Hiwatt Output Stages, NFB

[bea]

Not in yourBass but on the speaker itself.

Or maybe both. But yesterday it was definitely mostly the bass (its bridge pickup) - i tested 2 amps and two cabs (an 112 with an Eminence Beta-12) - always the same symptoms. Then i tried the neck PU alone - it worked. I had to open the bass...

As the Beta sounded really nice with the Eminent i was using (ok, in comparison it lacked a bit of fundament), i did not go back to the 3015.

[bea]

Not in yourBass but on the speaker itself.

Most suspect are ultraflexible tinsel/braided wires connecting fixed terminals on frame to *very much* moving voice coil terminals on the cone.
Way more so in a Bass speaker and worse if the cab is open in any way (including ports).

Well, it must have been the bass. Today i played the G-2000 through the 3015 during the whole rehearsal. Pretty loud this time, but without any problems.

The G-2000 sounded really cool. A bit different than before due to the ECC83 i am now using instead of the ECC81. It sounded more "dense", not as "open" than with the 81, but i can overdrive the 2nd triode. Maybe a bit darker, less treble - although the simulation tells a different story. The G-2000 has chances to replace the Mywatt as the main amp for our duo due to its greater versatility.

[Mike Sulzer]

Well, it must have been the bass. Today i played the G-2000 through the 3015 during the whole rehearsal. Pretty loud this time, but without any problems.

The G-2000 sounded really cool. A bit different than before due to the ECC83 i am now using instead of the ECC81. It sounded more "dense", not as "open" than with the 81, but i can overdrive the 2nd triode. Maybe a bit darker, less treble - although the simulation tells a different story. The G-2000 has chances to replace the Mywatt as the main amp for our duo due to its greater versatility.

Bea,

That phase splitter needs a higher current tube than an ECC83(12AX7) in order to drive the output stage to full power. Also the voltage across the 12AX7 is close to the maximum spec. That circuit is designed for the ECC81(12AT7).

[bea]

Yes, it does, and of course it uses an ECC81 as a phase splitter.

I have developed a preamp for it, and designed it with the ECC81 in mind as well - mainly in order to be able to reuse the original pots which are 100 kOhm tandems. It was the ECC81 in that first position which was microphonic.