Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: plexi50 on May 19, 2012, 11:44:01 am

Title: Small Tube Power Amp?
Post by: plexi50 on May 19, 2012, 11:44:01 am

I was going through my closet today and i found this 6T9 tube power amp. The two front knob controls are from switched off to on position and CWR. The front panel has a 1/4 jack input and on the rear there is an RCA connector. Microphone use? I just wonder what it was built for if anything specific. And of course im wondering what it sounds like

Title: Re: Small Tube Power Amp?
Post by: Platefire on May 19, 2012, 12:05:53 pm

I like it! I was looking for a small amp like that on e-bay for a long time except with a pre-amp tube also---like a minature champ. Every time the price would get so high I would back out. Small amps like that are very popular. Platefire

Title: Re: Small Tube Power Amp?
Post by: plexi50 on May 19, 2012, 12:40:08 pm

I hooked it up to a Tubeworks preamp but no sound. Pulled the cover off the power amp and the voltage from the PT secondary DC B+ are there reading 170VDC. No bias voltage though from what i can tell. I need to go see what the 6T9 pinout data is. Im pretty sure the bias is the 2.2k resistor and cap combo

I suppose i could test the tube to see if it is a good tube! Im working in reverse today! This tube was used in a Hamm radio power transmitter. 1.5 watts. The tube is good

Title: Re: Small Tube Power Amp?
Post by: DummyLoad on May 19, 2012, 02:04:44 pm

cool tube. neat little amp! been looking for some 6T9 to play with for some time now.  :icon_biggrin:

slap a 6AV6 in front of the works, otherwise it's an anemic champ.

--DL

from the GE essential characteristics 14th ed.

general:

base 12FM
Vfil 6.3V
Ifil 930mA

triode:
Pd max 1.5W
Vp max 300V

characteristics - A1 amp
Vp 250V
Vgk -2V
IK 1.3mA
Rp 45K
gm 2100umhos
mu fact. 95

pentode:
Pd max 12W
Vp max 275V
Vg2 max 275
pg2 max 2W

characteristics - A1 amp
Vp 250V
Vg2 250V
Vgk -8V
IK 35mA
Ig2 2.5mA
rp 100k
gm 6500umhos
Rload 5Kohm
Po 4.2W

outline:

pin#    funct.
1        filament A
2        triode anode
3        n/c
4        triode control grid
5        triode cathode
6        internal shield
7        n/c
8        pentode control grid
9        pentode cathode + sup. grid
10      pentode screen grid
11      pentode anode
12      filament B

Title: Re: Small Tube Power Amp?
Post by: kagliostro on May 19, 2012, 03:13:12 pm

There are interesting things in your closet  :icon_biggrin:

Kagliostro

Title: Re: Small Tube Power Amp?
Post by: jeff on May 19, 2012, 04:04:49 pm

If one of your knobs is loose and it falls off, put it in the closet and the amp fairy will bring you an amp too.

Title: Re: Small Tube Power Amp?
Post by: plexi50 on May 19, 2012, 05:46:32 pm

Quote from: jeff on May 19, 2012, 04:04:49 pm

If one of your knobs is loose and it falls off, put it in the closet and the amp fairy will bring you an amp too.

I took your advice and waited 1 hour. When i went back to look in the closet i found this!