Rabbit
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Post by Rabbit on Nov 29, 2013 17:46:04 GMT
Just ideas.
Thinking about multi use as well as dedicated to one headphone. Two headphone sockets - one with filter, one without?
Big lion phone battery then the battery life is nothing to worry about? What about those batteries that Neco uses? Although not outputting the same power, it goes on forever. it's unbelievable.
For me, ideal is impossible I think ....
Adjustable gain Vol pot to enable line in Large lithium or lion battery so charge at any time and a big 'un. Lots of power Possibility to use a mains adapter Ability to configure for T40 Ability to bypass filter Slight bass boost (fixed) for crap headphones and iems Battery flat warning (Great if no impact on battery) Metal case for toughness Abilty to percolate coffee Pink just to annoy people and our shared father figure Built in alarm clock.
Don't think it's workable though.
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solderdude
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Post by solderdude on Nov 29, 2013 19:58:19 GMT
The perculator should not be a problem and a bright pink colour is my first choice.
The amp would turn from an affordable small form portable amp to a much more expensive bigger sized desktop amp with battery option.
The next question is would there be more interest in a multifunction desktop amp that could also run of batteries. If it were going to be as powerful as say the Ember the batteries would have to be +/- 18v, so 36V in total and would have to be rather big in size as well.
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Rabbit
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Post by Rabbit on Nov 29, 2013 20:54:09 GMT
OK .... I was just dreaming!!
Just looking at possibilities Frans. My preferences may well not be everyones'.
For someone like me, the size isn't an issue. I don't shove these things in my pocket to use with a T40!! I'd use the Senns or Klipsch with no amp. If I'm feeling outrageous, I might wear the Senn px100 either with a small amp but in a foldup bag.
I wouldn't be wearing something like the T40 in public - more like in hotels or travelling around rather than walking around with a small amp in my pocket. Actually, I rarely carry amps around while walking tbh.
However, I put the lot in a bag on my shoulder so the amp size isn't such an issue to me. (Within reason) I guess it's getting too big for its boots (in my head)
It is so tempting to make them to try and suit everything, when you actually think about it isn't it?
What do you other guys think about an amp with a filter. Go for tiny and portable? Or big and fat and portable (ish) Come on ..... this is exciting adea - a new amp with the potential to be shaped so that it suits your chosen headphone like a glove and a hand!!
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gommer
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Post by gommer on Dec 4, 2013 20:26:35 GMT
If considering rechargeable, then you could also consider LiFePo4 cells (e.g. 4 or 5x standard AAA size, 3.2V nominal per cell). If looking for chargers: bq parts (TI) are the usual suspects.
Cheers, Marc
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solderdude
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Post by solderdude on Dec 5, 2013 9:50:45 GMT
LiFePo4 cells in 9V battery clip size have the same capacity as NiMH. LiFePo4 is great for traction e.t.c. as it is not as polluting and materials needed are plenty. It is my intention to have the possibility to use alkaline and NiMH as the charger can be really simple for NiMH (a resistor) and I only need to have a discharge protection while using the same battery clip (PP3).
A li-ion in the same size has about 2.5x the capacity of NiMH but just like LiFePo4 requires a dedicated charger which would limit the type of batteries used. Also the lower voltage limit circuit needs to be at a different voltage point.
As it is planned for now it looks like NiMH (overnight/trickle charge) or alkaline (jumpers need to be set to select). Will not become desktop/portable (for that the O2 exists) but portable only with a dedication to one headphone in mind.
The filters can be swapped out for other filters or 'bass boost' or other generic filters or no filter at all (just an amp) with a selectable gain in that case.
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solderdude
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Post by solderdude on Feb 19, 2014 20:19:55 GMT
The audio part is getting there slowly.
I abandoned the low idle current wish as combining that with a high output power didn't yield the desired results. Currently experimenting with the T50RP plug-in module.
Next step is the battery management. 16V internal voltage and 5V powersupply/charging as most have a 5V wallwart lying around. I hope to reach around 0.5W into low impedances.
If that works well it is time to finalise the schematic and start on the PCB. It will be part SMD part TH.
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Rabbit
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Post by Rabbit on Feb 19, 2014 20:31:04 GMT
You make this forum great, Frans. I thought you'd left it to rest for a while!! A 16v portable? Fantastic!! 0.5 watt is an equivalent to X-Can V2!!!!
