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"Cheapish" Tube Preamps

flameas

Member
2019-11-16 11:20 am
Hello!

Lookin to try out a cheaper tube preamp (with replacement tubes under 500 usd for sure).

Schiit Saga + would be the obvious choice perhaps, but was looking at chinese things as well. For example :
€193.3 |Tubo de válvula Nobsound HiFi 12AX7B preamplificador estéreo de Audio para casa Preamp Ref Marantz M7-in Amplificador from Productos electrónicos on AliExpress

I have limited experience with tubes, what would you recommend for that Chinese one? It says its using 3x12ax7b + 6z5p. I would love to increase sound stage, vocal performance and 3D sense of space.

Thanks for all the replies!
 
Can you solder and do some assembly?

Rather than go used, about the only thing new (and decent) in your price range is a kit. The Elekit TU-8500 (see link) is $550. A spare pair of tubes is about $30. I've heard it and it sounds not bad, better than I expected actually, for the money. It has a SS phono section too. Anything better for your budget and you'll have to buy a board, some parts and do some metal working.

In the link the first picture the TU-8500 is the thin one on the bottom. On top of it is a small power/integrated amp. The second picture is the TU-8500.

Cheers, Steve

ELEKIT TU-8500
 

rayma

Member
2011-04-29 8:37 pm
Try this, it's very neutral with a good volume control.
 

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I'd definitely go either passive, or at most a simple cathode follower stage after a pot. $500 I think is enough to build a very nice preamp. You could easily build a 4p1l directly heated tube with Colman regulators etc. But even a tube with a gain of 10 makes little sense in your power amp has a sensitivity > than 2vrms.
A 12ax7 in a line amp I don't get.
 
Those nobosound tube pre's are in general decent build, but have the shitiest tubes that i've ever seen. I have a WADA preamp from them, and changed the tubes and the output cap, and it sound more than decent for about 300€. Most of the caps inside are wima mkp's, and the rest of the circuit of the model i had is also rather decent. The only thing i need to doublecheck yet is the PSU, but i don't hear no issues yet...

I bought it as an experiment, but it replaced the (recent restrored) very good Luxman C-02 (transistor class A) pre in my main system now. I still have that luxman on the shelf, but every time i connect it, it sound worse to my ears than that modified cheap chinese preamp.

But this is not genreal rule. I think i was lucky to have a good model, because i've also seen a lot of very bad examples of cheap chinese tube stuff. I did study the pre before (and got some extra info from the seller). But if you don't understand the circuit and has no knowledge of this kind of devices and the parts used, it's a shot in the dark that you do. Then you better get a good passive preamp like the Tisbury minipre i also have wich is wonderfull on it's own, certainly for that price...

Tisbury Audio - Mini Passive Preamplifier
 
>"A 12ax7 in a line amp I don't get"

A deliberately placed distortion generator, perhaps? If the distortion is primarily second harmonic, well there's all kinds of audio attributes associated with that. I've read about 20X+ OP's budget preamps who's distortion is "primarily second harmonic" as a claim to fame sonic attribute...

Therefore, apparently a preamp isnt just to set the volume level. While doing so it can introduce its own character - hopefully desirable - into the music. In architecting a system, one could choose to have the "character" in a preamp, followed by a ruler clean power amp, or have something imparting no character followed by a tube amp with its lovely characteristic. Or both, or neither.

So a good question would be what is someone looking to do, by wanting a preamp? Just level the volume? Or level the volume and "warm" the sound - or whatever. One of the fun things about audio is the sometimes illogical nature of what actually sounds most pleasant to some individual - distortion being one consideration, where one would think "well, zero, right?". Depends.
 
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kodabmx

Member
Paid Member
2011-10-31 1:00 am
Toronto
For 500$ I'll build you an integrated amp with 10WPC... It would use 6N1/3/14/24P, 6N6P or 6CG7, 6F12P, and 6P43P triode connected. Virtually flat from 25Hz - 50kHz.

500$ is a lot for a preamp that doesn't include phono and digital...
 
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I figure you could make a good cathode follower-line level buffer with 3 sets of input jacks, one set of output jacks, input selector switch and volume control for not too much money.

Hammond 8" x 10" enclosure = $25 or so
Hammond 269BX 300VCT 86mA, 6.3VAC 2A power transformer = $60 or so
9-pin mini tube socket (chassis mount) = $5 or so
6N6P or 5687 twin triode tube = $10
8 pcs chassis-mount RCA jacks = $20
3 position stereo input selector switch plus 36-position stereo attenuator kit = $35 (including resistors)
IEC inlet (for AC wiring) with fuseholder = $5
DPST power switch (chassis mount) = $5
Power indicator lamp (neon or LED, as you wish) = $3
Various 1/2-watt metal film resistors = $5
2x cathode load resistors (7W wirewound) = $10
2x 6.8uF polypropylene film output coupling caps = $15
2x 0.22uF film caps = $2
3x 220uF 300V electrolytic caps = $18
2x UF4007 rectifier diodes = $2
hookup wire = $10

That comes to $230 or so.

Did I miss anything?
--

PS - Or just build this:
Aikido Octal All-in-One

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