what do you think about this lv linestage?

[PreSapian]

SM2YER Goran's Homepage

i'm wanting to try this build to get my feet wet into tubes. do you think it's a worthy design to try?

 

[DF96]

I don't read Swedish so I don't know what performance he is claiming for his very poor design. You can't run a cathode follower off a 12V supply, unless you simply want a signal distorter. It is not a line stage, but a 'tube buffer'.

Most systems don't need a line stage. If your system does need a line stage then there are some good designs around, which I am sure others will bring to your attention.

 

[PreSapian]

i want to play around with low voltage first before i get into the serious stuff and the linked schematic above seemed easy enough to follow.

if you have any other LV tube buffer that i should try please let me know.

p.s. google translate does almost perfect swedish>english 😉

 

[DF96]

Low voltage is the problem. If you must use low voltage then look for a design using ECC86 as that was designed for low voltage. Still not good, but better than using other valves at 12V.

 

[PreSapian]

that tube is not available to me locally... how about 6111? or operate the first circuit in 24v?

 

[DF96]

24V would be better. 96V better still! Some low mu valves can work, to an extent, at lowish voltages but it is still a compromise. If you must work at low voltage use semiconductors.

 

[flatheadmurre]

Since i read swedish i can tell he is a ham feller just tinkering and he´s not trying to sell this as the ultra highend.'

He only claims it as his DIY blog.

 

[MrCurwen]

Make the low voltage thing, learn how to solder and take readings etc, and be aware that it's for soldering experience, not listening. Like said it will not be in any HIFI sense satisfactory.

I made my learning projects in tube guitar amps; there the 'lousy' performance was quite satisfactory. =)

 

[DF96]

Yes, the page name shows he is a Swedish radio amateur. In the past that would have meant that he knew a fair bit about DIY electronics, but times have changed since I got my amateur ticket.

 

[PreSapian]

so the circuit works. no hum. it's actually dead quiet. but the sound is just... meh. no matter what tube i try it sounds thin and closed in.

so, i think i wanna go hv 😉

how would the grounds be tied together in this circuit if i'm using separate trafo for filaments?
and can i expect this circuit to give a satisfying performance from the hv upgrade?

thanks gents for helping me thus far.

 

[DF96]

In most systems the only 'satisfying performance' from a buffer or line stage would be to avoid doing anything to the signal at all i.e. you would get the same sound but a smaller electricity bill by omitting the circuit. Rare exceptions are when the power amp is insensitive (so a low gain line stage is needed) or the interconnect cables are long (so a buffer with even better driving ability than the source can help).

What is your situation?

 

[PreSapian]

most people, not all 😉 what would satisfy me right now is thick slow tube sound with rich 2h distortion.

and i don't mind paying 2 extra cents a day for getting that.

this buffer is just for practice but i still want to see how far i can take it.

 

[ilimzn]

I suppose it comes down to how you define your HiFi. If it's so that things sjould not 'sound' like anything except your source material, then this circuit is not for you.
If you want it to sound 'tubey' (whatever that is) then it's really not important whether it's a buffer, amplifier or whatever as it's really a distorter, and this circuit will be a very good one. This is because it insists in using the least suited tube at the lowest possible voltage...

 

[PreSapian]

i don't think the circuit's good enough for what i want which is big, wet sound with h2 warmth. (my definition of 'tubey', since you bring up that word)

i do know what wire with gain sounds like, as i've completed b1 just last week, and this tube circuit doesn't sound nearly as enjoyable as that.

but like i said, flavor of the week.

 

[DF96]

You can get plenty of second-order distortion by adding some diodes and resistors, or a badly-used BJT. No need for valves.

 

[lexx21]

Search under the tube section on diyaudioprojects.com for a preamp that uses the 6N7 tube. VERY simple build, very good sound. Will need about 250V for the plate, but that is dead simple to achieve. Just get the correct transformer. There are a lot of high voltage power supply schematics to use as examples.

 

[PreSapian]

thanks, lexx. is it the one also found on enjoythemusic as blue velvet preamp?

seems like i have a choice to make between this and the 12b4...

 

[lexx21]

Not sure. I have never seen that one. The people who have made the 6n7 amp have really enjoyed the results. There is also a schematic there for using the C3M tube which also gave good results. The 6N7 is pretty inexpensive, where the C3M runs about US$70 for a pair. Eventually I will try that one out as well but have other projects to build first.

Here is the link for the 6N7 preamp....

DIY Audio Projects Forum • 6N7 metal tube preamp

Hope this helps.