Choosing Headphone Amp for Fostex T50RP

[WSM_2020]

Hi, everybody! I am a newby here.

I purchased Fostex T50RP MK3 a bit more than a week ago and found out, rather predictably, that Yulong U100 DAC is not enough indeed for the headphones to shine, though it operates really fine given that it can provide 100 mwt @ 32 Om only. So, now I am head and ears in the forums and reviews of the headamps forming a list of the suitable choices. By now it includes: Fiio K5, SMSL sAp II Pro, Topping A30, JDS Atom, Topping A50 and Schiit Magni Heresy.

In Fiio K5, sAp II Pro and A30 there is the same TPA6120A2 as an amplifier, still A30 looks as the best realization of its potential judging from the tests here. Amplification schematics in Atom (DC coupled circuit), A50 (a pair of LME49720 OP-Amps) and Heresy (OPA1662 op-amp for voltage gain with local feedback, OPA1688 (8 stages) as output buffers with local loops, no overall loop feedback) present incomparably more creative solutions. But will I feel a real difference with Fostex T50Rp MK3 listening to my content through these devices? How do specifically A30, Atom, Heresy and A50 match my headphones? Can they somehow contribute to their signature or improve it? Or will all of them stay absolutely neutral?

 

[Bob-23]

it operates really fine

Hello! Welcome!
So what do you miss? U100 got quite favourable reviews, are you sure you need another amp? Apart from that, well implemented opamps of the correct (audio) type don't 'sound' different, nor do film caps in the signal path, so ac-coupling is not 'worse' than dc-coupling, on the contrary, a cap in the signal path gives you a certain dc-protection (at least, of the dc before the cap). A good amp is, so goes an old saying: wire plus current. If you really shouldn't have enough power, if you've got audible distortions at normal listening levels (or if the sound is clearly coloured because of an high output impedance, what is yours?), only then I would consider buying a new amp. And if you compared noise and distortion figures of the amps you listed - and I guess you did so - and it's, say, below -100db, you won't hear a difference between them (I guess you won't even hear it at -80db). - But maybe your U100 is sufficient. To me, btw, built quality is always an important criterion.

 

[Jimbob54]

Have the T60s (same but wood cups). These are relatively low impedance (50ohm) but pretty damn insensitive 'phones @92dB They take some oomph to make them sing (I'll not comment on the pros and cons of how well they sing). I'm not clever enough to say which of the candidate amps are best suited to the T50s but they need some welly.

My main concern for you is , you're buying new kit to suit one pair of relatively cheap 'phones. I'd say its likely you may be tempted for more (or have more already) and so a clean somewhat powerful amp with low output impedance (2 or less ohm) should serve the T50 and any future easier to drive 'phones. Others will say which of your candidates dont fit this spec. Or may flat out tell me I'm wrong.

EDIT- I have the Atom so will run the T60 off it over the weekend and give my unqualified opinion.

 

[WSM_2020]

Bob-23
ThanX a lot for a reply! You see, Yulong U100 is a great DAC indeed but in a head amplifying region it officialy provides 100 mwt @ 32 Om only that is insufficient for such insensitive 'phones as T50RP. In many cases, one should switch loudness to 70% minimum in Windows only to reach a comfortable, not too silent level.
So u insist that no headamps influence the sound u hear from your 'phones? I've already met this opinion.

Jimbob54

EDIT- I have the Atom so will run the T60 off it over the weekend and give my unqualified opinion.

U r wellcome! As for your supposition, at least Atom, Magni Heresy and A50 will be ok, I believe, for every possible upcoming 'phones ...

But I happen to have excluded Fiio K5, SMSL sAp II Pro, Topping A30 from my choice as founded on rather outdated or, at least, not very good TPA6120A2, but now I also consider the used Magni 2 Uber and Magni 3 "old". Can anybody point out if there is any real difference between Magni 3 "old" and Magni Heresy?

 

[Veri]

I have the Atom so will run the T60 off it over the weekend and give my unqualified opinion.

I would wait for Jimbobs report. In any case, magni heresy/atom or drop 789 are all superb single ended amps, bonus on the 789 that it also has balanced headphone output with even more power.

 

[WSM_2020]

bonus on the 789 that it also has balanced headphone output with even more power

... And is alas! 3 times more expensive ... )))
I've changed my mind about the used Magni 2 Uber and Magni 3 "old" - they are literally useless when there is Atom ...

 

[Jimbob54]

I would wait for Jimbobs report. In any case, magni heresy/atom or drop 789 are all superb single ended amps, bonus on the 789 that it also has balanced headphone output with even more power.

I'm crumbling under the pressure...

 

[Veri]

I'm crumbling under the pressure...

Haha

 

[Jimbob54]

@WSM_2020 @Veri

Swift and conclusive. Smsl su8 dac at full vol (so I believe 2v) into the Atom. Low gain, decent volume in the t60s, 3 o clock loud. High gain, noon is about my upper limit.

No distortion noted obviously.

I have the 789 but only fed balanced so any results wouldn't be applicable re pot positions but I'd say a decent turn on low gain, maybe gain 2 would be ample. Then there is gain 3 should you be a masochist. But its more amp than you need. EDIT- I tried on the 789 single ended. Noon on gain 2 is ample. Masses of headroom with the T60.

This thread tells me that if you are going to explore headfi, an amp with around 100mw @32 ohm is probably not a good starting point unless you absolutely know its going to be IEM and low impedance/ higher sensitivity cans.

