Tung Sol 5998 combinations

[hy fi]

Didn't want this to get lost in the tube rolling thread since this is more of a specific question...

I'd like to know what those of you who use the Tung Sol 5998's think is a good combination with them. I've read through the forums and seen one person who likes Amperex Bugle Boy 7316 and another with CBS Hytron 12BH7 in combo for the 5998. It also might be a good idea to list the cans you use as this can obviously influence the sonic signature. Tubes can be expensive so opinions are highly valued.

Thanks

[Laudanum]

It's also the source and any other components in the signal chain that will have an impact.   I was using a Sylvania 6SN7 (with adapter) when plugging source direct into Crack.   Im using a 12BH7 now, Sylvania at the moment.  For 12AU7 I actually liked an Amperex (Herleen) or GE.

[Lar]

I`m also using a 6SN7 Electro-Harmonix with adaptor, running Squeezebox threw Emotiva XDA-1 Dac with great results.Thats with HD - 600`s

[Laudanum]

Should have mentioned my phones.  Main phones are Beyer Dynamic 880's and 990
s.  Also use AKG K602's and MB Quart 805's.

[Mr. Davis]

I like my 12ua7 tungsol black glass.  My crack is not stock though. I've made some upgrades.  YMMV.

[Doc B.]

FWIW we have a Mullard ECC82 with a 5998 in our demo Crack. It got pretty good reactions from the crowd at RMAF.

[hy fi]

Yeah a lot of people commented about that one at the RMAF. Am I correct in assuming it had the speedball upgrade? Anything else special or upgraded about it?

[grufti]

I switched back to the 5998 some time ago and it is paired with an Amperex PQ 6085/E80CC.

The 5998 is at a healthy operating point in this pairing. The Speedball handles the heat dissipation ok. I like it that way with my HD600 and MB Quart 95.

Unfortunately the gain of this combo is a bit too high. I never get past about one third on the volume pot.

One caution: I have a separate power supply for the heater and I float the heater voltage.

[Doc B.]

Yes, it is a prototype in that we adjusted the operating point to lower the output impedance. It runs some of the components harder than the current setup does so we are evaluating it's long term reliability before we decide whether or not to release it. The sonic differences are mostly heard when medium impedance headphones (say, 70-120 ohms) are used. With high impedance cans up in the 250-600 ohm range the differences between the circuits are pretty subtle.

If we do release it it should be a pretty simple update to a stock kit, a bit more involved one for a kit with the Speedball installed.

[hy fi]

Ok, anyone have a good source for 5998's? I cannot find anything below $100...

[Laudanum]

Ok, anyone have a good source for 5998's? I cannot find anything below $100...

Good luck.  Try Tubeworld.  Expensive for NOS but Brendan may have UOS that test well and he will back them.  Also, the straight glass are less money but I dont think they are all Tung sol made which is the tube that is usually commented on so YMMV with those.   Watch out also for 7236 is supposed to be a computer rated version, but again I think they are straight glass and different actual manufacturers and slightly different specs.  Also, you could luck out on a 2399 which, from everything I can find is just a relabeled Tung Sol ST shape 5998.  I have one and it is structurally identical and sonically the same.  Information I have is that 2399 was basically just the internal part number for a Burroughs corporation 5998. 

Patience is the key with 5998's, unfortunately.

[hy fi]

Thanks for the info Laud!

[Beefy]

Also, the straight glass are less money but I dont think they are all Tung sol made which is the tube that is usually commented on so YMMV with those.   Watch out also for 7236 is supposed to be a computer rated version, but again I think they are straight glass and different actual manufacturers and slightly different specs.

The 'straight glass' ones are specifically 5998A. They have plates similar to the 6080/6AS7 rather than the dimpled plates of the regular 5998. But the electrical characteristics of the 5998A are supposedly the same as the 5998.

To confuse things a little, I believe that the 7236 is a computer rated 5998A, not the regular 5998.

To confuse the situation further, people largely like the 7236, but dismiss the 5998A as a poor tube. Couldn't ever work that one out.

In any case...... if it were me, I would either pony up the $$$ for a 'proper' 5998, or just stick with the 6080/6AS7. You really aren't missing much with a $15 RCA 6AS7G.

[grufti]

This all sounds spot on to me.

I tried two different 7236 tubes before I switched to the 5998 and didn't like them. They also measured not much different from the original 6080 tube. The regular 5998 is what I have gone back to now.

The 'straight glass' ones are specifically 5998A. They have plates similar to the 6080/6AS7 rather than the dimpled plates of the regular 5998. But the electrical characteristics of the 5998A are supposedly the same as the 5998.

To confuse things a little, I believe that the 7236 is a computer rated 5998A, not the regular 5998.

To confuse the situation further, people largely like the 7236, but dismiss the 5998A as a poor tube. Couldn't ever work that one out.

In any case...... if it were me, I would either pony up the $$$ for a 'proper' 5998, or just stick with the 6080/6AS7. You really aren't missing much with a $15 RCA 6AS7G.