High ouput source for my EMP

[Tomcat]

Quote:

Originally posted by AdamZuf 1.so your 770 pro (250 Ohm) are now driven well, after you switched the 12AU7 to E80CC? Answer: Better than ever. Even withn the 250 Ohm Beyers, the E80CC is so much better than every 12AT7 and 12AU7 family tube I have tried, there's no comparison. 2.would you say it adds a bassy quality to all headphones you tried this tube with? No, It's not a bassy quality, it's an increased sense of authority, control, power, dynamics and effortlessness. One aspect of this is better bass slam, but increased authority and body seem to improve musicality across the board. Any 12AT7 I know sounds simply nervous in comparison. 3.if so, was it true for several brands of E80CC (if you had the chance to test it) ? I have tried only one Siemens E80CC (which has been made in the Dutch Heerlen factory by Philips - the only other E80CC plant I am aware of is Tungsram in Hungary). 4.heard talks about the E80CC ain't a REAL substitude for 12AU7. why is that? Pin-out and heater voltage are identical to the 12AU7/12AT7/12AX7 group, but the E80CC draws twice the heater current. The E80CC's gain is slightly higher than that of the 12AU7, while the 12AT7 and the 12AX7 have twice, respectively four times the gain of the E80CC. That's why the "inmates" at www.audioaslyum.com have used it as a 12AU7 subtitute (that's what got me interested). Notice that, orginally, the EMP uses a single 12AT7 as the gain stage/input tube, not a 12AU7. But it seems that the E80CC has enough gain to work splendidly with the 48 Ohm W100 and the 250 Ohm DT-990Pro. However, things might be different with a Senn HD600 which - regardless of its nominal impedance of 300 Ohms - has an impedance curve that reaches about 600 or 700 Ohm at 100 Hz. 5.i understand you're using the E80CC for quite long time with no problem. for how long is that? Just three months. But none of those people at Audio Asylum who have replaced their 12AU7s with E80CCs have reported about any problems. And they have been using their E80CCs for years. So far, I'd say: it's a risk worth taking.

 

[AdamZuf]

great reply, tomcat!

"it seems that the E80CC has enough gain to work splendidly with the 48 Ohm W100 and the 250 Ohm DT-990Pro. However, things might be different with a Senn HD600 which - regardless of its nominal impedance of 300 Ohms - has an impedance curve that reaches about 600 or 700 Ohm at 100 Hz."

would you please explain more why this is a problem?
(and why does a headphone that reaches such high impendance rates in its curve is considered for less {600/700 Ohm -> 300 Ohm)

and i assume that the 250 Ohm Beyer DT880 won't have a problem with the E80CC either, like the DT990 Pro, right?

 

[Tomcat]

Adam,

Generally, headphones with higher impedance need more voltage swing than current from the amp. That's the reason many high impedance headphones aren't driven to adequate levels by portable sources. PCDPs don't provide enough voltage. The voltage gain when using the 12AU7 in the EMP isn't all that great. The 12AU7 has an open loop voltage gain of about 17. The original 12AT7 has a gain of 60, and the E80CC is rather close to the 12AU7 at about 25. The 12AU7 only worked well with low-impedance heapdhones that seemed happy with the current it provided. In my experince, the E80CC has been more versatile, it's a great match with the Beyer 770 Pro as well.

However, I don't own the Sennheiser HD600. I presume there might be problems because of its high impedance in the upper bass, but that's just a guess.

Your other question: Why is the nominal impedance of a headphone just the lowest point of its impedance curve? Good question. Some people feel that a flat impedance curve is more important than a flat frequency response if we want to predict the speaker's sound under real-world conditions. However, some amps, especially tube amps, don't like low-impedance loads. So the lowest impedance figure is more important if you want to judge the risk of instability (and possibly even damage) for the amp. And while the EMP has been designed to drive low-impedance headphones, it seems to work best with loads from 40 Ohms on up - Audio Technica cans for example - while it seems to be a less than ideal match for Grado headphones at 32 Ohms. However, even this is something that might be changed to some degree by rolling in an E80CC.

