Transformer for Tube Pedals: Allied 6K1VF

[iccaros]

hmm, This transformer could also be used to make a small amp, 12ax7 uses 3 ma and a 6au6 uses 10ma..  both fit easily in a 1590.. with a 2K:8ohm OT should also be small, 70v line transformers are only $4  Going submini a 5902 uses a max 20ma..  that would be pushing it, but the chances of pulling max can be limited with OT choice and voicing..

This transformer just got a lot more interesting.. Thanks

[liquids]

Let me kind of simplify my questions....may seem obvious, but I'm making sure.

As for the rectified DC voltage yielded by the high voltage secondary of these transformers under no load, all else being equal, should I view the 6K88 transformer which says "500VCT" as equivalent hammond 269JX, and the 6K1VF as equivalent to the 269AX?


6K88: http://www.hammondmfg.com/263.htm
6K1VF: https://www.alliedelec.com/Images/Products/Datasheets/BM/ALLIED_TRANSFORMERS/227-0001.PDF
269JX and 269AX: http://www.hammondmfg.com/263.htm

[liquids]

and...if anyone could tell me what to do with the 'grey' sheilded wire (star ground it to the chassis?) as shown on the 6k88 I'd appreciate that as well!

[defaced]

Gray wire goes to chassis ground. That's connected to the copper shield band on the PT. 

The 269JX has 500ma more heater current than the 6k88.  Their HT ma ratings will be similar once rectified/filtered.  Aside from the heater current, they're basically comparable. 

The 269AX has WAY more HT current than the 6K1VF and double the heater current.  I wouldn't consider these comparable.  You could build a small amp out of the 269AX, but the 6K1VF would only be good for a preamp. 

[liquids]

I realize all that and was talking strictly the voltages of the primary under no load...but the answer to my question is in there. 

[defaced]

So now ya tell me?!  Sorry, yea, I didn't get at all.  But to directly answer your question, yes, the rectified/filtered DC voltage will be comparable.  The only thing to keep in mind is whether the voltages on the data sheet are loaded or unloaded.  If they're loaded voltages, the 269AX may have higher voltage than the 6K1VF for a given loading, but I wouldn't expect a huge difference. 

[liquids]

For anyone curious and for reference for anyone who travels down the road; with the 6K88 I'm getting ~118VAC at the wall, 284VAC on each side of the secondary unloaded....


When rectified and filtered into DC (40uF-->1k 5W --> 40uF) unloaded I get 394v;  under load of 2x12AX7s I get 380v.

[liquids]

Likewise, I've soldered up a lot of preamp variants - dumble, carvin legacy, SLO, Dr. Z Mazerati GT / Monza, Mesa Lonestar, all at various B+ voltages...

I tend to leave out the EQ in the preamps since I'm running these preamps into my amp, with the exception of those that utilize a tone stack between drive stages, which can serve as a way to control bass response, In which case I've utilized passive interstage low-end shaping.

In the end, to my ears, every tube circuit benefited from a control to cut high end post-clipping, and /or a low end boost to make up for the bass lost between stages when trying to keep the circuit from being mushy.  For some of these circuits, the effect of driving the phase inverter is a key part of the clipping, so I even went as far as to build a phase inverter as a final gain stage and tap off one of the plates, leaving the other triode in the phase inverter wired but unused.

No matter what I did, I got the most pleasing sounds from sending a tube preamp into a tone-shaping active EQ before I sent it into my amp...

To that end, I found I was able to duplicate just about every tone I dialed in with a tube preamp with a well-tuned & active-EQed fet-based circuit I use currently.

So in the end, for practical reasons I'm probably sticking with fet-based overdrive circuits when it comes to my rig.  But it will always be fun to tinker with preamps and tubes at high voltage, to hear the sounds that tube preamps produce in a controlled environment, even if only to simulate them in another way...

[iccaros]

For anyone curious and for reference for anyone who travels down the road; with the 6K88 I'm getting ~118VAC at the wall, 284VAC on each side of the secondary unloaded....


When rectified and filtered into DC (40uF-->1k 5W --> 40uF) unloaded I get 394v;  under load of 2x12AX7s I get 380v.

Good info.. thanks