rostele2
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HD414
May 9, 2017 9:24:33 GMT
Post by rostele2 on May 9, 2017 9:24:33 GMT
Going off at a bit of tangent here:- You are right about the HD414, but it has an amazing neutral sound, so I DO use it for a lot of tasks, then see what the result is on the 650s. I am most interested for obvious reasons to have a proper correction for all these, so finding this site has been quite fortuitous. I discovered a list of surround headphones, so it could make a thread all of its own! The Pioneers TBQH weren't marvellous, but then I discovered they were made back in 1975! My own amplifier system dates from 1977, as does the UHJ decoder, (I got the boards and chips from Sansui direct) so it's still going strong 40yrs later, this year! The main boards were built up using a superb Linsley hood FET preamp design, called the Lineac which I have never wanted to alter. Being as my main system IS surround, for auditioning precisely this sort of material, I was looking for ages for rear channel speakers. I chanced on something from another incredibly innovative British engineer AR SUGDEN and his connoisseur stuff. There were a lot of good people in the 60s and 70s in Yorkshire, when you realise that is where CALREC were situated too. These are omnidirectional and I have only ever seen ONE pair like it. In fact they are perfect for rear channel material, and used the much underrated Richard Allen drivers, because them and Sugden were friends! One of the frustrations of 99% of all "hi end" audio shops is the way they can't even get an auditorium right (which is mentioned elsewhere here!), but then they section off all surround material to "home theatre" and turn their nose up at such people. I usually turn around when they sniff "we only do high end stereo", and say, well that's fine if you want to live in 1960, not in the 21st century! I have almost never heard a surround system as a result which is a) correctly adjusted, b) in a room that actually works, c) has decent speakers, d) has correct front/rear balance e) has a player that is reads advanced formats properly - needs usually meridian or oppo to get it right... Then try to find a player that can read multichannel wav files (forget it!). I ask why did Microsoft bother to invent such a format and never use it, you can even create multichannel mp3 files, but again a total lack of interest and soft makes it pointless. Finally I got some help from Pyramix, so as of next week it's going to be down to testing the latest "ovation" release.
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solderdude
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HD414
May 9, 2017 9:32:37 GMT
Post by solderdude on May 9, 2017 9:32:37 GMT
Surround headphones exist but don't think the quality of the drivers is audiophile. It's more about the effect. You could look into the Smyth Realiser. Never heard one but is said to sound quite good/realistic. It lets you use all kinds of headphones. All the 'start to end' must be linear is down the drain but the sound experience may be overwhelming.
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rostele2
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HD414
May 9, 2017 14:23:53 GMT
Post by rostele2 on May 9, 2017 14:23:53 GMT
While zooming off into the surround nether regions it opened some forgotten avenues of SQ and the near miss Quad made. I have plenty of SQ records left, and some like the DSM stuff sounded ok. (I made my own decoder with the MC13xx series cmos chips) Quad was never really good on headphones, because the rear channels are not sounding the same as the fronts, as I found out myself. I would be tempted to have another better shot at it, as those old headphones have standardised drivers which are easy to change. The last versions of SQ once they had sorted it out, were pretty good, certainly better sounding than DTS surround. The BBC UHJ was more Ambisonic stuff, and suffered from poor S/N ratios I found. I didn't know it was the same Fosgate that sorted out that made SQ Dolby's Pro Logic II, and won an Emmy for the Development of Surround Sound for Television. That's what comes of wandering off and getting side tracked. As usual nothing new since the 1960-70s eh?
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solderdude
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HD414
May 9, 2017 15:15:39 GMT
Post by solderdude on May 9, 2017 15:15:39 GMT
Most surround headphones are only targetted at gamers as it gives audible clues where shots are fired from and where someone is walking etc. Hardly hifi and all of them are 2 driver headphones with signal processing.
I still have a home made dolby surround decoder with compressors and bucket delays to create the extra delay needed for the rear speakers.
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rostele2
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HD414
May 21, 2017 6:59:03 GMT
Post by rostele2 on May 21, 2017 6:59:03 GMT
Just for the record, from the Evaluation board thread, this is where I ended up. It appears after lots of tests to give pretty much the best result, - reducing some of the excess brightness at 2.5-3.5khz & 5-6.5khz, and giving a slight boost 12khz> Lots of people probably still have these lurking around, and don't realise the frequency response from 6.5-10Khz is quite exceptional. (Senn just note a little lump up there). They show the bottom graph below, which doesn't really correspond to reality. I struggled with various calibrations, signal generators and obvious transducer variations. In the end it's a toss-up between impedance matching v insertion loss v adjustment of frequency response, a true art of compromise. You can't do anything about the high distortion below 120hz, but on the other hand there is nothing as light as this even today which won't damage your hearing. That's part of the fun of wearing a piece of history, that probably put Sennheiser on the map.
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garyc
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Posts: 45
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HD414
May 23, 2017 13:55:28 GMT
Post by garyc on May 23, 2017 13:55:28 GMT
This caught my interest as I used to own a pair of HD414s in 1979 (and may still do, if I can get to a box in the garage where I think they are). I was struggling to follow the words and so decided to try simulating the circuit (many years since I've done anything like that). I found PartSim online and came up with this (the plot is 20hz to 50kHz in case its not clear): Where net1013 is the junction between the first paralllel resistor/capacitor and the second resistor (R1/C1 to R2 in this). The 60 ohm is to simulate the inductor resistance. I found it impossible to simulate with 2 inductors in parallel, maybe some strange feature of the simulator, so just left it as a single lumped inductor, did the same for the 270/33 caps.: It looks to me like a 1.09dB drop at 2.5kHz. Does that look right Franz? (edit: I think there is something strange with the simulator, or the way I am using it, as even if I change the inductor to 50nH is still shows the dip at 3.9kHz) (edit2: no it's me, I have nH instead of mH!!!. I'll update the freq response in a while) (edit3: circuit now has 10mH and shows the 2.5kHz dip and slight rise from about 19kHz). Changing the values to 2.35mH with 70 resistance gives a dip at 3.9kHz of 1.07dB Making the inductor 10mH/70ohm with a 300 instead of 680 gives a 2.1db dip at 2.8kHz:
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solderdude
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HD414
May 23, 2017 15:10:11 GMT
Post by solderdude on May 23, 2017 15:10:11 GMT
Rostelle2's measurements, analyses and experiments don't look anything like real life events.
