Line stage preamplifier

[anders.a]

Hi Everybody

I’m planning to start my first DIY preamplifier. I’m a beginner and not really the “engineering” type. So have patients with me. This is what I plan to build:

Figure 18
MI articles

A linestage preamplifier.
My question is: Is this drawing (the first link) for one channel or two? (I said a was a beginner)

I have some basic knowledge about resistors, capacitors and tubes ohms law etc, etc. But not so much that I could deviate from the drawing. Also know this is potential dangerous and will kill me and burn down my house if I’m not careful.

[DougL]

It is one channel.

HTH

Doug

[Irakli]

Nice preamp, but transformers used are quite expensive. Just letting you know. Will not work as good with cheap trannies.

[ethermion]

Figure 18 does say "Schematic of one channel". Attention to detail is on of the ways to not die or burn down your house.

Also does not look like a beginner's project, at least not on a beginner's budget. In my humble opinion, a pre should not sound "great", it should sound like nothing - and be priced accordingly. What source? What amp? What cable run? Why not just a pot?

Have fun!

[anders.a]

Thanks.

Next question.
1) I’m sourcing materials right now. The resistors will work with ordinary 0,4W resistors?
No 2W-5W resistors necessary?

Ethermion thanks
stupid me.

[hemgjord]

No offence but I just have to ask; are you going to use it as a balanced pre-amp or are you just going to ground one of the input and output terminals?
Balanced topology has many merits but it adds on cost and complexity.

/Olof

[anders.a]

No offence taken
I have no idea. What ever works I guess. I do not know how to make balanced pre-amp or what a balanced pre-amp is.

[Arnulf]

Anders, are you building this as a fashion statement ("look at me mom, I've got tubes !") or to solve a problem ? The latter we can help you with, but you need to describe your problem.

If your problem is merely first construction of a tube pre-amplifier, there are plenty of circuits floating around, some are also avaliable in kits (check out "Aikido" by John Broskie; no affiliation here and I don't collect % from his sales but he has some good ideas and he knows what he's doing).

If on the other hand you'd like to learn something along the way, then present your problem first (i.e.: "you'd like to amplify your input signal with output impedance of only 1M 42-times and feed it to your amplifier with 47K input impedance") and you will get the best help possible here.

[anders.a]

My problem is as I have described them.
Maybe I'll try Aikido instead of this. I don't know. But this tread is for the this amplifier.

So anybody have an idea about the resistors?

[SY]

Originally Posted by anders.a

I do not know how to make balanced pre-amp or what a balanced pre-amp is.

Stop.

This is not what you want to hear but it needs to be said- if something VERY basic in the design like this is beyond what you know, you should not be working with high (potentially lethal) voltages and very expensive parts. You'll end up with junk, a lot poorer, and soured on building audio equipment. It's time to hit the books (Morgan Jones's "Valve Amplifiers" should be read thoroughly and digested), get a basic background, and cut your teeth on some simpler, less expensive rigs where a bit of smoke won't cost you too much.

Your likelihood of success going down this path is near zero.