Dynaco Fever

[SunnyDaze]

7: Assuming that the amplifier is operating properly, quality manufactured tubes will last an awful long time. My Magnavox 8800 has original power tubes from 1960.

I've pondered this a time or 2...do power tubes degenerate at an excelerated rate compared to say the tubes in a pre amp? I've still got original tubes in a 490t cd player and it sounds OK to me?

I've always read that quality power tubes will last 1/2 as long as small signal tubes, all other things being equal. 

[AdamG]

You can think of them somewhat like (DC) lightbulbs, in that the higher the voltage running through them the brighter they'll burn, but the shorter they'll live. Bigger power tubes, especially if you've got the bias cranked on them beyond MFR specs, will almost definitely have a shorter life than small-signal tubes. It's just a lot more work to do!

[EmperorNorton]

Speaking of Dynaco fever,  I have a SCA-35 on the way.  It should be here around Christmas.   I am very anxious to hear the mystical 'warm tube sound."

[schwarcw]

I've always read that quality power tubes will last 1/2 as long as small signal tubes, all other things being equal. 
[/quote]

If that long.  The high output AC voltage tubes generate a lot of heat.  The tube life is a of the function of the heat generation by the tube.  Heat kills tube life.  Signal tubes operate at a much lower temperature compared to power tubes.  I always enjoyed the EL84 (6BQ5) more than the 7591, GZ34 or the KT tubes.  The EL84 playing with an efficient or small speaker sound very nice.  Smooth, buttery or just more involving are words that come to mind.  I have not owned a set of Klipsch speakers so you will need to judge that for yourself.  Also cheaper tubes will have shorter life. 

I have heard many nice sounding ST-70 Dynacos with mid size speakers playing at reasonable sound levels.  If you are not interested in a nice three dimensional stereo image, and just want to play music at high volume levels to shake the walls, I recommend a solid state amp.  tubes don't add SQ when listening to music at 90 dB or higher.  Your just making noise

If you want a lot of power and the smooth sound of tubes, use a tube preamplifier and a solid state amp.  High ouput tube amplifiers will never match the dynamics of a good solid state amps.

[Reverend]

High ouput tube amplifiers will never match the dynamics of a good solid state amps.

I don't agree with that.   

[OldiesButGoodies]

If you want a lot of power and the smooth sound of tubes, use a tube preamplifier and a solid state amp.  High ouput tube amplifiers will never match the dynamics of a good solid state amps.

Well said Carl I fully agree.   


 

[AdamG]

I don't know if 'never match the dynamics of a good solid state amp' is fully true, but cost-effectively it is I feel. I love my tube-pre w/ solid state power combo. Some people say tube pre + tube amp is too 'tubey', it's all very setup dependent. I think I'm going to stick with this setup as my main for now though.

[StephenWVU]

I think it is a dangerous assumption that if you run a tube preamp and a solid state amp you will get that perfect dynamic sound with the added smoothness. I think it is more about matching individual sound signatures and hoping the equipment plays nice. Sound signature of both the preamps and amplifiers can easily be changed with tubes (assuming you aren't trying to replace 16 300B tubes). My recommendation is if you can buy the piece of equipment and sell it to make a profit or at the very least break even, it doesn't hurt to try it in your system. If you can't resell it and at least break even then there is always another deal (possibly a type of equipment you didn't know existed).

[Reverend]

If you want a lot of power and the smooth sound of tubes, use a tube preamplifier and a solid state amp.  High ouput tube amplifiers will never match the dynamics of a good solid state amps.

Well said Carl I fully agree.   


 

I think he meant a good quality SS amp.  Not a HT amp.   

[bmwr75]

Some small signal tubes (preamp tubes) will last 10,000 hours.   Power tube typically last 1/5th as long if biased as they should be.

[SunnyDaze]

If you want a lot of power and the smooth sound of tubes, use a tube preamplifier and a solid state amp.  High ouput tube amplifiers will never match the dynamics of a good solid state amps.

Well said Carl I fully agree.   


 

When you increase the number of turns in an OT, you increase the capacitance and primary leakage inductance, both of which may compromise dynamics, especially at higher frequencies. Keep increasing turns and you lose HF extension.

You can roughly calculate the high frequency cut off as:

FrequencyCutoff = PrimaryImpedance  / (2 x 3.14 x LeakageInductance)

Less turns in an OT means reduced low frequency output. It's all a balancing act.

[Sir Thrift-a-Lot]

High ouput tube amplifiers will never match the dynamics of a good solid state amps.

I don't agree with that.   

I sort of agree.   The way I understand it is that at low output, tubes and solid state will have roughly equal dynamic range.   But as you get close to max output, tubes have the effect of compressing the signal while SS clips it.   To my ears, the compressed tube sound is "better" than the clipped SS sound, but the SS does technically have more dynamic range at that point.

[Sir Thrift-a-Lot]

I think it is a dangerous assumption that if you run a tube preamp and a solid state amp you will get that perfect dynamic sound with the added smoothness. I think it is more about matching individual sound signatures and hoping the equipment plays nice. Sound signature of both the preamps and amplifiers can easily be changed with tubes (assuming you aren't trying to replace 16 300B tubes). My recommendation is if you can buy the piece of equipment and sell it to make a profit or at the very least break even, it doesn't hurt to try it in your system. If you can't resell it and at least break even then there is always another deal (possibly a type of equipment you didn't know existed).

I absolutely agree with this.

[schwarcw]

I think it is a dangerous assumption that if you run a tube preamp and a solid state amp you will get that perfect dynamic sound with the added smoothness. I think it is more about matching individual sound signatures and hoping the equipment plays nice. Sound signature of both the preamps and amplifiers can easily be changed with tubes (assuming you aren't trying to replace 16 300B tubes). My recommendation is if you can buy the piece of equipment and sell it to make a profit or at the very least break even, it doesn't hurt to try it in your system. If you can't resell it and at least break even then there is always another deal (possibly a type of equipment you didn't know existed).

Nothing is perfect, and everything is subjective.  Let your ear be the judge.