Rabbit
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Post by Rabbit on Mar 30, 2013 14:00:13 GMT
These two headphones are quite amazing in what can coaxed out of them with a few mods. I have both and my modded T40 outperforms many other headphones that I have by quite a long way. Solderdude has documented modifications very carefully and shows us all how it's done here: diyaudioheaven.wordpress.com/schematics/headphone/
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dicky
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Post by dicky on Mar 31, 2013 17:19:02 GMT
Hi Ian, I have modded a pair of T50s and I'm using Frans' filter too (I haven't boxed it yet though; as I understand a new PCB is in the pipeline). I built the 3k lift filter on veroboard using transistors and although a little noisy at (unrealistically) high volume levels, it is really quite stunning. I'm still messing about with wool to get the bass right - but to be honest they are quite remarkable. I think I like them flat - but with some bass lift. [The noise may be a result of EMI - or my veroboard design.] Dicky
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Rabbit
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Post by Rabbit on Mar 31, 2013 17:30:01 GMT
I'd not known a thing about you having a go with them at all Dicky!! After all that Fracas on the other site, I gave up.
I have a T40 that Frans modified and a filter that he built for me. It is superb. The filter produces a slight amount of noise, but you'd have to be listening at daft levels to pick it up.
It was the filter and the maker that seemed to cause such an issue and tbh, I was surprised at the 'closed' attitude shown by subjective people!! As you probably saw, I lost the plot slightly and revolted.
Got tired of the childishness so I had a tantrum too. ;D
The T40 is drop dead gorgeous. I really like it a lot. Frans went to a lot of trouble to get it to measure evenly in both cups and flat as well - as flat as he could muster. They are seriously good tbh.
I also have a straight T50. It's brilliant for monitoring. I use either the standard pads or swap them for more bass, with the 940 pads.
I like both a lot. I notice that the other thread went quiet so left it at that, but for me, they outdo the Senn 600/650's and seem to just get out of the way of the music.
Not harsh and play beautifully at life volume too.
I like it so much that I'm looking for a high current portable amp to drive it properly so I can take it away with me and get the same kind of quality when I'm away from home!!
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dicky
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Post by dicky on Mar 31, 2013 17:52:46 GMT
I always thought you were revolting! I initially didn't like the T50s - but I was quite surprised how quickly I tuned into them - in fact, despite being rolled-off at both ends they were an intriguing listen. But with the filter they are stunning and, with certain music, I can forgive the lack of bass. Frans may be able to suggest a modification to the filter for portable use - as he has done for the DT1350s. I'm currently finishing an amp/filter for my DTs and I'm running it off a pair of LiPo helicopter batteries in series ~24v. It's about the same size as a Neco width and height but a bit longer. Maybe Frans could tweak the T50 filter to do the same.
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Rabbit
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Post by Rabbit on Mar 31, 2013 18:30:51 GMT
In actual fact, I don't mind the T40 rolled off. I could use it like that easily - just put the volume up!! They need a lot of current really to drive them properly and that's the problem for portable using an opamp I guess. Trouble is, I've been spoilt and I like them so much that other headphones tend to sound a little edgy to me!!
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dicky
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Post by dicky on Mar 31, 2013 18:37:44 GMT
I'm still waiting for my second LiPo to arrive - but when it does I'll try the T50s on my DT1350 filter/amp. Obviously, they won't sound 'right' but it'll give an idea of the potential to drive the T50s as a portable. As I mentioned above, I'm using +/- 12v with NJM4556 opamps. As far as I'm aware, these are about the most powerful delivering double the current compared to the usual alternatives.
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Rabbit
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Post by Rabbit on Mar 31, 2013 19:00:57 GMT
Be careful of heli batteries. I managed to upset one last week and it burst into flames after a serious heat up.
It scared the beejaysus out of me.
I was in the house and it had finished charging it. I unplugged it and as soon as I did, something must have shorted out.
It started to get really hot. I heard a faint hissing noise, so I ran for the door and chucked it.
It was like a bomb. Fully charged and angry. Once it calmed down, I stuck it in a water trough and walked off as though nothing had happened.
They are LETHAL.
