Few questions regarding valve Amps like lyrita yaqin jolida etc

[corElement]

1. What factors determine the life of a tube amplifier

2. Do tube amps themselves (not output) emit a "hum" when they are on?

3. Is the background from which sound emerges dark/black or is there a hint of "hiss" when volume is increased?

4. In regards to a soundcard like STX and it's "pre-amp" control interface, if one has a tube poweramp only where you only turn the tube amp on and off, can one "avoid" getting a "seperate preamp" and reduce clutter in the signal by just using the soundcard's controls itself?

5. When there is a signal running to the tube amp do the tubes heat up only then, or are they always heated up to a specified amount acc to the amp designer?

6. How are tubeamps affected by frequent power cuts and what can damage them?

7. When power is cut from the amp, do tubes continue to play for a second or two till the signals gone through?

8. What factors determine the possibility of amp-rolling?

9. What controls the tube to be or not be overdriven? Preamp volume voltage? power supply?

10. Are high quality SET tubeamps necessarily a lot heavier than medium-end solid state?

11. I see a lot of non toroidal transformers used in tubeamps, whats the reason?

Thats all for now, hope these arent very difficult questions >.<

 

[ranjeetrain]

It is advised to soft-turn on a tube amp. Yes, when you turn them off, they cut down slowly. They are not instant on-off devices.

They benefit from not being touched (they admire admiration from a distance). Frequent power cuts will somehow reduce their life.

A well designed amp, connected into a proper AC outlet, will not give any hiss, tube or SS doesn't matter. If am amp is giving hiss, check the electrical connection, grounding, the amp itself. Something is wrong.

You can run a tube power amp directly if you so wish.

 

[odyssey]

I can take a crack at some of the questions

In a well designed and executed tube amp, there should be no hum or hiss - it should be no different from any solid state

In general the rule of thumb for tube amps is as follows
1. Never switch on tube amps unless there is a load connected
2. Never switch on and off within 1 minute (wait for about a minute for either action)
3. Output transformers are the main reason for the sound (all things being equal) quality/difference. In addition, for certain SETs, the output transformers are huge. We will be getting some SET amps, one of which is almost 65Kgs !! the main reason is due to the weight/size of the output transformers

As far as I know the tube amps have a certain plate voltage and that is applied irrespective of the signal being present or not. how much heat they dissipate is a result of the configuration/efficiency.

regarding toroidal vs EI transformers - tube amplifiers require high voltages, which in turn translate to a high number of turns. A toroidal with a high number of turns is much more expensive than the EI ones. However, some manufacturers do use toroidal ones - Balanced Audio Tech (BAT) is one such

cheers

 

[corElement]

It is advised to soft-turn on a tube amp.

What do you mean soft turn on?

They benefit from not being touched (they admire admiration from a distance). Frequent power cuts will somehow reduce their life.

That's..a little concerning..considering Gurgaon's power situation = multiple power cuts every hour.....

 

[corElement]

I can take a crack at some of the questions

In a well designed and executed tube amp, there should be no hum or hiss - it should be no different from any solid state

In general the rule of thumb for tube amps is as follows
1. Never switch on tube amps unless there is a load connected
2. Never switch on and off within 1 minute (wait for about a minute for either action)
3. Output transformers are the main reason for the sound (all things being equal) quality/difference. In addition, for certain SETs, the output transformers are huge. We will be getting some SET amps, one of which is almost 65Kgs !! the main reason is due to the weight/size of the output transformers

As far as I know the tube amps have a certain plate voltage and that is applied irrespective of the signal being present or not. how much heat they dissipate is a result of the configuration/efficiency.

regarding toroidal vs EI transformers - tube amplifiers require high voltages, which in turn translate to a high number of turns. A toroidal with a high number of turns is much more expensive than the EI ones. However, some manufacturers do use toroidal ones - Balanced Audio Tech (BAT) is one such

cheers

Thank you that was pretty informative.

1. By load connected you mean speakers should be connected yes?
2. In my situation where when power goes every hour and there is a 10 second delay till generator power kicks in (sometimes twice in 1 minute) I am be at the mercy of bad power. What kind of damage should I expect in this kind of scenario?

