Super Rocky

[Cressy Snr]

I just put back the KT77s into the Super Rocky; these being the valves I designed it to use in the first place. Just because you can use all sorts of output valve in your design, it doesn’t mean you should. Does it.

The modern production Gold Lion KT-77 has the magic of the EL34, with the tighter bass and slam of a KT88; what’s not to like?

Now let’s get on with that blasted phono stage and stop piss balling with this.

[Ant]

Do you want the built nuvistor phono stage board to play with?
The mains TX, a cap board and big coffin dropper resistor, a load of those little 150h chokes in it (156c?) and nicks mj reg board is all there, it just wants taking out of the crap box it's in, laying out on a board and wants a 2. 1v heater supply doing for the nuvistors.
It's got 2ds4 nuvistors in it wot I got off Paul years ago.
It was built for mm input, designed for me by nick, Andrew and mike back in 2011
Oh and it wants an ez81 recifier which I dont have for some reason

[Cressy Snr]

Do you want the built nuvistor phono stage board to play with?
The mains TX, a cap board and big coffin dropper resistor, a load of those little 150h chokes in it (156c?) and nicks mj reg board is all there, it just wants taking out of the crap box it's in, laying out on a board and wants a 2. 1v heater supply doing for the nuvistors.
It's got 2ds4 nuvistors in it wot I got off Paul years ago.
It was built for mm input, designed for me by nick, Andrew and mike iirc
Oh and it wants an ez81 recifier which I dont have for some reason

Yes.

[Ant]

Just sorted the heaters, I've bought a pair of velleman k1823 regulated supplies, they will do 1.5v to 35v dc at a max of 1.5a with a heatsink, got a pair of heatsinks too.
Just a little lm317 reg board, for a fiver plus vat, it looks like a very useful little board for small signal valve heaters on a budget.
The 4 nuvistors each take 2.1v at 450ma iirc, the transformer I was using is a 4v job that was powering them through a diyhifisupply module originally.
Each velleman module could power the 2 nuvistors per channel.
I was also looking at using one of these boards to replace the old and wonky 18vdc power supply in the jbe psu box

I'll dump it outside yours in a bag

[steve s]

Hi Steve, both power supplies are choke input. The limiting resistors aren’t mentioned for either the GZ37 or the EZ81, when they are used with choke input filters.

Of course.. my apologies steve

[Cressy Snr]

As well as our Ant, getting the Dynavector MC cartridge, in the big box Nigel (Shaman) sent to my place. I got a really nice bunch of valves he was clearing out.

Aside from the British 4V valves, this stash of tubes was virtually identical to the stash that went to Steve’s a couple of years ago when I’d lost interest. Funny how things come round. I now have enough 6922s to build half a dozen valve phono stages

There was a couple of wartime Sylvania 6SL7 in the box, which will come in very handy for the Super Rocky, and a nice bunch of used but good rectifiers, plus a few nice NOS rects.

I took out the Hazen grid mod a couple of days ago, and while I was in there, fitted a couple of 50K Allen Bradley mono on/off/volume, switched carbon track pots from the 1960s.

The older 250K Allen Bradleys were getting a bit crackly, as they have been knocking around collecting dust for over ten years; at least since I had them in my 6B4G monoblocks.

Below is the Super Rocky, sporting the aforementioned Sylvania 6SL7s and a huge old indirect-heated rectifier, plus a little EZ80: all from Nigel’s box.


With this little lot in situ, the Super Rocky gives that classic tubey sound I’ve sought since I started building valve amplifiers. Once you get out of that audiophile mindset, the music becomes much easier to enjoy.

It might not be high-end but in combination with the Fane speakers, it has soul in spades. It’s nothing like the DHT, the OTL, or the solid state sound. There’s no trace of any kind of forensic analysis or unforgiving characteristics in the presentation.

Without a time machine, I can never know for sure, but what I think I’ve ended up creating, in terms of the amp and the big, efficient, 12in single-driver speakers, is my idea of how a mid ‘50s high quality domestic system would have sounded if fed with modern sources.

