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Re: An Exercise in Daftness.

Posted: Fri Dec 07, 2018 2:49 pm
by Dr Bunsen Honeydew
That is promotion, they all start as bodgers :mrgreen: eventually a few end up as :ugeek:

Re: An Exercise in Daftness.

Posted: Fri Dec 07, 2018 5:47 pm
by Lurcher300b
Not at all, I used to know someone who served a apprenticeship as a fettler after school, no formal training in bodging required.

Re: An Exercise in Daftness.

Posted: Fri Dec 07, 2018 5:52 pm
by Dr Bunsen Honeydew
There you go the true amateur DIYer = bodger until qualified by experience.

Re: An Exercise in Daftness.

Posted: Fri Dec 07, 2018 6:06 pm
by Dr Bunsen Honeydew
You qualify initially as a bodger when you buy your first soldering iron, I was a teenage bodger (sounds like a film title) when I got my first Antex 15w iron. You young whipper snappers get Chinese soldering stations dirt cheap now, losing the pleasure of waiting for the feckin' thing to warm up enough to solder a phono plug.

Re: An Exercise in Daftness.

Posted: Fri Dec 07, 2018 8:10 pm
by setting son
At least SMD wasn’t a thing then.

Re: An Exercise in Daftness.

Posted: Fri Dec 07, 2018 8:27 pm
by Dr Bunsen Honeydew
We only just got transistors back then, and not very good ones.

Re: An Exercise in Daftness.

Posted: Tue Dec 18, 2018 11:29 pm
by SteveTheShadow
Because this is an output transformerless amplifier, I've had a bit of fun playing with different speaker cables.

Of the cables I tried, NVA LS5 mk1 is better than NVA LS2, which is in turn better than some nonedescript Maplin speaker cable I've had knocking about for years. The differences are not nearly as marked when used with a valve amp with output transformer, such as the one I had running at the Owston do.

Re: An Exercise in Daftness.

Posted: Tue Dec 18, 2018 11:40 pm
by Dr Bunsen Honeydew
I have been saying this for years (decades) that output transformer swamp the effects of cable. This has led to most valve users claiming that a bit of wire is a bit of wire, and insulting anyone who says different. Where as REALITY is the problem is not the cable, it is the amp. Early germanium output transistors (1960's) needed either output transformers (Rogers) or output capacitors (just about everyone else) and then any electrical cable would do. Cables ONLY became a consideration with silicon output devices, especially Darlington pairs showing that cables had *a sound* unless the output was so filtered and comp-ed it was basically the same as with OT or EC coupled amps.

EDIT - Ooops! just re-read the post it seems you say differences not as much. Interesting, as my experience is as above.

Re: An Exercise in Daftness.

Posted: Sun Dec 30, 2018 4:54 pm
by SteveTheShadow
Right!
I've made a couple of mods to the amp, since I last posted.
Image
First one was a duplicate power tube supply. So now each 13E1 has its own dedicated arrangement.
Each one is 2500uF-choke-2500uF (front centre). The chokes are the 2 Amp Triad Magnetics coils, as used in the Bruce Rozenblit Mini-Beast amp; no point re-inventing the wheel. The HT is switched for both supplies, via the 250V, DPDT, 10A switch, mounted on the black acrylic plate at the front.

In the back left of the picture can be seen an EZ81 tube rectifier. I put this in as the best way at the moment to give a slow start to the input/driver stage power supply. There was just enough room on the board to put a small 6V transformer to supply the EZ81 heater.

The rectifier is configured as a hybrid bridge. I used an electrical switch back box I had spare from the room renovation. Knock out one of the apertures and the resulting hole is the right size for the B9 socket the EZ81 uses. It has knocked 18V off the HT to the input and driver stages (now 304V) but that's of no consequence in the grand scheme of things.

We all know that the power supply is everything with amps, and this one is no exception. With the uprated power supplies, improved weight, solidity, authority and more music coming from the back of the studio have all reported for duty as expected.

Re: An Exercise in Daftness.

Posted: Tue Jan 01, 2019 3:33 pm
by Geoff.R.G
Dr Bunsen Honeydew wrote:
Fri Dec 07, 2018 6:06 pm
You qualify initially as a bodger when you buy your first soldering iron, I was a teenage bodger (sounds like a film title) when I got my first Antex 15w iron. You young whipper snappers get Chinese soldering stations dirt cheap now, losing the pleasure of waiting for the feckin' thing to warm up enough to solder a phono plug.
I still have my original Antex 15w soldering iron!