 

[AdamZuf]

Tomcat, you are top replier!

so the theory for best performance:

12AU7 - for low impendance cans (such as grado's at 32 Ohm)
E80CC - for everything in between (40 Ohm to 250 Ohm)
12AT7 - for high impendance cans (such as senns at 300 Ohm)


anyone wants to approve/disapprove this and add comments about personal experience with tube rolling with the EMP?

 

[JaZZ]

Tomcat...

[edited due to previous misunderstanding]

...I don't think the EMP has any trouble with Grados (at least mine), it even drives the Sony F1 (12 ohm) without any problem. The good thing with the Grados is their flat impedance curve, otherwise the high output impedance (~120 ohm?) would cause some serious colorations with such low-impedance cans. This is the only valid principal caveat against the cooperation between EMP and low impedances, IMO.

BTW other high-impedance headphones, like AKG or Beyer, partly have even larger impedance amplitudes than the HD 600 (the nominal 250-ohm DT931 goes up to 700 ohm at 80 Hz). Why do you think the input tube changes the EMP's ability to drive high-impedance loads? Reason tells me that this depends exclusively on the output tubes. Of course the gain may limit the achievable volume in some cases, but this has nothing to do with impedance curves.

 

[AdamZuf]

Quote:

Originally posted by Tomcat in my experience, nothing has given the EMP more authority, solidity, liquidity and effortless, glorious and fatigue-free musicality than the E80CC as the input tube. I am convinced that no tube from the 12AT7 family comes close. Not even the highly regarded Sylvania 6201. . .it's an increased sense of authority, control, power, dynamics and effortlessness..

what about fast representation and soundstage?

did you listen to the RKV MKII?

 

[Tomcat]

Quote:

Originally posted by AdamZuf so the theory for best performance: 12AU7 - for low impendance cans (such as grado's at 32 Ohm) E80CC - for everything in between (40 Ohm to 250 Ohm) 12AT7 - for high impendance cans (such as senns at 300 Ohm)

Adam,

I don't know. As I said, the E80CC could be the cure for all of life's problems.

It might be the best tube for any headphone. And I haven't tried the 12AU7 with Grados.
Quote:

what about fast representation and soundstage? did you listen to the RKV MKII?

No, sorry, I don't know the RKV.

It's not easy to say what a fast representation really is. Quite often, if we perceive something as fast, the oppsosite is true. In fact, the system may have a hard time handling transients, it has an etched quality and highlights transients artificially through added distortion. Seamlessness, cohesiveness and liquidity can be more reliable indicators of speed. At times, it's not what we notice but what we don't notice that makes for a truly great, accurate and musical component.

Soundstage: The E80CC's is simply huge, deep and immersive. To my ears, it's more natural than that of even the 12AU7, and that has been very noticeably better than that of the 12AT7, with the 48 Ohm W100, of course.

 

[AdamZuf]

any moderators to change the thread title to:
High output source for my EMP
instead of:
High ouput source for my EMP
?
bugs me

and if you do that, you can also delete this request

thanks!

 

[AdamZuf]

Tomcat,
be sure i'll get that E80CC and try it with the senns.
hey, maybe i'll take them to the store in jerusalem and try the RS-1 with it!
(the EMP is very easy to take to stores to audition products, and while it's warming up i can audition hi-end speakers

)

 

[Tomcat]

Quote:

Originally posted by JaZZ ...I don't think the EMP has any trouble with Grados (at least mine), it even drives the Sony F1 (12 ohm) without any problem. The good thing with the Grados is their flat impedance curve, otherwise the high output impedance (~120 ohm?) would cause some serious colorations with such low-impedance cans. This is the only valid principal caveat against the cooperation between EMP and low impedances, IMO. BTW other high-impedance headphones, like AKG or Beyer, partly have even larger impedance amplitudes than the HD 600 (the nominal 250-ohm DT931 goes up to 700 ohm at 80 Hz). Why do you think the input tube changes the EMP's ability to drive high-impedance loads? Reason tells me that this depends exclusively on the output tubes. Of course the gain may limit the achievable volume in some cases, but this has nothing to do with impedance curves.

