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6T9 valve RCAs and GEs
http://diyaudioprojects.com/Forum/viewtopic.php?f=9&t=97
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Author:  billnchristy [ 09 Jan 2009, 22:45 ]
Post subject:  Re: 6T9 valve RCAs and GEs

Question for the 6T9 master:

Both of the top left filaments on mine glow a lot brighter than the right one...is this normal?

Author:  mwhouston [ 10 Jan 2009, 17:58 ]
Post subject:  Re: 6T9 valve RCAs and GEs

billnchristy wrote:
Question for the 6T9 master:

Both of the top left filaments on mine glow a lot brighter than the right one...is this normal?

The first thing I would look at would be the voltages are the same to the tubes. I'm not sure one glowing brighter than the other would really cause much of a problem. Bruce could answer this, he is "Tube Man".

If it is not a voltage difference try some different tubes. At least try to get manufacturer match and date or batched matched is even better. Or pay a bit more and have them professionally matched from the supplier. There are a lot of NOS 6T9s out there, go for these over the old used ones. At least you have a starting point.

My amp images extremely well with other the RCA or GE tubes. Both were NOS.The tubes must be reasonably closely matched to get a good image.

Author:  akhihar [ 27 Feb 2009, 11:01 ]
Post subject:  Re: 6T9 valve RCAs and GEs

Hi Mark,

I am building a 6T9 and planning to use Hammond 369JX for the power tranny. However, the guys at this site http://ankythera.com/Projects/stereo_tube_amplifier.htm claims that the specs of 269JX (115V version) are too close to 6T9 requirement. And he suggests a different transformers and Bridge rectifier.

Can I use what he suggests? I am concerned about any effects on the bass response and want to be a careful on chossing the preper tranny and circuit. Do you have any issues with 60mA capacity of 369JX? I would very much appreciate your (or any one's) comments.

Thanks

Author:  billnchristy [ 27 Feb 2009, 12:02 ]
Post subject:  Re: 6T9 valve RCAs and GEs

When I added everything up it was looking more like 67ma or so...will that be enough to cause problems? Don't know.

I went with an Edcor transformer rated at 250ma to be safe.

Author:  akhihar [ 27 Feb 2009, 12:23 ]
Post subject:  Re: 6T9 valve RCAs and GEs

Hi Bill,

Thanks for the reply. What mods have you done to the PSU circuit with Edcor tranny? Earlier you mention you got only 243V with it. Are you fully satisfied with the amp performance and audio with your Edcor tranny? Do you mind posting a copy of your circuit?

Thanks

Author:  billnchristy [ 27 Feb 2009, 13:58 ]
Post subject:  Re: 6T9 valve RCAs and GEs

Here is my circuit, it is nothing like the stock one at all.

I used Cornell-Dublier 220uf 450v caps and a Ohmite thick film chip resistor

I actually have 261v measured, the simulation was a tad off.

I love the Edcor stuff, great prices, great looks, great performance.

Author:  mwhouston [ 27 Feb 2009, 17:55 ]
Post subject:  Re: 6T9 valve RCAs and GEs

akhihar wrote:
I am building a 6T9 and planning to use Hammond 369JX for the power tranny. However, the guys at this site http://ankythera.com/Projects/stereo_tube_amplifier.htm claims that the specs of 269JX (115V version) are too close to 6T9 requirement. And he suggests a different transformers and Bridge rectifier.

Can I use what he suggests? I am concerned about any effects on the bass response and want to be a careful on chossing the preper tranny and circuit. Do you have any issues with 60mA capacity of 369JX? I would very much appreciate your (or any one's) comments.

I'm sorry I'm not able to tell you exactly which Hammond I used. When I pick power trannies for valve systems I usually overrate them The reason is I find they all 'tend to get hot, some very hot. So I believe by overrating the power tranni it should run cooler.

The Edcors are fantastic and I recommend them. They are cheap and well made.

Author:  akhihar [ 27 Feb 2009, 21:53 ]
Post subject:  Re: 6T9 valve RCAs and GEs

Mark,

Thanks for the reply.

My issue is that I haven't found an equivalent Edcor with 240V input. Could you suggest any other model? I am stuck with this tranny issue.

Thanks in advance.

Author:  billnchristy [ 27 Feb 2009, 22:58 ]
Post subject:  Re: 6T9 valve RCAs and GEs

My Edcor stays cool. The Hammond 269ax I use in my preamp gets pretty warm, nowhere near as warm as the area around the tubes but warm nonetheless.

Author:  akhihar [ 28 Feb 2009, 00:29 ]
Post subject:  Re: 6T9 valve RCAs and GEs

Hi Bill/Mark,

I am sorry to bother you guys. But, if I use Edcor XPWR106 (275-0-275 output), what changes I should make to the original Sparetimegizmos' PSU so as to get 250VDC? My knowledge on electronics is limited, so I need your help.

Thanks

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