Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: MartinB on August 16, 2016, 05:48:54 am
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I'm thinking about doing a 6v6 plexi (in the manner of Mark Huss, Sluckey et.al), and I'm currently looking around at what parts are affordable and easily available in the UK. I might also add a 1-tube reverb, as I did this on a 50 watt plexi build for a friend and I was pleased with how it came out.
I've found a couple of suppliers of power transformers intended for 2xEL84 18 Watt type amps which look like they would do the job:
This one from Ampmaker has a single 275V 160mA secondary and with the 3A heater filament it should be fine with the extra ECC83 for the reverb. But I would need to use a bridge rectifier and JCM900 style capacitor coupled bias supply. The B+ would be somewhere around 360V, which is a little lower than I've seen on other similar builds but should work OK if I bias accordingly and perhaps adjust the dropper resistors for the preamp. http://www.ampmaker.com/store/0-190-275V-20W-power-transformer.html (http://www.ampmaker.com/store/0-190-275V-20W-power-transformer.html)
Alternatively, this one from ValvePower has a 290-0-290V 120mA secondary and 2.5A heater filament. The B+ would be a little higher and I could use a more conventional bias arrangement. Does this one look like potentially a better option? http://www.valvepower.co.uk/transformers.htm (http://www.valvepower.co.uk/transformers.htm)
Both suppliers also have an 8K 18-watt output transformer, or I could use one of these if I wanted to try it with 6.6K. http://livinginthepast-audioweb.co.uk/index.php?p=xfrmrvt1557 (http://livinginthepast-audioweb.co.uk/index.php?p=xfrmrvt1557)
Which would you go for?