JaZZ,

When I tried the 12AU7, it obviously limited the amps voltage gain, and my higher impedance Beyers simply sounded sluggish and uninviting. The Beyers have lower efficiency than my ATs, this could have been a factor as well.

I have tried the EMP (with the recommended 12AT7 as input tube) with Grado headphones a couple of times, and the tonal balance seemed somewhat bright. You could say that that is the Grado house sound, but I directly compared the EMP to the Grado RA-1 amp, when driving the SR-225 and the RS-2. The tonal balance of both Grados seemed to be improved when driven by the Grado amp (the EMP has an output impedance of about 80). The EMP had other things going for it (smoothness and liquidity, for example), but tonally, the Grado amp was a better match. Now, with the W100, it wasn't a contest. The Grado RA-1 sounded simply bland, boring and congested.

Some Head-Fiers have remarked on the Grado headphones' desire to be driven with lots of current. Here is a thread from November with a post by 88Sound, who owns two Grados, two ATs, the EMP, the Grado RA-1 and the solid-state Grace 901 amp. And he prefers the Grace 901 with his Grados and the EMP with his ATs. He feels that even the RA-1 provides the Grados with insufficient current.

 

[JaZZ]

Tomcat...

...the Grados suit neither my EMP nor my HA-2 very well...

, it's just not an ideal synergy with both, but certainly not a serious electrical mismatching. (I'm not pretending you stated this, BTW.) I'm generally very skeptic about the assumed current-supply and impedance-matching issues often reported; I guess in most cases it's nothing but a sonic mismatching. I mean: if there's a certain current supplied from an amp and it's more than enough for the volume you listen to, why should there be any problems with the supply assumed anyway? If there are limitations audible in the form of distortion, all headphones will show them, just depending on their efficiency. Statements like «this and that headphone needs a lot of power to sound right... it's most likely just a better sonic synergy with a certain amp in those cases.

 

[AdamZuf]

just a little update, after a few months of rest to this thread. (boy have i grew here in this time)
i talked to Stephan Brocksiper, the manufacturer, and he told me that the volume out works like a passive pre-amp: it's before the active circuitry.
you can input every signal level that you would like, you can never overload it.
i asked him what about the volume pots' effect when operationg in really low level (as some amplifiers will react differently to the position of the pot), and he said that the volume pots are carefully selected and are of high resolution (if i understood it correct), so no need to fear from high output source with easy to drive cans - it will sound as good as it should be, even if you're using 10% of the volume. from my experience - it's a very good and easy to adjust pot.

 

[JaZZ]

Interesting news, Adam! I can confirm this: the EMP's volume pot is of excellent quality.

 

[AdamZuf]

Quote:

Originally posted by JaZZ Statements like «this and that headphone needs a lot of power to sound right... it's most likely just a better sonic synergy with a certain amp in those cases.

maybe the extra power prevents the amp even to start efforting itself - and the sonic benefit from the amp is still %100, intact.
for example, my EMP clips with the DT880 at a quite high volume on loaded, demanding music. when i'm not far from clipping, i can say the amp doesn't perform at its best, because the headphones efforts it, but it might be also a synergy thing in other cases, as you said.

i can think of surfers that show their best with big waves - other will prefer the smaller ones

 

[JaZZ]

I guess I'm rather with the medium ones...

Especially with tube amps the dynamic limitations towards their maximum level appear relatively early compared to solid-state amps and are accompanied by increased distortion. I wasn't speaking of such special cases where the amp is driven near its limits – there of course the power maxim is valid.