20W@10%THD (16W@1%THD) to 8 ohms monobloc Parallel amplifier
Hey, solid state gurus! The contest parameters are posted in the chip amp forum where it is popular to use 10% distortion figures when expressing output power of lower voltage chips. So after a few hours and much help (thanks!), I've listed the same power specs, described more appropriately at post 1. And, there is the option of building a more interesting, higher powered, higher quality monobloc with parallel chip or parallel output devices. See also the following extract from the TDA7265 datasheet.
Hey, solid state gurus! The contest parameters are posted in the chip amp forum where it is popular to use 10% distortion figures when expressing output power of lower voltage chips. So after a few hours and much help (thanks!), I've listed the same power specs, described more appropriately at post 1. And, there is the option of building a more interesting, higher powered, higher quality monobloc with parallel chip or parallel output devices. See also the following extract from the TDA7265 datasheet.
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I would not recommend running from a single 9v battery plus rail splitter, particularly with lowish impedance headphones, a real split supply is recommended. assuming an impedance of 33ohms these days would be a guess. being sonys they probably arent too bad, but headphones these days get down under 20ohms and a power supply using a rail splitter here simply wont cut it, it will add to the return impedance of the amp and power supply.
if it can be a small AC powered supply (say 9VA with 0-10-0-10vac secondaries) I have some excellent PCBs for 'the wire' which has quite superb performance that pretty much defies proper measurement with audio precision system 2. I might even be able to rustle up a kit for her, has she done any soldering before?
ahh just looked at the link, yeah a cmoy.. hmm tbh unless the headphones really need the higher voltage gain, the iphone/ipad will have better performance than a standard cmoy with split battery PSU
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qusp,
My daughter has no real experience except watching me building boards myself. I understand that amplifying the signal coming from the Ipod or phone probably won't help that much if at all in the sound quality for headphones. I am just trying to give her something to wet her appetite for electronics and see if that interests her. She has good math skills and that seems to be one of the requirements here to do real electronic designs though she could also use those for mechanical design. Myself I would love to see an amplifier that was taking the un-amplifiied signal as a wave file or whatever output you could get from an Ipod and convert it and amplify it but that is another animal completely. If you are stuck with an ac power supply you are also stuck to that wall wort, you won't be walking around with that. JM's idea is interesting but I do see a problem with the impedance match to the LM386 device. Who would want to have to have 4 sets of headphones attached to have low enough impedance? Is there anything else that could be used or should the whole design just use a discrete circuit so you could actually drive the 33ohm load of a standard headphone? Are we just talking about the dc impedance of the headphones, I could easily measure their Sony headphones and see what the real dc impedance is? I know this is way off topic here, perhaps this should be a new thread and start a new challenge?
Steven
My daughter has no real experience except watching me building boards myself. I understand that amplifying the signal coming from the Ipod or phone probably won't help that much if at all in the sound quality for headphones. I am just trying to give her something to wet her appetite for electronics and see if that interests her. She has good math skills and that seems to be one of the requirements here to do real electronic designs though she could also use those for mechanical design. Myself I would love to see an amplifier that was taking the un-amplifiied signal as a wave file or whatever output you could get from an Ipod and convert it and amplify it but that is another animal completely. If you are stuck with an ac power supply you are also stuck to that wall wort, you won't be walking around with that. JM's idea is interesting but I do see a problem with the impedance match to the LM386 device. Who would want to have to have 4 sets of headphones attached to have low enough impedance? Is there anything else that could be used or should the whole design just use a discrete circuit so you could actually drive the 33ohm load of a standard headphone? Are we just talking about the dc impedance of the headphones, I could easily measure their Sony headphones and see what the real dc impedance is? I know this is way off topic here, perhaps this should be a new thread and start a new challenge?
Steven
Hey Steven,
OK i'll shoot you an email after this, we are talking AC impedance, not resistance, if you know the model it will be easy to find online, its probably written on the box. actually with a decent design there is improvement possible, but not with the cmoy IMO
yeah the boards i'm talking about are tiny, its a pretty simple build, I run mine portable, but its a bit power (current) hungry due to the output buffers. 9v cells wouldnt cut it for long and it would need 2 in series at a minimum, while still only lasting ~2hrs. I use 4 x A123 LiFePO4 2300mah cells, 9v are usually 200-400mah. so its not going to cut it portable. unless you're a bit loco like me.
it depends on what shes willing to carry, the cmoy honestly I would avoid it, it may be an educational exercise, but you still want a result thats better than the ipod is already. it has to pay off or its not very interesting is it?
there are quite a few designs, of which I have numbers on file. the O2 is probably the best bet for portable, but its a bit large too. runs on battery, but probably not what your average girl is going to want to have to carry. I have a spare PCB for that too if shes keen though.
there are some variations on the cmoy theme that are passable, with 2 x 9v and output buffers, but then you may as well build something really decent.
anyway enough OT, sorry guys. been watching the thread, dont have the time to devote to an entry at the moment, not a lot of action here lately.
