Another fun build. Driver and phase splitter.

[Tubeglow]

I guess its not Battery + then.


Tubeglow.

[G8HQP Dave]

By British convention, the main positive supply rail to a valve circuit is called HT, or sometimes HT+. This is still the case even if the circuit in question is one of those daft 'tube buffers' which tries to run a cathode follower from +12V. The diagram showing the circuit is a circuit diagram, not a schematic. The things we use to label the front panel are transfers, not decals.

We find it amusing that the EU Low Voltage Directive is about safety with lethally high voltages such as 240V AC.

We expect Americans and others who don't speak British English to use their terms, and we can mentally translate when we look at their websites. We assume they can do the same when they look at our websites.

[Radio Wrangler]

The low voltage directive came out of the electricity distribution industry where 240v was the lowest voltage they worked with. Low in their terms.

I think they go it wrong.
Low voltages ought to be safe under normal circumstances, and High voltages ought to be the dangerous ones.

There hasn't been a formal definition, but in a dry indoor environment anything up to 50v is considered safe for live working, anything over 50v is considered to need protective measures.

In other environments lower voltages have been proven dangerous. People have lost hands due to metal watch bracelets welding across large battery cells in cars and lorries (Nice English word). There is one recorded fatality due to someone 'experimenting' with a 9v battery.

Combined LV and LV battery! Nope, I don't see people changing.

LT and HT are correct period names, and are right for period equipment.

David

[AC/HL]

I all depends on where you stand in the hierarchy. 230V is high to me, but not to a real Power Engineer. There is a definition for safe power, SELV which is 60V or less.
Unfortunately there can never be a definition for safe.

[DangerMan]

Originally Posted by Tubeglow

If you don't do this the valves will flash over in about a week.
The valves had not run in at this point and the Kiwame resistors had not changed to 2nd harmonic.

I can understand the valves could have issues with gas if some samples aren't pumped thoroughly and have been stored, thus requiring the getters to mop up residual gas traces (however unlikely)... but I really can't swallow the statement about the resistors.

Are they not stable ?
Do they double in resistance when they "change to second harmonic"? (I nearly said "double in value" but that's probably too ambiguous when discussing such components!).
Or does their distortion change from "zero" or "odd harmonics" in nature, to predominantly (or entirely?) "even" harmonics ?

I am genuinely intrigued about their composition and construction and what is believed to happen, to see whether the two can in any way be scientifically associated.

However, I know what I suspect.

I don't understand why one would deliberately choose an unstable distorting resistor over a stable linear one.... that's what it comes down to, I suppose.

Pete

[Phil G4SPZ]

I've just Googled "Kiwame resistors" and there's no mention of their properties or effect changing over time. Stability is what they claim, and at $1 per resistor I would expect nothing less. So what are you suggesting happens when they 'change to second harmonic'?

[ValvoStef]

And more interestingly, why would they change to second harmonics? Never heard or come across such behaviour on a resistor. I don't understand this.

[Radio Wrangler]

Given the current one-liner at the foot of my postings, I can just see me shouting commands to my uniformed minions, and the echoes as orders are shouted onwards down the chain of command:

"Start the nuclear reactors!"

"Prepare the positronic ray weapon!"

"Switch the resistors to second harmonic!"

All that seems missing is the command to fire, but then a minion reports back "But sir, you got Kiwame resistors and they won't switch!"

"Drat!"

"Tear out the resistors!"

It's a shame, Barbarella and Bond would have gone together so well. But then this is no more fictional than some of the esoteric properties ascribed to components.

David

[Radio Wrangler]

Taking a more serious slant, I found a website with those resistors on it and also some even more expensive cast ones at £25 per resistor. They announced that they'd managed to get stocks of NOS American carbon-composition resistors and described their benefits and wonderful sound in the most effusive prose. Other websites were pretty much the same.

The expensive cast ones got effusive prose as well, as did the Japanese ones mentioned above. It must be difficult being an audiophile... All the resistors are wonderful. How can anyone possible choose? They all have different tonal characteristics... all marvellous.

Now one thing about these Kiwame resistors got me interested. They were described as carbon film and lower noise than metal film resistors. The main bit of equipment used for developing low noise electronics is the Agilent (used to be Hewlett-Packard) Noise Figure analyser, which is a family of instruments covering different frequency ranges, and its matching family of precision noise sources used to calibrate it. I originated it and led the hardware development. A few years of my life went into that stuff, and I measured a few components along the way. I also had the use of a huge database showing failure rates of components both specifically and by general family, across a large corporation with many thousands of products. Perhaps I learned a bit along the way.

