of stuff that keeps me up at night. I'd rather design in a protection circuit than have to respond to the "your amp killed my phones" support call. But maybe that's just me... I'm also one of those weirdos who wears a seat belt while driving even though I'm not planning to get into an accident.

Tom

 

[adydula]

i wear my seat belt too, because its the law, and its common sense...

I agree the T2's thump is not desireable, but its there for sure, but its not that big of a deal to me.

I dont think folks who spend $3000 on headphones would be using this low end. low cost amp....IMO.

That said the designer of this amp I believe wants people to get into electronics, soldering, thinking about circuits etc...and we all have
to start somewhere...maybe he was trying to get folks to tackle this issue and others as well??

Who knows...what this amp proves to me is even stuff that measures poorly can sound good.

I have a tube amp that sounds better than any other amp I have ever used....its thd is atrocious....and when using a SS amp that measures as good as some of the amps
out there and that you mention etc...its no contest here....its indeed magic and really clean amps can and do sound good but there are others that sound better to me.

If highly great measured amps were indeed the holy grail then why dont they sell that well. If its audio nirvana then I would think the world would beat a path to your door?

Sometimes mediocre is ok.

..and for a tired, retired EE here....it still baffles my analytical and objective schooling..that said the T2 still is ok fine...

--and to all DIY'rs out there DONT put your $3000 cans into ANY amp for the first time!!

Alex

 

[tomchr]

I dont think folks who spend $3000 on headphones would be using this low end. low cost amp....IMO.

Maybe not. But why exclude them as potential users? Also, I'd be rather miffed if my Etymotic IEMs or any of my Sennheisers got fried, even though they're 14-26 dB lower cost than the Focal Utopia.

That said the designer of this amp I believe wants people to get into electronics, soldering, thinking about circuits etc...and we all have
to start somewhere...

True. And if they have the experience that their first DIY project fried their headphones, do you think they'll be further encouraged to pursue DIY as a hobby? In my view, the turn-on thump is a design oversight. I think the designer should own it, and either release an updated version of the circuit that includes a turn-on/off muting circuit, or release a muting circuit as a highly recommended add-on module. But that's my opinion.

Who knows...what this amp proves to me is even stuff that measures poorly can sound good.

Well... One data point doesn't really prove anything. My experience was that the amp sounded mediocre at best. Then again, I'm comparing against low distortion precision designs, which I happen to prefer.

If highly great measured amps were indeed the holy grail then why dont they sell that well. If its audio nirvana then I would think the world would beat a path to your door?

Not necessarily. Purchasing decisions are rarely the result of rational thought. Often, they're the result of an emotional reaction. That's where psychology comes in.

Sometimes mediocre is ok.

Sure. And maybe the T2 will (re-)kindle the DIY hobby for some. I'd be fine with that.

Tom

 

[JazzVinyl]

Have you compared this to the Rudistor NX-03 by chance? The NX-03 also uses a minimum part count and Darlinton transistors.

 

[adydula]

Nope.

The commercial amps I have tried are the Schitt Asgard, Schitt Lyr, the O2, Bottlehead Crack with CCS, Bottlehead Mainline, WooAudio 6SE, JDS Labs Element, Burson Fun (4 different Op amps) and about 9 other DIY amps. of various types, and IC's.

The one thing is my experience with this amp "sonically" has been excellent and very surprising to me after Tom's measurements. His experience was mediocre at best.

So different people seem to have varying experiences so our "psychologies" are indeed different! I know ten other people that have built and listened "with" this amp and have had a good experience...even with the thump...so go figure.

:>)

Alex

 

[bagwell359]

[QUOTE="adydula, post: 15177958, member: 166678"
I have a tube amp that sounds better than any other amp I have ever used....its thd is atrocious....and when using a SS amp that measures as good as some of the amps
out there and that you mention etc...its no contest here....its indeed magic and really clean amps can and do sound good but there are others that sound better to me.
Alex[/QUOTE]

Amp circuits with a good deal of THD often sound more liquid, romantic, warm, coherent than transistor amps. People will spend a great deal of money for this distortion. I had my dynaco's, audio research's, even a Cary and Jadis. But two things got to me: tube amps of enough wattage could not control woofers well enough. And I started to hear all that THD as an ever present smudge over the sound even when the recording had ZERO of that element in the sound.

I finally discovered Nelson Pass amps, and they had all of that SS detail, but when the recording is suave or soft, or whatever - that's what you get. Threshold Stasis 3, Aleph 5, X150; preamps" Adcom GFP-750, P, Ono - outside of the Aleph 5 which was IMO a misstep it's all the same.

Currently the Cronus Magnum is known to have rotten specs and great sound. It is possible I am sure that such amps exist. It's also possible that measurements that are no longer in vogue like TIM and SID would reveal more.

I'm a great believer in DIY, I hope that the issues here are solved to the point where measurements and opinions meet.

