Topic: Newbie and Not-so Noob Thread: Questions (FAQ) on anything Tubes

[stradale]

Thanks for the link joan2 . Well somebody had to ask the noob questions. But oh look now, I know what choke is and so do other readers of this thread.

Please tube gurus, don't lose patience, because in all probability, more noob questions are coming your way. In the meantime, I'll check out the link that our sis joan2 so kindly provided.

 

[arnoldc]

i don't think joan2 is a she... may be jon-jon? well, only joan2 can say

and by the way, i'm no guru... i'm also one of you.

[vintage_dog]

Vintage,

    Im using an Scott integrated amp with el84 tubes. Im thinking of getting an ST70 and preamp. Do you think its worth the upgrade for the cost or just save up for a higher brand? Im using Rotel CDP and B&W603 speakers. Thanks

Levi

The ST70/preamp combo will be a definite upgrade and this set-up is hard to beat even by today's tube gear.  go for a preamp that is non-vintage:  a foreplay or other tube-based preamps

[levi]

Racio told me that ST-70 is a minimal upgrade coming from the Scott that is why Im having 2nd thoughts if I will push thru with the plan. Its not yet in the near future so i still have time to save up for other brands also. thanks

[joan2]

don't think joan2 is a she... may be jon-jon? well, only joan2 can say

i am very much a "he" my wife can attest to that, my handle, joan2 had some romantic connotations....let's live it at that.....
i have been an electronics enthusiast since high school. circa 1970. finished electrical engineering at  national university in 1975, i also started out with vaccum tubes, then graudated to solid state in the early 70's up to the present....i have a lot of ideas, but no money to work on tubes at this time....solid state is the way for me, less money needed here...i built a lot of leach amps, this amps is the best sounding amp i have ever built...i also build my own transformers, i design them.....

[joan2]

Racio told me that ST-70 is a minimal upgrade coming from the Scott that is why Im having 2nd thoughts if I will push thru with the plan. Its not yet in the near future so i still have time to save up for other brands also. thanks

from what i have gathered reading magazines, the dynaco st70 was designed by david hafler as an "el cheapo" amp....they never anticipated it would be such a hit that it bacame....

[stradale]

Actually I was fishing for a reaction with that sis remark because I was beginning to wonder how a gurl knows so much about this decidedly male dominated hobby . Well thanks for all your feedback bro joan2. Hope to learn more from you.

[joan2]

always glad to be of help, all knowledge belongs to GOD and i have no reason to keep it to myself...i am also here:http://www.pinoypc.net/tehboard/viewthread.php?thread=12746

[stradale]

.

and by the way, i'm no guru... i'm also one of you.

Don't be so modest Mr. Cruz. You built your first tube amp when you were in high school. Kami, tatay na di pa namin alam kung ano ang choke .

[Garp]

Question to the gurus:

I read in a forum that tube rectification is better than SS rectification because supposedly tube rectification does not produce any switching noise (?) that results in some sort of brittleness to the sound. But if someone were to use schottsky or HEXFREDS diodes then this switching noise is supposedly eliminated. Has anyone tried this? SS rectification seems cheaper and someone asserted that it produces a more dynamic low-end. What's your verdict here, oh great tube sages?  

[arnoldc]

.

Don't be so modest Mr. Cruz. You built your first tube amp when you were in high school. Kami, tatay na di pa namin alam kung ano ang choke .

ser, solid state ang ginagawa ko nung high school! first time tube DIYer ako  

[arnoldc]

Question to the gurus:

I read in a forum that tube rectification is better than SS rectification because supposedly tube rectification does not produce any switching noise (?) that results in some sort of brittleness to the sound. But if someone were to use schottsky or HEXFREDS diodes then this switching noise is supposedly eliminated. Has anyone tried this? SS rectification seems cheaper and someone asserted that it produces a more dynamic low-end. What's your verdict here, oh great tube sages?  

again hindi ako guru, based on experience lang ha...

i use fast recovery diodes for my foreplay preamp, i like the sound that way, and is cheap and very easy to build.

i've experimented on hybrid PSU for my 300B... half solid state, half tube and i noticed that although i'm using 5U4G, voltage (B+) ramp up is slower (meaning tubes won't be stressed as much while they heat up). not bad at all.

there are tube rectifiers that offers slow B+ rise, such as 5AR4 which I also have. it has different rating than 5U4G and must be designed accordingly.

is the other one better? i would say it depends on the circuit.

[rtsy]

I read in a forum that tube rectification is better than SS rectification because supposedly tube rectification does not produce any switching noise (?) that results in some sort of brittleness to the sound.

