[PolloLoco]

This may be obvious, but I just learned that if you buy a vintage amplifier, you're probably going to want to check the DC offset of the speaker jacks before connecting expensive equipment to it. There's detailed instructions online, but basically it involves connecting a voltmeter to the positive and negative jacks of a solid state amplifier once it's been powered on and warmed up - with nothing connected to it. Don't do this with a tube amp. If the DC offset is too high, which can happen over time - it can damage your speakers or in this case headphones. 0 to 20 mv is typically great.

Since I'd bought a refurbished Adcom GFA545 II - the vendor showed me photos that the DC offset for each channel was about 6.5mv before the filter caps. Checking the speaker terminals yesterday, I got a result of 0.5mv (left) and 1.5 mv (right) - which is outstanding for an amp that's over 30 years old. The vendor did a heck of a job of refurbing and recapping this amp.

That said - I had an annoying issue with my Adcom GFA545 II amp that I felt I needed to resolve. When shutting it down, out of my He6 I hear a phaser sound, then 3 seconds later a loud BRAP sound. I don't THINK it's loud enough to damage the headphones, but I wanted to be absolutely sure. When researching this issue, I discovered that most if not all Adcom amps have this issue and speakers will make this sound. There's no speaker relay in Adcom amplifiers, and when the filter caps discharge - your headphones or speakers will make this annoying sound.

I resolved this by adding a speaker switch, and turning off the port where my headphones were connected to - prior to shutting down the amp. Specifically I bought an Adcom GFS3 for about $30 on EBAY. Now when I shut down, I turn on the protection button on the switch, and disengage my headphones by pressing the matching button. It works great and I've noticed no degradation in audio quality. I'm very happy this has worked so well!

 

[Armaegis]

And for the newbies for whom this is new information and are running out to get yourselves a multimeter, please remember to put the multimeter on DC instead of AC, otherwise you'll be wondering where that awesome 0mV reading came from.

 

[paradoxper]

This may be obvious, but I just learned that if you buy a vintage amplifier, you're probably going to want to check the DC offset of the speaker jacks before connecting expensive equipment to it. There's detailed instructions online, but basicall it involves connecting a voltmeter to the positive and negative jacks of a solid state amplifier once it's been powered on and warmed up - with notithing connected to it. Don't do this with a tube amp. If the DC offset is too high, which can happen over time - it can damage your speakers or in this case headphones. 0 to 20 mv is typically great.

Since I'd bought a refurbished Adcom GFA545 II - the vendor showed me photos that the DC offset for each channel was about 6.5mv before the filter caps. Checking the speaker terminals yesterday, I got a result of 0.5mv (left) and 1.5 mv (right) - which is outstanding for an amp that's over 30 years old. The vendor did a heck of a job of refurbing and recapping this amp.

That said - I had an annoying issue with my Adcom GFA545 II amp that I felt I needed to resolve. When shutting it down, out of my He6 I hear a phaser sound, then 3 seconds later a loud BRAP sound. I don't THINK it's loud enough to damage the headphones, but I wanted to be absolutely sure. When researching this issue, I discovered that most if not all Adcom amps have this issue and speakers will make this sound. There's no speaker relay in Adcom amplifiers, and when the filter caps discharge - your headphones or speakers will make this annoying sound.

I resolved this by adding a speaker switch, and turning off the port where my headphones were connected to - prior to shutting down the amp. Specifically I bought an Adcom GFS3 for about $30 on EBAY. Now when I shut down, I turn on the protection button on the switch, and disengage my headphones by pressing the matching button. It works great and I've noticed no degradation in audio quality. I'm very happy this has worked so well!

Bravo! Very prudent.

 

[PolloLoco]

And for the newbies for whom this is new information and are running out to get yourselves a multimeter, please remember to put the multimeter on DC instead of AC, otherwise you'll be wondering where that awesome 0mV reading came from.

Yeah, I should stress that if people want to test their vintage speaker amps, that they look up the detailed instructions online first. I didn't want to make my post too long.

 

[cerealmilk]

Does the EF400 run it well? Has anyone tried it? Im interested in this headphone as it has gotten a lot of talk

 

[musicinmymind]

Does the EF400 run it well? Has anyone tried it? Im interested in this headphone as it has gotten a lot of talk

You need min of 10w on 50 Ohms from a quality amp, it can be speaker or headphone amp and with EF400 it may not sound optimal. The fundamental qualities of HE-6 is texture and raw attack, without right power it will sound very bright and thin. There are cheap options out there, especially class D speaker amps.

 

[sajunky]

HE-9LE should pair well with EF-400. 10W at 40Ohms is very close. In the Audio GD range it is currently a champion on the price per sound quality scale, but there are models with more power, if you really need it. I would stay away from D-class amps.

 

[rodel808]

I've been using a Matrix HPA-3B amp with my he6sev2 and sounds great to my ears. My math is not great. Specs says the following:
[balanced]
3800mW at 33ohms at THD+N=0.01%
1500mW at 300ohms at THD+N=0.01%
800mW at 600ohms at THD+N=0.01%

What's the wattage at 50 ohm? Am I missing out a lot with this amp?