I won't touch cracked carbon or carbon composition resistors with a barge-pole, and I have a definite preference for metal film resistors over carbon film resistors.

Where 'Tantalum' resistors are mentioned I presume they mean Tantalum nitride, which is also fired onto ceramic as thick film resistors for surface mount parts and on thick-film hybrid circuits. Also Ruthenium oxide is used, which sounds even more esoteric. I noticed the price of 'Tantalum' resistors is really quite staggering. By the way, the thick film resistors I've measured were noticeably more noisy than metal film. Some exhibited 20dB excess noise. Tantalum is getting to be in short supply and prices are rocketing, just look at tant capacitors. Still, the resistors get a lot of praise.

Down at the lower end of the price range were some branded as 'Holco' If these are Holsworthy Electronics of Holsworthy in Devon, I've used a lot of their parts and found them to be of fully satisfactory quality. The noise is down close to what the Maxwell-Boltzman constant decrees is the absolute floor, and the reliability is fine. Even up to high RF frequencies and with receivers with over 100dB dynamic range I've found no distortion from them. There are plenty other makers of good metal film parts. I used precision measuring equipment and reliability information collected over decades and millions of parts. Maybe I'd have had different results if I just listened to them?

I have no connection with any resistor manufacturer other than having used an awful lot of them in especially demanding applications.

David

[ValvoStef]

Interesting read, thanks for that

[Tubeglow]

Here is an interesting read,

Old news to some I know.

I'm not agreeing or disagreeing with the article.

http://www.nutshellhifi.com/library/FindingCG.html

Tubeglow.

[Phil G4SPZ]

Undoubtedly it is an interesting read, but it seems to me that you're trying to dodge the two fundamental questions that you've been repeatedly asked - (a) please can we see the circuit of your amplifier, and (b) please explain what you mean by "resistors changing to second harmonic"?

I find this quite odd.

[ValvoStef]

I agree with that. If it is homebrew then I can't see any reason why not publish the schematics. It would be of some interest to me - and other members of this forum.

[Tubeglow]

I can't post it because it s a Futterman design.
With Technics mod.

I posted this in post 23# and the link to the circuit diagram.

I also posted it as a build for interest I'm not claiming anything wonderful or spectacular. As I have been told this is not an audiophile site.

Tubeglow.

[Radio Wrangler]

I too can't see any reason for wanting to keep it secret. Everybody has a go at building various published or commercial designs. The number of Mullard designs built by folk on this group must run far into double figures. It's the best way to find things out.

The bit about resistors changing to second harmonic sounds like nothing more than a bit of pseudoscience picked up from a cult website, probably an American one considering other terminology.

Given that the designers of some amplifiers generally accepted to be excellent; Leak, Quad Radford on our side of the Atlantic and Hafler, etc on the other side, knew nothing of boutique components or cult theories there must be a lot of good knowledge in their writings and the material they referred to.

Perhaps we should help the guy work his way through the GEC amplifier book, or the Mullard designs, or if he likes the American flavour, Terman and the Rad Lab series. I suppose we'd have to put Langford-Smith's Radiotron manual somewhere mid-Pacific. Lacking in all the boutique stuff, they are a lot less confusing that much of what's on the internet.

David

[Tubeglow]

OK,

I'm done I don't like the tone.

Tubeglow.

[Station X]

I guess the tone is down to using the wrong resistors.

[AC/HL]

To be honest, if you'd read some of the earlier threads you should have realised that this is not the Forum for you. There are audio enthusiasts on here, and we appreciate a lot of your input, but references to overpriced, overhyped brands of standard components always lead to the kind of response you got.

[Wendymott]

I cannot help it..........Here goes.......I often found that Audio enthusiasts could be come fanatical, "I was going to use another word, but considered it not helpful" about their chosen subject. I was friends for many years, until his passing, with a guy whose passion was audio construction #, both amplifers and speakers, where the heaters of the pre amp valves and the PA containing KT66's were DC fed, and the tuning of the speaker ports and the crossovers, were... to my "cloth ears" were time that could have been spent on more interesting things..
But without those guys and may be girls.. we would not have the products of today.. I often think the youngsters of today, with their university degrees, will still have a lot to learn from us "old uns".

Regards
Wendy G8BZY

[kalee20]

I can understand some resistors sounding 'nice' if they produce second-harmonic distortion - it could brighten-up the sound.

On that basis, carbon-composition types would have a following. But it's NOT hi-fi.

However, I wouldn't touch them these days. I like my resistors to be linear, with no voltage coefficient. I'd also worry that a resistor that produces second-harmonic distortion must be polarised, so you have to fit it in the circuit the right way round.

Shame we never got to see the complete phase splitter circuit diagram...