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Homebrew Equipment A place to show, design and discuss the weird and wonderful electronic creations from the hands of individual members. |
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2nd Apr 2014, 5:10 pm | #21 |
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Re: Another fun build. Driver and phase splitter.
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2nd Apr 2014, 8:36 pm | #22 |
Dekatron
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Re: Another fun build. Driver and phase splitter.
Can you post the circuit? I've never come across those valves before and I'm always interested in other people's builds.
Cheers
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2nd Apr 2014, 8:44 pm | #23 |
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Re: Another fun build. Driver and phase splitter.
Just posting the circuit is not a good idea, I know what your thinking but this is not as straight forward as you might think. Mr Miller is the driving force so to speak.
The circuit is not complicated however read this first. The power supply has enough power to probably make your first contact your last. This is a very good OTL. http://www.mellowacoustics.com/artic..._amplifier.pdf The power consumption of these amps is a real eye opener. just look at the heater currents for a start. The nature of OTL is as it says no output transformer..ie no direct isolation between the output valves and the speaker. My amp is based upon the futterman circuit so no further explanation is really necessary. http://www.audiodesignguide.com/otl/ However this is an audiophile design and my amplifier is designed with some strange ideas. I know this is not a good exercise to continue on this site. The heat is a major issue with these designs..not to be taken lightly it will destroy electronics and cause thermal runaway. A red plate 6C33C has to be seen to understand this as the glass tube melts. How you wire the heaters has an effect on how long the tube sockets last is another example. However for someone who knows what they are doing its one step away from something like a 211 SE triode design. However you have current to deal with as opposed to HV b+. Tubeglow. Last edited by Tubeglow; 2nd Apr 2014 at 9:08 pm. |
2nd Apr 2014, 9:09 pm | #24 |
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Re: Another fun build. Driver and phase splitter.
I can never see the point of OTL valve amps, except for headphones, when there is a perfectly good appropriate technology available: semiconductors. Each to their own.
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2nd Apr 2014, 9:16 pm | #25 |
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Re: Another fun build. Driver and phase splitter.
I know what you mean,
however its a challenge maybe to far for some. A bit like 211 SE like Ongaku. I have listened to these amps. A bit like a krell with Magnepan. The point of posting was really with the idea of people building valve amps and not having any starting ideas for a build (how you can build). Rather than to pursue audiophile design. (Which posting the circuits will possibly cause a conflict with the site) That was the idea of lots of pictures to inspire more simple builds. The technical problems are a great challenge..and source of hours of redesign. I really like my RH amp its really good fun! The Mozart type is very good. Tubeglow. Last edited by Tubeglow; 2nd Apr 2014 at 9:25 pm. |
2nd Apr 2014, 9:55 pm | #26 |
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Re: Another fun build. Driver and phase splitter.
For interest,
6C33C data. http://www.jogis-roehrenbude.de/Russ...atasheetMB.pdf NB the switchable heater power is good in OTL in SE the output transformer needs to match the valve due to the effect on THD. Another thing to remember is how old the OTL circuits are..and its nice to have a piece of a MIG fighter playing music. 6C33C in a MIG fighter radar unit and military background..as you can see it provokes some very diverse ideas. http://www.goodsoundclub.com/Forums/...px?postID=6140 Once you start researching this kind of thing it can get quite interesting (Mu stage.) Tubeglow. Last edited by Tubeglow; 2nd Apr 2014 at 10:19 pm. |
2nd Apr 2014, 10:29 pm | #27 | |
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Re: Another fun build. Driver and phase splitter.
Quote:
People here have plenty of starting ideas. We generally start from Mullard or Leak designs, as you will see with a little searching. |
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2nd Apr 2014, 10:33 pm | #28 | |
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Re: Another fun build. Driver and phase splitter.
Quote:
As engineers, we are more interested in the circuit rather than the make of resistors...it's the circuit that produces the sound so it's just out of interest that's all. Anyway it's up to you....I'd still like to see the circuit though! Cheers
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2nd Apr 2014, 10:34 pm | #29 |
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Re: Another fun build. Driver and phase splitter.
Ok,
I get your point. I won't post anymore information. As you say its not inspiring anyone. I also see why Dave found it amusing. I thought it might be interesting, but I now realise it was an embarrassing waste of effort. Moderators please delete this thread thank's. Tubeglow. Last edited by Tubeglow; 2nd Apr 2014 at 10:44 pm. |
2nd Apr 2014, 11:01 pm | #30 |
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Re: Another fun build. Driver and phase splitter.
I've come across Krell, Magnepan, and Ongaku before, but I'm more likely to mention Bruel & Kjaer, Audio Precision, Tektronix and Hewlett-Packard.