3. In regards to plate voltage, I'm a little confused, I'm not sure if im talking about the right thing but if i remember correctly Virenji from Lyrita had once mentioned he prefers not driving his tubes to their maximum and prefers running them conservatively even though some people say tubes like 845 perform their best pushed to the limit at the cost of their life expectancy. What I'm curious about is how is this "limitation" put in place. Like the gm70 I read can push 40watts but virenji drives it to 15watt in his integrated SET and 30watts on his monoblocs. Is it the use of more transformers that allow higher voltage resulting in more use of those watts?

Thanks for answering the questions again

 

[iaudio]

Yes, speakers should always be connected to the tube amp when powering it on. Learnt this from Rajiv

 

[odyssey]

CorElement

its about how hard you push the tubes in terms of voltage applied. A good example would be to see the cheaper chinese tube manufacturers, they push the tubes to the limit and derive higher wattage, however this drastically brings down the life expectancy of the tube. A good design may use twice the number of tubes to maintain the same overall power rating but also keep the life expectancy higher, but then this also increases cost
It may also be true that pushing a tube harder may change the sonic signature but I dont know how this is exactly affected.

cheers

 

[jai1611]

One additional point - the life of a tube depends to a large extent on the number of times its switched on/off (more than absolute number of hours used). Very frequent switching on-off will reduce tube life

 

[soundofmusic]

@ Odyssey , If I want to Bias the tube amplifier, should i do it with the speakers connected? sorry for the noob question.

And whats that SET weighing 65kg's and when it is expected:licklips:

cheers

 

[odyssey]

yes, it should be connected

 

[viren bakhshi]

Hello corElement,

All your questions brought a smile to my face, since they echo a lot of the apprehensions people have about tube amps. I'll answer them more in a general way.

Everything is related to the execution of the design. Tube amp circuits are very simple and straightforward. And, all variations have already been explored and documented. Beware of companies that tout revolutionary innovation in tube circuitry - they are pulling your legs!

The circuits are built around the tubes you use. Input stages are primarily voltage gain stages, running in class A at low currents. These tubes are not stressed at all, and should last a good many years. The output tubes provide the power, through a coupling transformer, to your speakers, and are the ones running at higher currents. Heat generated is the detriment to these tubes, determining their service lives. The tubes can be run over a large range of operating conditions (voltage and current) - the designer selects the optimum point for his design. If you opt for maximum power, you run the tubes hot, limiting their service life. Usually, you compromise, and select an operating point for adequate power and good sound.

Tubes have heaters, which light up to incandescence, to help generate the electrons for signal transfer. That is a fixed heat load on the tube. Operation, under high voltage and current, puts an additional heat load on the tube. Those conditions are selected by the designer, and effect the life of the tube. The initial warm up is to allow the heaters to come to full temperature, before operating the tube.

Tube amps run at high DC voltages, from 200V to 1200V. They are far more tolerant of supply voltage fluctuations, than solid-state amps. Most of the damage is caused by voltage spikes during brownouts, or interruptions in supply - spikes as high as 1000V. As you can see, this is a mere burp for a tube, and rarely causes any damage. In any case, if you have recurrent supply problems (Gurgaon is notorious!), look to installing an appropriate UPS to protect all your equipment.

Tube amps are transformer based, both for supply, and audio output. In single ended designs, the full DC current flows through the output transformer, and will cause saturation of the transformer core unless an air gap is introduced in the core. With the air gap, the input inductance falls, and a larger winding, with a larger core, is used to compensate. The transformer size, and weight, and cost goes up! Besides, EI core transformers allow easy adjustment of the air gap - hence, their use. Selection for purpose!

Regards,
Viren

 

[CLEARCUT]

Clear me some doubts about push pull and set amps. Pros and Cons. Can set be engaged in to drive nominal multi driver speakers.

 

[viren bakhshi]

Hi,

This might explain a few things:
AUDIO FILE

Other than that, you have to listen to the amplifier and speaker combination, to gauge whether they work for you or not. Regardless of whether the amp is a single-ended or push-pull design. If specifications told us all we need to know, we wouldn't be having these listening sessions! And, amps don't discriminate against music - play what you will. A well designed system will reproduce all music well.

Regards,
Viren

 

[corElement]

That was quite an eye opener! Thank you for taking the time to reply to my questions Mr. Bakhshi I googled some of the stuff you wrote further to understand better!

Hmm, by "input stages are primarily voltage gain stages" does it refer to the voltage gain from the preamp?

In regards to UPS, suppose we consider amps where one is 3 w and the other being approx 20 w, what kind of UPS rating should one be looking at for each?