Topic: correction filter PCB (Read 5580 times)

Solderdude · « **Reply #10 on:** December 05, 2012, 12:35:34 PM »

If you are interested in this PCB (or simply would like to read it) there is a pdf file.
It can be downloaded here:
http://hoved-fi.dk/viewtopic.php?f=62&t=2335
For those contemplating buying one or more boards, please read this manual before you do.

I would like to improve this manual so if you have any questions or remarks, suggestions or improvements (even language wise as I am not native English speaking) please PM me.
(thanks to firev1 for his textual suggestions to improve the article, the link above is for this newer version)

omegakitty · « **Reply #11 on:** December 05, 2012, 04:52:55 PM »

Is the amp power requirement so high for the T50rp due to their inefficiency or does the correction filter require a lot of overhead? I'm thinking about giving it a go with the HD800, but I think my amp puts out less than 200 mw into 300 ohms.

Solderdude · « **Reply #12 on:** December 05, 2012, 05:46:55 PM »

The power requirements for my version of the T50RP are high because there is a lot of boosting the lows (probably due to the velour pads) and the impedance is relatively low and efficiency mediocre.

correction of an HD800; notch filter for the highs and perhaps a tad more lows (depending on used output resistance of the amplifier)
an HD800 driven from 120 Ohm usually has enough bass, driven from a low Ohmic amp they may sound a bit lean on the bass.
The filter can certainly correct that.
I will see if I can get the part values sorted for HD800 correction (should be possible).
I already made them for LCD2-3 (they have the same correction) and DT1350 but the last one I need to verify when the boards arrive (in about 1 week from now)

For the HD800 you won't need a powerful amp as the lows might only be boosted marginally and HF part is filtering only.

Ringingears · « **Reply #13 on:** December 06, 2012, 06:50:43 AM »

Hi Solderdude,

I have this great sounding hybrid amp that a nice man in the Netherlands designed, I think as the Sunrise was occuring and another nice man in Arizona built.

Will the filter work well with this amp and a pair of LCD-2 rev.2's that were made in August??

Hi Frans, it's Ron from RG. Do you think with some practice I can put this together, or would I be in over my head? In other words too much for a very out of practice "solder dud"

Nice start to the manual. How many boards would be required for the above application?

firev1 · « **Reply #14 on:** December 06, 2012, 07:47:51 AM »

Quote from: Ringingears on December 06, 2012, 06:50:43 AM

Hi Solderdude,

I have this great sounding hybrid amp that a nice man in the Netherlands designed, I think as the Sunrise was occuring and another nice man in Arizona built. Will the filter work well with this amp and a pair of LCD-2 rev.2's that were made in August??

Hi Frans, it's Ron from RG. Do you think with some practice I can put this together, or would I be in over my head? In other words too much for a very out of practice "solder dud"

Nice start to the manual. How many boards would be required for the above application?

As I have told solderdude via PM, those getting the boards may want to try working up a curve via VSTs like those from rs-met/electric q you and then reverse calculate resistor/caps values from there. Those might be more precise in the sense. You can do the same to get the "perfect" values to use with your amp and headphones. I reckon an LCD2 or 3 only needs a low shelve filter (center 1.5khz) to sound more flat?

I think it would be a pretty easy build except that you have to do a bunch of preparation(like the BOM) before hand including making face plates for the thing as well. You only have to solder caps, resistors and ICs after all.

Imo for HD800 just placing the appropriate impedance adapters will do and with a couple of minor adjustments, its gold. Actually maybe I do want one(in the future) to wire up to my speaker systems since I don't have an equaliser to use with them when I do playback via CD and this seems like a way more cost effective option than getting a proper analog equaliser for the job.

Solderdude · « **Reply #15 on:** December 06, 2012, 07:29:45 PM »

The latest version is up as there were some small errors and improvements.
It can be downloaded here:
http://hoved-fi.dk/viewtopic.php?f=62&t=2335

The PCB itself will be quite easy to populate if the BOM list is present.
IMO the more difficult part is the mechanical work for the housing and power supply.
Those will also be the most expensive parts.

The manual (pdf file) will be updated with BOM lists (and corresponding simulated FR plots) for HP's for which a simulation is done.
So far I have LCD-2, LCD-3 (slightly different), DT1350* ready but not yet incorporated in the file.
For HD800 the outcome is there could be different corrections based on FR graphs from different sites.
Purrin's graphs differ in some aspects from Tyll's and Golden Ears's.
I will be including the different 'solutions' in the listing.

* The DT1350 correction plot will be based on my own and the one GE measured (I think mine sounds close to what he measured and one Purrin measured).
Purrin has ruthlessly shown not all DT1350 have the same 'choclatty' flavor.

NOTE this PCB is and will not be God's gift to headphones but is very likely to give improvements for quite a few of them.
The FR will not be completely flat and accurately compensated but should be closer to 'flat'

Solderdude · « **Reply #16 on:** December 11, 2012, 07:56:00 PM »

PCB's have arrived..

Populated the board for my T40RP and the BOM list below it is for the DT1350 with HD25 pads.
I need to build that one but it will act as a headphone amp at the same time and run of a single 9V battery.
The filter thus is used as amplifier stage as well.
a 'custom FR corrected' C'Moy for my chocolate flavoured DT1350.

When I am about to start shipping (Jan 2013) I will have some 'suggestion' BOM lists also.
requests for headphones can be made here or via P.M.
LCD2/LCD3 HD650 (old & newer) are already in the pipeline.

Not all headphones CAN be (somewhat to considerable) corrected and not all 'suggestion parts lists' will give the desired effect immediately.

Ringingears · « **Reply #17 on:** December 13, 2012, 01:55:37 AM »

Hi Frans,
Put me down for one. I'm jumping in head first into the deep end.

Looking forward to the BOM for the LCD-2 rev. 2. Needs a little "bump". Sending you a PM.

Ron (RG)

Solderdude · « **Reply #18 on:** December 13, 2012, 09:40:28 PM »

price is known...

Total = 8.50 Euro (about $ 11.00 at this moment) and that's included shipping costs and PayPal fees.
It will be sent in a regular envelope that fits in the mailbox so no taxes e.t.c.
Each PCB will be sent in it's own envelope.
Shipping will start in Jan 2013... watch this thread.
Those having expressed interest will be contacted in due time.
I will give full support via PM/this thread and if all 20 PCB's are sold and there is more demand I can order more PCB's.

fishski13 · « **Reply #19 on:** December 14, 2012, 04:29:39 PM »

i'm in for a board.

thanks SD!

Author Topic: correction filter PCB (Read 5580 times)

Solderdude

Re: correction filter PCB

omegakitty

Re: correction filter PCB

Solderdude

Re: correction filter PCB

Ringingears

Re: correction filter PCB

firev1

Re: correction filter PCB

Solderdude

Re: correction filter PCB

Solderdude

Re: correction filter PCB

Ringingears

Re: correction filter PCB

Solderdude

Re: correction filter PCB

fishski13

Re: correction filter PCB

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Author Topic: correction filter PCB (Read 5580 times)

omegakitty