[CPL593H]

Got a pair of AKG K702s to replace the mid-fi Sennheiser 448s. The 702s with the Bravo are well matched, a very musical combination. The 702s are a bit etched on the high frequency but that is supposed to diminish with several hundred hours. Anyway this change just swamped all the tube rolling which I'll give up on for a while till the AKG's break in. I'm hearing detail that I did not know existed.

 

[igotyofire]

Quote:

Originally Posted by HiFlight /img/forum/go_quote.gif About the best upgrade you can make for the Bravo is to replace the cheap 1A switching power supply with a better quality 2-2.5A switcher or regulated supply. We did an A-B test with mine a recent mini-meet and the better quality 2A supply sounded much better. Using a larger power supply will not harm the amp.

so ur saying somthing like this is what will work, is that the correct size 5.5mm?

12 Volt DC - 2.5 Amp Power Supply

 

[goebish]

No, 24V are required.

 

[Mannevond]

Quote:

Originally Posted by CPL593H /img/forum/go_quote.gif Got a pair of AKG K702s to replace the mid-fi Sennheiser 448s. The 702s with the Bravo are well matched, a very musical combination. The 702s are a bit etched on the high frequency but that is supposed to diminish with several hundred hours. Anyway this change just swamped all the tube rolling which I'll give up on for a while till the AKG's break in. I'm hearing detail that I did not know existed.

I second this. I have K701 which is equivalent to K702, just white and no detachable cable. Mine have played for 150 hours or so now, with me "peeking" in on the sound every now and then. The harsh trebles are going away and the bass is starting to become more defined.

All in all a great combo if one has the patience to wait for the phones to open up. I have a pair of Sylvania JAN 6DJ8 from the 60s (NOS) on the way here, can't wait to hear them. Also waiting for two Tesla goldpins (don't remember the exact model, but supposed to be 6DJ8 equivalents) and considering getting several other tubes.

 

[LeTiger]

Henry is a truly great fellow, got back to me swiftly and is sending a replacement board for the amp (didn't even require me to ship the current one back to him! - said I can send it back when the replacement arrives)

I feel sorry for the fellow right now, that with issues seeming to crop up, but I have faith that the replacement (and possibly a slightly sturdier power supply) will fix the issue yet. He is really nice, and I am definitely glad I got the amp from him (instead of some of the other "bravo" amp sellers popping up on Fleabay)


Quote:

Originally Posted by CPL593H /img/forum/go_quote.gif If you are using a computer for source it may be noise from devices like hard drives.

- Hard drives??? Really?......

Frankly that surprises me, perhaps if you could explain that logic a bit more?

I made sure to test the amp about 30 feet away from the wi-fi router (through a floor and 2 walls to boot, plus I am running wired with no wi-fi capabilities), cell phone turned off, and I have an LCD (crt's apparently known to create a similar issue), was still having the hum/hiss. Really curious as to how you think HDD's would affect interference ( I have a desktop, so the amp was about 3 physical feet from the computer enclosure)

Anyway, Henry was good enough to send me another board, so hopefully a solution will pan out.

 

[goebish]

I had a lot of noise/hiss/interferences when used directly on my computer (X-Fi Fatal1ty headphone out), now that I use it with an iBasso D10 DAC (optical) the sound is just wonderfull.

 

[nsx_23]

Anyone got a link to an auction for one? I'm having trouble finding one on ebay.

 

[goebish]

I think Henry said he need to find another 6N11 tubes lot, as he sold all the stock he had for now.
Shouldn't be too long, keep looking on ebay.

edit: looks like he's using russian EH6922 (electro harmonix) instead of chinese 6N11 now: Valve Class A Tube Headphone Amplifier preamp audio amp - eBay (item 260534776993 end time Feb-06-10 23:05:00 PST), but it's overpriced.

 

[JazzVinyl]

Quote:

Originally Posted by LeTiger /img/forum/go_quote.gif Henry is a truly great fellow, got back to me swiftly and is sending a replacement board for the amp (didn't even require me to ship the current one back to him! - said I can send it back when the replacement arrives).

This sounds really good. I hope he is willing to do this for me as well. If he does, I will feel a lot better about my purchase.