OK i'll shoot you an email after this, we are talking AC impedance, not resistance, if you know the model it will be easy to find online, its probably written on the box. actually with a decent design there is improvement possible, but not with the cmoy IMO
yeah the boards i'm talking about are tiny, its a pretty simple build, I run mine portable, but its a bit power (current) hungry due to the output buffers. 9v cells wouldnt cut it for long and it would need 2 in series at a minimum, while still only lasting ~2hrs. I use 4 x A123 LiFePO4 2300mah cells, 9v are usually 200-400mah. so its not going to cut it portable. unless you're a bit loco like me.
it depends on what shes willing to carry, the cmoy honestly I would avoid it, it may be an educational exercise, but you still want a result thats better than the ipod is already. it has to pay off or its not very interesting is it?
there are quite a few designs, of which I have numbers on file. the O2 is probably the best bet for portable, but its a bit large too. runs on battery, but probably not what your average girl is going to want to have to carry. I have a spare PCB for that too if shes keen though.
there are some variations on the cmoy theme that are passable, with 2 x 9v and output buffers, but then you may as well build something really decent.
anyway enough OT, sorry guys. been watching the thread, dont have the time to devote to an entry at the moment, not a lot of action here lately.
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qusp,
Thanks for the response. Yes I wouldn't expect much from one of those 9v batteries myself. Reminds me of my high output bike light, I changed the batteries to a larger array of NiMh cells so I could actually ride for more than a little over an hour and still get home safe without a headlight! Since this isn't part of the contest here she wouldn't be held to the Altoids sized tin anyway but that just seemed like a nice size and form factor. Your right that if it doesn't sound better than the internal amplifier it isn't worth much as a project, but she will have to learn something and get her feet wet. Better sound is always the object so I will look forward to your input. Perhaps one of the chips meant for an automotive application is the way to go, but this is so out of my purview, I would be learning as much as she is at this point. Not really but I am a noob in circuit design.....
I hope you had a great New Years down under and that everything else has settled down there for you. Send me a PM and I'll talk to you.
Steven
Thanks for the response. Yes I wouldn't expect much from one of those 9v batteries myself. Reminds me of my high output bike light, I changed the batteries to a larger array of NiMh cells so I could actually ride for more than a little over an hour and still get home safe without a headlight! Since this isn't part of the contest here she wouldn't be held to the Altoids sized tin anyway but that just seemed like a nice size and form factor. Your right that if it doesn't sound better than the internal amplifier it isn't worth much as a project, but she will have to learn something and get her feet wet. Better sound is always the object so I will look forward to your input. Perhaps one of the chips meant for an automotive application is the way to go, but this is so out of my purview, I would be learning as much as she is at this point. Not really but I am a noob in circuit design.....
I hope you had a great New Years down under and that everything else has settled down there for you. Send me a PM and I'll talk to you.
Steven
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OK Steve, we'll take it to email, will send something through within the hour. need to see if I can search out where the old headwize forum projects are being hosted since the forum closed, pretty sure Kevin Gilmore is hosting them somewhere. the headphone section here of course has a few of interest.
thanks for the well wishes mate!
thanks for the well wishes mate!
Who ever mentioned a rail splitter?
I'm talking *battery* power , 6 to 9V single rail of course.
What's the point of listening to an MP3 player on the go, strolling Nature while pulling a 220V line cable around ?
Or a couple pound batteries
Maybe you didn't get it.
This headphone booster can drive *up to* 4 x 33 ohm headphones (or 3 x 20 ohm ones, if that worries you
) ..... even one pair of 8 ohm ones, if you find such dinosaurs at Salvation Army It will be very happy driving just a single 33 ohms set ... or none at all, if you want to use the output as, say, a line driver or something or simply pull al headphones and forget to turn it off.
Ouch !!, sorry but I guess you are , say, overdesigning here.
Mine will happily run idle over 60 Hs on a humble 9V Duracell, shorter depending on listening level, which will be quite low because this amp an be *deafening*.
Under real world use, and a single pair headphones, I estimate around 20 hours continuous music playing.
And using 4AA Duracells, multiply that duration by 5 or 6 , how's that?
Your Daughter will become *bored* with this before that
Of course, you can always use rechargeables there, a sensible move.
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JmFahey,
Thanks for straightening me out on the impedance match. I took from your statement that you need to have 4 headphones running in parallel to get the impedance low enough! I am all for rechargeable NiMh or lithium batteries. I'm sure that most of us have chargers laying around to do that these days. I am all ears for suggestions on all sides.