Again, I'm no tube sage but look up the review of the ST70 Series I and II in Enjoy the Music or TNT Audio.  They compare tube vs. S/S rectification there.

[vintage_dog]

Racio told me that ST-70 is a minimal upgrade coming from the Scott that is why Im having 2nd thoughts if I will push thru with the plan. Its not yet in the near future so i still have time to save up for other brands also. thanks

levi, if you have time, drop by the house and we'll audition both the scott 299b and the st70/preamp combo.  that way you can decide for yourself if the st70 is an upgrade.  

i also have to ask you what speaker you intend to use and your budget for your amp.  there are of course numerous options.  in the PP category, we can audition a few amps at home  

of course, there is always the 300b SET amp that racio likes... and we can listen to one as well

[levi]

OK and thanks. Im usually visit my in-laws in Tahanan village every weekend. I will give you a call if I have nothing to do or next time you have a small eb, I will try to attend. Im using B&W 603 presently for the Scott but I have no plans of changing it for the mean time. I just reoriented again my sala and audio setup and it is sounding great but there is always the question what if.......

[joan2]

I read in a forum that tube rectification is better than SS rectification because supposedly tube rectification does not produce any switching noise (?) that results in some sort of brittleness to the sound. But if someone were to use schottsky or HEXFREDS diodes then this switching noise is supposedly eliminated. Has anyone tried this? SS rectification seems cheaper and someone asserted that it produces a more dynamic low-end. What's your verdict here, oh great tube sages?

can you post the link here so i can analyse? to me it sounds garbage....consider this:

a solid state diode has an average forward voltage loss of less than 1 volt, a tube rectifier can have as much as 40 volts froward loss, furthermore a tube rectifier needs a 5volt heater at 2amps or so, therefore for an output current of say 100 milliamps, for a solid state diode, 0.1watt is lost, whereas for a tube rectifer, 10.4 watts is lost, so now which one makes more sense?

about the switching issue, both tube and solid state diodes switch from conductive(forward bias) to cut-off or simply off(reverse bias) states based on the nature of the ac voltage inputs which reverse its polarity at a rate of 60 cyccles per second in this country....yes, switching noise and ripples (sawtooth) are produced as a result of rectification, but that is the reason for using filter capacitors and chokes, to minimise these components of the rectified dc voltage....as to which is more musical will depend ultimately on your "subjective" ears, but figures will clearly point out which is superior, need i say more?

i've experimented on hybrid PSU for my 300B... half solid state, half tube and i noticed that although i'm using 5U4G, voltage (B+) ramp up is slower (meaning tubes won't be stressed as much while they heat up). not bad at all.

there are tube rectifiers that offers slow B+ rise, such as 5AR4 which I also have. it has different rating than 5U4G and must be designed accordingly

by nature, tube rectifiers are soft starters because it takes time for its filament to heat up and start giving out electrons, a solid state rectifier on the other hand can conduct current instantaneously, a 5U4 differs from a 5AR4 only is its current handling capability....

(meaning tubes won't be stressed as much while they heat up)

it is best to have the plate voltages come on when the filaments have stabilised....

[joan2]

dynaco st70 fans, these pages will make you smile::
http://home.snafu.de/appelt/dynaco/st70.htm
http://home.snafu.de/appelt/dynaco/st35.htm
http://home.snafu.de/appelt/dynaco/dyna-mk2-sc.gif
http://home.snafu.de/appelt/dynaco/dyna-mk3-sc.gif
http://home.snafu.de/appelt/dynaco/dyna-sca35-sc.gif
http://home.snafu.de/appelt/dynaco/dyna-mullard-sc.gif
http://home.snafu.de/appelt/dynaco/dyna-mullard-sc.gif
http://home.snafu.de/appelt/dynaco/dyna-williamson-sc.gif

[arnoldc]

....as to which is more musical will depend ultimately on your "subjective" ears, but figures will clearly point out which is superior, need i say more?

exactly the point. if you ask hypertriode which ST-70 you should get, he would always recommend the tube rectified version rather than Mk II (solid state) because the former is more "musical."

by nature, tube rectifiers are soft starters because it takes time for its filament to heat up and start giving out electrons, a solid state rectifier on the other hand can conduct current instantaneously

compared to solid state yes.

a 5U4 differs from a 5AR4 only is its current handling capability....it is best to have the plate voltages come on when the filaments have stabilised....

not exactly complete. the 5AR4 is indirectly heated (slow B+ rise) whereas the 5U4G is directly heated. the voltage drop of 5AR4 is only 17V compared to 44V for the 5U4G.

