BMF
contributing
Posts: 99 
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Post by BMF on Aug 13, 2013 1:14:02 GMT
page 35 of the July 17th manual. Jeremy may have altered some values as he personally would like to have a tad less highs and a bit more bass. As the highs increase the bass becomes relatively less so that could make sense. Really flat isn't every ones cup of tea (it is mine though) If I get feedback it should be changed I can alter it in the manual. I cannot find the link or page for July 18th Manual, page 35, for the new and improved Active Filter.... |
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BMF
contributing
Posts: 99
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Post by BMF on Aug 13, 2013 1:14:28 GMT
correction: July 17th Manual
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solderdude
Administrator
measureutternutter
Posts: 4,886
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Post by solderdude on Aug 13, 2013 7:30:56 GMT
Links to the filter manual can be found here. It is easier to point to this page as that one is always updated with links to the latest version instead of posting links to manuals that may be outdated. The links to outdated manuals will point to a small pdf stating it has been replaced by a newer version and where it can be downloaded b.t.w. Best not to save it to a harddisk but instead always view or download the latests version as I too make mistakes and update filters when new insights, measurements or feedback from users prompts me to change the manual. Easiest to drop me an e-mail or PM to order PCB's.
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Post by micmacmo on Aug 13, 2013 21:11:55 GMT
Frans, I was looking at the BOMs for the filters for the T50RP w/SRH-940 pads and for the T50RP Paradox (pages 35 and 37 respectively). I'm not sure which flavour I'd prefer and was wondering if it's possible/reasonable/advisable to create one filter with collet sockets, so I could swap out key components. From what I see, the differences between the two versions are:
C102 and C202
C104 and C204
R103 and R203
R104 and R204
R110 and R211
R112 and R212
Thoughts? More trouble than it's worth?
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solderdude
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Post by solderdude on Aug 13, 2013 21:59:58 GMT
These filters are fundamentally different and also have slightly different compensations.
The 'Page 35 version' is slightly closer matching (or should I say opposite) to the actual headphone response.
It's the notch sections that are slightly noisy and in the page 35 version only one of them is used resulting in a SLIGHTLY lower noise floor.
The benefit of the 940 pads filter (page 34) is you can individually set the 4kHz boost and boost above 10kHz ranging from no boost at all to 'full' boost and everything in between by simply turning the corresponding pots.
BUT because the 8-10kHz peak is also lifted a bit this needs to be addressed with felt in front of the driver to lower the 10kHz peak by a few dB.
The boost in the highs stops again around 22kHz and drops off fast (the membrane doesn't do much there anyway)
The Pro's of the Page 35 correction filter is only one section is present and that section lowers the 8-10kHz peak.
The increase in highs (above 2kHz going up to 50kHz) is 'fixed' to a level BUT if Rx06 is replaced with a 1k potmeter you can increase or decrease the highs lift with the turn of a potmeter.
After adjusting the highs you will, however, also have to readjust the 10kHz filter a bit as well as they are 'linked'.
Another 'tweak option' might be the sublows/lows that could be increased a bit if so desired.
Components that may have to change value is Cx02 and Rx03.
For those wanting to experiment here you could insert small sockets for Cx02 and Rx03 to 'play' with values and solder in fixed values when ready.
One could do the same for Rx06.
The Page 35 filter can be used with modded T50's that do not have a piece of felt in front of the driver and with those that do have a piece of felt in front of it. The 10kHz notch section can also be made to filter a bit more in case a treble reflector is used by the way. Rx07 should be increased to 10k in this case so you can dial down the 10kHz notch a bit more.
Also the Mad Dogs and Paradox versions can be (greatly) improved with this filter.
For the Smeggy Thunderpants the filter cannot be used.
Personally for all modded T50's I would recommend the 'Page 35' version and perhaps replace Rx06 with a 1k potmeter if you want some 'tone control' in the highs.
On page 37 a filter design is present that does not have a mild bass boost intended for the Paradox and is because of the 'flat' lows as the Paradox versions have completely closed and heavily damped cups.
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Deleted
Deleted Member
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Post by Deleted on Aug 16, 2013 19:39:48 GMT
finally ordered the outstanding parts for my filter tonight.
so hopefully next weekend i can finish it
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BMF
contributing
Posts: 99
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Post by BMF on Aug 17, 2013 0:46:11 GMT
finally ordered the outstanding parts for my filter tonight. so hopefully next weekend i can finish it The Sound Quality improvement is incredible...No Hyperbole...Just Fact as I hear it. |
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Deleted
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Post by Deleted on Aug 18, 2013 19:03:22 GMT
why is it these filters get no mention on head-fi?
just curious
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Deleted
Deleted Member
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Post by Deleted on Aug 18, 2013 19:18:15 GMT
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solderdude
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Post by solderdude on Aug 18, 2013 19:18:32 GMT
Maybe because the filters were not introduced there (I am not a member there, nor do I want to be).
