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Member Back to Top Post by solderdude on NOTE: The Kameleon has been replaced by the (portable Kameleon 2)





The

It only has a 3.5mm stereo jack input socket and 6.3mm stereo jack output socket.







This amplifier must be connected to the headphone output of a portable player/phone/tablet/laptop and cannot be connected to a line-out or line-out dock.

There is an on/off switch and a power indicator as well as an indicator that is lit when the battery needs recharging (the amp switched to standby).

On the rear there is a charger connector and a charging indicator LED.







The Kameleon is intended to drive those headphones that do not perform that well directly from a DAP and can also correct the tonal balance of a several headphones so they sound tonally MORE balanced. While the amplifier is designed to be connected to sources with a headphone out with their own volume control it can be connected to a pre-amp out providing the output resistance of that pre-amp is lower than 100 Ohm and is capable to drive >500 Ohm loads.



This amplifier is not suited for:





Those looking for a high powered (desktop) amplifier.



Those looking for the newest amp they just haven't tried yet.



Those that believe op-amps cannot sound good.



An amp to drive their (C)IEM's or high efficiency headphones.



Those looking for just another cheap C'Moy portable amplifier.



Those that have never ever been satisfied with ANY (portable) setup period.



Those that believe only 'guru selected' components will sound good.



100 hours of playing time and rechargeable within the hour.



Those looking for a very small sized pocket amp.



Those that are afraid of the word 'equalizer'.





Those looking for a (not very small) portable amp for driving higher quality headphones from their low powered DAP headphone out AND have the connected headphone tonally 'corrected' will certainly benefit from this amp.



All headphones will need a different correction IF you aim to achieve tonal accuracy. A variable tone control to accommodate for this would be very complex and costly to make. Not really suited for a portable at all with all those variable controls.

For this reason the Kameleon uses filter modules designed for a specific headphone that simply plug into the amplifier board.



Those filter boards can be relatively cheap and small, they are individually configured to compensate the frequency response for a specific headphone.

Headphones that just need that 'nudge' can be corrected in a way that makes them sound more realistic than when connected to a 'standard' amplifier.

One can also make filter boards that lift (or lower) bass levels, or highs or use the amplifier 'flat' like all other amplifiers are.







Several headphones already have a filter made for them and many others can be designed/made.



if you want to know if your favourite headphone can also be driven/corrected with this amplifier please ask in this thread.



Bare PCB's can not be ordered anymore, Kameleon 2 PCB's are still available.



I will not be selling finished amplifiers nor in kit form but will only supply bare boards until stock is exhausted.

After that and Jeremy will be supplying the boards as well.



Also shall I offer any technical support and evaluate if headphones can be corrected and design the filter (consult and design is free of charge).



More info on this amplifier (also specifications etc.) can be found in www.mediafire.com/view/0i2zm9094g7cqly/Kameleon_portable_headphone_amplifier.pdf )



This design originated from





For those that have built the portable Kameleon amplifier there is a small (easy to do) modification for the battery management section.

This has no influence on the audio quality.



When batteries are brand new or getting older after many many hours of usage the internal resistance of the battery is a bit higher than under optimal conditions.

This causes weird behaviour on start-up. Mostly when batteries are in need of recharging.

During the development a variable power supply was used and this one, of course, did not show this poor behaviour.

It only happens with real batteries.



The modification consists of adding a small electrolytic capacitor (10uF) with a voltage rating of 16V or higher.



HOW to do this is decribed in the



Do note that this applies to the portable version only so NOT the desktop version nor the inline-Kameleon as these do not run on batteries and thus do not have that circuit.

The same applies to the early portable Kameleon 2 amplifiers (the ones with the volume control).

But as this one has the parts mounted differently another instruction is needed.

