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Part Sourcing Assistance/Advice Thread


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Never underestimate the obfuscating twats on diyaudio I asked a question regarding Kemet vs. Vishay-Polytech tantalum-polymer capacitors (since the Vishays are considerably cheaper and appear to

Started one last night, actually.

there needs to be a Mouser Prime service

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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. :)

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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.

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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.

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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. :)

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  • 2 weeks later...

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 by luvdunhill
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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.

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  • 4 weeks later...

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.

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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 by Pars
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