alex_o rules

*g* yeah, I did some stupid stuff back in Van. My intentions were good, but it is what it is. Life's changed a great deal in that five years. Shame on me.

?! Ok. I am a 35 year old guy who has lived in GA for quite some time and grew up near Buffalo. I mean, sure Buffalo is near Canada and all, but this is pretty insane.

Ok- this is annoying me. Kevin and I exchanged a few PMs and he had mentioned the 'trevornetwork' thing, and that I should do some searching on HF. I decided to do so, and I think the only thing he and I have in common is our name. We don't even live in the same country!

No idea. After I purchased the amplifier I noticed the same guy 'teejay' on HF selling a pair of 'mint condition HD800 that are just a bit dusty'. I'm not sure what his deal is. I did a really thorough cleaning job and it looks exactly like the pictures Naaman posted up a few years ago. I take much better care of my stuff than momo it seems.

That's fair. Consider this one case closed.

Understood. Is there a substantial sonic difference between +/-360 and +/-400? I will be using SR-Omegas.

I did. Look, I'm not looking for people that don't know me to be my buddy. I do think that being negative because someone is not one of the regulars or an EE is not that great. Seriously, this forum is loaded with posts with people looking for even basic troubleshooting from more experienced folks.

I'm primarily referring to Augsburger's response above and Grawks plastic chassis response. There have definitely been some helpful posts in the thread, it just went downhill when the seller was brought up.

Clue me in here. I'm newer to the headphone scene and have built a few simpler amps, the most complex being a beta22. I suspect that many people that build amps are not electrical engineers, and probably could not detail why more sophisticated designs were done the way they were. Moreover, I'd imagine that many (most?) people in the DIY scene are not well versed in how active components work. When I came here it was with a question about the PSU on a Blue Hawaii I bought. I had my hat in my hands looking for some tips. Instead I feel like I'm being lambasted for purchasing an amplifier from a guy that I'm finding out is not well regarded. Look, I know that the Blue Hawaii is a complex design, but just because I did not build it because I know my own limits, doesn't make me a bad guy.

Well, I'm not sure why there is so much hostility in this thread. I purchased an amplifier from someone I am now finding out was less-than-reputable, that was built by someone who was very well respected. My goal is to do what I can to get it as close to where it was as possible. All in all it seems to work quite well, and after the cleaning it looks excellent both in and out. The reason why I am here asking for some assistance. There seems to be a many talented people on headcase, and I thought it would be a great place to help me out. Voltron nailed I think, by saying there are alot of bad BHs out there. That's why I did not attempt to build it myself, and decided to buy one instead.

Admittedly I felt that I was gaining knowledge and contributing. I have read many other threads on troubleshooting gear. Also, the chassis is made of aluminium with wood accents. The heatsinks are securely attached to the chassis. Am I not getting something? Sent from my ADR6400L using Tapatalk

Hmmm. Interesting. I was unaware of the history. I briefly played it yesterday, and it seemed to work fine. Other than the odd voltage out of the power supply and the dust it seems to be ok. My concern is that someone, possibly momo messed with the zeners for some reason. Oddly, I did not see any obvious evidence of tampering on the zeners in question. Is there any other history on momo, or the amp?

I'm getting a bit worried here. Some history please?

I've built amplifiers and other electronic devices before with success. Using a meter to measure DC voltage between two points is well within my capability. It's pretty simple to measure DC voltage between the +/-400V and ground. It's also simple to measure across the zeners. I would say that since I measured approximately ~150V on the two zeners labeled 150V, and then measured about 50V on the zeners in question would seem to imply I did not do anything wrong.

Also, to verify my measurements I used two calibrated meters, a LEM LH1025 and a Fluke 179. Both produced the same measurements.

Well, the one I have in undoubtedly the same one in Naaman's pictures. Here are the pictures of the unit sent by the guy in Texas. I of course, cleaned the amplifier so it looks like new. http://img848.imageshack.us/g/img8888.jpg/

Yes, I did purchase it from a guy in Texas, and his email address was momo- something, Is there some history I should be aware of?

I am not entirely sure, no. Currently the heatsinks are aluminum and about 2"x1.5" on the mosfets and transistors. They are probably the same ones that Kevin shows in the single box Headamp configuration shown on the BH project page.

I understand that it is working as configured other than the +/-350V rails being ~360V. However, my understanding is that for a BH to perform to spec it requires a total rail voltage of +/-400V and the 50V zener is supposed to replaced with a 100V for the BH.

Another observation is that the 4N60B MOSFETs get quite hot (Are these a IRFBC30 equivalent?) whereas the 2SA1968 transistors stay relatively cooler.

Ok. I just measured across the zeners that are not between the heatsinks, and with positive on the cathode side and got ~156V, ~156V, ~51V. I did notice that the 150V zeners had the cathode on the right side, and the other had it on the left side.

Ahhh, so not ground reference. Just one side to the other should be equal to 150v, 150v, 100v if I understand correctly.

Ok. So after a little bit of discovery, I can confirm that the transformer meets the required specs for the BH on the secondaries. The caps are all 450V as well. I adjusted the bias pot referencing ground before the 5M, and got 560V without headphones plugged in. Examining the zeners, I was unable to determine if the silk screened 50V was used or the proper 100v was used. Would it be possible for you to provide some insight on determining the zener's value? Also, I have a gut feeling that something is not right in the supply. Can you provide some voltage measurement points to help me determine if there is an issue? Thanks for bearing with me on this!

I measured the PSU output voltage to be +/-360V approximately. I will examine the string of zeners to see if they are 150+150+100 or 150+150+50. I will also take a look at the caps, and the transformer. It appears to be a custom victoria magnetics torroid, but I'll take a look at its specs. Finally, with regards to the bias, I am feeling a bit thick here. So, without headphones plugged in, measuring before the 5M to ground I should measure ~560V? (Isn't pro bias 580V?) I should then use the trimpot to adjust.

Hi Justin, The amplifier was built by Naaman, so I suspect he knew what he was doing. Mind you, I do not know how many hands it passed through to get to me! With that said, why did you say 'goodbye headphones'? Also- how would +/-360V affect the functioning of the amplifier? Is the Zener's value the only factor in controlling the output of the power supply section? Lastly, is your KGSS/BH power supply more similar to Kevin's BH supply or KGSS supply? Are they much different? Thanks! Trevor