The





The Kameleon is a portable amplifier and doesn't have a volume control.It only has a 3.5mm stereo jack input socket and 6.3mm stereo jack output socket.This amplifier must be connected to the headphone output of a portable player/phone/tablet/laptop and cannot be connected to a line-out or line-out dock.There is an on/off switch and a power indicator as well as an indicator that is lit when the battery needs recharging (the amp switched to standby).On the rear there is a charger connector and a charging indicator LED.The Kameleon is intended to drive those headphones that do not perform that well directly from a DAP and can also correct the tonal balance of a several headphones so they sound tonally MORE balanced. While the amplifier is designed to be connected to sources with a headphone out with their own volume control it can be connected to a pre-amp out providing the output resistance of that pre-amp is lower than 100 Ohm and is capable to drive >500 Ohm loads.This amplifier is not suited for:Those looking for a (not very small) portable amp for driving higher quality headphones from their low powered DAP headphone out AND have the connected headphone tonally 'corrected' will certainly benefit from this amp.All headphones will need a different correction IF you aim to achieve tonal accuracy. A variable tone control to accommodate for this would be very complex and costly to make. Not really suited for a portable at all with all those variable controls.For this reason the Kameleon uses filter modules designed for a specific headphone that simply plug into the amplifier board.Those filter boards can be relatively cheap and small, they are individually configured to compensate the frequency response for a specific headphone.Headphones that just need that 'nudge' can be corrected in a way that makes them sound more realistic than when connected to a 'standard' amplifier.One can also make filter boards that lift (or lower) bass levels, or highs or use the amplifier 'flat' like all other amplifiers are.Several headphones already have a filter made for them and many others can be designed/made.if you want to know if your favourite headphone can also be driven/corrected with this amplifier please ask in this thread.Bare PCB's can not be ordered anymore, Kameleon 2 PCB's are still available.I will not be selling finished amplifiers nor in kit form but will only supply bare boards until stock is exhausted.After that and Jeremy will be supplying the boards as well.Also shall I offer any technical support and evaluate if headphones can be corrected and design the filter (consult and design is free of charge).More info on this amplifier (also specifications etc.) can be found in THIS ARTICLE This design originated from THIS THREAD For those that have built theKameleon amplifier there is a small (easy to do)for the battery management section.This has no influence on the audio quality.When batteries are brand new or getting older after many many hours of usage the internal resistance of the battery is a bit higher than under optimal conditions.This causes weird behaviour on start-up. Mostly when batteries are in need of recharging.During the development a variable power supply was used and this one, of course, did not show this poor behaviour.It only happens with real batteries.The modification consists of adding a small electrolytic capacitor (10uF) with a voltage rating of 16V or higher.HOW to do this is decribed in the latest manual on the last page, but the modification guide alone can also be downloaded HERE Do note that this applies to the portable version only so NOT the desktop version nor the inline-Kameleon as these do not run on batteries and thus do not have that circuit.The same applies to the early portable Kameleon 2 amplifiers (the ones with the volume control).But as this one has the parts mounted differently another instruction is needed.The modification guide for the portable Kameleon 2 can be found HERE

Dave

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Member Back to Top Post by Dave on

Can I ask that Frans supplies Javier with everything he will need to build me a Kameleon with a filter board to suit my AKG K550 cans and advise me of the cost involved please. I will pay immediately by whichever method you prefer.

Javier, can I ask that you build me a Kameleon and filter board as above and advise me of the total cost and preferred method of payment - I am very happy to pay in advance - you may leave off mains plug on the power lead as my limited talents do extend to wiring up a UK mains plug and it may save a bit on postage. Talking of saving on postage I am also happy to supply and fit the two x 9v rechargeable batteries. My only 'deadline' requirement is that I get my hands on it before mid June if possible please .

My intended source is Blackberry Playbook running Neutron player if that has any bearing on the amp bits.

TIA,

Dave. Hi Frans, and subsequently Javier,Can I ask that Frans supplies Javier with everything he will need to build me a Kameleon with a filter board to suit my AKG K550 cans and advise me of the cost involved please. I will pay immediately by whichever method you prefer.Javier, can I ask that you build me a Kameleon and filter board as above and advise me of the total cost and preferred method of payment - I am very happy to pay in advance - you may leave off mains plug on the power lead as my limited talents do extend to wiring up a UK mains plugand it may save a bit on postage. Talking of saving on postage I am also happy to supply and fit the two x 9v rechargeable batteries. My only 'deadline' requirement is that I get my hands on it before mid June if possible pleaseMy intended source is Blackberry Playbook running Neutron player if that has any bearing on the amp bits.TIA,Dave.

Dave

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Member Back to Top Post by Dave on

Another numptie question I'm afraid - sorry . I have just had a quick read through of your on-line details and notice that you specify the use of an OPA551 op-amp. From my days of swapping op-amps in my Beresford 7520 DAC I know that major differences can be heard using different op-amps. Is your specifying of OPA551 fixed for good technical reasons or can other op-amps be used to change sound signatures (without defeating the main purpose of the Kameleon and/or filter?) I ask because the OPA551 appears to be soldered in place on the PCB and if op-amp rolling is possible for those that like faffing around with such things I wondered if using a socket to facilitate changing op-amps might have any benefit.

TIA,

Dave. Hi Frans,Another numptie question I'm afraid - sorry. I have just had a quick read through of your on-line details and notice that you specify the use of an OPA551 op-amp. From my days of swapping op-amps in my Beresford 7520 DAC I know that major differences can be heard using different op-amps. Is your specifying of OPA551 fixed for good technical reasons or can other op-amps be used to change sound signatures (without defeating the main purpose of the Kameleon and/or filter?) I ask because the OPA551 appears to be soldered in place on the PCB and if op-amp rolling is possible for those that like faffing around with such things I wondered if using a socket to facilitate changing op-amps might have any benefit.TIA,Dave.