They too are reassuringly expensive. The interesting thing is that several brands of equipment operating by different principles tend to offer results in agreement with each other. As blind coincidence becomes progressively more improbable, then there emerges the simple solution that they are most probably right. Building a few valve amps is a sort of rite of passage, but few move on to the more difficult challenge: Designing a good and original semiconductor amplifier. It isn't the restoration of vintage equipment, but a thorough understanding of all the techniques used in the past along with their strengths and weaknesses is a good starting point. David
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2nd Apr 2014, 11:06 pm | #31 |
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Re: Another fun build. Driver and phase splitter.
What's the problem with posting the circuit? It's not the first time that high power amps have been shown on these pages with accompanying circuits. Very often they invoke lively discussion which is what it's all about. In fact it's more likely to inspire someone else to build. Just seems odd that's all. Most people who build something different, which this is, are happy to share information.
Rich
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2nd Apr 2014, 11:43 pm | #32 |
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Re: Another fun build. Driver and phase splitter.
It could be argued that, by having a fascination with valves, many of us on this site are slightly barmy when transistors and their follow-on integrated circuits have proved themselves thoroughly capable for decades and to offer hugely sophisticated features as a knock-on of component density.
In the end, it's a harmless diversion that most of us could take or leave. For some of us, the particular fascination might be oscilloscopes or signal generators, others get a thing for communications receivers or pre-war domestic radios. I think, though, that we each have a broad interest in what everyone else here does and there are a few members whose acknowledged speciality is the painstaking and quality restoration of the classic valve amps. I've no doubt that they would agree that it's a good thing to use high quality components to ensure good performance, reliability and long life of associated parts. Where they would differ from the so-called "audiophile" camp is on the necessity of spending 10x or even 100x the money on components bearing brands that seem to be conspicuously absent from unambiguously respected masters of their trade, say Tektronix 'scopes or Hewlett-Packard signal generators. I'd also be interested to see the circuit- I'm prepared to be open-minded about anything a bit "different" and I'm encouraged to see that, by using the hefty 6C33 regulator triode, it's not depleting a valve that's useful for other purposes. It doesn't have a huge voltage rating or a top cap, so it won't pass muster for RF PA or line output use, say, and even for the down-and-dirty business of series regulation, we have plenty of HV power semiconductors to take its place, so why not make a slightly off-the-wall audio power amp with it. (And I really don't believe all the obscurantist stuff about MiG fighters etc. that the net is awash with. Sorry.) There are folk here with genuinely outstanding knowledge and understanding of all sorts of circuitry (not me!) and they may be able to offer useful advice on simple improvements that will be effective. And it won't involve sandalwood capacitors, bamboo charcoal resistors or directional interconnects with depleted uranium pins. |
3rd Apr 2014, 8:59 am | #33 |
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Re: Another fun build
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3rd Apr 2014, 9:26 am | #34 | |
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Re: Another fun build. Driver and phase splitter.
Quote:
Show us the circuit diagram. Show us the measurements. Then you'll get an interesting discussion. We're not frightened of high voltages - everyone's read the disclaimer. Chris
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3rd Apr 2014, 1:29 pm | #35 |
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Re: Another fun build
The reason is linked to the definitions of low voltage and high voltage as defined under regulations. In days gone by there was low/medium and high.
The voltages used in some valve /tube gear will fall in the low voltage category and could not really be termed HT. This can be misleading so I use the term B+ also because it gives a reminder that the amount of current released is linked not to the supply but the amount of capacitance in the supply. Tubeglow. |
3rd Apr 2014, 1:34 pm | #36 |
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Re: Another fun build. Driver and phase splitter.
This is a UK forum. The terms LT, HT, EHT and valve are well understood in the UK.
I see no reason for giving them American names. My car has a bonnet and a boot, not a hood and a trunk.
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3rd Apr 2014, 1:38 pm | #37 |
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Re: Another fun build. Driver and phase splitter.
Then its low voltage.
http://www.conformance.co.uk/adirect...?id=lowvoltage NB tension is not English. ie HT. https://www.google.co.uk/#q=what+is+...ch+for+voltage Tubeglow. Last edited by Tubeglow; 3rd Apr 2014 at 1:55 pm. |
3rd Apr 2014, 2:43 pm | #38 |
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Re: Another fun build. Driver and phase splitter.
I'd better relabel my reproduction batteries to make sure I'm not breaking the law then.
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3rd Apr 2014, 2:47 pm | #39 | |
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Re: Another fun build. Driver and phase splitter.
Quote:
Perhaps the batteries are French..but the CE still applies. Perhaps B+ batteries LOL Tubeglow. Last edited by Tubeglow; 3rd Apr 2014 at 2:53 pm. |
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3rd Apr 2014, 2:56 pm | #40 | ||
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Re: Another fun build
Quote:
The electrical safety regulations may have changed, but nobody is going to go back and re-write all the existing documentation in order to warn technicians about 'medium voltage'. Just because it's not formally called 'high' doesn't mean we don't have to be careful with it. Quote:
Chris
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