Tubes/Tube Amps for Low Impedance Headphones

BTW, my ZDS works very well with the ETHER-Cs. Love the ZDS!!

Congrats on the purchase.

 

Thanks! Pretty excited - especially after I called and worked out the snafu about the follow up to the order - they are working on it - no worries at all. Just have to give the time for Craig to piece it together. I was hoping that it might be ready before I have 30+ guys over for a SQ car audio meet - many of them have an interest in hearing a great headphone set up, but alas.....not going to happen by April 9.

 

I'll be curious to hear how the Stratus sounds like planars - I ordered one for my HD800s, but had pulled the trigger on a HEK in the meanwhile!

 

Any feedback on the Taboo MK3 'round here? This is an amp I've long been considering for planars but just haven't found much on it.

 

The taboo is good, though it's overkill for most planars. Most of the volume knob is unusable, even with the he-6.

 

Bottlehead SEX amp

 

It's on my bucket list to try the PrimaLuna DiaLogue Premium HP integrated amplifier, with headphones and with my Maggies. I emailed them about the headphone amplifier a couple years ago and shared their response over on HF.

Spoiler: email with layered responses from PrimaLuna

Hi there, I'm interested in the DiaLogue Premium HP Integrated Amplifier to use in a combination video 2.0 system using a pair of Magnepan 1.6QR speakers where I'll also use a pair of headphones, either Sennheiser HD650 or Sennheiser HD800.

I'm very curious about the product's headphone amp and was hoping for more technical information.

I noticed on your product page the following description: "Finally, we added an all-tube headphone amp. In fact, it's one of the best headphone amps you can buy. Remember whether a speaker driver is mounted in a box or in a headphone, it's still a speaker. And the amplifier requirements are the same. So it makes sense that if you have an incredible amp with the finest output transformers, put it to use to run the headphones by simply dividing the output power. That's exactly what the larger tube headphone amps do. Compare the HP to the most expensive and esoteric stand-alone headphone amplifiers in the world and you will see what we mean."

I'm wondering if you could provide me with more technical details about the headphone amplifier:

1. Is it run through the same circuit as the speakers, including the transformers, with just a resistor or something to reduce the output power? The reason I ask is because this is in line with the above description, but the description also says it is an "all-tube headphone amp" which would imply an Output Transformerless design. Is there anything else in the headphone circuit path that's not in the speaker path?

2. What is the output impedance through the headphone output?

3. With the stock tubes you include, what is the output power at 32, 300, and 600 ohms? I'm most interested in the 300-ohm figure for my Sennheisers, but the others are pretty standard in headphone measurement world.

4. When headphones are inserted, does the unit automatically mute the speakers?

Lastly, unrelated to the headphone questions above, do you think the amp can power my Magnepan 1.6QR effectively? I know they are current-hungry, 4ohm, with a flat impedance curve due to the planar technology.

EDIT: Since this email conversation, PrimaLuna has posted official headphone amp specs for the Dialogue Premium HP integrated amp on its website:

• 11.4 watts (32 Ω, 1% THD)
• 6.56 watts (64 Ω, 0.70% THD)
• 3.05 watts (150 Ω, 0.60% THD)
• 1.58 watts (300 Ω, 0.60% THD)
• 0.82 watts (600 Ω, 0.60% THD)

Uses a "voltage divider network" to drop power from the tube circuit to an acceptable level for headphones. (source)

 

Got a PrimaLuna ProLogue driving some mini maggies on my desk and their DiaLogue HP driving my LCD-X... incredible amps, an upgrade from my old WA7. End game for me. The reason I have 2 amps is so I have a dedicated headphone amp as well as the speakers since I play both at the same time often to get fuller body feel for the music even with headphones on. In this scenario I am certainly under-driving the DiaLogue HP's full capabilities as a speaker amp and it only ever gets to quarter volume with my LCD before being too loud to listen too. Bass control is absolutely perfect and there is great warmth across the entire spectrum, oodles of tube sound. The only issue I notice is with low impedance phones like T5p the background has a little noise but only if you put the volume around 50% which would blow your ears off. I was expecting perfect black background but it isn't so with low impedance cans. Could be my power setup or something causing interference with such high gain. Would love it if there was a gain switch for the headphone output on the back to cut the gain in half and give more volume knob range and less background noise. You could easily cut the gain to a quarter and still drive the hardest to drive cans in the world with ease.

The ProLogue driving the mini maggies has absolutely no background noise, dead black even at full volume. I haven't tried yet but I should try the mini maggies through the DiaLogue as well. Sure it would really make them sing.

 

Sounds like a pretty incredible amp! I had to go look up PrimaLuna and the DiaLogue HP and do some investigating but I can immediately see why it costs what it does. I bet it sounds incredible.

And just to add my two cents to this discussion, my new to me Laconic Night Blues Mini is doing a bang up job of sounding awesome with my Hifiman HE-400S headphones which are rated at 22 ohms. I've also plugged in my mobile/exercise set (the Logitech UE6000's which I paid the princely sum of $50 on Ebay for) and they sound great as well and are rated at 32 ohms. I don't have a ton of experience with "true" tube amplifiers (I owned the Lyr 2 which is a hybrid for quite a while) but I value the NBM and it's ability to play well with a variety of headphones. It's the reason I only kept the Valhalla 2 for a week. It sounded awesome on high impedance headphones but did not play well with the low impedance cans.

 

The ZDS with its selectable output Z between 3 and 20 ohms makes it versatile with both low-Z and hi-Z headphones.

 

I just grabbed a Project Ember my self! Had the Starlight and I loved up, was going to get the Sunrise III but I wanted Auto bias and enough power to drive me HE 4, but compared to the Schiit Vali 2, I liked the Project Starlight a lot more! Sounded better with the same tubes, input and headphones, the only problem though is you need to manually bias, which can be annoying