How to build your own tube preamp FAQ

Some Frequenty Asked Questions. (actually most of it I thought of myself)

How does it sound?

Oh the sound! It’s very transparent. Doesn’t have a strong character. For those looking for transparency in their system, this is highly recommended! However, if you are looking for a sweet sound, then I recommend the 5965 in a different configuration. Will post this on my Projects page later.

Why does it sound kind of “edgy” in my system?

A friend did describe my preamp as “edgy” too (though my tin ears can’t tell). Solder grid stopper resistor of 120-150 ohm on grid of both channels and it worked great!

I don’t like your power supply filter and would prefer 100H-100uF-100H-100uF.

Of course! This is a DIY project remember? So do it anyway you like. I opt for a low capacitance high inductance power supply filter circuit but you can do it anyway you like. You could build it as capacitor input power supply. No problemo.

I finished building it, and proceeded to power on without tubes…

Oh no! Don’t do that! Without tubes, the transformer is not being “loaded”. The voltage can get very high! If it gets higher than the voltage rating of your capacitor, your electrolytic cap might explode! Always power on with tubes installed.

I hooked it up to the rest of my system but it hums… can play music though.

Hum is good. It means you are almost there. (this doesn’t sound comforting heh?) Write to me and we’ll try to work out how to reduce hum.

I don’t like your choice of parts. I would prefer tantalum resistors, Black Gate capacitors, Jensen copper foil capacitors, silver wire, teflon socket…

Be sensible. Start off with something cheap and move on. The sound you get is a combination of the various “sounds” of all the parts you put in. Splurging on parts without knowing for sure how they will sound TOGETHER in a circuit is not very smart. Get it working first, then (if you wish) break your bank with all the audiophile parts in the world. Don’t be suprised if some of the expensive ones don’t suit your taste.

Your ground wire looks so puny. You are not macho at all.

Yikes! You are right. Definitely not macho at all. I was lazy. You could use a thicker gauge wire, or parallel a few strands to get a lower impedance ground.

Are you offering a kit?

I prefer to concentrate on just parts. Look, I have given the transformer winder info. (so no middle man charge here!) I have even given the wiring diagram, step-by-step. The rest is up to you. You can find someone in your area to do your chassis, to my (oops, your) liking. Time is scarce and for all my trouble asking someone to do the chassis etc, I will need to charge you. Definitely no more “value for money”.

I heard that running one tube for each channel sounds better than utilizing both triodes in one tube.

I haven’t tried this as the other tubes I have been familiar with are all run both channels in one glass but if you DIY it, you can do it any way you like. Do let me know how it sounds. If it really sounds better this way, everyone should know. On an unrelated note, thank God I’m not offering kits. Otherwise, can you imagine how much work I have to bear to have all chassis reworked? 🙂

I actually prefer integrated amps. Never like the idea of preamp-power amp.

Ditto here. But then everyone has his/her own opinion. And my way is no superior to your way, vice versa. If you use power hungry speakers, solid state power amps is a must without breaking the bank. Tube preamps offer the opportunity to get tube sound at a lower cost. Alternatively, use this preamp circuit as your CD player output stage!

How many 5687/6X4 do you expect to sell?

I’m not expecting to sell many. The whole idea of doing this is to show you that building tube amps (or preamps) is very simple. There’s nothing magical inside. There’s nothing to “tweak here and there otherwise it won’t work”. You know, that kind of nonsense some folks spew to fool you into thinking DIY tube amps is only for electrical engineers. Once you understand this and start your first DIY project, trust me, this is going to be your most rewarding journey.