I will post simulations of his various circuits and my proposed one later this evening (when time permits) In the simulation you also have to incorporate the 2k driver. This will be a complex one but a 2k resistor will be good enough from net 1013 to ground.
The inductor needs to be 9.4mH (2x 4.7mH in series) but would be better to use 10mH in reality.
The question still remains how the actual FR of the HD414 is.
When doing the parallel inductor simulation try to simulate this by paralleling 2 'series circuits' of a 4.7mH + 70 Ohm. That will probably give no problems when simulating.
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solderdude
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HD414
May 23, 2017 15:16:34 GMT
Post by solderdude on May 23, 2017 15:16:34 GMT
That second simulation sounds about right.
The resonance frequency of the series circuit is lower than calculated because of the 68nF. When you remove that in the sim you will find the calculated and simulated values will be the same.
It would be great to find a real FR of the HD414. 10 million are sold but can't find one anywhere over here. I think most of them are binned alas.
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HD414
May 23, 2017 16:26:31 GMT
via mobile
Post by marveltone on May 23, 2017 16:26:31 GMT
What about Tyll's measurements? You seem to be fairly familiar with how his results compare with yours.
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garyc
contributing
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HD414
May 23, 2017 16:59:51 GMT
Post by garyc on May 23, 2017 16:59:51 GMT
In the simulation you also have to incorporate the 2k driver. This will be a complex one but a 2k resistor will be good enough from net 1013 to ground. The inductor needs to be 9.4mH (2x 4.7mH in series) but would be better to use 10mH in reality. The question still remains how the actual FR of the HD414 is. When doing the parallel inductor simulation try to simulate this by paralleling 2 'series circuits' of a 4.7mH + 70 Ohm. That will probably give no problems when simulating. Thanks for the tips - I did actually have a 2k resistor for the driver in one iteration, but in my fiddling trying to get the sim to work about I obviously lost it somehow and didn't notice. I only found PartSim yesterday and have yet to become familiar with its foibles. Is there a (free, or cheap) Windows based simulator that you can recommend?
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solderdude
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HD414
May 23, 2017 18:22:20 GMT
Post by solderdude on May 23, 2017 18:22:20 GMT
What about Tyll's measurements? You seem to be fairly familiar with how his results compare with yours. The problem is Tyll never measured it. Can't find a single measurement on any website about the HD414. The only 'plot' I can find is this one: Which seems to jive with how I remember them. No deep bass and a bit on the bright side.
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solderdude
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HD414
May 23, 2017 18:34:23 GMT
Post by solderdude on May 23, 2017 18:34:23 GMT
I only found PartSim yesterday and have yet to become familiar with its foibles. Is there a (free, or cheap) Windows based simulator that you can recommend? Not that I know of. I use this programm at work so never had the need to look for programs. The similutor seems to give the correct answers so would just use that.
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solderdude
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HD414
May 23, 2017 19:33:07 GMT
Post by solderdude on May 23, 2017 19:33:07 GMT
Here are some simulations of various configurations Rostelle suggested. for all plots: left = 10Hz, first vertical segment 100Hz, 2nd = 1kHz, 3rd = 10kHz on the right = 20kHz dB scale = 3dB/div Below the original with 2x 4.7mH in parallel. The difference between using 100 Ohm and 120 Ohm is 0.08dB. About the same as between 560 and 680 in the series circuit. At the lower frequencies the attenuation = -0.5dB At the target frequency = -1.5dB but opposite 10Hz the attenuation is just -1dB from about 1kHz to 8kHz. Below what it would look like with the inductors in series As can be seen there is slightly more treble but still just about -1dB attenuation. The reason the inductor value doesn't have a large impact here is because of the 68nF and the 680 Ohm resistor value. Below a circuit as calculated to have -2.5dB attenuation at around 3kHz. The total resistance Rind + 170 Ohm = 300 Ohm will give -2.5dB which it also does in reality. It shaves off about -2.5dB and less nearing 1kHz and 8kHz. Will remove some of the presence and leaves the upper treble there. At 20kHz the signal is up +0.2dB (inaudible). I have no idea how accurate that posted graph is though so maybe it needs a somewhat different correction. From what I read the bass can't be improved with EQ though which is a shame. Old and decayed pads (flatter or much softer) will give somewhat more bass in the signal. Try to find your HD414 and describe the sound (compared to known headphones)
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garyc
contributing
Posts: 45
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HD414
May 23, 2017 22:13:24 GMT
Post by garyc on May 23, 2017 22:13:24 GMT
Had a look in the garage and all I could find were some mouldy HD420s, which were the replacements for the HD414s.
There are a few pairs (white/black, some with DIN speaker connectors, some with defects) for sale on eBay Germany, BINs around 80 euros and best offers. Not even with the bargiest of barge poles I fear.
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HD414
May 24, 2017 1:53:32 GMT
Post by marveltone on May 24, 2017 1:53:32 GMT
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