HD650 feature - orange hr 2-01

Sennheiser HD650

For a while now I’ve been enjoying great sound from a few different headphones. The problem with great sound though is that every time you get better equipment in one area, it makes you want to upgrade in other areas. That’s been the result of my purchase of the HFI-680s and then, more-so, the Shure SE535 LEs.

I loved my Audio Technica ATH-AD900s, but it was time for them to find a loving new home and for me to return to Sennheiser, a brand I’d previously sworn off due to some poor experiences at the lower end of their range.

I was offered the HD650s by a good friend of mine who is very knowledgeable in the world of head-fi. In addition to the stock 650s, he also had an after market cable for them. The cable is custom-made with silver-plated copper. There are plenty of options available on eBay and from companies like Cardas and Toxic Cables. Custom cables will generally set you back a couple of hundred dollars on top of the cost of the headphones, but they are often worth the cost.


The HD650s were Sennheiser’s flagship open headphone for many years before the introduction of the new HD800s. They are still considered an audiophile headphone, but their price is significantly less “audiophile” these days. They can now be had for less than $500 in Australia brand new. They were once more like $800.

The HD650s are an open style headphone so they don’t seal out external noise and the sound from the headphones themselves also leaks out to the world around you. Other than being open, here are some key features and specifications you might want to know:

  • Impedance: 300 ohms
  • Connector: 6mm stereo jack (with an adapter for 3.5mm connections)
  • Cable length: 3m (detachable)
  • Frequency response: 10 – 39,500 Hz
  • Sound pressure level: 103dB

What these stats tell us is just that the HD650s are difficult to drive (300 ohms). You won’t get much volume trying to run them out of an iPod. On top of that, studying more complex information actually reveals that the sound will lack mid-bass driven from anything less than a good amplifier.

Having tried the HD650s from my iPod and Cowon X7 I can confirm that they sound OK, but not special and you need to be at full volume to get a decent listening level. All-in-all not an option for most portable players without an external amp.

The fact that Sennheiser supply the HD650s with a hard-wired 6mm plug should tell you that they aren’t expecting people to use them with iPods and similar players with 3.5mm outputs. The 6mm jack is clearly for amplifier connectivity.

Finally, the frequency response range of the HD650s is encouraging and suggests that they should provide great detail at the top end while also giving the right amount of rumble down low, but figures don’t always translate so we’ll have to wait and see…


I don’t normally review the packaging of equipment. Although it’s nice to unbox a well-packed item, the memory of packaging fades quite fast and it’s the item’s performance that matters. Although that rings true for the HD650s, their packaging reminds you of their previous place in the Sennheiser range. They come in a great looking corrugated silver cardboard sleeve. Under the sleeve is a beautiful silver box with a hinged lid.

When you lift the lid you’re greeted by a moulded foam bed which snugly houses the headphones and the black, 3m cable. You can see the photos to the right.

It’s safe to say that unpacking the HD650s feels like a special event. You’ll want to keep the box just because it feels so special.


The bass from the HD650s is very good, but not powerful (like the HFI-680s for instance). As you can see in the graph here, It’s boosted between 3-6dB across the 20-400Hz range and this helps to give the sound some body and groove, but doesn’t detract from the detail and clarity produced by the HD650s.

I have heard / read some people suggesting that the HD650s can be a bit dark, and looking at this graph you might think the same, but the reality is that the sound is clean and extremely well separated and defined, but it’s smooth! Don’t be fooled by that high frequency drop-off or the bass hump – these cans offer really well-balanced sound. I’ll discuss the effect of the high frequency response later, but for now it’s all about bass.

Attack: The bass is mostly clean and tight with the HD650s. They are slightly slower that some other options on the market, but that’s resolved with the custom cable I’ll discuss shortly.

Most people will still be happy with the stock cable sound. The bass is quick and fairly tight with just a hint of bloat. It sounds like it’s slightly slow-moving between notes and as if the notes bleed into one another slightly. It’s really slight so no big deal and the changes made by an aftermarket cable completely negate the issue.

Score: 8.8 / 10 (stock cable)

Mass: The mass of the bass from the HD650s is just right. It’s solid and present and, with the exception of the minor bloat caused by the slightly slow response discussed above, it’s clean. While it can’t compare with the rumble and vibration created by my HFI-680s, it is more natural in general and allows the rest of the music to shine through in and around the bass.

Score: 8.7 / 10 (stock cable)

Custom Cable: Attaching the custom cable to the 650s fixes all ills! The bass gets tighter, punchier and more lively – pretty much perfect. It’s very good to start with, but impossible to fault once improved by the custom cable.

