First tube project.

[dome406]

I recently built a gainclone amplifier, the one from audiosector lm3875. I am very pleased with the sound. I have always been interested in tubes so think that I will make one as my next project.

I dont want to make an amplifier I would prefer just to introduce and get a feel of what tube amps sound like, e.g. warm musical sound. Would building a tube preamp do this and would the preamp kit from bottlehead.com be good for this.

Thanks very much

[A3rd.Zero]

As I have never heard a Bottlehead amp I cannot speak from personal experience. However, general consensus seems to be that their are better, cheeper kits.

The Gainclone is a fun project but there are few tube projects that are "done for you" as much as the gainclone. Would you be willing to build something from a schematic? or do you want a kit that has a building manual?

Check headwize.com for some project amps that have schematics and parts lists. Or just go all out and find a schematic somewhere and build from there. One thing to keep in mind though is that building from a schematic and sourcing all needed parts is a deal harder then building from a project, which is a deal harder then building a kit.

Milo

EDIT: This is a good start. Lots of people build it, its cheep, fun, and likes the senns. Also if you build it small then its good for the bedside which opens up room for a new tube preamp for the living-room .

http://headwize.com/projects/showfil...=cmoy5_prj.htm

[Sheldon]

Originally posted by dome406
I dont want to make an amplifier I would prefer just to introduce and get a feel of what tube amps sound like, e.g. warm musical sound. Would building a tube preamp do this and would the preamp kit from bottlehead.com be good for this.

Thanks very much

I'm inexperienced myself, but I have some tube amps and have built one. I see no reason you can't make a tube amp sound pretty much any way you want - warm, cold, good or bad. Depends on the design and execution. Building a preamp will allow you to hear what that preamp sounds like in your system, nothing more.


Sheldon

[dsavitsk]

Originally posted by A3rd.Zero
As I have never heard a Bottlehead amp I cannot speak from personal experience. However, general consensus seems to be that their are better, cheeper kits.

Consensus among whom? I think the actual consensus is that Bottlehead kits represent excellent value for money. I have never heard anyone who has built one of their kits say anything negative. Indeed, judging from the bottlehead furum, most people that build one end up building a bunch.

Originally posted by A3rd.Zero
The Gainclone is a fun project but there are few tube projects that are "done for you" as much as the gainclone. Would you be willing to build something from a schematic? or do you want a kit that has a building manual?

There are actually tons of tube projects that are "done for you". The Bottlehead is a good one. Welborne Labs makes a low voltage preamp kit that is supposed to be very nice and quite a bit safer than some of the others. Hagtech (Jim is a member here) makes a preamp kit. DIY HiFi Supply makes a kit. Audio Note UK makes highly regarded kits. There are also a few others, but these are probably the most popular.

[karma]

i would start with a preamp than work your way up to a amplifier.

Bottlehead is nice but there are others out there with a little searching

[Bandersnatch]

Hey-Hey!!!,
I'll second the idea that there others than Bottlehead to consider. That said, I bought a manual from Doc and found it very educational. The issues I have with the Foreplay have largely been resolved with the revsiion III, but it isn't a $150 kit anymore either.

There are far simpler circuits and Far, *FAR* better pre-amp tubes than the 12AU7.

I'd also suggest looking at system requirements before getting something as high-gain as a Foreplay. A low gain or buffer circuit is probably a better idea.

On buffers, a pentode cathode follower is hard to beat. For a reasonable parts bill, and literally $10 of tubes you can do the whole thing. Tube rectifier included.

Power Iron is simple and cheap too. Set yourself up a means to deliver ~200V and you're off to the races. Even even less is OK too.

There is not much to it( says me after building a half dozen or so ). If you can deal with a schematic and bill of material, with construction notes...you've come to the right place.

You'll need some tools, pen and paper, DuncanAmp's PSUDii power supply simulator, and Frank Philipse's page of tube data sheets, and of course a calculator for working out the various forms of Ohm's Law.
cheers,
Douglas

[dome406]

Thanks for all of the replies, I could work off just a schematic so it doesn't necessarily have to be a kit.

What do you recommend the specifcations I use for the tube preamplifier because I dont really know, or what I need for optimum performance. The gainclone I have built is the LM3875 non-inverted using dual 18v transformers and would like a 'warm musical tone'.

Thanks very much

[Bandersnatch]

Hey-Hey!!!,
Let's start with some measurements. A test-tone CD and a load resistor, or loudspeaker should be able to tell you how much input signal your amp needs.

You'll compare this to the output voltage of your CD player and see if you ever need gain. Be aware you'll have some variation between CD levels( and perhaps later speakers and amps ).

Do you have any measurement gear? volt-Ohm meter, O-scope?
cheers,
Douglas

[Brett]

Originally posted by Bandersnatch
Hey-Hey!!!,
Let's start with some measurements. A test-tone CD and a load resistor, or loudspeaker should be able to tell you how much input signal your amp needs.

You'll compare this to the output voltage of your CD player and see if you ever need gain. Be aware you'll have some variation between CD levels( and perhaps later speakers and amps ).

Do you have any measurement gear? volt-Ohm meter, O-scope?
cheers,
Douglas

I second this idea. Most systems have too much gain and preamps are often of little benefit for non-phono systems apart from the switching and volume facilities. No point in making a preamp with lots of gain to just throw it away again in the VC.

Why build a preamp at all? Why not a poweramp with a VC and some switching all in the same box?

[dome406]

I have basic multimeter, the speakers are 4ohm i just use a cd walkman as input at the moment. but dont know its resistance .