[Predator88]

I just had a thought. If someone is building a desktop computer and used one of those cases with the headphone output on the front, why not add a cmoy in there and have it output through that jack. Or replace the jack in the front of the tower with a better type. Wouldn't have to be a cmoy of course, this just seemed easy and small. Part of the fun is having the amp separate and in a nice case but it could be fun to have this as an option.

 

[FallenAngel]

I think people have tried that, but inside the computer, it's like a low powered radio station with horrible distortion. Serious shielding is necessary to prevent noise as well as the PC power supply is a VERY bad power source.

Might work with some serious tinkering, but may not be worth it for most.

 

[picklgreen]

Aside from the noise (this is easily taken care of using copper shielding), you have to remember the fact that your main speakers mysteriously turn off when you plug in your headphones into that jack...

but of course the sound out of that jack is really really really bad. You're better of with a USB DAC (alien dac?) and a CMOY.....or a M³.

 

[Uncle Erik]

It's not DIY, but the Coolermaster Musketeer III is a tube (!) headphone amp that slips into a 5.25" drive bay. I've got one in my box and it's alright. I'm surprised that Head-Fi isn't more into them, as they're only about $50. The tube (12AU7) is up front and visible, as well.

 

[Tomo]

Hey,

I beg to differ. I do not believe RF Interference being significant inside the computer. Your amp may be already unstable and easy to oscillate.

RF-Pickup is a fact of life for most of the people around here. So always try to avoid unstable designs and unsafe building habits. Also, you should avoid amplifiers with high voltage gains.

Personally, I never needed more than X2 or X3. There is no need to use X10 or X20. This simply adds to the unstability. Use Multi-Loops or something and reduce the gain down.

PC audio output can easily go close to earsplitting volume nowadays, so you might wanna simply have a buffer amp so you get all the clean current.

Tomo

 

[tomb]

Tomo,

You must have an unusually quiet and clean PC.

No one else has had such experience to my knowledge. The gains you quote are inappropriate for all but the lowest impedance headphones, too - most likely Grado's and very few others. You can't drive a Senn on 2X or 3X. A discrete current buffer may be different - especially with that Szerkes you have - but an opamps's stability rises with higher gains. 7 is common, 14 is not unusual and typical for a Senn.

None of us are after ear-splitting volumes, anyway. The quest is for non-clipping peaks and ample power reserve to ensure that capability. High voltage slew rates are desired for higher impedance phones - Senn's, Beyer's, some AKG's, etc.

No offense, but YMMV x10.

 

[picklgreen]

MY CMOY's drive me Sennheiser HD600 just fine with a gain of 4. The key is to use 1000uF power caps, not 470uF and certainly not 220uF!

 

[SoundGoon]

Quote:

Originally Posted by Uncle Erik /img/forum/go_quote.gif It's not DIY, but the Coolermaster Musketeer III is a tube (!) headphone amp that slips into a 5.25" drive bay. I've got one in my box and it's alright. I'm surprised that Head-Fi isn't more into them, as they're only about $50. The tube (12AU7) is up front and visible, as well.

Uncle Erik, any way I could bother you for a few pics of that?

 

[picklgreen]

You can read about it here.

 

[Tomo]

Hi, Tomb.

I don't see it. HD580 runs nicely with X1 from an amp I built for my Gradoes. I think you are absolutely right if you needed voltage swing. But now many portable units and headphone jacks can generate enough swing to blow the crap out of any cans. I think most sound cards can do that especially all these cool sound cards we are using. So all I really need is a buffer.

Have you checked all the configuration for your computers? There are several setups you can fiddle with in the computer. Some of your settings maybe set so that the volume is dropped way too low. I get opposite problem. My volumes settings likes to torment me with higher volume setting. Sorta Murfy's Curse.

Anyways, the noise are there whether it's in the computer or not. If you are not careful and unlucky, your amp may oscillate. Some oscillations are tolerable or not audible. But the voltage gain will make this oscillation worse and possibly make it unbearable.

That's all.

DOWN WITH THE POOR WIRING JOBS!

Tomo

 

[tomb]

Quote:

Originally Posted by Tomo /img/forum/go_quote.gif Hi, Tomb. I don't see it. HD580 runs nicely with X1 from an amp I built for my Gradoes. I think you are absolutely right if you needed voltage swing. But now many portable units and headphone jacks can generate enough swing to blow the crap out of any cans. I think most sound cards can do that especially all these cool sound cards we are using. So all I really need is a buffer. Have you checked all the configuration for your computers? There are several setups you can fiddle with in the computer. Some of your settings maybe set so that the volume is dropped way too low. I get opposite problem. My volumes settings likes to torment me with higher volume setting. Sorta Murfy's Curse. Anyways, the noise are there whether it's in the computer or not. If you are not careful and unlucky, your amp may oscillate. Some oscillations are tolerable or not audible. But the voltage gain will make this oscillation worse and possibly make it unbearable. That's all. DOWN WITH THE POOR WIRING JOBS! Tomo

... and my Grados do OK on gains of 14 ... not great, but OK. 7 is definitely better, but there are many different kinds of headphones with different impedances than Grados. Given the choice, I would opt for the greater stability that comes with higher gains. That kind of gain is easily absorbed by a Senn.

Volume is not the issue - an AM radio with frequency response of only a couple thousand cycles will blow the crap out of your cans, too - but it won't sound very good. As an example of the strategy for quality amplification, check out Amb's latest, greatest B22 killer amp - over 43V p-p output, with slew rates of ~185V/µS.

... as for the PC noise, well, we'll just have to agree to disagree - I think if you search for threads on noise in a PC and quality of sound cards, you'll have trouble sifting them through them: there will be so many.

 

[Tomo]

Ummm ...

Stability has to do with topology and how you do the wiring. There is not a direct relationship with how much gain you got. In fact, for some topology, G=X1 is perfectly stable solution. But as you already know some opamps are not stable at X1.

X1 gain means even if there is noise, you don't amplify it. This way, you contain the noise problem so it doesn't become problem. This is the easiest and most straightforward way to go at noise problem.

Of course, there are opamps that operate more stable at higher gain, but this does NOT mean the headphone amplifier should have that much gain. We have researched and discussed about multi-looping (to death) and it ought to work well. (Because opamps can operate at decently high gain, but overall gain can be more reasonable gain.)

Tomo

P.S. I understand the details regarding B22. I ought to try it out. But remember there are two types of pursuits of audio listening. Euphonics and Purity. Who knows you might love the "distortion" you get off of transformers and oil-caps (yumm).