hi, I got a mail from Analog Devices a few days back, about a new opamp (among other things). And the new AD8646 looks quite interesting. Here's the sales pitch: Quote: AD8646 24 MHZ RAIL-TO-RAIL DUAL AMPLIFIER The AD8646 and the AD8647 are the dual, and the AD8648 is the quad...

hi, Today after my first week at university, I wanted to try out some Sennheiser headphones at Musik Hug in Zurich. Well, the HD600 was a rather big disappointment (it just sounds to boomy and undefined for me), but I have made some other nice discoveries. A nice sales guy noticed my Grado...

Umm, yeah. A friend of mine is in the army right now (swiss army, so no fighting, just sitting around and following stupid instructions). And he asked me if I could build him an adapter to attach his iPod via the throat microphone input to the tanks audio system. So, there's a few problems...

You have an opamp, but no resistors, protoboard, solder and solder iron? Well, just draw the whole stuff with a pencil Graphite is an electrical conductor, but not the best - a 1cm trace with a width of approx 0.8mm has a resistivity of approx 15kR. And half the length seems to have...

After hearing horror stories about fried headphones (fried expensive headphones), and not wanting to include DC blocking caps on my sources/amps, I thought about possible remedies... and one would be an active headphone protecting circuit, which disconnects the headphone if it measures high...

Hi, this question just came into my mind: are there alternatives to the LM317A which provide better regulation? Yeah, I could [edit: build not buy] a Jung superregulator, but something with the simplicity of a TREAD but with better specs would be nice. Should be able to handle large...

Hi, I always thought that just shutting off the LED completely at a certain voltage is a suboptimal solution, you may not know if the amp is still running by having a quick glance at it, leading to possible deep discharge of the rechargables. So, I came up with this circuit: The green...

Hi, Well, the cat is out of the bag about my new amp design, and instead of cluttering the other related threads with general discussion about the amp, I just make a new thread. Here it is: edit: pic updated Features: -Uses compensation output per default -Designed for NE/SA/SE5534A...

Hi, I'm designing a new amp, and parts for it should of course be available everywhere. And I'm not really sure about the 3.5mm jack You can see the outline here: The part number in Eagle is Lumberg 1503 08, but I'll be using a chinese clone of it ('cause the original lumberg part is not...

Hi, what are the advantages of having an opamp in the ground channel when there's already a buffer there? I've heard that the opamp can help reduce the DC offset and lower the output impedance, but I have no idea how exactly that should work. Could anybody explain this to me?

Hi, I want to use a SE5534A (or NE5534A if the SE edition is not available) in a new amp design. The ground channel needs to be unity gain, and without compensation the 5534 series is only stable at gains 3 and higher. The AD744 also got a compensation pin, and isn't unity gain stable too...

this is the first song I downloaded in quite a while - it's somewhat catchy, and why not download some pop music now and then. but the sound quality.. the distortion is just mad... this really is quite unbelievable. not audiophile bad (I hear the general distortion in my cheap...

Hi, my brothers wants to buy some halfway decent bluetooth headphones, and he's interested in the Motorola S805. Has anybody heard it? Or has anybody another suggestion? Oh, and a normal 'phone plus bluetooth adapter is most likely not an option for him - also because this headphone doubles as...

I was looking at some boutique parts website, and yeah, boutique parts are bad for your wallet. so - why not build your own cap? all you need is - nonconductive material - conductive material so, aluminium foil and cling wrap would theoretically be sufficient to diy your cap. but we're...

I'm packing for my trip to hungary... I've got a sports bag full of clothes, food for the first day, toilet articles etc. And a rucksack, devoted solely to various electronic gear Included: Nikon D70s with two lenses iPod Cmoy Sony MDR-CD555 iBuds portable loudspeaker a vintage '89...

Hi, I said to myself that I'm gonna buy a decent turntable if I graduate - and well, I passed, and so I now have to buy a turntable I thought about buying a Pro-Ject Debut III, together with a Grado Cartridge (already got that, so I could either use the supplied or the grado). Phono preamp...

Today, I had finally some time to put my denon cdp together, and it's headphone out just blows my cmoy away. The output from every chan goes from the DAC to a NE5532 (yup, two opamps in one chan) for the brickwall filter and such, and then to one half of a JRC4556, latter being the same chip as...

Well, I just have to write something to prevent getting insane. In 3 hours, I will know if I passed the final exams in my school which I need to go university. Or if I can't attend university and have to look for something else. This is crazy. So much significance, packed in a single...

Hi, I have troubles understanding how the power rail isolation of the PPA exactly works. It's a JFET on each rail, which will limit the max current draw of each channel. Will it limit current spikes? But I thought that current flowing is given by U = R * I, R being fixed, and U being the...

Hi, I'm wondering if I listen to loud. With my iPod 5.5G, I'm listening through the lineout with a cmoy, and my headphones are the Grado SR80. The SPL of these headphones is 98db/mV. I'm mostly listening slightly below unity gain (tested by connecting the cmoy to the headphone out and setting...

My Grado headband got ripped off in an accident... and because I wanted a more comfortable substitute NOW, I made one of items I had close at hand. A search in the basement lead to the discovery of some foam pieces, and a roll of red electrical tape (I've run out of black...) So.... here's what...

Hi, just found those in a thrift store. I had a quick listen with my cmoy - bass not to boomy, and they do have some soundstage. After listening ten seconds, I was convinced that they were worth the price. Now at home - compared to the Sennheiser HD497, they sound a lot more emotional...

Hi, I recently got a vintage cell phone. The phone itself is garbage, but there was a nice 7.2V, 1350mAh LiPo rechargable supplied with it (even reloadable on it's own in the telephone recharger). So... this makes of course a great battery for a portable low-gain high-current-draw amp...

Yeah, the thread title got a bit long Wouldn't it be possible to bias the opamps in your source (if the output is unbuffered) to class A by adding just a CCS between the input jacket of your headphone amp and the opamp? If there are any output caps, they might be in the way, but you could...

original posting below. see post #17 for this prototype ---- Just had an idea while writing a reply in this usb dac mod thread: http://www.head-fi.org/forums/showthread.php?t=244738 This and other DACs (for example the headroom total bithead and the aliendac) both take some or all of...