[Etrius]

I'm kinda new to the tube amp scene. I'm having an MPX-3 SLAM built. The stock gain tube is gonna be a 6SN7EH and the output a 6BL7GTA.

I really haven't heard any mention of the 6BL7 tube to date. Any thoughts on this config from experienced enthusiasts? How might it would sound on RS-1's? I'm considering requesting 5687 output tubes based on what I've read.

Also, EH seems to get bad press. Any advice on the gain tube?

 

[peter_josephina]

While not a common tube, I have read that this tube will work well in many designs.

The problem of course is the limited supply of good NOS American made tubes.

 

[sacd lover]

Quote:

Originally Posted by Etrius I'm kinda new to the tube amp scene. I'm having an MPX-3 SLAM built. The stock gain tube is gonna be a 6SN7EH and the output a 6BL7GTA. I really haven't heard any mention of the 6BL7 tube to date. Any thoughts on this config from experienced enthusiasts? How might it would sound on RS-1's? I'm considering requesting 5687 output tubes based on what I've read. Also, EH seems to get bad press. Any advice on the gain tube?

Gain tube ..... my solution was to have an octal to loctal adapter made and use sylvania 7af7 or 7n7 tubes. The 7n7 tube is electrically identical to a 6sn7 except for the tube base. In fact, the 7n7 tall bottle tube from the 1940's is essentially a sylvania tall bottle 6sn7gt/ vt-231. The 7n7 was made for a long time and has three distinct versions .... but they are all very good to excellent sounding tubes. the price of these tubes is consistently $6.50-9 depending where you buy the tubes from. The 7af7 is another sylvania tube .... short bottle, round plates and the silver coating at the top of the tube like that seen on the older 6sn7gt/ 7n7's. These generally run about $10 each.

If you want to go with 6sn7's there are many good ones .... sylvania 6sn7gt/ vt-231, ken rad black glass 6sn7gt, hytron 6sn7gt tall bottle, RCA gray or clear glass etc .... But be prepared to pay some stiff prices.

There are three similar tubes in the 6bl7gt family. The 6bl7gt, 6bl7gta and the 6bx7gt. The 6bl7gt can be hard to find but the other two are definitely available. These tubes are so rebranded I have never really figured out which tube construction was made by whom. The construction of these tubes also varies wildly .... so when you order some ask for a construction matched pair. Dont worry about the brand name. I have opened two green 1950's sylvania boxes and had two completlety different tubes more times than I care to count.

All these tubes sound very similar so dont worry about finding the "best" 6bl7gt or variant as they are all excellent tubes. Myself I like the 6bl7gta as this tube is the middle ground tube. The 6bl7gt is a warmer, richer sounding tube while the 6bx7gt is probably the most uncolored and characterless tube I have ever used. I tend to use the 6bl7gta the most as it mates better with a wider variety of gain tubes.

 

[jbloudg20]

Quote:

Originally Posted by sacd lover Gain tube ..... my solution was to have an octal to loctal adapter made and use sylvania 7af7 or 7n7 tubes. The 7n7 tube is electrically identical to a 6sn7 except for the tube base. In fact, the 7n7 tall bottle tube from the 1940's is essentially a sylvania tall bottle 6sn7gt/ vt-231. The 7n7 was made for a long time and has three distinct versions .... but they are all very good to excellent sounding tubes. the price of these tubes is consistently $6.50-9 depending where you buy the tubes from. The 7af7 is another sylvania tube .... short bottle, round plates and the silver coating at the top of the tube like that seen on the older 6sn7gt/ 7n7's. These generally run about $10 each.

Might I ask wehre you got the adapter made?

 

[sacd lover]

Quote:

Originally Posted by jbloudg20 Might I ask where you got the adapter made?

Originally an engineering student from NY made them for me. But he is to busy with school and a job to do them anymore .... so now I get them from Singlepower.

 

[jbloudg20]

Quote:

Originally Posted by sacd lover Originally an engineering student from NY made them for me. But he is to busy with school and a job to do them anymore .... so now I get them from Singlepower.

That's kind of what I thought. I'm going to build my own.

 

[sacd lover]

Quote:

Originally Posted by jbloudg20 That's kind of what I thought. I'm going to build my own.

Make sure you use insulated wire ..... lots of the wires cross.

 

[jbloudg20]

Quote:

Originally Posted by sacd lover Make sure you use insulated wire ..... lots of the wires cross.

I plan to use some shielded/insulated wire. I found an adapter on ebay, but I refuse to pay 40 a pop for them, knowing I can make them myself.

Thanks for the recomendation on the 7n7.

 

[sacd lover]

Quote:

Originally Posted by jbloudg20 I plan to use some shielded/insulated wire. I found an adapter on ebay, but I refuse to pay 40 a pop for them, knowing I can make them myself. Thanks for the recomendation on the 7n7.

Be careful breaking open old octal tubes .... there can be gases you dont want to breathe.

 

[sacd lover]

Quote:

Originally Posted by jbloudg20 That's kind of what I thought. I'm going to build my own.

Adapter in an amp.

http://i79.photobucket.com/albums/j1...Picture004.jpg

Tube + adapter.

http://i79.photobucket.com/albums/j1...Picture084.jpg

Adapter showing loctal top socket.

http://i79.photobucket.com/albums/j1...Picture082.jpg

 

[jbloudg20]

Quote:

Originally Posted by sacd lover Be careful breaking open old octal tubes .... there can be gases you dont want to breathe.

Glad you reccomended that... Hmm target practice time?