Small caveat here: these are not headphones for bass heads. I love their sound because it recreates natural, live-sounding bass, not enhanced bass.

If I had to find fault in the bass it would be that it still can’t create the rumble that other cans like the Ultrasones seem to create. That might be the impact of open vs closed cans and it’s a minor complaint because the bass is so smooth from the 650s. To explain what I mean: one of my favourite bass test tracks is Marrakesh by Incognito. It starts with a heavy kick drum in the intro and the 650s recreate the sound beautifully, but they can’t create the feel of the kick drum.

Remember, this is a silver-plated copper cable. I can’t comment on the impact of pure silver or other plating options.

Bass score with custom cable: 9.3 / 10

Vocals / Mids

Vocals and mids are where the HD650s sound best. The midrange is smooth and velvety, but completely detailed. Instruments and vocals sound realistic and are beautifully textured and layered (i.e. you can hear what each different instrument is doing).

I’ve found with a number of my recent purchases like the HiFi-Man Re-272s, the Shure SE535 LEs, and now the Sennheiser HD650s, that the ability to reproduce midrange sounds with clarity and definition is what makes headphones addictive and seductive. The HD650s have seduction in spades – they are engaging and enticing.

I’m not reviewing the custom cable separately here because it does make a slight difference to the mids, but only by a fraction. The custom cable just makes the mids slightly more liquid and lush.

Score: 9.8 / 10


I was really worried about the detail retrieval of the HD650s before I bought them. All of my previous headphones had been brighter (i.e. higher levels of treble in the frequency response graph) so I was worried that I would find the Sennheisers dark or veiled as some people describe them. That’s definitely not the case.

The HD650s have taught me a valuable sound lesson: detail is not all about treble response. The HD650s have  detail oozing out of them and yet they are never bright or harsh and can be quite forgiving on poor recordings. You’ll know that it’s a bad recording, but your ears won’t bleed after listening to it.

There are definitely other options which reveal even more detail that the HD650s, but the trade-off is that you can find yourself drawn into listening to details, not music. The HD650s’ strength is their ability to provide detail, texture, and clarity while staying absolutely musical and enjoyable.

Score: 8.5 / 10

Details with the custom cable: The custom cable brightens up the sound slightly and brings out a hair more detail, but it’s just right. The sound is a tiny bit quicker and it makes it more lively and exciting without getting fatiguing or harsh, just more detailed, textured and complex (in a good way). The resolution of details with the custom cable reminds me of the HiFiMan Re-272s.

Score 9 / 10


This was another area where I was slightly concerned about the HD650s. Generally speaking, staging is created by the reproduction of high frequencies as these are the sounds we use in the “real world” to place where a sound comes from. With the high frequency drop off you saw earlier in the frequency response chart, there could be negative effects on staging, but the HD650 creates a really nice, well controlled sound stage.

The stage from the HD650s isn’t huge, but it’s nicely defined and consistent. I don’t feel like the stage projects forward much (if at all), but the placement of individual sounds is excellent so that instruments and performers each have a defined space in the stage.

I’ve also used the HD650s for a bit of gaming and they are excellent at providing directional cues for gaming.

Score: 8.4 / 10

Staging with custom cable: Once again the custom cable makes a huge difference here. The cable brings more air and space into the stage. It doesn’t make the stage suddenly massive or anything, but definitely improves it.

Score: 8.9 / 10


The HD650s could be the best value for money on the market. They are a flagship quality headphone with a mid-level price. Some similarly priced options like the Beyer DT880s and AKG Q701s are also very good, but don’t tend to do everything as well across the board. The DT880s can be a bit bright and fatiguing while the Q701s can sound a bit bland and analytical without EQing.

That’s not to say the HD650s are the perfect headphone, but it will be hard to find a better all-rounder for the money.

Overall score (stock cable): 8.9 / 10

Overall score with custom cable: 9.4 / 10

In relation to upgrades…

A custom silver-plated copper cable for the HD650s

Custom silver-plated copper cable

There are heaps of ways to upgrade the HD650s and they respond incredibly well to these upgrades by all accounts. I have only added the custom cable, but the difference that created was astounding.

Amping also apparently makes a big difference to the sound of the HD650s. I look forward to buying the Bottlehead Crack valve amp very soon so I can compare it with the Audio-gd NFB-5.2 used for this review. The Crack gets stellar reviews when paired with the HD650s so I’m excited to hear the difference.