Thanks for straightening me out on the impedance match. I took from your statement that you need to have 4 headphones running in parallel to get the impedance low enough! I am all for rechargeable NiMh or lithium batteries. I'm sure that most of us have chargers laying around to do that these days. I am all ears for suggestions on all sides.
Who ever mentioned a rail splitter?
I'm talking *battery* power , 6 to 9V single rail of course.
What's the point of listening to an MP3 player on the go, strolling Nature while pulling a 220V line cable around ?
Or a couple pound batteries
yep, you sure are confused... but have a great knack for exaggeration
the Cmoy, which was linked in the post I quoted was what I referred to, not you, or your as yet unknown design..... the cmoy most often calls for a split rail using a single battery, usually with plain resistors, but some versions use a rail splitter. both are a bad idea
I asked if AC was acceptable, IE was portable completely necessary, because I have spare PCBs and parts for 'the wire SE-SE' which I was pretty much offering to gift to Steven; I wasnt suggesting AC for portable...
a couple pounds of batteries? guess its a while since you looked at modern battery tech...
Maybe you didn't get it.
This headphone booster can drive *up to* 4 x 33 ohm headphones (or 3 x 20 ohm ones, if that worries you
It will be very happy driving just a single 33 ohms set ... or none at all, if you want to use the output as, say, a line driver or something or simply pull al headphones and forget to turn it off.
A capacitively coupled portable amp that will drive 7 ohms in a linear fashion on a 9v battery? its clear you are not familiar with some of the modern headphone loads.
Ouch !!, sorry but I guess you are , say, overdesigning here.
that battery powers a portable Balanced ES9018 dac, balanced headphone amp with ~2.5Wpc @ -110dB THD+N for ~8hrs and the whole thing including batteries, >10 linear regulators, transformer coupled electrical spdif (mini BNC), toslink spdif, battery monitor and digital volume control fits in a case 25 x 120 x 160mm, while weighing significantly less than 1lb.
overkill? yeah but not in the way you thought. its overkill in the manner that I built a very high quality home dac and headphone setup into a portable unit. (pics linked below)
Mine will happily run idle over 60 Hs on a humble 9V Duracell, shorter depending on listening level, which will be quite low because this amp an be *deafening*.
Under real world use, and a single pair headphones, I estimate around 20 hours continuous music playing.
And using 4AA Duracells, multiply that duration by 5 or 6 , how's that?
Your Daughter will become *bored* with this before that
Of course, you can always use rechargeables there, a sensible move.
ahh yes, deafening, the age old yard-post of headphone amp drive quality...
i'm looking forward to seeing the 'headphone booster' too
what sort of output caps are needed for driving 7ohm loads? I presume it needs output caps with single rail? I calculate 1000uf or up to 10000uf for a 7ohm load.
but yes lets post a thread in the headphone amps forum.
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Hey guys, this is a power amp thread. Here is a link to the DiyAudio.com headphone amp area: Headphone Systems - diyAudio
Meanwhile, back to power amp in a mint tin contest, which is more like:
At least 9W@10%THD (7.5W@1%THD) per channel to 8 ohms stereo amplifier
OR at least 20W@10%THD (16W@1%THD) to 8 ohms monobloc Parallel amplifier
An LM386 headphone amplifier is not quite that strong.
Meanwhile, back to power amp in a mint tin contest, which is more like:
At least 9W@10%THD (7.5W@1%THD) per channel to 8 ohms stereo amplifier
OR at least 20W@10%THD (16W@1%THD) to 8 ohms monobloc Parallel amplifier
An LM386 headphone amplifier is not quite that strong.
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Dear danielwritesbac, don't worry
*I* asked some details about in/out connectors and clearly will post a project following the original rules.
Remember what was actually written in Post #143.
A couple posts later our friend Kindhornman asked about its suitability driving earphones, while battery driven.
Out of courtesy I suggested there were *other* ways to do it , even hinted that LM386 were the way to go, yet it's clear it would be posted "here" (DIY Forum) but of course in another thread.
Because I think it deserves its own.
Why a simple question and answer (which should have finished that issue there and then) gave birth to around 30 posts, is beyond me
OK, back to the original project.
Which on my side still needs getting a suitable tin can, as mentioned.
Most or all of the rest of the stuff is already available.
Maybe I'll have to wind a custom transformer, but I think I already have wire and lamination, must check stock.
In fact, just *now*, in this boring long afternoon with *all* shops closed and nothing good on TV, by sheer coincidence, I'm building a 12V battery powered amp. 16W bridged into a 6" 4 ohms speaker; but I'm not posting it here because it's *not* housed in a tin can, but in a little "guitar type" Tolex covered combo, which although *loud* does not exactly match the OP specs.