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dicky
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Post by dicky on Mar 31, 2013 19:07:36 GMT
Understood. There are some scary LiPo fires on Youtube. I've got a charging bag and the whole amp goes into it for charging. I can always revert it to 2*9V batteries if need be. I went down the LiPo route because I could bring the balance charge connectors out onto the rear of the amp for charging - this way I don't need to keep opening the amp up and disconnecting the batteries to charge them.
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dicky
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Post by dicky on Mar 31, 2013 19:30:45 GMT
Hi Mick, did sealing them change anything?
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Dave
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Post by Dave on Mar 31, 2013 19:49:34 GMT
Hope this is not too far off topic but seeing a reference to silcon sealant reminded me that if anyone wants some really serious silicon sealant you might want to try Aquasure. As it's name suggests it is fully water tight when cured (24 hours) and grips like sh1t to a blanket . It's main application is repairing leaks on SCUBA dry suits so it needs to be reliable. Not cheap but when needs must ..... Obtainable from any SCUBA gear shop. Dave.
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Rabbit
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Post by Rabbit on Mar 31, 2013 19:50:40 GMT
I reckon they'll sound better, Mick!! The whole cup vibrating as one an all that.......
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dicky
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Post by dicky on Mar 31, 2013 19:53:39 GMT
I was wondering if the bass would tighten up - the cups wouldn't breathe if they were completely sealed.
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Rabbit
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Post by Rabbit on Mar 31, 2013 20:02:37 GMT
I don't know. I would imagine the more rigid the cups are, the better tbh. Less vibration in the structure of the headphone - although in some cases, the vibrations may cause pleasant sonics.......
They did a similar thing with Grados and the use of those inert metal cups on the SR325.
I had the first 325i in the country and I noticed that they were very slightly improved in comparison to the original gold coloured one. The biggest difference was the material of the cups.
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solderdude
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Post by solderdude on Mar 31, 2013 21:14:18 GMT
The way I did my experiments with different types of wool/dampening without using the 4 screws along the way was by altering something and taping them to the cups temporarily and sealing them all around the baffle with tape. Slap on the pads, measure, listen, rip of the tape and adjust.
No need to screw it shut all of the time. The screws can be taken in and out quite a few times if NOT tightened too much bt.w.
Complete seals are not needed as the cups are open at the back and under the screw in the middle anyway.
Do mind the 3.5mm socket of the original cable when applying deadening materials on the baffle. It must NOT be at the spot where the socket is as it is almost touching the baffle without it already.
I have not seen any differences in measurements (FR and waterfall) of the plasticine doing something but that only means it isn't a very obvious change. It only costs a little money (malleable eraser) so do it anyway because it won't hurt.
Best mods to me are discussed in the articles. felt (or other reflection deadening materials) and the right amount of wool. Unfortunately the proper amount is hard to determine by ear unless you aim for 'best sound to your ears'. If you aim for 'flat reference' a measuring rig is obligatory.
In case someone wants their headphone(s) measured and is willing to pay for shipping both ways and carries the burden of possible damage or losing it in the mail you can send headphones to me to be measured.
Nice to see you posting here Mick (and all the other familiar names as well)
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Post by imagemaker18 on Mar 31, 2013 23:35:59 GMT
I was somewhat frustrated by not getting enough bass on my T40/T50 headphones with the cotton and fiberglass packing that was included in the modding kit I had ordered a while back, so decided that in this case less was more. I got rid of the cotton and fiberglass, and by trial and error, arrived at 0.6 gram of fluffed-up raw sheep's wool in each cup. I tried to be as accurate as possible by using a precision electronic scale with claimed accuracy of +/-1/100gram in order to equalize the response of both L & R cups. This indeed rendered the best bass response I was able to get so far, while at the same time being well controlled, without muddying up the mid and high frequencies. As I mentioned to you, Frans, while the LM4562 sound wonderful in the active filter, and I would be perfectly happy with them, stranded on an island , I decided to tinker and roll OpAmps. I had four AD8620 OpAmps, mounted on SMT to DIP BrownDog Adapters, lying around in my parts bin, so I gave them a go. The result is indeed very pleasing - the HF are silkier, while the bass is very solid and somewhat tighter. All in all, TO MY EARS, more musical. Other people's mileage may vary. I am also looking forward to trying out the TLE2072A as well. I do love the way the AD8620 sound though, so they may end up taking permanent residence in the filter. Cheers! Israel
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