• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

How's this for a first amp?

(link removed by moderators)

I'm thinking of building the above as a first tube amp/preamp/headphone amp. I like is because all the transformers are fairly easy to get (could get them from local stores, and they're cheap!)

Are there any suggestions anyone would make about components to make it sound nicer? The main thing about this amp is that all the parts (incl. the tubes, although not any high voltage transformers) are locally available.

What changes would make it better for headphone use (Grado SR-60s or SR-125s). Maybe as a preamp for a headphone amp/real amp?

Thanks,

- Raffi.
 

PRR

Member
Paid Member
2003-06-12 7:04 pm
Maine USA
www.diyaudio.com
> How's this for a first amp? link removed

Please do not build that. It is HOT CHASSIS and deadly. While it can be made safe, and stuff like this was the standard cheap 1950s record-player, I don't see enough information and warnings on that page to be sure you can build it and live.

> make it sound nicer?

Replace everything. The 35L5 and its 70L7 relative were made for CHEAP gear. I suppose if you did not grow up on 1950s recordplayers, you have missed something, but it probably isn't worth missing except to appreciate how far cheap gear has come. Naked high-gain pentodes are NASTY. Fixing the faults plus making it safe means changing everything.

> all the transformers are fairly easy to get

That trick of using a filament transformer as an audio output can be done with much cleaner and safer plans. A filament transformer is not as good as a good audio transformer, but may be far better than the junk iron they put in 1950s recordplayers.

A much safer plan, common iron, cheap tube, suitable for headphones: half-watt 6EM7 amp.
 

raffir

Member
2003-04-22 5:15 am
Canada
Thanks!

Whoa! Thanks! Good thing I asked around here first...

I'll have a loot at that half-watt 6EM7 Amp. Could I use it in a preamp, too, to provide colouring? I like the looks of it, especially the bit about powering it using Radio Shack parts (or wait...I suppose I mean "THE SOURCE" - a Circuit City production or some such nonsense).

Another one that looks nice is:

http://www.t-linespeakers.org/tubes/SEP_50EH5.html

It seems to come from a more reputable source as well..

Thoughts?
 
Re: Thanks!

raffir said:

Another one that looks nice is:

http://www.t-linespeakers.org/tubes/SEP_50EH5.html

It seems to come from a more reputable source as well..

Thoughts?


The 50EH5 amp is great if you have the iron on hand or can get it real cheap. The tubes are cheap to buy. If you were planning on buying the iron new, the money could be better spent on something a little more common.

I put together a 50EH5 amp. Details are on my webpage.

Good luck.