[galneon]

I had the 598s when I started out in this hobby and got rid of them due to their insufferable highs and terrible bass presentation. 660s would be an immense upgrade to them in every way, including fun.

Thanks, that's exactly the kind of thing I hoped to hear. I just pulled the trigger on some DT 1990 Pros--I'm good with a solder iron and will have no issue changing out the 3-pin XLR for 4-pin if I feel compelled (and I probably will). The 660S will be my second (and final) stop if the 1990s don't work out.

 

[GearMe]

Every of months Amazon sells of its stash of 'renewed' 660s, basically refurbished units, for around $400. They are currently out of stock, but it's worth keeping an eye on the page as they renew their stock of them frequently.
https://www.amazon.com/dp/B07JMCM1VB/

Also, I would imagine that there will be some sort of Black Friday deal on them this year, and that's right around the corner. If anything pops up, rest assured someone (maybe even me) will post it on the deals thread.
https://www.head-fi.org/threads/the-deals-discussion-thread-read-the-first-post.692119/

I'm also holding out for a lower price. $400 new and I'd buy a pair immediately.

I tried the renewed and had bad luck...would be in at $350 on new but don't expect that anytime soon; hence I bought the 58X's when I sent the 660s back. Assuming the 660's stay >$400 over Thxgvg, will pull the trigger on the HD6XX's and wait patiently for the 660's to come down in price.

 

[K-Lawn]

I tried the renewed and had bad luck...would be in at $350 on new but don't expect that anytime soon; hence I bought the 58X's when I sent the 660s back. Assuming the 660's stay >$400 over Thxgvg, will pull the trigger on the HD6XX's and wait patiently for the 660's to come down in price.

A guy on reddit bought a pair of refurbished 660s from Amazon and the pair he received had swapped out drivers. I believe they were 600 drivers in the 660s earcup.

 

[Mike F]

More listening done and lots to report, but for now I have a question. There seems to be a real discrepancy between the SW frequency response graph for the HD660S vs HD650 and HD600 and the FR graph from DIY-Audio-Heaven. The one from the latter source (top graph) is what I hear when I compare the HD660S and HD650.

Given that SW is in the business of accurately measuring headphones for calibration and that they have a good professional reputation, it seems to me that the only explanation the two FR graphs can be so different is that Sennheiser did in fact make a revision to the HD660S. The differences in these graphs would also explain the differences that people have reported between early and recent examples. It would also explain some of the early bad reviews, not least the one from SW. AFAIK nobody has previously pointed out the discrepancy between these two graphs and suggested the above explanation. Opinions?

PS HD660S is green and the HD650 orange in the DIY-A-H graph.

 

[Ichos]

Yes that graph was also known to me.
A lot of depends on the measuring rig and the compensation.

 

[Mike F]

Yes that graph was also known to me.
A lot of depends on the measuring rig and the compensation.

Sure, but that can’t explain the kind of discrepancy we see in those graphs, can it?
OTOH those graphs would certainly explain the differences that people have reported hearing in early and more recent examples......

 

[kman1211]

More listening done and lots to report, but for now I have a question. There seems to be a real discrepancy between the SW frequency response graph for the HD660S vs HD650 and HD600 and the FR graph from DIY-Audio-Heaven. The one from the latter source (top graph) is what I hear when I compare the HD660S and HD650.

Given that SW is in the business of accurately measuring headphones for calibration and that they have a good professional reputation, it seems to me that the only explanation the two FR graphs can be so different is that Sennheiser did in fact make a revision to the HD660S. The differences in these graphs would also explain the differences that people have reported between early and recent examples. It would also explain some of the early bad reviews, not least the one from SW. AFAIK nobody has previously pointed out the discrepancy between these two graphs and suggested the above explanation. Opinions?

PS HD660S is green and the HD650 orange in the DIY-A-H graph.