“I say Mr Cholmondley-Warner, your new steerio gramophone system has top-hole tone!”
“It certainly does Mr Grayson, it certainly does”

[simon]

Or, to mix Paul Whitehouse programmes, niiiiiiiiiice!

[Cressy Snr]

A rectifier visual fest.



Warms the cockles of your heart.

[Dave the bass]

Warms the cockles of your heart.

And the room too, win-win!

[Mike H]

Now let’s get on with that blasted phono stage and stop piss balling with this.

[Cressy Snr]

Yeah but no but; the Mazda UU_ rectifiers are the only 4V ones I’ve got, so that’s that particular avenue for p*ssing about closed.

I just think they’re beautiful looking rectifiers, even better when lit up, and they are better off being appreciated, than gathering dust at the bottom of a box.

Owning a hand-built valve amp is (for me at least) about much more than hi-fi, much more even than reproduced music. I only have to look at the aesthetics of my system as a whole to realise that it’s modelled closely on sometime in the 60s, as is most of the stuff I listen to, and there are personal reasons why this is so. These put any audiophile pretensions I have or may have had on very shaky ground. I’m no longer sure I’m a hi-fi enthusiast in any recognised sense of the term. I just like making things, seeing what happens and how far they take me

[pre65]

I just like making things, seeing what happens and how far they take me

Nowt wrong with that Steve.

[Ray P]

I really wouldn't worry about it Steve. There are no specific criteria to be met and who cares about wearing a badge anyway?

There's only one person (well, possibly two?) you have to make smile with your music tastes, system sound and DIY projects. Be happy.

[Cressy Snr]

I’m not worried Ray. In fact I’m happier with the system now than I’ve ever been. I know that there’s no one sound and that everyone is different in what they expect/want out of a home sound system.

After a lot of messing about, I’ve returned to 1950s valves (EL34 and KT77) a simple two stage, single-ended circuit, a traditional choke-input power supply feeding each stage, a big single speaker driver in a large sealed box, a breathed on old idler drive motor unit in a massy plinth and a 1970s, high end tonearm with modern MM cartridge.

I’m not skilled enough to get the best out of direct heated triodes because I am too lazy to develop those skills properly. TBH, I’m far happier bumbling along with the easy-to-work-with indirect heated power pentodes strapped as triodes.

Been Jack of all trades, master of none over the years. So there was a simple question that came up after I returned to valves. It was, “is it better to do one thing well, or do lots of things with mediocrity?”

The 13E1 OTL was built to answer a different initial question - ‘can you build an OTL amplifier without having it blow up on you?’ Once the answer was “yes you can” then the practicalities of the heavy electric consumption and excessive heat, began, slowly but surely, to outweigh the fantastic sound it produced. It’s still nice to have it around though.

So we were then back to the other question, ‘if you can’t use the OTL as your daily driver, and still want to continue with valves, do you embrace the “do one thing well” philosophy or are you just going to repeat past mistakes?’

I went with “do one thing well” and a positive outcome of that, is because I stayed focussed and built and designed the amp for KT77s, those are the valves it sounds by far the best with. A few minor component changes, some internal tidying, plus a nice pair of lovely vintage rectifier valves and I have what I wanted. Great sound and one thing done well.

The icing on the cake would be a pair of NOS Gold Lion or GEC KT77s for fifty quid the pair. Dream on.

[Ant]

This is why I build turntables. I'm not good at amps, the se 6s4s was as close as I came to decent. speakers were reasonably ok(long forgotten mltl things with twin chr70s a side), nuvistor phono stage was not designed by me so that doesn't count.

I can do turntables (and bore the pants off everyone while I'm at it)

the b1 f5 combo is all I'll ever need amp wise, something clicked when I got the f5. the big fanes work really well with the f5 too so they will stay.

I can piss about all day with ideas for decks, and be happy doing it. Amps frustrate me