Super Rocky

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Ant
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#46 Re: Super Rocky

Post by Ant »

Just build a new one. Time taken is not an issue right now :mrgreen:

Compare it with the NVA as a control
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steve s
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#47 Re: Super Rocky

Post by steve s »

My lads got my nva phono2 I much preferred my ear over it.. It sounded dull to me.
I doubt the benefits will be as big as a power amp seperationg out the power supplys.

My last two valve amps have single power supplys, but separate smoothing per valve. 1st one was lclc on driver and lc on outputs.. 2nd was cc per output valve, clc on the drivers. branched off a big single choke Not a lot of difference between them soundwise, but I need to do some measurements to confirm, there is a great advantage of much less weight with more caps than chokes and more so with less power supplies...
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izzy wizzy
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#48 Re: Super Rocky

Post by izzy wizzy »

Cressy Snr wrote: Mon Apr 13, 2020 10:55 am I’m torn between building a completely new valve phono stage, or reverse engineering the single regulator board in the NVA stage and converting it to four regs (2 per channel) all fed by the giant +35/-35V remote supply.
Before you go this multireg route, ask yourself what are you trying to achieve? I know that might sound like a dumb question but it might not be when you apply it to a very low level amplifier vs one that swings around a lot like a power amplifier. I do agree isolation of stages is still important and is a good focus to have.
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Paul Barker
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#49 Re: Super Rocky

Post by Paul Barker »

pre65 wrote: Mon Apr 13, 2020 9:46 am
Paul Barker wrote: Mon Apr 13, 2020 9:32 am I’m not as qualified to talk phono stages as many here. But Steve you mentioned possibly building the wad phono stage. It was a good budget self build phono stage. True Reality phono stage sounded better to me. I’ve built both. Both were are fair stretch ahead of the stock EAR phono stage and better than it after the Thorsten mods, which to me barely made an impression.

In those days I never quite got around to the one whihc was praised by the better names I leraned could be trusted in those days; AusLerch (sort of play on names Arthur Lurch design adapted by some Ausy, the circuit for which was readily available online in the ‘90s but last time I searched for it the original is no longer available. But there is plenty of info about the method.

Nick G and Mark J have both built versions of the concept afaik.
There is a thread on here that you might remember Paul.

http://www.audio-talk.co.uk/phpBB2/viewtopic.php?t=3957

And this

http://www.diyparadiso.com/proj/chrisbrady.htm
Thorsten has nothing to do with the Australian version of Arther Lurches design.
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Cressy Snr
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#50 Re: Super Rocky

Post by Cressy Snr »

Been playing all last week with different rectifiers, which is most unfortunate, as I have far, far too many of the bloody things and I’m not about to make a boring list of them, then run down chapter and verse on their sonic differences. And despite the tweakery that follows, the Super Rocky remains the best non OTL amp I’ve built to date, whatever rectifier is in use. It’s just been a matter of a nip here, a tuck there in order to nudge the tonal balance into a state that will give long term musical satisfaction.

I finally settled, after much auditioning, on the 1960s, Fivre 5R4GY as it, together with a nice, 1970s, RTF EZ80 on the input stage supply, provided the right DC conditions, power supply impedances and what have you, to make the Super Rocky put its best foot forward.
D3E73FF0-9130-4973-942E-F34F698E8CE5.jpeg
It’s not what I expected; expectation being the stumbling block in this instance. An excess of expectation bias and a surfeit of poor sonic memory, was leading a merry dance, with this rectifier rolling lark and in the end it pissed me off. I have Mullard GZ34, GZ37, GZ33, and even a Brimar U52 ferchrissakes; all very expensive, especially the U52. Round and round and round, I went; rolling these expensive rects in and out until the ears just got tired of it.

Eventually, I gave up with the drinking by the label, put them away, and admitted that none of the posh rectifiers was providing the right electrical conditions for long term satisfaction with the sonics of the amplifier. They all allowed impressive results in their different ways but after a couple of hours, something or other would come up with the tone, something that became an irritant. It was this nonsense that caused me to decide eventually that I could no longer be arsed with valves (daft move). Maybe I should just build some better speakers, but that’s an argument for another day as I can no longer ‘get out more’ anymore :lol:

All is well. :)
Last edited by Cressy Snr on Wed Apr 15, 2020 4:47 pm, edited 2 times in total.
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Ant
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#51 Re: Super Rocky

Post by Ant »

I bought those fivre rectifiers years ago! I remember buying 2, one for me and one for mi dad, (rang him and asked if he wanted one when I ordered one for me)
Had mine in the se 6s4s and in the sep kt88. They weren't much money, mine went bang in the sep.
Bloody good though
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#52 Re: Super Rocky

Post by Cressy Snr »

A bit more tinkering today.
The 100 + 100uF, 500V JJ can cap at the rear has been replaced by a 50 + 50uF F&T can cap, to good sonic effect. A decent balance has been struck, I feel, between decent hum levels and power supply speed. In fact, hum levels have barely changed at all, the thing is still virtually silent. The top end detail is very nice indeed. It’ll never be as ‘fast’ as a well executed direct-heated triode power stage, but it’s close.

Whilst I was under the hood, I also fitted another two red 4mm speaker sockets, so that 4 and 8R speakers are now catered for. The 4R setting will work nicely with Steve’s speakers, if we ever get out of this Covid-19 nightmare.