Honestly I find the graphs interesting as well, numerous factors could be to play such as the measurement rig, compensation, unit variation, etc. Upper regions tend to be especially fickle to measure from what I gather. You’d be surprised how different, different rigs can measure. I stopped worrying too much about measurements a long time ago, as while they are a useful tool, the lack of a universal compensation standards and numerous factors with measuring headphones makes it hard. Not to mention differences in who measures it, external factors, etc. Seems to be a really tricky thing to measure headphones. Newer better equipment with more accurate ear/ear canal shapes, and comparing raw measurements while using the same scaling on the graphs do help. Sadly you have to be careful comparing graphs from different sources due to a variety of reasons. What I’m curious about is how Sennheiser themselves measures them compared to the HD 650.

 

[cactus_farmer]

How is the bass of the HD660s compared to the HD650? Which extends deeper and slams harder? And is it significant or a tiny difference?

 

[Ichos]

@Mike F

I agree but can't comment on different batches of a headphone when I don't have evidence.
I order to be sure about this both batches should be measured with the same rig.
Anyway I don't trust SW and I don't hear what I see on the graph.
According to it the 660S should be more warm than the 650 with more midbass hump and some treble peaks.
No way the 660S has that midbass hump shown at this graph.

 

[Ichos]

Take a look at the rtings measurements.
Side by side comparison.
This looks close to what I am hearing.
There is no way SW is correct.

https://www.rtings.com/headphones/1-2/graph#245/2031/816

 

[Mike F]

@Mike F

Anyway I don't trust SW and I don't hear what I see on the graph.
According to it the 660S should be more warm than the 650 with more midbass hump and some treble peaks.
No way the 660S has that midbass hump shown at this graph.

That’s my point....... I DO trust SW (I’ve used them program for a while and their calibrations are amazing) but I certainly don’t hear what their graph suggests either, but I certainly do hear what the DIY-A-H graph suggests.

There are three options as far as I can see:-

1. SW got it totally wrong (highly unlikely)

2. Sennheiser made some measurable (and audible, according to quite a few reports on here) changes to the HD660S.

3. FR graphs are so inconsistent and unreliable as to be totally useless and meaningless.

If anyone can come up with another alternative, I’d like to hear it!

 

[MattTCG]

That’s my point....... I DO trust SW (I’ve used them program for a while and their calibrations are amazing) but I certainly don’t hear what their graph suggests either, but I certainly do hear what the DIY-A-H graph suggests.

There are three options as far as I can see:-

1. SW got it totally wrong (highly unlikely)

2. Sennheiser made some measurable (and audible, according to quite a few reports on here) changes to the HD660S.

3. FR graphs are so inconsistent and unreliable as to be totally useless and meaningless.

If anyone can come up with another alternative, I’d like to hear it!

FR graphs can be inconsistent and unreliable, but that doesn't make them worthless. They are often simply a good starting place or a good first look at how a headphone may perform. But certainly they should never be taken as Gospel from anyone...no matter how expensive the equipment or how experienced the tester.

 

[Ichos]

@Mike F
Please see my post above.
This measurement is on par with solderdude.
As for the other I don't know but why is highly unlikely that SW isn't wrong?
Why do we have to speculate that Sennheiser made changes?
Tylls measurements of one of the early models is on par with the diy one's.
Maybe SW measured the headphones with different rigs / parameters and just superimposed the graphs , I don't know.

 

[Mike F]

@Mike F
Please see my post above.
This measurement is on par with solderdude.
As for the other I don't know but why is highly unlikely that SW isn't wrong?
Why do we have to speculate that Sennheiser made changes?
Tylls measurements of one of the early models is on par with the diy one's.
Maybe SW measured the headphones with different rigs / parameters and just superimposed the graphs , I don't know.

We posted at the same time. I’ll have a look when I get chance. Playing the show at the moment!

 

[Mike F]

Ichos, it’s going to have to wait until I get home tomorrow. I’m just on my phone at the moment and I can’t make sense of this graph......