I'm sure the heresy would be fine too. Ditto the O2 (but dont know its output specs- and why not get the JDS Atom anyway?)

 

[Bob-23]

they are literally useless when there is Atom

I forgot to mention the Objective 2 (O2), it's also an option. The Atom measures a bit better than the O2, but that's beyond audibilitiy. The Atom has muting relays for switch-on delay which is definitely better than the muting of the O2, but , on the other hand, cheap relays may be the first parts that fail. The O2 has a solid metal case instead of a plastic one, which usually provides a better shielding. And there is a big plus for the O2 : its repairability. Because it's handsoldered with traditional through-hole components, any defective part can easily be removed and exchanged. (But, of course, you need a soldering iron for that, or, least, know somebody who owns one...) I build the O2 several times (for me and friends) - no noise, no distortion (Gain1x/2,5x). (But don't get me wrong, I don't sell.)
Here's some information about the project:
http://nwavguy.blogspot.com/2011/07/o2-design-process.html
https://spectrum.ieee.org/tech-history/silicon-revolution/nwavguy-the-audio-genius-who-vanished

 

[WSM_2020]

Bob-23
Objective 2 (O2) provides only 32 Oms @613 mW, - how can u be sure it would be enough?! I need a practical proof of that as it is really important for me: if it is true, I can get a used O2 for 60$ instead of approximately 140$ for a new Atom!

Jimbob54
Perhaps, I'm not clear enough in my mind, as the 9-th of May is our Russian Sacred Victory Day and I've toasted to it ... numerously, but I'd like a more precise conclusion on JDS Atom operation.

 

[Jimbob54]

Bob-23
Objective 2 (O2) provides only 32 Oms @613 mW, - how can u be sure it would be enough?! I need a practical proof of that as it is really important for me: if it is true, I can get a used O2 for 60$ instead of approximately 140$ for a new Atom!

Jimbob54
Perhaps, I'm not clear enough in my mind, as the 9-th of May is our Russian Sacred Victory Day and I've toasted to it ... numerously, but I'd like a more precise conclusion on JDS Atom operation.

Not sure I follow?

 

[ninetylol]

I had both T50rp and T60 and from my humble opinion they really prefer to have a lot of juice (headroom). You probably can't go wrong with a atom or heresy or anything with more than 1w into 32 ohms. I used a Arcam rhead for both.

 

[solderdude]

The efficiency is around 103dB/V so to reach impressive levels and be able to boost the subbass a bit you will need an amp that can reach 7V into 50 Ohm is about 1W.
The O2 can deliver 0.93W in 50 Ohm (good enough)
The Atom, Heresy, Magni3+ all can reach about 1.5W into 50 Ohm.

 

[Bob-23]

Objective 2 (O2) provides only 32 Oms @613 mW, - how can u be sure it would be enough?

Isn't it 6 x your current setting? HD600 (300 Ohm) & K702 (62 Ohm) & HD662-Evo (36 Ohm) & Px-100-II (32 Ohm) are easily driven by O2.

 

[WSM_2020]

solderdude

The O2 can deliver 0.93W in 50 Ohm (good enough)

How really interesting! So, you presume that a legendary O2 will be quite enough for me and I should run and order this 60$ used wonder?!
But, wait, here https://www.audiosciencereview.com/...be-hybrid-cth-and-jds-o2-headphone-amps.3928/ we can see only 0.65 w for 50 Oms ...

Bob-23

Isn't it 6 x your current setting?

You might have noticed that the thread is about Fostex T50RP MK3, one of the insensitives ...

 

[Jimbob54]

solderdude

How really interesting! So, you presume that a legendary O2 will be quite enough for me and I should run and order this 40$ used wonder?!

Bob-23

You might have noticed that the thread is about Fostex T50RP MK3, one of the insensitives ...

Have you reached a conclusion then? I suspect from the several options given here, it will come down to availability/ costs of importing to wherever you are.

I got a used atom on Ebay already in the UK for £70 (about same in Euro), YMMV elsewhere.

 

[Jimbob54]

Have you reached a conclusion then? I suspect from the several options given here, it will come down to availability/ costs of importing to wherever you are.

I got a used atom on Ebay already in the UK for £70 (about same in Euro), YMMV elsewhere.

By the way, you seem to want someone to give you a definitive answer based on both experience and the maths. You're going to struggle. Solderdude knows his stuff and says per the maths the O2 is sufficient. You also want someone to tell you they have run the T50 with one ? You might be waiting a while. For me, you want the cleanest, most powerful amp you can get for your budget. If there is only a few $$ between the O2 and an Atom or a Heresy, get either of the latter.

 

[WSM_2020]

Jimbob54
I've already understood that Solderdude is a gury here but how has it happened that his figures the figures from Amir's review do not coincide?!
Here, in Russia, I can get used O2 for 60$ and new Atom and Heresy for 140$ and 200$, respectively ...

 

[Jimbob54]

Jimbob54
I've already understood that Solderdude is a gury here but how has it happened that his figures the figures from Amir's review do not coincide?!
Here, in Russia, I can get used O2 for 60$ and new Atom and Heresy for 140$ and 200$, respectively ...

(Possibly) Amir's measurement is up to clipping, Solderdude may just be quoting absolute max measurement , i.e volume knob to max regardless of clipping/ distortion.

I doubt you would want to listen to either for very long, it will be loud.