Recent content by Daniel Pumphrey

Yes the Triplet idea is lenses glued together or positioned together to correct distortion. I have some lenses from Cameras which do this. Very nice lenses. Ultimately I want a Nikon scope adapter to adapt my Nikon macro lenses and bellows to work on circuits and watches etc. The reading...

I wish there were more ears to test the above amps. It would be great to actually have a blind test with lots of listeners and headphones as well as including the Etymotic ER4-S in the test. I personally feel this is the best test phone for amps like these. If I didn't build my own and had to...

I'm not criticising JMT's work at all here, but just want folks to remember the actual designers. I actually don't remember the first DIYer to use an Altoids box, but it is neither of the folks mentioned in the above posts. (It is in Cmoy's Addendum to the pocket amp.) Anyway, I do admire the...

Part Numbers from manufacturers can and are often the same but they are never the Same parts. Do not trust these numbers from Manufacturer to Manufacturer. Many companies use the term OPA as a prefix for an Opamp too. Some manufacturers use the same number for two or more totally different...

A JMT Altoid amp is basicly a Cmoy, so why don't you folks call it what it really is. If he uses the Hansen board, then it is a Levalois version of a Cmoy Amp not an Altoids amp. Putting it in a mint box does not change it into a new creation. Cmoy designed it, added the crossfeed and a few...

Why do you ask for advise and then act repulsed at the answer? Loudness is not all there is to good audio. Lots of amps get loud when turned up. You will certainly like the change of sound with the addition of a good amp. Headphone amps are designed to work best with the load a headphone...

I am working on several designs which will drive the 501. One is actually pretty simple and is intended for any portable device. It simply boosts the current of the actual headphone out from a portable. This is a good solution for portables which have no lineout and allows them to easily drive...

The real needs of the AKG K-501 should be defined by the current capability and not the wattage rating of the amp intended to drive it, from what I have been able to determine. Some designs like the Szekeres and even the dreaded old 386 are high current amps. I think this is why I still...

There are innovators alive and inventing right now. History will decide what is important and usually gets it wrong, but I am impressed with lots of things Today. I remember that someone at GE invented the transistor and GE thought it was pretty useless. The Japanese saw the possibilities and...

The OPA 627 Opamp is 14.00 each from Digikey, maybe a little more with a recent price increase. There is a 20.00 version which is not really an improvement over the other. There is also a Metal Can Military version which Is expensive. The buf 634 8 Pin Dip is around 5.00. There are three other...

Hi, I would recommend the Meier Corda and my reason is the fact that it can be easily upgraded with better opamps. I just recently built a new amp using the BB OPA 627 and Buf 634 and this is The amp for the 501. The 501 is very inefficient compared to almost any other available in it's...

This is cool and cruel at the same time. Some guys trying to develop a device, build it and sell it, and make a profit. The big guys will come along steal it and make it cheap overseas and put them under probably. Soldering surface mount without the needed tools is cruel, but obviously there a...

Jung might be important, but what about Forrest Mims the I II III IV? Just Kidding! My hero is Einstein who ushered in the new age. Dan

So many views, but one of the main problems is the impossibility of putting into words the effect that good music has on our beings. Name dropping can never approach the sublime. You can spend a fortune and never reach the feeling you might get from a great performance played back on a 30.00...

You Go Apheared. I am of an age when Television was still new, Black and white and very heavy and hot. The repairman came to the house to fix them by replacing one or many vacuum tubes that resided inside. A Television looked like the space ship from Close encounters on the inside. All these...