Cheers...

 

[igotyofire]

Quote:

Originally Posted by goebish /img/forum/go_quote.gif No, 24V are required.

wow those are hard to find!

 

[boomy3555]

Quote:

Originally Posted by goebish /img/forum/go_quote.gif I think Henry said he need to find another 6N11 tubes lot, as he sold all the stock he had for now. Shouldn't be too long, keep looking on ebay. edit: looks like he's using russian EH6922 (electro harmonix) instead of chinese 6N11 now: Valve Class A Tube Headphone Amplifier preamp audio amp - eBay (item 260534776993 end time Feb-06-10 23:05:00 PST), but it's overpriced.

I put Electro Harmonix in my Indeeds and they worked in some and not in others (I have Indeeds) I strongly believe that these guys are sensitive to even slight tube differences and require some ajdustment when switching tubes.

 

[Judge Buff]

Quote:

Originally Posted by boomy3555 /img/forum/go_quote.gif I put Electro Harmonix in my Indeeds and they worked in some and not in others (I have Indeeds) I strongly believe that these guys are sensitive to even slight tube differences and require some ajdustment when switching tubes.

X2 but I have really only needed to tweak the pots twice in all of the tube rolling I've done. I had to do it when I removed the crappy 6N11 stock tube and put in a PCC. When I switched to 6dj8s/6922s, I did a little tweaking to make the sound presentation "balance-out" in the phones. I couldn't tell you what pot did what though... The pots are really sensitive and they aren't precise at all.

I think that the older valves are more standardized and were manufactured to tighter tolerances than the Russian and Chinese tubes are now. There's just a bunch of retrotechno junk out there. I also wouldn't buy a JJ/Tesla on a dare, from what I'm reading. Those rebranded remakes are expensive junk, too.

 

[jcoops16]

Quote:

Originally Posted by goebish /img/forum/go_quote.gif edit: looks like he's using russian EH6922 (electro harmonix) instead of chinese 6N11 now: Valve Class A Tube Headphone Amplifier preamp audio amp - eBay (item 260534776993 end time Feb-06-10 23:05:00 PST), but it's overpriced.

WOW. I concure that is steap, considering most of us got it for 40-50 shipped.

 

[Judge Buff]

Quote:

Originally Posted by jcoops16 /img/forum/go_quote.gif WOW. I concure that is steap, considering most of us got it for 40-50 shipped.

I would bet that he's paying retail for the EH6922s. They are definitely overpriced tubes.

 

[CPL593H]

Quote:

Originally Posted by LeTiger /img/forum/go_quote.gif Henry is a truly great fellow, got back to me swiftly and is sending a replacement board for the amp (didn't even require me to ship the current one back to him! - said I can send it back when the replacement arrives) I feel sorry for the fellow right now, that with issues seeming to crop up, but I have faith that the replacement (and possibly a slightly sturdier power supply) will fix the issue yet. He is really nice, and I am definitely glad I got the amp from him (instead of some of the other "bravo" amp sellers popping up on Fleabay) - Hard drives??? Really?...... Frankly that surprises me, perhaps if you could explain that logic a bit more? I made sure to test the amp about 30 feet away from the wi-fi router (through a floor and 2 walls to boot, plus I am running wired with no wi-fi capabilities), cell phone turned off, and I have an LCD (crt's apparently known to create a similar issue), was still having the hum/hiss. Really curious as to how you think HDD's would affect interference ( I have a desktop, so the amp was about 3 physical feet from the computer enclosure) Anyway, Henry was good enough to send me another board, so hopefully a solution will pan out.

Here's the explanation for what I'm quite certain is hard disk noise. I'm using a Xonar DX sound card with back panel and front panel output. I didn't pay any attention to the routing of the wire for the front panel, just used it as it came with the computer case.

So I hooked the Bravo amp to the front panel and heard very audible noise that seemed to be correlated with hard drive operations. (the front panel wire runs through the HD bay). The sound went away but I could get it to come back by doing something like opening Photoshop. So I hooked the amp up to the back panel jack and zero noise. I didn't worry about it after that I guess I could shield or reroute the wire. I suppose it could be associated with something else in the case, any ideas?