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 Post subject: Sand or Glass
PostPosted: 12 Jul 2010, 05:59 
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This thread picks-up where the 6V6 competition thread left off with relation to mixing sand devices or "SDS" with pure tube devices.

For me, apart from diode rectification, I will keep tube amps SS free. I'm not talking hybrid amps here where you may have a tube front-end or driver stage and an SS power stage but where SS devices are use to create constant current sources, buffers or signal boosters or whatever.

I'm not saying they are good or bad, sound right or sound wrong but for me, I just don't do them. I have built a number of descrete SS amps, chip amps and OPAMP based preamps so I am away what SS circuitry has to offer. I have also built a number of tube based amps and have been schooled in both camps.

But I'm sure you-all have some comment to make here. Go for it.

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 Post subject: Re: Sand or Glass
PostPosted: 12 Jul 2010, 07:14 
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Location: Vänersborg, Sweden
I am in no way a vacuum-taliban. Tubes are nice to work with as there's no need for printed circuit boards and the passive components are big enough so the markings can be read w/o microscope.
However this doesn't stop me from getting dirty in the sand pit and I have several randy sandy projects on my list. I even find it amusing mixing various technologies and would very much liek to try out a PP-amp with either transistors or OPAMPS for input devices and EL34s as output devices. High-breeds are always fun! :up:

Else I am to finish a l'Audiophil Monstre-amp (8W classA, siliconed). I have a SymAsym, 50W transistor amp, in plastic bags and a T-amp, also "almost finished". Not to mention a nostalgic microcomputer based on RCA's CDP1802 from the 70's, two analog synthsizers, one 32-step sequiencer, some synthesizer modules and two VU-meters based on a IN13 tube.

Edit. Miss Spelling

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Last edited by Soundbrigade on 12 Jul 2010, 07:44, edited 1 time in total.

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 Post subject: Re: Sand or Glass
PostPosted: 12 Jul 2010, 07:42 
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I would like to think that this thread has brought out the "Sacramento" side of your duck family.

I have great respect for your comments and projects so far. Looking forward to you stirring this spicey pot.

Hybrids? I'm happy with mixing SS and tube front-end and back-end.

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"Rosso" - E88CC SRPP preamp | ”Salt Cellar II” - 6EM7 mono wine box triode amp |


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 Post subject: Re: Sand or Glass
PostPosted: 12 Jul 2010, 07:48 
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Somewhere, where you may confront the "unlucky" blend of sand and vacuum is when using CCS like in the OddWatts. How would an OddWatt look like with an KT88 or 6080 or 6S33S as current sink?! :shock:

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 Post subject: Re: Sand or Glass
PostPosted: 12 Jul 2010, 08:07 
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Soundbrigade wrote:
Somewhere, where you may confront the "unlucky" blend of sand and vacuum is when using CCS like in the OddWatts. How would an OddWatt look like with an KT88 or 6080 or 6S33S as current sink?! :shock:

You know I have thought of that. Why can't a tube be a current sink. Come on Sacramento sketch one. Two KT88s is totempole current (or voltage) sink topology?? I'd like to see that.

But is it required? What happened to good old resistive loading, transformer coupling. Is different better? Is simple simply better?? Or is there something to be had??

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"Rosso" - E88CC SRPP preamp | ”Salt Cellar II” - 6EM7 mono wine box triode amp |


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 Post subject: Re: Sand or Glass
PostPosted: 12 Jul 2010, 08:09 
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I dunno, let's leave that to the other members to answer. :idea:

I've seen several schematics with pentodes as current sinks for preamps and iput/driver stages in power amps.

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 Post subject: Re: Sand or Glass
PostPosted: 12 Jul 2010, 10:43 
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Location: England
If you went out an bought a brand new car in the 1920's you would have an engine and some basic controls, you had to find the skill to control the thing, never mind in the snow or whatever. Now if you go out and buy a new car it comes fully loaded with an entertainment system and anti lock brakes etc. Purists will argue that it will be less fun to drive and not as good asif it was left without these aids, but looking at it from a wide angle point of view they have ultimately improved the car.

If you wish to go along the route of nothing must be contaminated by 'sand' then go for it, but if it means you can provide tube amp heaters with the cleanest power supply known to man then why not use a voltage regulator etc.

Personally I cant tell the difference between my granddads old tube amp with not a chip in sight and his newer one which uses a few voltage regulators and other niceties which make things better on a general point of view.

But then you are building the amp so each to their own! :mrgreen:

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 Post subject: Re: Sand or Glass
PostPosted: 12 Jul 2010, 20:05 
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Location: Canada
kkkittehz wrote:
....but if it means you can provide tube amp heaters with the cleanest power supply known to man then why not use a voltage regulator etc.

Hi.

I think battery should be "the cleanest" answer to heating tubes as a home DIYer without touching sandy stuffs.

I am using 6V sealed lead acid (SLA) cell to heat the tubes of my phonostages, rechargeable by
an outboard SMPS which is switched off & electrically & physically isoated from the amp itseslf when not charging to eliminate RFI contamination.

c-J

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 Post subject: Re: Sand or Glass
PostPosted: 12 Jul 2010, 20:41 
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cheap-jack a good way to go for a pure DC filament. In my tube pre and power amps I use center-tapped AC filaments and have no problem with hum. I'm not sure I would ever bother with DC filaments.

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"Rosso" - E88CC SRPP preamp | ”Salt Cellar II” - 6EM7 mono wine box triode amp |


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 Post subject: Re: Sand or Glass
PostPosted: 13 Jul 2010, 08:45 
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Joined: 18 Jun 2010, 12:46
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Location: Northern VA
Pure DC is ususally a must when dealing with a high gain phono pre.

Amps and line stages have very little gain in comparison.


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