On a whim, I also tried out some modern production 6L6s I had knocking about, from the push-pull pentode days and they biased up excellent. It was only a small step from that to a pair of Osram, grey glass KT66, out of a quad I bought off Steve a couple of years ago. These, being the British variant of the American 6L6, biased up exactly the same, and they are being given an airing below. They don’t half sound good :D
D1ADF4D3-FC9B-4E06-88F9-D709650B1C97.jpeg
In the amps I’ve built around EL34s, the grey glass KT66s have TBH sounded a bit meh, as has anything else based on the 6L6. But...in an amp purpose built for KT77s, the old KT66 sound glorious, as do the 6L6 variants I have. So, we now have the bonus of being able to use 6L6 and KT66 as well as the KT77, without any penalties in terms of the overall sound quality. I’d call that a result. :)
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Ant
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#53 Re: Super Rocky

Post by Ant »

What happened to those kt120s?
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little eddy
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#54 Re: Super Rocky

Post by little eddy »

Cressy Snr wrote: Thu Apr 16, 2020 5:36 pm ... to a pair of Osram, grey glass KT66, out of a quad I bought off Steve a couple of years ago. These, being the British variant of the American 6L6, biased up exactly the same, and they are being given an airing below. They don’t half sound good :D
That's what i ended up using in my Rocky, (again thanks to Steve S).

What is the gain stage valve/config have you ended up using?
TD-125/RB250/MC25FL & 'Snail' phono, NAS/SBT with CS4398 DAC, 41MP pre & MoFo Power, still messing with OBs.
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#55 Re: Super Rocky

Post by Cressy Snr »

:)
little eddy wrote: Thu Apr 16, 2020 7:38 pm
Cressy Snr wrote: Thu Apr 16, 2020 5:36 pm ... to a pair of Osram, grey glass KT66, out of a quad I bought off Steve a couple of years ago. These, being the British variant of the American 6L6, biased up exactly the same, and they are being given an airing below. They don’t half sound good :D
That's what i ended up using in my Rocky, (again thanks to Steve S).

What is the gain stage valve/config have you ended up using?
It’s a single high-gain stage made up of the once maligned 6SL7. Crippling input capacitance, made worse by paralleling up the sections, and of course, the laughably poor drive current they used to say And yet...

https://vinylsavor.blogspot.com/2016/05 ... -6sl7.html
Nice, warm and smooth.
The kind valve a 50s throwback like me would like then :lol:

As Ed alluded to earlier in the thread, it’s all somehow ended up coming full-circle.
Last edited by Cressy Snr on Thu Apr 16, 2020 9:34 pm, edited 5 times in total.
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#56 Re: Super Rocky

Post by Cressy Snr »

Ant wrote: Thu Apr 16, 2020 6:44 pm What happened to those kt120s?
They’re upstairs in the shit tip.
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izzy wizzy
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#57 Re: Super Rocky

Post by izzy wizzy »

Cressy Snr wrote: Thu Apr 16, 2020 8:09 pm :)
little eddy wrote: Thu Apr 16, 2020 7:38 pm
Cressy Snr wrote: Thu Apr 16, 2020 5:36 pm ... to a pair of Osram, grey glass KT66, out of a quad I bought off Steve a couple of years ago. These, being the British variant of the American 6L6, biased up exactly the same, and they are being given an airing below. They don’t half sound good :D
That's what i ended up using in my Rocky, (again thanks to Steve S).

What is the gain stage valve/config have you ended up using?
It’s a single high-gain stage made up of the once maligned 6SL7. Crippling input capacitance, made worse by paralleling up the sections, and of course, the laughably poor drive current they used to say And yet...

https://vinylsavor.blogspot.com/2016/05 ... -6sl7.html


Just the kind valve amp a 50s throwback like me would like then :lol:

As Ed alluded to earlier in the thread, it’s all somehow ended up coming full-circle.
Before I went the super gm route in the phono, I really enjoyed a paralleled 6SL7. It has a wonderful character especially the older ones.
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#58 Re: Super Rocky

Post by Cressy Snr »

izzy wizzy wrote: Thu Apr 16, 2020 9:31 pm
Before I went the super gm route in the phono, I really enjoyed a paralleled 6SL7. It has a wonderful character especially the older ones.
Yep, the black glass Tung Sols I have are lovely.
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#59 Re: Super Rocky

Post by Cressy Snr »

Now I know that the Super Rocky is compatible with 6L6 types, I fished out half of a quad of Tung Sol reissue 7581A from my remaining box of power valves. I‘d bought this quad from Hotrox, when I was messing around with push-pull pentode amps, but somehow never got around to trying them.

They biased up spot on and first thoughts are that these are actually excellent sounding tubes. They’re big, generous, warm, weighty, liquid, romantic and sparkly. Accurate? who cares, and what the hell does that mean anyhow? This is how I want valves to sound. Sod everything else.
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#60 Re: Super Rocky

Post by Cressy Snr »

Added a series resistor to the existing power valve cathode resistor on the Super Rocky, a double-pole switch, that switches a short, in and out across said series resistor. Also wired pin 1 to pin 8 on the power valve sockets. This means I can now use EL34s as well as 6L6 types, KT77 and KT66.

Now, with a flick of a switch and a change to a higher drop rectifier, the SR will work properly with EL34s; which means it’s now capable of running with all the power valve types I have left.

I have it running El34s at the moment to good effect. I like to think of trioded single-ended EL34s as “Kodachrome valves,” because they give those nice bright colours, and give you the greens of summers, make you think all the world's a sunny day, oh yea! :D
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