Part Sourcing Assistance/Advice Thread

[PretentiousFood]

Any tips for a low mu, low power triode or triode-strapped thing? Linearity isn't a big deal for once, and DHTs are cool too. Right now I'm looking at either the 26 (mu of 8, but pretty filament), 6080, or 7233. It's for a phono so they need to be quiet.

[dsavitsk]

It's for a phono so they need to be quiet.

 

Probably rules out the 6080, etc. May rule out the 26, too, which is notoriously hummy and microphonic. Look at the 12B4A.

Edited December 19, 2014 by dsavitsk

[luvdunhill]

EF184, or similar?

Edit: ah LOW .. Ok, nm, can't read.

Edited December 19, 2014 by luvdunhill

[PretentiousFood]

Shoot, was hoping this could be an excuse to try out thoriated tungsten. Thanks for the heads up. Are regulator tubes also generally more prone to microphonics? The 12B4A looks like a great bet (and silly cheap), thanks!

 

EF184 or something similar will very likely be making an appearance elsewhere in there.

[dsavitsk]

Every 6080 or similar tube I have played with has been noisy in some way. But the number of tubes I tried is low, and it was quite a few years ago. Others have had better luck.

[recstar24]

People still build tube amps?

[nopants]

is that a real question

[n_maher]

Started one last night, actually.

[FrankCooter]

The 26 and the 6080 are about as far apart as you can get in the tube world. Neither is really suited for phono use. I own about 30 type 26, none of them are quiet. The type 112A is similar to the 26, and usually a little quieter, but not much.

 

The only thoriated tungsten tube that I can think of that MIGHT work in this application is the 10y, which is expensive.  Any DHT will be  difficult and problematic in a phono application. If you're determinined to try it, I'd look at the Russian 4P1L or 6P21S. They both work well as the output of a headphone amp, and are dirt cheap.

 

Lots of options if go for an indirectly heated type. I like small power tubes anytime low gain is required. Not much beats the tonality of a triode-connected 6V6.

[dsavitsk]

is that a real question

 

I believe it is a commentary on Ryan's experience of trying numerous tube amps, and eventually ending up with a particular solid state amp that has a tube-like presentation, but that bypasses the issues that seem to follow tubes.

[PretentiousFood]

The 26 and the 6080 are about as far apart as you can get in the tube world. Neither is really suited for phono use. I own about 30 type 26, none of them are quiet. The type 112A is similar to the 26, and usually a little quieter, but not much.

 

The only thoriated tungsten tube that I can think of that MIGHT work in this application is the 10y, which is expensive.  Any DHT will be  difficult and problematic in a phono application. If you're determinined to try it, I'd look at the Russian 4P1L or 6P21S. They both work well as the output of a headphone amp, and are dirt cheap.

 

Lots of options if go for an indirectly heated type. I like small power tubes anytime low gain is required. Not much beats the tonality of a triode-connected 6V6.

 

Thanks for your comments!

 

I've tried the 4P1L in a single ended amp with constant current heating, and haven't had much luck keeping it quiet. Something in there is rattling, but I'm not sure if it's the heater or the grids. I've tried starving the filament as well and hadn't noticed much of a difference. Might just be a bad batch.

 

The idea was to use an inverted triode for the input stage. This divides the already small input signal by mu, but makes it easy to DC couple the amp from input to output while only using tubes for amplification, and provides an extremely high impedace, low capacitance input without the use of feedback. I'm not convinced that it's worth the tradeoff, but there's an easy way to find out. Since the triode is inverted, dissipation will be shifted from the plate to the grid, and the curves defintely won't match the datasheet.

 

I wouldn't bother sticking a 10Y here, but I'll look into the 6P21S. Picked up a 12B4A for now, and I'll be tracing the inverted curves as soon as the tracer is in. Failing that, I guess a couple of transformers and mosfets can't sound THAT bad.

[luvdunhill]

Does anyone have:

Technical specs for the Jensen clamps

Or...

a creative way to mount a transformer can to a PCB? I would like to have the option on my PCB to also support this transformer, but with no mounting bushing or threaded holes, it's tricky. The part is:

http://www.jensen-transformers.com/wp-content/uploads/2014/10/jt-346-axt-112.pdf

Edit: looks like I could just screw these to a PCB:

Mouser Part #:

598-VR4A

Edited January 1, 2015 by luvdunhill

[n_maher]

Have you already seen this?

http://www.cde.com/resources/catalogs/hardware.pdf

[luvdunhill]

Have you already seen this?

http://www.cde.com/resources/catalogs/hardware.pdf

Yeah, just found that. I think I can make that work!

[n_maher]

Might be worth thinking about sizing the holes in the pcb for some sort of vibration isolating grommet. It'd have the dual benefit of isolation nd lowering the stress at the mounting point.

[GeorgeP]

Anyone able to recommend a good source of 2sa1486 that ships to north america and doesn't have Bdent level pricing? Any recos are greatly appreciated.

[nopants]

Justin recommended http://www.chip1stop.com/web/JPN/en/search.do?classCd=&did=&keyword=2sa1486previously iirc

[GeorgeP]

Thanks. I checked them before and they are only a little cheaper than bdent for 50 or so and shipping wipes out any savings.

[mypasswordis]

If you don't need them heatsinked you can use a stn9360 mounted to an adapter, or if you can make do with a 400V part there's the ksa1156.

[GeorgeP]

Thank you, sir, those had slipped my mind. Will still need some 1486 though.

[DefQon]

How many you need?

[deepak]

Does anyone know a source for teflon terminal strips that have through hole pins? Thanks

[DefQon]

Is there any new equivalents from Linear Systems that can be substituted for EOL Toshiba 2SJ109 dual jfets?

 

I know dual 2SJ74's can be done to give one J109 but it's hard to match by specs. Both 2sj74 and 109's are hard to source and very costly ($20-50 a piece for genuine 109's) when they do show up.

 

I've got a problematic (I think) 2sj109 in an SRM-3 amp that keeps blowing a nearby 100ohm resistor and the led light indicators in the output stage do not light up.

[Pars]

The singles aren't hard to match (for Idss), and most of the time are closer matches than what is in the duals (at least from my experience). Linear Systems makes the LSJ74, which seem to only be available thru diyaudio.com in lots of 8 for ~$50. I think the 2SJ74s can still be had? There had also been a run of heat-sink thingies for grouping pairs of these into a single connected unit, but those are probably unobtanium anymore.

 

I would pull the 2sj109 and test it if I were you. Someone familiar with the SRM-3 may pop in and give you more enlightened advice.

Edited February 5, 2015 by Pars

[nopants]

if you're referring to the diyaudio to-92 heatsinks, you can still get them if you're willing to wait a few months