 

[Armaegis]

You don't necessarily *need* 10 W at 50ohms... but it all comes down to what your typically listen at and the headroom/dynamic range of your music.

Power is calculated typically as P = IV or P = (V^2)/R

When extrapolating from a given power rating, people often assume the voltage is constant and so using the second formula it is an inverse proportion relationship. Using the Matrix HPA-3B above and only the first line of values, smooshing around some algebra that would give you P = 3800*33/50 = 2508 mW which intuitively feels about right, as increasing load means there's less current and thus less power.

However, if we do that same calculation using the second line at 300 ohms, this doesn't match: 1500*300/50 = 9000 mW which is higher than from the first line.
Likewise using the third line: 800*600/5 = 9600 mW which is higher still. So what gives?

Here are the parts that a lot of people neglect: that amp has not only max voltage swing, but also max current available, and ALSO those measurements are at 0.01% which doesn't actually correlate to maximum V or I, blah blah blah. Let's ignore this last part for the sake of brevity.

Going back to those Matrix numbers, if we crunch out the voltage and current swing:
3800mW @ 33 ohms -> V = 11.19 and I = 0.339
1500mW @ 300 ohms -> V = 21.21 and I = 0.071
800mW @ 600 ohms -> V = 21.91 and I = 0.0365

Ok so here we can see that *roughly* there's a max voltage swing of 21 volts and max current of 339 milliamps.

Starting from the first line of 33ohms, and knowing that as we increase load that gives us a little more play on voltage but we can't exceed 339mA... if I plug in 50 ohms at 339mA that will give me roughly 5760mW (with a corresponding voltage of 16.967 V). Again that's all completely neglecting the THD aspect of the measurements.

Also, 5W vs 10W at 50ohms is only a 3db difference. Nothing to worry about.

 

[msing539]

So I've been reading this thread for days now... I have the iFi Pro iCAN Signature, which I think sounded good with the HE-6 and 6SE, but now I'm wondering if a speaker amp would have driven them to another level.

Is there a sub $400 amp recommendation if I'd use the iFi as a pre? Adcom? I also have an Onkyo RC160 HT Receiver laying around gathering dust, but I'm not sure if this is an ideal solution. Also have the HE adapter incoming.

 

[jerick70]

So I've been reading this thread for days now... I have the iFi Pro iCAN Signature, which I think sounded good with the HE-6 and 6SE, but now I'm wondering if a speaker amp would have driven them to another level.

Is there a sub $400 amp recommendation if I'd use the iFi as a pre? Adcom? I also have an Onkyo RC160 HT Receiver laying around gathering dust, but I'm not sure if this is an ideal solution. Also have the HE adapter incoming.

Try the newest Emotiva BasX A2m at that price. Great little amp for the price. You can use it amp coupled out of the front 6.5mm headphone connection. Or hook up something like the HiFiMan HE-Adapter off the speaker taps if you like a 4 pin XLR connection. Either way you get the full amp power.

 

[Shane D]

So I've been reading this thread for days now... I have the iFi Pro iCAN Signature, which I think sounded good with the HE-6 and 6SE, but now I'm wondering if a speaker amp would have driven them to another level.

Is there a sub $400 amp recommendation if I'd use the iFi as a pre? Adcom? I also have an Onkyo RC160 HT Receiver laying around gathering dust, but I'm not sure if this is an ideal solution. Also have the HE adapter incoming.

Did you feel like the iCAN was missing anything? I LOVE the combo, although I do turn up the bass boost AND 3D sound effects.

I can't think of two components in my collection that mesh better than these two.

 

[msing539]

Did you feel like the iCAN was missing anything? I LOVE the combo, although I do turn up the bass boost AND 3D sound effects.

I can't think of two components in my collection that mesh better than these two.

Oh the bass knob is on--it's always on. What made me question the iFi is because I'm able to achieve 'similar' levels of bass impact with other Hifimans, and I always thought the HE-6 was supposed to have more. Much more than the 6SE or 5. It's technically great, but I wondered if I was starving it for power. Though on paper, the iCan should be plenty.

 

[msing539]

Try the newest Emotiva BasX A2m at that price. Great little amp for the price. You can use it amp coupled out of the front 6.5mm headphone connection. Or hook up something like the HiFiMan HE-Adapter off the speaker taps if you like a 4 pin XLR connection. Either way you get the full amp power.

Thank you, I'll look into this one for sure.

 

[jerick70]

Thank you, I'll look into this one for sure.

Sure thing mate. I purchased one of these for my son for Christmas. I wasn't expecting much. (I had the OG flex amp from Emo at one time, and it wasn't that good.) My son ended up not liking the A2m so I took it and added it to my collection. I was floored at how good it was for a $350 amp. IMO it is as good or better than some of the TOTL amps I've listened to in the past. Clean, Awesome bass that is layered and authoritative, but still has a lot of micro-detail through the whole spectrum. Really quite impressed with this amp.