Only on Changstar the filter was introduced but none of them had put any feedback on it on there.
Willing to bet some key persons there wouldn't appreciate positive feedback on the filter there either.
By the way,
Those that have ordered the boards will be happy to learn they have been shipped.
Didn't have enough stamps, finally had some time to get them last Saturday.
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Deleted
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Post by Deleted on Aug 18, 2013 19:39:12 GMT
Maybe because the filters were not introduced there (I am not a member there, nor do I want to be). Only on Changstar the filter was introduced but none of them had put any feedback on it on there. Willing to bet some key persons there wouldn't appreciate positive feedback on the filter there either. By the way, Those that have ordered the boards will be happy to learn they have been shipped. Didn't have enough stamps, finally had some time to get them last Saturday. Frans "Willing to bet some key persons there wouldn't appreciate positive feedback on the filter there either." having heard the Ember, i would say thats their loss! |
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Rabbit
Administrator
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Post by Rabbit on Aug 18, 2013 21:34:11 GMT
It's a weird world imo Simon. Some people just get funny because they can't accept that there are other people out there with the same or more knowledge than them.
Then they start to turn ugly.
However, what they don't realise is what they are missing out on!
One guy once wrote to me that it was a waste of time using these filters. He advised me to get a decent headphone. However, the 'decent' headphone he was using was very skewed in any case and when I dared to mention the lack of bass on those headphones, (severely rolled off ) he said that music in real terms doesn't go down there so it wouldn't matter.
However, it is important (apparently) to be able to 'hear' frequencies way beyond 20 kHz in spite of the deep bass missing from his headphone! What makes me go right off them also is just how nasty they can get about it.
There are a few writers I see on forums who kind of radiate negativity in the way they write and nowadays, I avoid them like the plague. They refuse to even try things but are quick to criticise without even experiencing what we are talking about!
I think for them it's a competition to try to prove to the world how much they know. It's one thing that stops me writing on forums. Big chips and blinkered. Quick to use theory when it suits them, but equally quick to describe things with no proof of anything other than what people say.
The filters work really well and if anyone wants to know just how well, then all they have to do is look at the frequency response of the altered headphone. There's the proof!!
Pure jealousy.
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Post by micmacmo on Aug 21, 2013 5:24:38 GMT
I'm just translating the BOM and manual into a shopping list and I have a couple of questions about Power Option 4. I'm hoping you kind folks might be able to supply answers.
Is there any reason I shouldn't use a used AC/DC converter? I have a bucket of them left over from dead/defunct/replaced devices and it's a shame not to put them to good use...if they fit the need. According to my DMM, they're producing their labeled voltages.
I have a 5VDC, 3A converter and a 12VDC, 1A converter. Any reason I should choose one over the other?
When it comes to the DC/DC converter module, is there a theoretical advantage to choosing one with an output voltage of 9V, 12V, 15V or 18V? (Otherwise, I'll use the availability of compatible C3, C4, C5 capacitors as the deciding factor.)
Thanks for any expertise you can offer.
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solderdude
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Post by solderdude on Aug 21, 2013 5:46:14 GMT
Do you mean 5V input 3W (instead of 3A) or 5V/15W converter
same for the 12V DCDC converter is that 12V/1A (12W) or a small 12V/1W version.
12/15W converters are rather big and overkill.
2W to 4W is recommended.
The outputs of the DCDC converter are those dual voltage or are they single voltage and do you plan to use 2 of them ?
I would choose 12V or 15V as not all opamps can do 18V.
when using 2 (similar) regulators there is a theoretical chance they work on frequencies close together and as all DCDC converters emit common mode noise and have a small HF ripple present there could be 'product' frequencies in the audible range.
Say 1 is at 80kHz and another one at 79.5kHz the by product is 500Hz.
I recommend to use DCDC converters with dual output voltages (+/-12 or +/-15V) with a power rating of 2W but if mounted outside of the PCB 3W or 4W can also be used.
Be sure to add appropriate smoothing caps and or inductors as specified by the manufacturers datasheet.
Most DCDC converters may want a minimum and maximum capacitance connected to their output.
Also look at the type of capacitor used there (ceramic/electrolytic/tantalum)
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Post by micmacmo on Aug 21, 2013 14:18:41 GMT
Thanks, Frans. When I was asking about the 5V/3A and the 12V/1A converters, I was actually talking about the AC-to-DC wall wart (the thing that plugs into the AC wall outlet). Is there a reason not to use a wall wart from another device? And if it's okay, which of the two options (5VDC/3A or 12VDC/1A) is preferable? Or have I completely missed the point completely here? Let me know...it wouldn't be the first time and I'm totally okay with that.
(As for the internal DCDC converter module, I'll take your advice and look for a 2W module with either a 12V or 15 V output.)
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