[Garp]

Joan2, Arnold here's the link. I appreciate your responses although I have to admit that for a newbie I absolutely have no idea what you're talking about I need to read up more on the subject. Bear with me here: for example, why is less forward voltage loss a minus for SS? Isn't that a measure of efficiency on the part of SS? I surfed the net and diode manufacturers are touting even lower forward voltage loss which makes me think, being a newbie that I am, that low forward voltage loss is good.

http://www.audioasylum.com/forums/welborne/messages/2615.html

[arnoldc]

garp, ron welborne recommends SS for his DRD (direct reactance drive) new generation (or so he says) tube amps (45, 2A3 and 300B).

as i previously mentioned, it depends. welborne's previous amps sound best with tube rectification.

solid state is about efficiency. in some applications a 4mV decrease in forward voltage drop reduces the forward power loss by say 1%.

please allow me to quote:

"FORWARD VOLTAGE

Vf varies with: resistivity, thickness of silicon, level of dopant concentration, type of dopant, temperature, and current density.

Forward drop in a high-voltage rectifier is usually not as important an issue as it is in low- voltage applications. Consider, for example, a 1000-watt, 5-volt power supply. If its rectifiers exhibit a 0.7-volt forward drop, the power loss with 200 amps flowing would be 140 watts, or 14 percent of the power being handled. In contrast, the rectifier's forward drop in a typical 1000-watt, 1000-volt supply ranges between 1 and 1.5 volts.

At full output, the current is 1 amp, which with a 1.5-volt forward drop, translates to a 1.5 watt power loss. This represents less than two-tenths of one percent of the power being passed through the rectifier."

tubes are inherently inefficient. they generate so much heat (waste) a for a little audio power.

now, let your ears decide.

[av_phile]

I think you are referring to plitron torroids wound specifically for tube output, in their site they have push pull designs using torroids. I inquired a local tube amp maker and the price he quoted me for this push pull design (40w x 2) is 30,000. as for the SET's using torroids the article is from meta-gizmo.net(not sure).

Yup, i think its the plitron toroids i'm referring to.  But in general toroids are better transformer than the stack type, though very few are used in tube circuits.

Here's one i've come across, using output torroids.



And a quote from the page http://www.aha.nl/audio/pp2a3/index2.html
Some people believe that toroid transformers have no place in an audio cicuit, and should be used in power supplies only. Well, think again! The Plitron toroid transformers used in my first tube amp, the Velleman K4000, proved that they can sound really good, with great bass and very clear and natural highs. They also have a very wide bandwidth, wich is especially important in a non- NFB amplifier design. The transformers i used are the "high end" version of the normal toroid output transformers, designed by Ir. vd Veen, the VDV8020PP. This unit has a primary impedance of 8000 ohms, which is a bit high for this application. The advantages of a higher primary impedance are less distortion and a somewhat higher dampening factor, but it also means less output power. For maximum power, the VDV6040PP (6000 ohms) or the VDV3070PP (3000 ohms) could be used. All information about these types of transformers can be found at www.amplimo.nl.

Here's another from
http://www3.sympatico.ca/scarletaudio/pearl.html using toroids both for power and output.




So it seems there are tube amps using toroids.  But so far, have not found one in Manila.

[Audioboy]

Im really lost. I thought tube rectification is better than SS rectification. I need your advice guys, i am really bent on buying integrated tube amp. My budget is only less than 20k so that means that i have only limited choices like ts audio 34.1, vintage amp or phasetron tube amps. I talked to andrew sevilla of phasetron and requested him to make el34 with tube rectification this time because his previous versions were all SS rectification. He said he used ss rectifier inorder to produce more power.  he said further that if he uses tube rectification, instead of having 15 watts for SEP mode, only 8 to 9 watts is produced while SET mode produces only 3 instead of 6. Im not really sure if i got the figures  right but is it really true that from SS to tube rectification, there is a downgrade of power output?

I dont have budget kasi for new speakers thats why in the mean time i will have to plug it with my M73i. Im not sure however if what among my choices can fairly drive said speaker. I was thinking also of getting x10d nalang so save money and save myself from the hassle of plugging and unplugging wires using one set of speaker for two amps but i have reservation of getting it because eventually i would have to buy tube amp din.

Please help!

[av_phile]

I think I was able to retrieve the old site introduing the advantages  of toroids in tube amps (greater bandwidth) Here
http://www.vex.net/TorontoAES/99-00/sept-review.html

A more thoroughdiscussion is on downloadable pdf format
http://www.next-power.net/next-tube/articles/Veen/VeenEN.pdf

Here's another on line discussion:
http://www.normankoren.com/Audio/TENA.html



So for those DIY tube tweakers,  maybe changing those power and output transformer to equivalent toroids might further improve the sound of your tube gears.  

