|15th January 2014, 03:25 AM||#1|
Join Date: Aug 2013
Tubelab SSE without tube rectifier
This is going to be my first tube amp build, and I wanted to make all my design decisions as far in advance as possible to save hassle later. I've come to the conclusion that a tube rectifier isn't something that I need in this build. The designer included a means of switching between the tube and ss rectifier.
However, I was wondering if it was possible to get away with eliminating the tube rectifier completely? How would I go about doing this? If this is something I've missed on the website, I apologise.
While reading another thread on this topic, I saw a poster explain that this option would free up a 5v tap on the transformer. Could I use another ss rectifier to allow this to power a small cooling fan in the chassis?
One other unrelated question I had was is it likely that the use of a mains voltage pilot light likely to introduce significant hum? If the wire to power this was being taken from the back of the chassis to the front, where the light would be situated, coming close to many other components?
Thanks, and forgive my ignorance of this topic.
|15th January 2014, 07:24 AM||#2|
Join Date: Apr 2009
Location: Northern Manitoba
It does supply a nice slow warm up for the rest of the tubes which helps tube life. George has added SS diodes to the PCB to help the rect. tube last also in the last year which alone may allow you to jumper out the tube if you don't want it's option. You can add ICL's (give a bit of a slow start up ) to help if you go SS.
It may may help the bass/dynamics a bit as there will be no sag that the tube adds. It looks like the 5AR4/GZ34 adds the least of of any tube though.
To go SS (as an option to still plug in the tube instead also) you can buy different types of plug in ones or make your own out of a dead tube base or buy a new base. Some of the commercial ones have resistors in them optional to give the same voltage drop as some of the original ones do. The SS diodes already on the PCB can be left in place.
If you buy one below I think you want the no sag (no resistors in it) WS1 for the best reasons for going to SS as you don't want to add any more DCR (resistance) to the PS which will hurt the dynamics of the sound. That one looks like it has ICL's in it also.
Weber Copper Cap Rectifiers
It will raise the b+ a few volts which shouldn't hurt if you make sure you select a power supply transformer that will give a lower B+ in the safe range for the tubes you select.
I don't think small cooling fan(s) would be an issue on the PS even if you kept the tube and yes you would add SS diodes to run it. A 12V computer fan would run nice a quiet on less voltage also. You could add more fans for better cooling.
Maybe check the tubelab forum in the commercial section for maybe more info on pilot light etc. and google may be helpful. There are pics there also of completed amps etc.
Last edited by rmyauck; 15th January 2014 at 07:45 AM.
|15th January 2014, 02:22 PM||#3|
Join Date: Jul 2005
Location: West Virginia panhandle
The original SSE board and the new board has the option to use solid state diodes for rectification. To use this option, you must install the diodes, and connect a jumper between the two terminals for the rectifier switch. You can simply unplug the rectifier tube if not using it, or install the tube and remove the jumper to use the tube rectifier. You can leave the socket off the board entirely and don't wire the 5 volt winding to the board if you don't plan to ever use it.
The new (last 1.5 years) SSE board has an additional pair of diodes added for extending the life of the rectifier tube. These can be omitted if the tube is not used. The new board also has the provision for a CL140 intush current limiter. I would install this part with either a tube or solid state rectifier.
The 375-0-375 volt power transformer will produce about 460 volts of B+ with a solid state rectifier which may be too much for some EL34's and most 6L6GC tubes. It should be OK for KT88's and 6550's. You might consider a 360-0-360 volt transformer for the smaller tubes.
Wiring a pilot light to the 6.3 volt winding should not be a problem if the wiring is routed along the left side of the board with all the other power transformer wiring. The AC noise from the 6.3 volt winding is minimal compared to the 120 volt wiring that is already there.
You could use the 5 volt winding for a fan. You could also use the 6.3 volt winding by wiring a bridge rectifier across the winding, adding a small cap (100uF) and a 12 volt computer fan. I have done this with the SSE and the TSE. Most computer fans will run slowly and quietly on the 7 volts or so that this generates. Some may buzz from the poor filtering, but a big cap may create it's own hum, so some experimenting is needed. The 6.3 volt winding floats about 60 volta above ground to minimize hum, so don't ground any of the fan wiring.
Tubelab, I blow stuff up so that you don't have to.
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