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Post by deireleire on Feb 20, 2014 8:45:10 GMT
Doesn't the T50RP (since you are experimenting with it) need 2W (got this from your headphone power table). Is this the reason why the T50RP isn't so easy to match to a portable amp. But then again a sansa clip+ has 15mW output and it does a decent job (according to my ears) at low volume anyway. Glad to hear your progressing
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solderdude
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Post by solderdude on Feb 20, 2014 8:58:30 GMT
The T50RP can HANDLE 2W, it doesn't need it. For the needed compensation of +10dB you need more power than a stock C'moy. The efficiency of a modified T50RP is also a bit lower than the stock version At 0.5W it will go plenty loud !
15mW will not make it reach the desired levels. to make it sound twice as loud you will need 150mW. With 0.5W it will play 15dB louder than from the clip that is about 3x as loud so decent level. A 'standard' C'Moy will be able to deliver between 0.05W and 0.1W depending on the used opamps and won't compensate the FR.
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Post by deireleire on Feb 20, 2014 17:01:45 GMT
The T50RP can HANDLE 2W, it doesn't need it. For the needed compensation of +10dB you need more power. he efficiency of a modified one is also a bit lower than stock At 0.5W it will go plenty loud ! 15mW will not make it reach the desired levels. to make it sound twice as loud you will need 150mW. With 0.5W it will play 15dB louder than from the clip that is about 3x as loud so decent level. A 'standard' C'Moy will be able to deliver between 0.05W and 0.1W depending on the used opamps and won't compensate the FR. Thanx for the clarification, I'm still at the bottom of the learning curve It's starting to make a little more sense now... What do you think: Pure Sound "Frans filtered"
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Rabbit
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Post by Rabbit on Feb 20, 2014 17:07:08 GMT
How about 'Fran's filters.... the flattest sound since Holland' now with added power? The guy's a genius!!
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Rabbit
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Post by Rabbit on Feb 20, 2014 17:13:25 GMT
'No mountains or dips in frequency response to enable an undisturbed audio vision from an audio visionary' 'Nasty sound waves held back by the best audio dam in the world' it's name ..... The 'Sahara'. (Flat and powerful) or The 'Oasis' - clean and refreshing sound.
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solderdude
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Post by solderdude on Feb 20, 2014 19:39:10 GMT
picture of the working proto. Here it is working on a single (half depleted) 9V for which it isn't designed for it needs 2 full batteries. Gain is a bit low so have to alter some filter values. The principle works though. Sounds good too up till now. Easily driving the T50RP, filtered and all. new favourite portable rig. No name calling yet. Now I need to do the battery management thing.
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solderdude
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Post by solderdude on Feb 21, 2014 15:36:09 GMT
battery management seems to work (cuts of power to the amp below the minimum cell voltage and will power up again when charging.
Charging will be done from 5V DC as that is the most convenient voltage (can be charged from USB for instance)
Next hurdle will be the enclosure. I want it cheap and where the top can easily be removed to change filters.
When that has been set in stone I can design a PCB. It will have 3.5mm input, a power switch, 2 LED's one power (blue, green or yellow) and one red that says .... switch me off and recharge me.... asap.
Then prototype time on a PCB and finally production.
It will probably be available before the summer holiday.
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solderdude
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Post by solderdude on Feb 26, 2014 10:38:35 GMT
It seems almost impossible to put everything in a small housing. This is caused by the 9V rechargeables and battery management as well as the rather large amount of PS caps (lots of uF needed because it is a split rail design) For now the choice has fallen on this Hammond enclosureIt is available in silver or black and think it is the same one as used in the O2. heigth = 30mm, width 103, depth = 120 plenty of room left inside so the rechargeable batteries must be fixed (rubber clamping or double sided tape ?) The picture shows the differences in sizes FiiO X3, Sansa Fuze and the red proto amplifier. Everything fits in there because I really crammed it all inside of it and is impossible to open up to change the filter. I plan to use the bigger case between the 2 players. Not very small but also not very big. WON'T fit in a pocket though, the red one does. The top lid can be removed so it is easy to change filters. It will have a power 'on' LED, power 'low' LED and perhaps a 'charging' LED. A 3.5mm input plug (NO RCA as that can't be used) and 6.3mm output. NO volume control, this is a portable amp and can only be used from the HP out from a source that has volume control. It will still have benefits as the DAP in question does not see a headphone load (it sees almost no load) and thus performs MUCH better. A power switch. on the rear the 5V DC input plug (optional 12V DC input is also possible). Plenty of output power in low impedance headphones (much more than most other portable amps) The amp can be used when connected to the (trickle) charger but will not charge the batteries. It will only charge slowly (overnight) when powered off. I hope to let it play for at least 8 hrs on 1 charge (will depend on how much power is used)
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