6x4 or diodes ?? Any difference ?

[hugo]

Hi, i can choose between diodes and 6x4 tube on power supply of Drip Pultec v3... WHat do you think about it ? For sure the tube is cool lloking, but in term of performances and noise floor, is there any difference ?
thanks

 

[ln76d]

Try - you will see if it's worth
In some units yes, in some not.k
I wouldn't bother with noise issues.
Always you can make "dual rectifier".
Definately there should be voltage drop, or "sag" - with vacuum rectifier.

 

[bruno2000]

With as little current as a Pultec draws, the "sag" will make little to no difference....
Best,
Bruno2000

 

[ln76d]

Doesn't here matter higher resistance of tube rectifiers more than current consumption?

 

[hugo]

Out of all considerations...which choice would you make ? You have to choose...6x4, or diodes, not both..
I could test but i do not like free holes with solder inside...

 

[AusTex64]

I built my pair with 6X4's because that's what the originals used. I haven't done a comparison between diodes and rectifier tubes. I agree with Bruno2000 that voltage sag won't be an issue with that unit. I would bet either way will sound good.

 

[hugo]

I built my pair with 6X4's because that's what the originals used. I haven't done a comparison between diodes and rectifier tubes. I agree with Bruno2000 that voltage sag won't be an issue with that unit. I would bet either way will sound good.

Thanks for reply ! I have one question..There is like a "low noise" system on drip pultec v3.. It it possible to bypass it, but is it a good idea ? Is the noise floor so bad on vintages unit ?..

 

[ruffrecords]

Three factors affect noise floor:

1. AC interference from the heaters. This is down to good layout and routing
2. Hiss from the tubes. The Pultec has only about 20dB of gain so noise should not be an issue unless you get a bad one.
3. Hum from the HT. Some of this depends on the amplifier topology - some reject hum on the HT better than others. Most of it is down to smoothing. For mic pres the more smoothing the better in my experience. For line level signal you can get away with less but I would advise you not to leave any of it out.

Cheers

Ian

 

[abbey road d enfer]

Hi, i can choose between diodes and 6x4 tube on power supply of Drip Pultec v3... WHat do you think about it ? For sure the tube is cool lloking, but in term of performances and noise floor, is there any difference ?
thanks

The actual significant difference will be 20-30 V more on B+ with diodes. That may impact marginally the performance (more headroom, less THD), but not noise. As Ian wrote, noise performance in tube gear is conditioned by other factors.

 

[hugo]

Hi, i can choose between diodes and 6x4 tube on power supply of Drip Pultec v3... WHat do you think about it ? For sure the tube is cool lloking, but in term of performances and noise floor, is there any difference ?
thanks

The actual significant difference will be 20-30 V more on B+ with diodes. That may impact marginally the performance (more headroom, less THD), but not noise. As Ian wrote, noise performance in tube gear is conditioned by other factors.

Thanks a lot for this info. I already soldered 6x4 sockets last night...thinking the unit will be more sexy with a third tube, and it will maybe be useful the day i have to sell them..

 

[AusTex64]

I built my pair with 6X4's because that's what the originals used. I haven't done a comparison between diodes and rectifier tubes. I agree with Bruno2000 that voltage sag won't be an issue with that unit. I would bet either way will sound good.

Thanks for reply ! I have one question..There is like a "low noise" system on drip pultec v3.. It it possible to bypass it, but is it a good idea ? Is the noise floor so bad on vintages unit ?..

I built the version 2, which has AC tube heaters. The "low noise" section you're referring to is a section added for DC heaters. If it were me, I would take advantage of it, simply cause it's there and won't cost much in parts to populate. Having said that, original units have AC heaters and no one is complaining. My units have AC heaters and are dead quiet. Again, either way you'll probably be OK.