But stay tuned for the tin can one
*I* asked some details about in/out connectors and clearly will post a project following the original rules.
Remember what was actually written in Post #143.
A couple posts later our friend Kindhornman asked about its suitability driving earphones, while battery driven.
Out of courtesy I suggested there were *other* ways to do it , even hinted that LM386 were the way to go, yet it's clear it would be posted "here" (DIY Forum) but of course in another thread.
Because I think it deserves its own.
Why a simple question and answer (which should have finished that issue there and then) gave birth to around 30 posts, is beyond me
OK, back to the original project.
Which on my side still needs getting a suitable tin can, as mentioned.
Most or all of the rest of the stuff is already available.
Maybe I'll have to wind a custom transformer, but I think I already have wire and lamination, must check stock.
In fact, just *now*, in this boring long afternoon with *all* shops closed and nothing good on TV, by sheer coincidence, I'm building a 12V battery powered amp. 16W bridged into a 6" 4 ohms speaker; but I'm not posting it here because it's *not* housed in a tin can, but in a little "guitar type" Tolex covered combo, which although *loud* does not exactly match the OP specs.
But stay tuned for the tin can one
haha are you seriously trying to shirk any responsibility for the tangent? I suppose I shouldnt be surprised..... we arent getting in trouble at school here, be a man and wear some blame where its due please, then move on.
YOU carried it on and made a very confused, provocative and argumentative post directed at me when I wasnt even talking to you, about you, or your as yet unrevealed design. I couldnt help but reply to that, which is childish in its own way, but I wont lose any sleep over it.
do you think you may be punished, so are trying to squirm?
just apologize for the distraction and move on, it really is that simple
YOU carried it on and made a very confused, provocative and argumentative post directed at me when I wasnt even talking to you, about you, or your as yet unrevealed design. I couldnt help but reply to that, which is childish in its own way, but I wont lose any sleep over it.
do you think you may be punished, so are trying to squirm?
just apologize for the distraction and move on, it really is that simple
agreed, its quite interesting, I dont have time to take part but i'll be interested in the results. I would also think that laterals would be useful here, something using a current mirror or dual NP transistor part (or opamp) teamed with a couple of the alfet (semelab) bipolar to247-5 lead parts like ALF08NP16V5 due to simple biasing, inbuilt current limiting, thermal stability and overall being pretty bulletproof.
not the cheapest of parts though
not the cheapest of parts though
That's quite close.JMFahey said:
There's just one glitch:
An audio amp will power a 20 ohm speaker a lot more efficiently than a 0.2 ohm speaker. Likewise an audio power amp will power an 8 ohm speaker more efficiently than a 4 ohm speaker. So, the presence of batteries didn't indicate maximized efficiency. Got an 8 ohm option?
Staying tuned.
Tuned? I wonder who's going to put in a tuner to make mint tin integrated amplifier receiver combo?
See post 1 for the monophonic option that will be faster and easier to build.
Lateral Fet = Dmos = Power Mosfet, now widely available and very inexpensive in somewhat less convenient Dpak packages with different model numbers.
Dual Transistor such as dual BC560 (saturates easily at small signal), dual BC327 (doesn't saturate easily at small signal), are available from Philips-NXP and/or Fairchild in somewhat less convenient SMD packages with weirdly different model numbers.
Lateral Fet also available in a chip power amplifier, the TDA7296, which is a good part that suffers from a poor datasheet (needs a trimmer party to find hi-fi which is not in the datasheet) and a mad pinout that makes optimizing a PCB layout both difficult and dual-layer.
There's a few inconveniences, but I didn't see any big expenses.
Fine.
I mentioned it because that's what I was *actually* doing and relatively close to this project.
And since I'm limited by the 12V battery, 4 ohm loads draw more power than 8 ohm ones.
But let's go back to the original project.
I just NEED to get those d*mn tin cans !!!
Incredibly, none available in the dollar shops around here.
I remember when they were chock full of them in all sizes. Oh well.
Will try downtown.
As a side note on:
From Urban Dictionary: stay tuned
So stay tuned for the 2x9W or 1x20W mint can amp
I mentioned it because that's what I was *actually* doing and relatively close to this project.
And since I'm limited by the 12V battery, 4 ohm loads draw more power than 8 ohm ones.
But let's go back to the original project.
I just NEED to get those d*mn tin cans !!!
Incredibly, none available in the dollar shops around here.
I remember when they were chock full of them in all sizes. Oh well.
Will try downtown.
As a side note on:
It's common urban slang.
From Urban Dictionary: stay tuned
So stay tuned for the 2x9W or 1x20W mint can amp
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