 

[tomchr]

So different people seem to have varying experiences so our "psychologies" are indeed different!

Yeah... We're ~7B people on this here space rock. If we were all alike, it would be awfully boring. In terms of our psychology (cognitive processes, perceptive processes, etc.), we're actually remarkably similar. There's always some individual variability, however.

Amp circuits with a good deal of THD often sound more liquid, romantic, warm, coherent than transistor amps.

Great. Now you just need to define "liquid", "romantic", "warm", and "coherent"... That's usually where subjectivism breaks down for me. Nobody can agree on the definitions of the terms. For some cone breakup in a speaker sounds "precise" (positive). To others, it sounds "harsh" (negative). If you measure the frequency response of such a speaker, you'll find lots of resonances in the upper midrange and beyond resulting from the standing waves developing across the speaker cones. With such a measurement, you can at least make a determination before you buy as to whether a particular speaker is likely to sound good to you or not. Same applies for directivity or any of the other measurements.

It's also possible that measurements that are no longer in vogue like TIM and SID would reveal more.

Anything is possible. To me, high TIM/SID is a sign of bad design (the designer didn't bother looking at the internal nodes in the circuit) ... and there are plenty of bad designs out there.

I'm a great believer in DIY, I hope that the issues here are solved to the point where measurements and opinions meet.

I'm a believer in DIY and in progress as well. While we don't all have the same preferences, having measurements available makes it possible to determine whether to pursue an amp build before you sink a bunch of money into parts and time into a build.

Tom

 

[bagwell359]

@tomchr

My point about using subjective labels was only to point to the fact that they are distortions - I.E. when a "pleasing" flavor always appears - its no longer music, it's distortion.

In the headphone world lots of people like a "fun" profile. I guess I'm just an old goat, but, purposefully listening to a known incorrect profile is no fun.

I looked at your site - any headphone amps with XLR in/outs planned?

 

[tomchr]

See: www.tomchr.com
In the DIY world, I'm toying with the idea of a headphone amp in time for Burning Amp. Details to follow.

Tom

 

[wushuliu]

Had no idea Tom had done measurements on the T2. I was wondering when some would be available.

I've built and listened to the T2 and as much as I appreciate what Tomchr has done, people need to understand that he comes from a very different and strongly opinionated design perspective.

Right now I have an Asgard 3, Project Sunrise III (tube hybrid), the T2, and modified cheap JLH-based headamp. I've had all of them in rotation during the build and listening to the T2. All listening done with Soekris 1021 DAC and HD6XXs. My observations (Be warned, *subjective comments ahead. gasp.*):

1. It sounds very good stock. 'Mid-fi' tube amp sounds about right as a descriptor. Classic Class A sound. If you like that sound, you'll like this amp. Definitely not the lowest noise floor or separation - but I think that can be improved upon (see below).

2. I don't experience a turn on thump.

3. Output is indeed lower than typical but I think Mark Johnson's reason for doing so is an interesting choice - minimizing the channel balance impact of volume pots. With my HD6xx/650s this means I only have about a quarter turn or so to blow my eardrums vs. three quarters of the typical headamp. Big Deal.

4. I found a linear power supply (simple LM317 with an LC 'Noise Nuke') to be preferable to the SMPS - although the SMPS does sound very good. The LPS is smoother to me.

5. Since this is an inexpensive DIY and the board is nice and simple, there's plenty of room to try different things to see if you can improve what you hear/tailor the sound to your expectations. Ex: Personally I found the 3.3uf input cap to make the low frequencies a little congested/muddy, so I lowered until I found a value I liked (2.2uf). This opened the sound up for me and widened the presentation/stage.

Secondly, a member in the T2 diyaudio thread recommended bypassing the 3 IN4004 diodes with a large (3300-4700uf) cap to lower noise. I did this and found it did indeed have an audible impact for the better. The combination of reduced input cap value and the 1N4004 bypass IMO improved things considerably (to my taste). Furthermore, the layout and simplicity of the board allows you to play around. Skeptical of the bypass? Bloop, just drop the cap at each end of the diodes. Takes 10 seconds. Listen. Compare. Done. Same with any other parts on the board.

So I guess I would say I am somewhere in the middle in my assessment. Stock, it ranked about on par with the cheap but good sounding JLH-based amp (which makes sense since they share similarities). The Sunrise, which is a *great* amp, was clearer, lower noise, more extended in high frequencies, tubey yum yum. Asgard 3 I would consider more to Tomchr's camp - excellent micro-detail, low noise and distortion, 'neutral' (whatever that means). But after I made those couple of changes, the T2 is about equal with them. Just a different presentation - sort of a mix between the two.

Finally, I think the T2 is another important lesson in how low distortion is not a holy grail. Is it nice to be able to hear an ant walking along the studio floor during the recording? Sure. But it doesn't make or break an amp/speaker/headphone for me.