Wheeew! I'm not supposed to post this one but medyo I was happy with what I have been through. This is my second tube build(first build was the Aikido 5670-12AU7). Experience is the best teacher really.I was supposed to build guitar tube amplifier like how BAMF of philmusic did. I had 2 sets of Power Transformer,Output Transformer and Choke wound by JV Ultrahicom Enterprises at Paco specifically wound for push-pull 18 watter guitar amps. I had these parts collecting dusts for a while now. However, what will I do with those Guitar Amps after building it? I already have 2 guitar amps (85 Watt and 30 watt) and a Bass amp at home. Although, none of them are tubes.
I did ask Tony(leoman53) before about the difference between Output Transformer for a guitar amp and for HIFI Amplifiers. Those two OPTs are very different from materials used ,how its wound and more importantly how it sounds. But I can't help myself wondering about how those two will sound differently. So instead of building a guitar amplifier, I built a Single-Ended 6SJ7-6L6GC using guitar amplifier transformers and see/hear the results. Later nalng ang Guitar amp, I should be building a Marshall 50Watt Head next time instead of some 18watter amps.
I took Mr. Chey's design for Single-Ended 6SJ7-6L6GC from diyaudioprojects, but did a lot of tweaks:
With the Power Transformer I have with the following specifications, I have to modify its power supply.
Primary: 220V
Secondary:
320-CT-320V @ 150mA
350-CT-350V @ 150mA
12V @ 2.5A.
Looking at the specifications of JJ 6L6GC, the Plate and Screen could handle up to 450volts. Hmm so my Power transformer could handle more enough. I could have a plate Voltage of 400v+, and Screen about 250V.
Running those 6SJ7 with a plate voltage of 200V would be okay after a few googling.
Yes, that's the plan so I build it Wait! I only have a push-pull 18W output transformer. After few google searches, it looks like I could use a push-pull output transformer wired as a single-ended leaving the CT on the Primary windings un-attached I have used Hammond 1444-32 ordered online from RS Components The Brown wire is the CT on the Primary windings left unattached.I have also MKP Audiophiler Caps from Eleshop. I have fused the HV and Mains.I have also used X2 Caps, Thermistor and an Ferrite Cores at the mains.
There its finished!Measurements:Mains = 240V
B+ = 354 V
A+ = 205 V - voltage going to 6SJ7
6L6GC plate = 354 V
6L6GC Screen = 225.4V
6L6GC cathode = 23.3 V
Noise/hum/hiss measurements: 0.022VAC
Conclusions:Hay parang blog na. Overall I was very happy with the results. It was way better that my solid state power amplifier. It was punchy on the mid-range and smooth on the bass frequencies and not boomy like solid states. The sound gets distorted as I turn up the volume to about 3 O' Clock. Might be Output Transformer since its not for Single-Ended.
This thing gets hot in just 30 minutes of playing. I could touch the parts for about 2 seconds so it seems like those dropping resistors are about 50 to 70 degrees celsius.
What's next?Finish Aikido 6N1P. Get this amp a real Single-Ended Output Transformer!
Tube Sources:Epektos.com for 6L6GC
Gerry Sta. Maria for 6SJ7s
Tube Sockets:
AMCO and Watson