Another project…..
Since my 35TG amplifier and the TB3/1000 the other available amps remain on the shelves. Not that they are bad; they are simply not as good.
Especially with the EL82-amp that is a shame as the power supplies and enclosures are simply too good to collect dust.
So: restart with the enclosures and power supplies but a grand overhaul of the signal path.
As I have a nice stash of 6C45P’s and good results with this Russian “exotic” triode and have a pair of serious Silvercore amorphous PP-opt’s on hand a design came up which was minimalistic on the one hand but serious executed on the other hand.
The building was off course halfway when started as the power supplies were already done. The amplifier will be a push-pull parafeed 6C45P amplifier with a single gain stage. So no special input or output stage; just that single pp-pair per channel.
The power supply sees all AC; in the other half of the amplifier only DC is used. The connection is through the connecting rods between the two chassis parts.
There is in/near the signal path an abundance of trannies. Not only the input- and output transformer but also the parafeed choke. In total this amp weighs in at 26 kgs. And it delivers 2,6 Watt……..
But the quality of those Watts is grand !
The signal itself will see the input tranny followed bij an ALPS-pot. After that a grid-stopper and the 6C45P triode (coupled to the parafeed-choke); followed by cap and ending with the OPT itself.
Details of the power supply: I’ve found a single PI-filter not ripple free and a double PI-filter to sluggish in performance. The combination of an aircoil and a choke is an interesting mix in a power supply line. Stable and fast. Drawback is of course the extra material and chassis-place. But the gains are great: no hum or other nasties. Very important with this kind of flea power. With only 2,6 Watt you’re destined to use high sensitive loudspeakers and with them hum is a nightmare.
Effortless music. To be honest the 35TG amplifier sounds somewhat more refined. But is this bad ?
As a comparison I use a restaurant comparison:
– The 35TG amplifier is like a Michelin star restaurant. Great but it will cost you money, time, effort, etc.
– This 6C45P push-pull amplifier is like a serious brasserie. You can have great food here but in a relaxed atmosphere, wear your easy-going clothes, etc.
So now I can choose.
And not unimportant: this amp is more easy to transport so I think this will not stay at home.
I do wish you a musical 2017,
Reinout
(part 3) I never cared about sizes or whatever of that aircore. Of importance is the same wiresize.
Please look at an older post here (35TG amp; and teil 2) where you see the combination of the actual choke + the air core before that. This is my most succesfull combo. packed as one powerpackage.
Regards, Reinout (and yes: i do apply this even at the filaments of the TB3/1000 amplifier and the ripple is ridicilous low…no hum)
Thank you Reinout,
You have been very generous with your knowledge and experience.
I’m building a 211/VT4c SE amp to a Frank Blobaum design so I shall try an air core PS choke.
Best regards
tim
Good afternoon Tim, almost all my power supplies are build along the same line:
– rectifier (very good results with hexfred’s)
– snubber (to clip off the first nasties)
– air core (no formula; guideline = max 1/4 of choke afterwards in size AND EXACTLY the same wire gauge). Objective: flattening the rectified tops (which leads also to more mileage at the first cap)
– first capacitor;
– choke; getting out all nasties
– second capacitor; this is near the „user“. At least double the first cap.
(part 2 later)
(part 2) After trying more conventional pi and double pi filters i came to the conclusion that more C’/L’s indeed measure better…..but make the power supply bloodless. There was no „spark“ / „oomph“ / whatever. The first stage with an aircore does the trick. It will act somewhat as a double pi filter without sacrificing the speed in requested power line.
Would Reinout describe more about his power supply and use of air core chokes please?
Happy New Year
tim