[arnoldc]

juls, depende sa design!

kung gugustuhin, pwede. i can make a 8W 300B with solid state, tube or hybrid rectification. of course the PSU will be different for each, hence the cost.

re-evaluate your wants. amp ba o X10D?

av_phile, toroid OPT? why not? i'll get a pair from Plitron for my other project...

PAT 3050-SE is $227 each... teka mas mura pa ang Tamura F-475 dito ah?

[john5479]

mahal din pala ng torroids na to  

[av_phile]

mahal din pala ng torroids na to  

My suspicion actually.  But aren't audiophiles known to spend $$$ for even slight audio improvements?  And toroids' wider bandwidth improvement is not slight.

[arnoldc]

My suspicion actually.  But aren't audiophiles known to spend $$$ for even slight audio improvements?

I can be reasonable but not exhuberant (read: i will not buy a 50K Tamura OPT)

And toroids' wider bandwidth improvement is not slight.

Not exactly correct. Amorphous Tamura can go to 100kHz Plitron only 80Khz... the cheap F-475 can go up to 50Khz... FWIW - can your speakers? your ears?

[av_phile]

av_phile, toroid OPT? why not? i'll get a pair from Plitron for my other project...

PAT 3050-SE is $227 each... teka mas mura pa ang Tamura F-475 dito ah?

Malaki ba ang price difference?  

It's up to you if the price difference justifies a Plitron's 100Khz bandwidth over the Tamura's 30Khz bandwidth (unless you go to the higher F series, like the F-2003?)   After all the ears can only hear 20Khz bandwidth, right?   But i read elsewhere the high order harmonics of violins and picolos extend well beyond 50 Khz.  And great speakers have been known to have tweeters capable to reach this high.  Not audible, right.  But to some audiophiles, because the real instruments have then, home systems should have them nonetheless.

Anyway, you could just buy one, reverse engineer it and copy the construction, right? Could be a lot cheaper.

[joan2]

a 5U4 differs from a 5AR4 only is its current handling capability....it is best to have the plate voltages come on when the filaments have stabilised....
 
 
not exactly complete. the 5AR4 is indirectly heated (slow B+ rise) whereas the 5U4G is directly heated. the voltage drop of 5AR4 is only 17V compared to 44V for the 5U4G.

yes, you are correct, an indirectly heated tube has a cathode element covering the filaments, whereas a directly heated one has none, this also applies to all tubes, be they diodes, triodes, tetrodes, pentodes or  heptodes...

[joan2]

Joan2, Arnold here's the link. I appreciate your responses although I have to admit that for a newbie I absolutely have no idea what you're talking about  I need to read up more on the subject. Bear with me here: for example, why is less forward voltage loss a minus for SS? Isn't that a measure of efficiency on the part of SS? I surfed the net and diode manufacturers are touting even lower forward voltage loss which makes me think, being a newbie that I am, that low forward voltage loss is good.

if you don't understand then no problem, just let your ears decide, tube or solidstate rectifier, it doesn't matter  , the tube amp will be inneficient anyway,
just to give you an idea, a dynaco st70 will be dissipating heat as follows:
1. 4 x  el34 tubes with a quiscient plate dissipation of 20 watts say, and filament power 6.3x 0.9 amps for a dissipation of about 100watts.
2. 2 x 7189 tubes with quiscient plate dissipation of 10 watts plus filament loss at 5.6 watts say,

so therefore your amp is consuming electricity at the rate of 0.115 kw per hour just sitting there doing nothing!!!

regarding the link you posted, that is the opinion of the writer, no figures with which to judge was given, if you notice, he used snubbers on schottky rectifiers, so now the circuit became more complex with additional components....schottky  or regular ss rectifiers can benefit from bypass capacitors to take care of the noise...

Im really lost. I thought tube rectification is better than SS rectification. I need your advice guys, i am really bent on buying integrated tube amp. My budget is only less than 20k so that means that i have only limited choices like ts audio 34.1, vintage amp or phasetron tube amps. I talked to andrew sevilla of phasetron and requested him to make el34 with tube rectification this time because his previous versions were all SS rectification. He said he used ss rectifier inorder to produce more power.  he said further that if he uses tube rectification, instead of having 15 watts for SEP mode, only 8 to 9 watts is produced while SET mode produces only 3 instead of 6. Im not really sure if i got the figures  right but is it really true that from SS to tube rectification, there is a downgrade of power output?
 

the power available from the power transformer is fixed, and so by using solid state rectifier, power that would otherwise be lost to the rectifier tube can be used by the the output tube instead...this is as simple as it can get...