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Member Back to Top Post by solderdude on It is fixed for a few reasons.



A: It is hard to beat this op-amp that has a wide supply voltage (not important here) but above all output current range (needed for orthos).

B: It is soldered in because of height issues as the filter PCB is mounted above it. If you were to mount it in a low profile socket there is less room above it for the filter PCB but if you so desire Javier can fit a (low profile turned pin) socket.

C: The OPA551 has 'proven' itself in the Ember.

D: The changing of the sound signature comes from the filter in this amp.



Fitting other (single) opamps in there will SEVERELY limit the current capabilities and turn it into an 'ordinary C'Moy' with filter capabilities of course.



If you are only going to drive headphones with impedances > 120 Ohm you can use other op-amps.



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Member Back to Top Post by Javier on



I'm starting right now with the project and it'll take a few days before I can give early estimates for time and cost, please bear with me and be a little patient. Hopefully next week I'll be able to have something. Needless to say the more "order" the better



Sorry for taking so long to show up but these last day have been kinda hectic with unrelated to the topic stuff.I'm starting right now with the project and it'll take a few days before I can give early estimates for time and cost, please bear with me and be a little patient. Hopefully next week I'll be able to have something. Needless to say the more "order" the better

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Member Back to Top Post by solderdude on There was an error in the component list.

For the OPA551 in the 'Mouser' column I had listed 595-OPA551UA but this must be 595-OPA551PA

The other supplier numbers were correct.



It has been corrected in the latest article.



Some additional info that may be useful for those making one themselves.

The transistor can be any NPN transistor that is pin compatible with the BC547 and is not critical nor in the audiopath.

BC547B, BC547C, BC546B, BC546C etc. can all be used.

I suggest to mount it lying flat on the PCB (so the pins are bent 90o)



Also D6 consists of 3 diodes in series so one must create a construction with 3 diodes.

I used a bit of shrink tubing around it.

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Member Back to Top Post by solderdude on

It also had a removable top to have easy access to the PCB.

Also ordered 2200uF caps but these too were the wrong height.



So... I thought I would make a desktop amp from one of the PCB's.

It runs on a single 24V DC (Sunrise - Starlight) and has RCA in and a volume control and has slightly more output power.



In order to make the volume control possible I had to make a small buffer between the volpot and amp.

On the underside of the PCB I mounted an OP275 (SMD) as a buffer and hotmelt glued it to the PCB.







The inside of the amp is shown above.

I am going to use this amp with the HD650 on a permanent basis next to my PC.



The HD650 is now clear and sparkly sounding with neutral voices and incredible deep subbass.

Let's just say I rediscovered the HD650 as I found it too 'dark' and lacking those things I have come to like more and more.

Extension on both ends and 'realistic' sound.



The HD650 is an excellent headphone albeit a bit darkish coloured and somewhat lacking subbass and that a tad less on the lively sparkle/shimmer.

Sorted now.



Front of the amp:







Used parts I had in stock (balance control knob from a broken AV amp) and a switch I had bought a while ago but never used.



To remove the top panel I filed off a piece of the rear panel.

Now the lid slides open easily but cannot come off completely once the upper screws are in its place because I filed the edge of part of the lid.

This isn't seen from the top though.







The black galvanized Hammond enclosure isn't as nice looking as the silver version though.

Something to think about when ordering an enclosure for portable usage.





I had accidentally ordered a black enclosure but in the wrong height.It also had a removable top to have easy access to the PCB.Also ordered 2200uF caps but these too were the wrong height.So... I thought I would make a desktop amp from one of the PCB's.It runs on a single 24V(Sunrise - Starlight) and has RCA in and a volume control and has slightly more output power.In order to make the volume control possible I had to make a small buffer between the volpot and amp.On the underside of the PCB I mounted an OP275 (SMD) as a buffer and hotmelt glued it to the PCB.The inside of the amp is shown above.I am going to use this amp with the HD650 on a permanent basis next to my PC.The HD650 is now clear and sparkly sounding with neutral voices and incredible deep subbass.Let's just say I rediscovered the HD650 as I found it too 'dark' and lacking those things I have come to like more and more.Extension on both ends and 'realistic' sound.The HD650 is an excellent headphone albeit a bit darkish coloured and somewhat lacking subbass and that a tad less on the lively sparkle/shimmer.Sorted now.Front of the amp:Used parts I had in stock (balance control knob from a broken AV amp) and a switch I had bought a while ago but never used.To remove the top panel I filed off a piece of the rear panel.Now the lid slides open easily but cannot come off completely once the upper screws are in its place because I filed the edge of part of the lid.This isn't seen from the top though.The black galvanized Hammond enclosure isn't as nice looking as the silver version though.Something to think about when ordering an enclosure for portable usage.