Tube poweramp driver tube favorites
 

I'm in the imddle of designing a DIY bass poweramp, using 4 KT88s. I was just wondering if there is a favorite tube amongst talkbass users is the stage that drivers the power tubes. I'm thinking of 12BH7's, 6SN7's or ECC99's. Any other (common) type suggestions are welcome.
Thanks! :hyper:

I would say a 100 watt bass head with (4) KT66's would suit most of my gigs. Every gig I play through the FOH anyway. Why have 300 watts of all tube when you have to rely on the FOH. Is it for band rehearsals? Why everyone builds SVT copies has always puzzled me. KT 88's (6550) are known for being less reliable, more expensive than say a KT66 (6L6), but you have to use more KT66's to match the output of a KT88. Checkout the 65AMPS Apollo Bass Head or the discontinued Mesa Boogie Buster Series! They both use KT66s.

I replaced the JJ's in my Bassman 100T with Wing C and love the tone. They're pretty reliable too.

Where did you buy them?

Current production KT66 are pretty problematic, you can get much more reliable KT88. Fairly big band gave up on the KT66 amps they favoured, once the touring came up, because they couldn't be relied on.

What PI design are you planning to use ? I have three different designs in my amps:

- Weber 6S100, cathodyne PI using 12BH7 (both triodes are used in parallell). An EF86 is the driver stage before the PI. Power stage is 2xKT88. The cathodyne is probably not suitable for 4xKT88
- Hiwatt DR201, LTP PI using a 12AT7 (with fixed bias), a 12AX7 driver stage before the PI. Power stage is 4xKT88 or 6xEL34
- Weber AB200, a 6L6GC driver tube (in class A) driving an interstage transformer PI. Power stage is 6xKT88 or 6x6550

The B15N uses a 6SL7-GT in a kind of floating paraphase PI topology into 6L6GC's. Sounds good to me :)

I find the long-tail pair the easiest to design for specific requirements. Paraphase and cathodyne are a bit trickier.

IMHO, the 6SN7 makes a great PI tube. You can get various 6L6 and KT66 types fairly easily, but I don't know how good they are. The reissue Tung Sol 6SL7-GT's are good.

Dude is asking about preamp tubes. 12AX7, 12AT7 etc.

The driver tube is usually a phase inverter (PI) of some sort. The 12AU7 and 6SN7 are low gain tubes ideal for use as phase inverters. 6SL7 works great, too, depends on the chosen topology, gain, biasing / desired distortion characteristics, etc. So even a 12AX7 can work fine.

I really like the octals for bass, 6SN7, 6SL7, but 6N1P is good, too.