@ davorin, are these M102b (or bigger) cores in the transformers? They look very big & powerful
My new amp finally with 6550s
What input tubes are those 6SN7s? It reminds me of the Ella Consonance.
Nice, what output tubes did you use to manage OTL with only 2 pair?
Cool and .....interesting, I sow 2 big caps, with or without capacitor in output?
What I want to show in this place is not fully DIY project, but it is advanced tweaking of commercial chinese tube preamplifier.
It looks like this:
Schematics:
As you can see, the gain is huge, there is NFB loop to reduce gain, and there is a lot of caps (chinese MKT crap) in the signal path. Horrible. So I decided to completely rebuild the circuit. I used SRPP stage galvanic connected to the cathode follower, no NFB at all, and only one good signal capacitor per channel. Only the case and PSU left from original. Now it looks like this:
I replaced the potentiometer with metal can Alps and also rotary input switch with Lorlin. The tubes (chinese 6N3) was replaced by NOS 5670 General Electric.
Now the preamp sounds very good, it reminds me Canary Audio CA601 I serviced in the past.
It looks like this:
Schematics:
As you can see, the gain is huge, there is NFB loop to reduce gain, and there is a lot of caps (chinese MKT crap) in the signal path. Horrible. So I decided to completely rebuild the circuit. I used SRPP stage galvanic connected to the cathode follower, no NFB at all, and only one good signal capacitor per channel. Only the case and PSU left from original. Now it looks like this:
I replaced the potentiometer with metal can Alps and also rotary input switch with Lorlin. The tubes (chinese 6N3) was replaced by NOS 5670 General Electric.
Now the preamp sounds very good, it reminds me Canary Audio CA601 I serviced in the past.
Last edited:
Jono1 - nice tube amp!
As previously promised - pictures of my first tube inside - not very nice ( i use nos silver plated screened cable for mains and input wires and twisted wires for AC heaters), but its DIY
bottom cover and both channels finally sounds!
As previously promised - pictures of my first tube inside - not very nice ( i use nos silver plated screened cable for mains and input wires and twisted wires for AC heaters), but its DIY
bottom cover and both channels finally sounds!Attachments
Jono1 - nice tube amp!
As previously promised - pictures of my first tube inside - not very nice ( i use nos silver plated screened cable for mains and input wires and twisted wires for AC heaters), but its DIY
What do you mean, "not very nice". Man If my little tube amps looked anything like yours I'd be so proud. Your amp looks excellent, not only on the outside, but even the inside. So what if it's not engineered to be perfect, you did what you could, and it looks clean and tidy.Give yourself more credit, you did a wonderful job!
Jono1 - nice tube amp!
As previously promised - pictures of my first tube inside - not very nice ( i use nos silver plated screened cable for mains and input wires and twisted wires for AC heaters), but its DIY
I think that it is a great looking tube amp. Simple, clean lines, muted colour tone in the metal (I have seen too many with all too shiny gold lately), tubes are presented so you know what is making the music louder, and all the indicators that you need to make it work properly.
You see it is builds like yours that make me not want to post (but I will one day) and it is builds like yours that give me some insightful ideas to how I would want mine to look.
