I just recently finished a new amp on breadboard. It uses the OPA 627 (also tried the 2107)with the buf 634 250ma buffer. This amp totally changes the sound of the 501 by providing the ampunt of power this phone really needs. The lows sound like a cross between the accuracy of this phone with...

Well, What is the worst that can happen? It must be close to this. 1% of 302K, Waiting for reply! On an ancient MAC nonetheless. My good old laptop is is the shop and I just couldn't stand it anymore. Fired up the old POS! Is that a model number? Like the FORD POS from "Men In black" Anyway...

I worked on someone's recent ER4'S phones and noticed the serial numbers were much higher than my first set. I've had the ER4 phones for years since shortly after they were made available. The serial numbers of the drivers are ; 2466 and 2486. The recent set I saw were; 15,927 and 16,012. My...

Now that the smoke is beginning to clear over in DIY about the final unveiling on the RA-1 circuit board several thoughts come to mind immediately. In DIY we all had a laugh about the cheap components used in this amp. Now the next step is a clear and simple way to improve the performance of...

Well I finally got a page up on my website! http://www.wilkes.net/~dwpumphery/ The photos begin with my custom set of ER4-S's using .999 Fine Pure Silver wire braided. Sounds great. Then there is one of my first Cmoys with a lettered enclosure. This aluminum box came from an old bag phone...

Hi, I was wondering how many have amps built with the Hansen board. The reason is to ask about power-up thumps and if anyone else has absolute silence on power-up. I have built quite a few amps and have always had an ever-so-slight thump on power-up when using the BB chips 2132 and 2134...

Well I resisted the PPL idea of not using input caps for some time because I had some good very well matched 1 uf WIMA caps. I finally tried removing the caps on my most recent hot rod amp and must say the bass response has improved. I put some custom ferrite cores which have 6 holes with wires...

I recently finished several Hansen amps using the dual 9V Pactec box. The first amp did not work (I thought), and my two NiMH Rayovac batteries were fully charged. (These two batteries had proven track records but had not been used for a month.) I checked everything including battery voltages...

Yes, I was Really Floored and Disgusted with finally seeing the board for the GRADO Amp which had been hidden from view for a reason! I remember my first amps Cmoy and Szekeres blowing the grado away at my brother's, now I know why, I certainly had my suspicions from the really loud POP on...

This cable is a one-of-a-kind which I spent Many Hours making. It is constructed with 99.9 Fine solid PURE SILVER 26 gauge wire insulated by hand and braided by hand by me. The wire is highly polished and teflon coated for corrosion resistance before being placed in insulation. I will not make...

Hi All! In a post Some time ago at Headwise I talked about "My" discovery of a new 50 ohm ER4 headphone. After conversations with Don Wilson, the inventor of the ER4 phones it was revealed that this actually had been one of his suggestions when development of the ER4-P was underway. It was...

After the Demise of my beloved Headwise DIY I had to find something else to do with my time. It was very discouraging to basicly lose my posts and all the hard work others did too. I see some of the original posters from headwise here but it seems like many have gone on to other places and...

This headphone community has become an important part of many people's lives. I was upset when I thought it was over and I am sure others felt the same. This time I plan on putting together an email list of participants just in case. I also think this list would be useful to let people know of...