Topic: tube vs. ss rectified preamp

[JojoD818]

Oh good, you've also included them in this discussion... what can I say.

I've seen that post before and even read that thread as it was growing.

[ATJr.]

  yes, there are plenty to be learned  in those threads!

[JojoD818]

yep, those guys surely keep my mind and hands busy with experiments. 

[rascal101]

At 60Hz line frequency their is no necessity for fast recovery or ultra fast recovery diodes. If you look at the scope their is virtually no reverse recovery for general purpose, fast recovery, ultra fast recovery and shottky diodes. However, the forward voltage drop for these devices does matter. Greater forward voltage drop less headroom higher ripple voltage. But ripple voltage can be compensated by increasing cap value.

As such, properly designed and layout their should be no difference between the two.

[ATJr.]

@rascal101,

ageed, but many people says they hear differences, me i can not really tell. so who are we to tell them not to use fast rectifiers?

besides, these components are very cheap, using them is no big issue.

[rascal101]

@2ny,

Mahirap talaga mag explain sa mga iba't ibang tao. Sana maka experience din iyung mga iba kung ano ang nakikita ng mga ckt designers o mga nag d diy. This way mas maapreciate mo kung tugma ba iyung design sa listening.

Rascal101

[whipsaw]

Fellas,

I used to own an AMX pre amp which I have now sold to one of our member friends. It had a pair of 12AU7 tubes and a sovtek brand that looked just about as tall but twice as fat behind and between the 2 smaller 12AU7s. Another member told me that the AMX was solid state rectified, and the last tube did not actually function. And it never did in fact work. When he tested it, apparently, it would not light up, yet had no perceived effects on the sound. I am unsure if he mentioned that you could even pull it out.

Interestingly, the newer AMX pre amps did not have the 3rd tube. Could this have something to do with the rectifier? Or could this have been made so that if you wish to upgrade the pre amp into a phono stage, you can do so without having to add an extra tube since it is already there? Hope someone can help. Our friend might have just bought more (or less) than he expected.

cheers

whipsaw

[bumblebee]

Baka Sovtek 12AX7-LPS yun (used as a driver tube?). According to the link below, they often don't "light up" when working properly.

http://www.thetubestore.com/sovtek12ax7lps.html

[whipsaw]

bumblebee,

aha! that might just be it. darn good thing i didnt ditch it. it might just be doing something afterall.

thanks so much!

whipsaw

[H a n $]

Fellas,

I used to own an AMX pre amp which I have now sold to one of our member friends. It had a pair of 12AU7 tubes and a sovtek brand that looked just about as tall but twice as fat behind and between the 2 smaller 12AU7s. Another member told me that the AMX was solid state rectified, and the last tube did not actually function. And it never did in fact work. When he tested it, apparently, it would not light up, yet had no perceived effects on the sound. I am unsure if he mentioned that you could even pull it out.

Interestingly, the newer AMX pre amps did not have the 3rd tube. Could this have something to do with the rectifier? Or could this have been made so that if you wish to upgrade the pre amp into a phono stage, you can do so without having to add an extra tube since it is already there? Hope someone can help. Our friend might have just bought more (or less) than he expected.

cheers



whipsaw

I remember sometime that Andrew made preamps that have a 3rd tube for filter purpose ( to clean the power supply ).   

[whipsaw]

hey hans...

really? that sounds like a nice concept. i wonder if my jolida 707A has something similar...

whipsaw

[markmlists]

I remember some pdvd experts (sir Arnold ata) mentioning 5a4r "does not like high capacitance in the first cap" as it will shorten the life of the tube if you do, do they mean for the B+ or the heater? Can anyone clarify?

Is there a first cap restriction similar to this for 6sn7?

Thanks!

[Garp]

I remember some pdvd experts (sir Arnold ata) mentioning 5a4r "does not like high capacitance in the first cap" as it will shorten the life of the tube if you do, do they mean for the B+ or the heater? Can anyone clarify?

Is there a first cap restriction similar to this for 6sn7?

Thanks!

Hi, its neither. What's being referred to there is the first cap after the tube rectifier in a conventional CLC topology. If your amp is ss rectified, there's no such limitation. That guidelines is not applicable to preamp or power tubes.

[markmlists]

Hi, its neither. What's being referred to there is the first cap after the tube rectifier in a conventional CLC topology. If your amp is ss rectified, there's no such limitation. That guidelines is not applicable to preamp or power tubes.

Thanks Garp!

Sent you pm.

[Jagner]

I remember some pdvd experts (sir Arnold ata) mentioning 5a4r "does not like high capacitance in the first cap" as it will shorten the life of the tube if you do, do they mean for the B+ or the heater? Can anyone clarify?

Is there a first cap restriction similar to this for 6sn7?

Thanks!

This refers to the 5u4G.  which restricts the first Capacitor in a CLC filter circuit to 30 uF. 

[s2kov]

5Y3 => 20uF
5U4G => 30uF
5AR4 => 60uF

[markmlists]

Thankas to all. So pag CRC not affected by these limitations right?

[ATJr.]

Thankas to all. So pag CRC not affected by these limitations right?

yung frist capacitor ang me limitation, reason is we do not want to exceed the rated currents of the tube rects, unless there is enough impedance on the power transformer secondary to limit such currents.