Traynor Filter Caps

[dreric]

I have a Traynor Bass Master YBA-4 that I'd appreciate some advise on.

The filter caps are the original 40uf @ 450V. The low end is a little flabby and the amp has a little too much background hum. I thinks its time to replace them.

I've heard that the filter caps on the Tranyor amps were a bit weak and they benefit from higher uf.

Based on the schematic what values should I increase the caps to?

Do I have to adjust the dropping resistor values also?

I have some 100uf @ 450v that I'd like to use, is this too high?

Thanks

Eric

[philo43]

Since the Traynor has a silicon rectifier I would not be too concerned with doubling the value of the first supply cap (C18). This will certainly help with the bass response and should reduce the hum some. 40 MFD for the other three is probably OK. What concerns me is the 450 volt ratings. The schematic shows a B+ of 440 volts. This is too close for comfort. I would go with at least a 500 volt cap. I know my electric service is at least 10 VAC higher today than it was 30 years ago and that would put the B+ at over 500 volts on this design. Notice that the schematic specifies 115VAC at the power plug. This might be why the caps in Traynor amps are considered "weak."

Shouldn't have to change the dropping resistors.

I'm not an engineer and others may have better answers for you.

[David Root]

I have cheated on PS cap headroom like this Traynor, and got away with it. That doesn't mean it's good practice, especially if you play a lot regularly and crank it! One of these days it will bite my butt.

If you do the above with this amp, consider 2 x 200uF/350V caps in series on the plates and 2x80uF/350V on the screens. Don't forget the voltage balancing resistors, 220K/2W metal oxide. If they can be made to physically fit, that is!

[dreric]

I have cheated on PS cap headroom like this Traynor, and got away with it. That doesn't mean it's good practice, especially if you play a lot regularly and crank it! One of these days it will bite my butt.

Thanks for the reply. What do you mean by "cheating" on the PS cap headroom?

Thanks

Eric

[dreric]

Philo43

Thanks for your response. I was concerned by the 450v rating on the caps and seeing that confirmed that this could be a issue I'll get a higher voltage.

Thanks,

Eric

[Structo]

If you connect two 100uF 450v caps in series you will end up with 50uf and 900v .

[David Root]

By cheating on headroom I meant not leaving any headroom above operating voltage. When you switch on the high voltage, the caps see an inrush of heavy current and there is always some spikiness to the voltage, especially on the first cap after the rectifier, which is of course the plate cap.

Cut your caps some slack, use higher voltage ratings. The cheapest way to do this is by connecting two caps in series, you will double the voltage rating and get one quarter the capacity, as in my and Tom's examples above.

[Markusv]

David

To jump in
"If you say double the voltage rating and quarter the capacity"
Does that mean quarter the capacity of the 2 values together or quarter the capacity of one cap only?
So: .25*(200+200) I'm assuming its this one?
or: .25*(200)

Also if you paralles caps I know the capacitance increases- but what happens to voltage handling there? does it not increase as well?

Thanks in advance!

[rsi]

No. When caps are paralleled the voltage rating does not increase.

[Markusv]

Thanks rsi

Dreric

I have the same amp in a combo- think it is a '72- recently acquired and I love it! (original Philips power tubes)
I have upped the screen resistor on the power tubes to 1K1 as this may increase compression somewhat.
Also if yours is a combo you may want to look at something other than the stock square magnet 15 inch speaker it has.
I may be puttinng an Eminence Big Ben in there down the road for better/tighter Bass response
Lovely amps and incredibly well suited to mods. I don't want to lose the amp's basic character but I did bypass the cap on the first triode of the bright channel and the breakup comes on a bit sooner.
Other than that I replaced all ceramic caps with poly and kept the old parts for eventual resale value.

[selloutrr]

Does this traynor use the dynamic stick dual housing caps?
40mfd + 40mfd @450v?

F&T makes a 33mfd + 33mfd replacement that is cheaper then buying two caps.
Tubesandmore.com

the 40MFD are +/- 20% anyway. I've used them in a couple YGL-Mark3 head restorations and they worked great.

[Structo]

Yeah it still amazes me about the tolerance of aluminum electrolytics.
+- 20% is pretty huge on a large cap.

[dreric]

If you do the above with this amp, consider 2 x 200uF/350V caps in series on the plates and 2x80uF/350V on the screens. Don't forget the voltage balancing resistors, 220K/2W metal oxide. If they can be made to physically fit, that is!

Forgive me, I'm trying to understand how this works. Are you saying to replace the first cap with the 2 x 200uf/350v. I understand that this will give me 100uf/700v for the first (plates). The second cap goes to the CT of the OT, would I then use a separate 40uf/500v?

The way you've described it it seems that you are replacing the first two caps with the 200uf/350v and the third and fourth caps (screens) with the 2 80uf/350v. If that's correct I'm confused as to how they would be wired, I'm going from four B+ connections to two.

Lastly, I don't understand the connection of the "voltage balancing resistors"

Thanks for entertaining these questions.

Eric

[dreric]

Does this traynor use the dynamic stick dual housing caps?
40mfd + 40mfd @450v?

F&T makes a 33mfd + 33mfd replacement that is cheaper then buying two caps.
Tubesandmore.com

the 40MFD are +/- 20% anyway. I've used them in a couple YGL-Mark3 head restorations and they worked great.

Yes this model uses the dynamic sticks. Thanks for the tip on the F&Ts.

Eric

[dreric]

Thanks rsi

Dreric

I have the same amp in a combo- think it is a '72- recently acquired and I love it! (original Philips power tubes)
I have upped the screen resistor on the power tubes to 1K1 as this may increase compression somewhat.
Also if yours is a combo you may want to look at something other than the stock square magnet 15 inch speaker it has.
I may be puttinng an Eminence Big Ben in there down the road for better/tighter Bass response
Lovely amps and incredibly well suited to mods. I don't want to lose the amp's basic character but I did bypass the cap on the first triode of the bright channel and the breakup comes on a bit sooner.
Other than that I replaced all ceramic caps with poly and kept the old parts for eventual resale value.

Sounds like my amp. I've had it in storage for years. I got inspired to bring it out after playing through a friends Vibroverb, just to get the feel of the 1-15". The amp sounds great, just a little hummy / flabby.

I like the stock CTS but thanks for the tip on the Big Ben.

Eric