Solid rubber blocks - where to buy in UK???

[Andy Wade]

Anti-microphony valveholders used to be a fairly readily available component. Can't you find any to use with the old valves that you're seeking to use?

Oh dear... But I'm slightly puzzled, the 1.4 V battery valves you mention in another post are a post-WW2 thing and were produced well into the 60s (I well remember buying them new). These had B7G bases. But you mention octal bases and the 20s and 30s. The 20s was surely the era of bright emitters (?) and by the 30s we had 2 V and 4 V filaments, usually run from lead-acid accumulators, until AC mains became common. I can't recall any octal-based valves with 1.4 V filaments (but ICBW).

Well I certainly wouldn't, because you've swallowed a load of tripe.

[Eusebius]

have a look here:

hope that helped ;-) >>

Great! Nice one. Andy

[Frank Erskine]

DK32 DL35 U35

1C5 1H5

TNBAF

:-)

[Eusebius]

Well I certainly wouldn't, because you've swallowed a load of tripe. >

Absolutely not - I've been building audio equipment for 25 years, and using DHTs for preamps is something, like most people, I avoided because of the complexity of execution (microphony, filaments supplies, UX4 bases). I've been using them now for about a year, and I wouldn't go back to indirectly heated tubes. The sound - to me - has more clarity and better tone/timbre, and the difference isn't subtle. I'm not in the slightest doubt myself becase I've tried out several different circuits, abut 6 filament supplies, transformer coupling (PP and parafeed) and done this in conjunction with three colleagues all of whom are electronics engineers and are equally crazy about DHTs. We've done joint listening tests, put circuits on test equipment etc etc. Once bitten you're smitten. Yes of course it's esoteric, but there we are. What can I say!

[Eusebius]

DK32 DL35 U35

1C5 1H5

- there's a bucket full. In terms of triodes, there's 1G4, 1E4, 1LE3,

1LF3, VT239. I'm using the 1G4 right now. The flat plate versions seem to be more microphonic, hence the post.

[.]

well at least you didn't say "make it sound / it sounds warm" top marks, fella.

[The Natural Philosopher]

No,. I';ll just go on what my ears, my test instruments, and blind tests with volunteers told me over many years of designing audio amplifiers and preamplifiers.

I think you do not wot whereof you speak. Lots of people have made directly heated triode and tetrode front ends - you have to to get the hum down.

PROBABLY more than have made a decent FET preamplifier actually..

MOST people bang in a couple of chips and leave it at that. I did in fact take it a little further than that. A very few people could tell the difference, although the test equipment certainly could. Bottles represented nothing I couldn't do with FETS and standard transistors so I ditched em. You had to DESGN carefully though. Any fool can avoid overload with a 250v supply rail. Its less easy with 30v...

[The Natural Philosopher]

Those are all post WWII IIRC

[The Natural Philosopher]

we had noticed..

Oh...;-)

Now invest all the same effort in designing really low noise linear transistor pre-amps and select your devices for low flicker noise, 1/f noise and the like, and be rewarded with a completely hum free utterly linear design with a > 1Mhz bandwidth if thats your bag...

[The Natural Philosopher]

Ahh..that elusive valve warmth..finally traced to smooth second harmonic distortion in the pre-amp, and a moderately high output impedance and lack of treble from the cast iron output transformer, together with its ability to run into clip nice and softly so that cloth eared audio buffs couldn't realise it had..

>

[.]

since digitised & encoded to a reliable and reproducible collection of

1's and 0's, freely available to everyone else.

aint progress marvellous ?

[Ian White]

The DC voltage drop along the filament will give a spread of grid bias voltages within the same valve, thus creating a variegated and subtly shaded palette of coloration...

Ahem. Excuse me.

Now real valves, you don't dare switch on without a blower :-)

[Frank Erskine]

Yes - so?

[<me9]

No, they're baby valves. The real ones you stick in a boiler.

[Eusebius]

Ahh..that elusive valve warmth..finally traced to smooth second harmonic distortion in the pre-amp, and a moderately high output impedance and lack of treble from the cast iron output transformer, together with its

ability to run into clip nice and softly so that cloth eared audio buffs couldn't realise it had.. >>

I'm sorry to say this is recycled bollocks from a few decades back. Even if you updated your knowledge of valve equipment to take in the developments of the last years in circuit types and complexity (yes, heavily reliant on ss componants too) it would leave us with the fact that several professional musicians prefer valve equipment. At this point you may be tempted to argue that "it's well known that orchestral musicians are happy listening to music on kitchen radios" but again this would take you into another well known cul de sac. Don't you think that serious valve users have heard these arguments about as many times as professional musicians have been told to get a proper job?

[Eusebius]

Now invest all the same effort in designing really low noise linear transistor pre-amps and select your devices for low flicker noise, 1/f noise and the like, and be rewarded with a completely hum free utterly linear design with a > 1Mhz bandwidth if thats your bag...>

I'm a pro musician - sound is my bag. If you're talking test and measurement equipment I'd agree with you and I'm sure you're very skilled in your field.

[Eusebius]

You had to DESGN carefully though. Any fool can avoid overload with a

250v supply rail. Its less easy with 30v... >

The skills needed for designing filament supplies - all solid state - are exactly the skills I'm sure you have. Valve equipment these days relies a lot on ancilliary circuits full of ss devices and there's a lot of skill involved in getting the best reults, as with everything serious. I was totally unprepared for how different six filament supplies were from each other. I imagined clean DC would be enough, but it's a lot more profound than that - current sources sound better than voltage regs, yet voltage regs sound better with CMCs at the end while current sources sound worse...... I suspect we haven't even come close to optimum yet. Then there's the CCS circuitry on top of all this for diff pairs in balanced circuits.

[Matt]

Yes it really is. Do a double blind test, maybe even thousands of them and you'll realise that valves no matter what you do with them are pretty shitty, music digitised to CD "standards" is pretty shitty and vinyl is pretty shitty.

Gold plated mains plugs anyone?

How about speaker cable at hundreds of quid a metre?

Wooden spikes to stand your amp on?

Green pens for CD's

Crap science, lots of flashing lights/controls and the absence of flashing lights/controls has sold "hi-fi" to generations of idiots with more money than sense.

Thank f*ck for live unamplified music.

[.]

*amen* and pass the ammunition, brother ;-)

[Eusebius]

Postscript - I mounted the two valve bases on 8mm teflon sheet then fastened that to M6 bolts via rubber grommetts so the teflon dosn't touch the bolt. Finally used a chunk of eraser (soft rubber) under each corner between the teflon sheet and the chassis as damping. Noise is very well damped and preamp is now quiet in use. Needless to say, it sounds bloody marvellous. Andy