[HeadphoneAddict]

Quote:

Originally Posted by Johnnie /img/forum/go_quote.gif MooBin, The sound is amazing. I previously used the SRM-006t, which is no slouch, to drive my SR-404s. The GES takes it to another level. While it has a similar sound signature (at least to my ears), it's more resolving of details, has a much bigger soundstage and seems to possess effortless power. Though some say Stax is not suitable to rock and certain other types of music, with an amp like the GES, you really can enjoy any type of music. For me, it was also a no brainer given the cost of Stax's top-of-the line amp (SRM-007t) is on par with a maxxed GES. Unlike the Stax, however, the GES autobiases the tubes. The only downside is that the GES does not accept balanced inputs. It did a great job of driving HeadphoneAddict's O2s at the Denver meet last Saturday. This can is notoriously difficult to drive, but based on what I heard then, it has we wondering if I really need to upgrade my amp when I acquire a pair of the O2s. Hope this helps. Johnnie

Yeah, the maxed GES does sound good with the O2 Mk1 with the right tubes. These early 60's GE "Wurlitzer" 12AX7 are doing a very nice job with the O2 Mk1 frequency response, and better than the NOS 12BZ7 that come with the maxed GES. Those tubes are also good with most other stats like Jade, but a little bright with my HE60.

The RSA A-10 only achieved about 2dB, maybe 3dB, more max volume with the O2 Mk1 than the GES did - and both amps sounded very good with the O2. I did like that last extra bit of power for the O2, but would not use it often I suppose. My HE60 and Jade are a little more efficient than the O2 Mk1, and I can't seem to part with any of them - I recently declined to sell the HE60 to another buyer who made me an offer out of the blue, and declined to sell my O2 Mk1 to Ray Samuels as well. I feel bad, but what can you do...

 

[Covenant]

Just got my new Sylvania big bottle 6FD7's

How long do drive tubes - or 6FD7's specifically - take to burn in?

Edit: Okay What. BOTH pairs of 6FD7's I just got seem to cause nasty cracking noises through my headphones. Like very sudden, very loud sounds through either - or both - channels. I got a pair of Sylvanias and a pair of RCAs, and they both seem to do it.

 

[dannie01]

That's wired, I've a pair GE 6FD7 fat bottle now playing, they just sound great. ALos, I have one extra pair GE and Sylvania for stock, tested with about 20 hrs when received, both sound great without any problem. Just wondering you've got a pair of failure 6FD7.

 

[OutdoorXplorer]

My 6FD7 is doing great too sounding except I find it too much gain for now.

 

[sclamb]

Quote:

Originally Posted by Covenant /img/forum/go_quote.gif Just got my new Sylvania big bottle 6FD7's How long do drive tubes - or 6FD7's specifically - take to burn in? Edit: Okay What. BOTH pairs of 6FD7's I just got seem to cause nasty cracking noises through my headphones. Like very sudden, very loud sounds through either - or both - channels. I got a pair of Sylvanias and a pair of RCAs, and they both seem to do it.

Are the pins clean? I had crackling with one set of 6fd7 and cleaning up the pins got rid of it.

Simon

 

[jc9394]

Quote:

Originally Posted by sclamb /img/forum/go_quote.gif Are the pins clean? I had crackling with one set of 6fd7 and cleaning up the pins got rid of it. Simon

X2, happened to my pair too.

 

[Covenant]

I used an alcohol wipe on both, it didn't seem to fix the problem. What do you use to clean pins with?

 

[HeadphoneAddict]

Quote:

Originally Posted by Covenant /img/forum/go_quote.gif I used an alcohol wipe on both, it didn't seem to fix the problem. What do you use to clean pins with?

Rub it with a pencil erasor or use DeoxIT.

 

[Covenant]

Quote:

Originally Posted by HeadphoneAddict /img/forum/go_quote.gif Rub it with a pencil erasor or use DeoxIT.

Luckily I found a local store that sells DeoxIT, so I picked up some. Will try it out on the 6FD7's tonight

 

[Covenant]

Well, the DeoxIT didn't solve the problem. I cleaned the pins of both pairs of 6FD7's with it, by applying a coat, rubbing the coat off with a cloth, repeating, and then applying a last coat and leaving it on, as the DeoxIT instructions read. But both pairs of 6FD7's still exhibit loud cracking noises intermittently through the headphones.

In addition to the loud cracking sounds, I noticed that the 6FD7's make soft 'shhh' sort of sounds through the headphones also, sort of like the current-rush sound that the stock tubes make when they first reach operating heat. For instance, with the stock 6EW7's plugged in, when I switch the amp on, after about 10 seconds I get a "shhhh" sort of sound as the headphones recieve power from the amp, which then dissapears and goes quiet. With the 6FD7's, this sound continues intermittently long after the tubes reach operating temperature. During one test I had the Sylvanias on for close to an hour before they started making 'crack' noises, and during this time they were making the "shhh" current-rush type sound repeatedly every couple of minutes or so.

The seller wants me to ship the tubes back for further testing to see if it can be identified as a tube issue. But I find it odd that the problem is happening with not one, but BOTH pairs of 6FD7's, especially since they're matched pairs and were apparently tested for shorts/faults prior to shipping.

Anyone know what might be the cause here?

 

[jc9394]

That is strange, it may be both pair are bad. 6FD7 are higher gain than 6EW7, did you try using another source to see if the cracking sound from the source?

 

[takezo]

it could be the socket pin retainers (pin gripers) aren't making good full contact with the
pins from the tubes. you can test this by pushing in the 9 pins of the tubes in towards
the center slightly to create more tension when they are inserted into the socket. once
the tubes are in make sure they're not loose or moving around. you may encounter more
noise when you touch the tubes while the amp is on.

 

[Covenant]

Quote:

Originally Posted by jc9394 /img/forum/go_quote.gif That is strange, it may be both pair are bad. 6FD7 are higher gain than 6EW7, did you try using another source to see if the cracking sound from the source?

Yup, I switched in an RCA to mini cable and connected the Woo to my mp3 player to test and make sure the source wasnt the culprit.

Quote:

Originally Posted by takezo it could be the socket pin retainers (pin gripers) aren't making good full contact with the pins from the tubes. you can test this by pushing in the 9 pins of the tubes in towards the center slightly to create more tension when they are inserted into the socket. once the tubes are in make sure they're not loose or moving around. you may encounter more noise when you touch the tubes while the amp is on.

To be honest I highly doubt it. Why would the stock tubes work flawlessly if the retainers were loose? The 6FD7's felt secure in the sockets and couldn't wiggle.

Also, I didn't touch the tubes while on. I dont think either the soft noise nor the loud cracks were due to simple microphonics.

 

[El_Doug]

I should be able to formally become part of this group by early October... when my maxxed WES arrives

 

[dannie01]

We'll say pre-welcome usually

, This is great combo, please share your impression and pics.