damper diodes

[hihopes]

Are there any damper diodes that should be avoided?

Anyone had any disappointing experiences with any of them?

Anyone tried 6CT3?

[Tubologic]

For safety and aesthetic reasons I would avoid any damper diodes with top cathode caps.(EY500,etc...) There are plenty of U.S made N.O.S color TV damper tubes and the 6CT3 is a good candidate, but there are also more robust types like the 6CL3/6CM3/6CK3/6DW4...
Old tube manuals doesn't recommend using damper tubes as mains fequency rectifiers but I never had any reliability issues in this application. The reason is probably that some max. plate current derating is needed because damper tubes were designed for very short ( less than 10µS) pulses at TV horizontal line frequency, not mains frequency (50/60 Hz). I have never found any data's about this derating but It can be probably computed. Don't exceed 50% of the max. avg. plate current and keep the input filter capacitor under 50µF and you will have no problems. Nevertheless, damper tubes seems to take a lot of abuse, are very robust and reliable. The only disadvantage is that you'll need two tubes for full-wave rectification because there are no dual section damper tubes available.

[hkthienthanh]

6D22S is Diot damper very good

[MrCurwen]

For aesthetic reasons I would recommend a damper diode with a top cap!

[hihopes]

Thanks for the replies guys.

I think there is probably an optimum range of percentage total power in which these diodes sound best. I have seen here and there that people have reported disappointing results with some damper diodes, including a slightly dull sound, and better experiences with others. I suspect that the problems could be arising in cases where the diodes are not working hard enough, but this is no more than a guess on my part. My primary requirement is for a preamp requiring only 16mA or so @ about 200v. I am concerned that if I use a diode of heroic proportions, it won't work optimally.
Anyone have any experience in this line or any information you could point me to?

I have seen the 6d22s touted by a few people. I understand that it is the only current production damper diode, but there are a few things I don't like about it - mainly the high 1.9A heater current and the cathode cap. I am also concerned that it won't work so well with such a small current draw. Experience of it in similar setups would be welcome

[twystd]

I use the 6CJ3/6DW4B in my parafeed linestage. They are readily available NOS and cheap on ebay. It pretty much kicks butt in local preamp/linestage shootouts. I used to use a 6n1p-ev running about 8ma per triode for a total of about 16ma total current draw @ 200V. It sounded great, but I took it a step further and went with a 6n6p, @ 150V and 40ma total current draw.

The 6n6p sounded better, but I'm pretty sure it was due to the MUCH better linearity of the 6n6p, not the current draw through the damper diodes. I really like damper diodes, low voltage drop, delayed conduction, smooth slow voltage ramp up, lowest noise of any rectifier, and bullet proof to boot.

The only drawback is the high heater amperage, but I find that a small price to pay for all the benefits. That's all I plan to use in future projects.

twystd

[Blaireau]

Pwerful damper diodes like EY500A or PY500A can be found at ridiculously low prices, and can withstand several hundreds of mA. Their cathode to filament isolation is extremely high, allowing the use of a common heater winding for all the tubes. For a smaller current, EY88, or PY88 are also excellent. Color tv tubes are not yet hunted by audio fans, and you can find them for only a few kopecks in local sales. Long live to the Damper Tubes Liberation Front!

[hihopes]

Hi twystd. Are you sure it was the linearity of the tubes you were hearing and not more favourable operation of the damper diodes? I have not done a/b comparisons between 6n1p and 6n6p, but have heard both at one time or another and they did not seem to be much different quality-wise. I have 6n6p's lying in a box, along with 5687's because I have found other, much better-sounding (and more linear) valves to use in my pre.

I have been looking around at a number of suppliers in USA and Canada, plus e-bay auctions for damper diodes, and while it is true that prices are very reasonable, I have yet to find a supplier/seller who doesn't charge at least 3 to 4 times as much for shipping as they do from the far east. Standard shipping price to south Africa ex USA seems to be about $38.00, even for single tubes. Anyone know of a supplier who isn't this crazy?

[Vinylsavor]

Hi!

Originally Posted by hihopes

I think there is probably an optimum range of percentage total power in which these diodes sound best.

No, they work just fine at low currents too. TV damper diodes do not have their own 'sound'. The sonic results depend on the whole circuit, including power supply with it's filter caps, chokes, power transformer and also rectifiers. Mainly the filter and rectifier topology has an impact. These things are much moire worhtwhile to worry about.

For your application the 6BY5 would be great. It has 2 TV damper diodes in a single bottle and requires onle 1.6A heater current total. It can not withstand peak inverse voltages and heater cathode voltages in the same range as other dampers. But for your application they will be well below their maximum ratings.

Best regards

Thomas

[vinylkid58]

Originally Posted by hihopes

I have been looking around at a number of suppliers in USA and Canada, plus e-bay auctions for damper diodes, and while it is true that prices are very reasonable, I have yet to find a supplier/seller who doesn't charge at least 3 to 4 times as much for shipping as they do from the far east. Standard shipping price to south Africa ex USA seems to be about $38.00, even for single tubes. Anyone know of a supplier who isn't this crazy?

It's not the supplier, it's the Postal Service. To send a small box from here to SA, it's $39 plus a 10% fuel surcharge.

Surely you can do better than that locally for rectifier tubes?

jeff