Woo Audio Amp Owner Unite

[jc9394]

Danny, try to get a pair of Mullard GZ37, they sounds really good and won't break your bank.

 

[dannie01]

Quote:

Danny, try to get a pair of Mullard GZ37, they sounds really good and won't break your bank.

Thanks, John. Will search where's available.
 

 

[dannie01]

About the Mullard, found that available in brown base and black base and the price is almost the same. Any idea which one would sound better or they just the same sonically?
 
 


 
EDIT. Or maybe I'm color blind, they look both brown base?
 

 

[jc9394]

they both looks brown to me.

 

[2359glenn]

 
Quote:

 

Thank you, Glenn.
 
 
 

And what about a 5Z3, I learn that the 5Z3 in same specification and the 5U4G can be replaced with adapter, is that correct?

Yes the 5Z3 is identical to a 5U4 with a 4 prong base actually it is the predecessor of the 5U4.   You would need a adapter
 

 

[2359glenn]

 
Quote:

I have a metal base Mullard GZ34 and it sound as good as the EML I have but the amp runs much hotter.  I have bring this up to Jack and did said it is fine and try to keep the listening session under 8 hours.

The GZ34 raises the B+ voltage a little making the 6AS7s draw a little more current and the two 25 watt cathode resistors for these tubes are heat sinked to the
case. with the higher voltage these resistors will dissipate a little more heat. This won't heart anything the capacitors in the amp are rated at 105 deg Centigrade.
 

 

[dannie01]

 


 
Quote:

they both looks brown to me.

Haha, I am really a color blind.

 
Quote:

Yes the 5Z3 is identical to a 5U4 with a 4 prong base actually it is the predecessor of the 5U4.   You would need a adapter
 

Thanks Glenn, I will get a pair of Fivre 5Z3s locally and the seller is kind enough to give me apir of adapter free of charge.

 
 

 
Also, I will order these Mullard 5U4Gs to give them a try and compare how they sound with the Fivre.
 

 

 

[john57]

The 5AR4/GZ34 is rated for a 250 mA. draw. The GZ37 is rated at 275 mA. into a cap. I/P filter and 350 mA. into a choke I/P filter. Also, the GZ37 data sheet says 4 muF. max. for a cap. I/P filter.

The forward drop in a GZ37 is greater than that in a GZ34. So, the B+ rail voltage will be somewhat higher. Current production 5AR4s have improved significantly of late and that's what I'd use.
__________________
 

The 5R4 can deliver plenty of current too. 4 muF. is max. for that type too. Arc over at start up is NOT good.

There are reports about the GZ37 sounding mediocre when used as a substitute for the GZ34. My hunch is that the tube is stressed, even if it does not arc over with a substantial filter cap.

The data sheet I've seen was published by Chelmer Valve.
 

__________________
 
Eli D.
 
 
http://www.diyaudio.com/forums/tubes-valves/60100-gz37-substitution.html
 
My vote is the 5AR4/GZ34 since I did find that the 5AR4 sound much better than the 5U4 types in my situation with a more clear and sharper sound.
The Mullard that I have seen here have brown bases.
 

 

[Clayton SF]

I know the Chinese (Shuguang) and the Slovak Republic (JJ Electronic) currently produce the 5AR4. Are you aware of any others? Thanks.

 

[dannie01]

Quote:

The 5AR4/GZ34 is rated for a 250 mA. draw. The GZ37 is rated at 275 mA. into a cap. I/P filter and 350 mA. into a choke I/P filter. Also, the GZ37 data sheet says 4 muF. max. for a cap. I/P filter.

The forward drop in a GZ37 is greater than that in a GZ34. So, the B+ rail voltage will be somewhat higher. Current production 5AR4s have improved significantly of late and that's what I'd use.
__________________
 

The 5R4 can deliver plenty of current too. 4 muF. is max. for that type too. Arc over at start up is NOT good.

There are reports about the GZ37 sounding mediocre when used as a substitute for the GZ34. My hunch is that the tube is stressed, even if it does not arc over with a substantial filter cap.

The data sheet I've seen was published by Chelmer Valve.
 

__________________
 
Eli D.
 
 
http://www.diyaudio.com/forums/tubes-valves/60100-gz37-substitution.html
 
My vote is the 5R4/GZ34 since I did find that the 5AR4 sound much better than the 5U4 types in my situation with a more clear and sharper sound.
The Mullard that I have seen here have brown bases.
 

Thanks for the information, john57. Do you think this pair of 5R4 is good?
 


 

 

[2359glenn]

Quote:

I know the Chinese (Shuguang) and the Slovak Republic (JJ Electronic) currently produce the 5AR4. Are you aware of any others? Thanks.

Sovteck  5AR4  made in the Reflector factory in Russia
 

 

[musicman59]

Quote:

Thanks for the information, john57. Do you think this pair of 5R4 is good?
 


 

Danny,
You should try this Brimar. I have them for my WA5-LE and really like them.
http://www.upscaleaudio.com/products/Brimar-5R4GY.html
 
Also this Mullard GZ33
http://www.upscaleaudio.com/products/Mullard-GZ33-%7B47%7D-CV5745.html
 
 

 

[john57]

[size=12pt]My answer is no. I made a mistake dropping the A at first. The 5R4 tube is not the same as a 5AR4 tube. The 5R4 is like a 5U4 but designed to operate at higher voltages like 600V for transmitter tubes but that is not what you want. The 5AR4 has greater current capacity with less voltage sag which makes it a better choice in an amp. Also the 5AR4 is slower to warm up and gives the power tubes more time to warm up before all the high voltage is applied.  THe GZ33 might be a good substitute for a 5AR4 [/size]
Quote:

Thanks for the information, john57. Do you think this pair of 5R4 is good?
 


 

 

 

[2359glenn]

 
Quote:

The 5AR4/GZ34 is rated for a 250 mA. draw. The GZ37 is rated at 275 mA. into a cap. I/P filter and 350 mA. into a choke I/P filter. Also, the GZ37 data sheet says 4 muF. max. for a cap. I/P filter.

The forward drop in a GZ37 is greater than that in a GZ34. So, the B+ rail voltage will be somewhat higher. Current production 5AR4s have improved significantly of late and that's what I'd use.
__________________
 

The 5R4 can deliver plenty of current too. 4 muF. is max. for that type too. Arc over at start up is NOT good.

There are reports about the GZ37 sounding mediocre when used as a substitute for the GZ34. My hunch is that the tube is stressed, even if it does not arc over with a substantial filter cap.

The data sheet I've seen was published by Chelmer Valve.
 

__________________
 
Eli D.
 
 
http://www.diyaudio.com/forums/tubes-valves/60100-gz37-substitution.html
 
My vote is the 5AR4/GZ34 since I did find that the 5AR4 sound much better than the 5U4 types in my situation with a more clear and sharper sound.
The Mullard that I have seen here have brown bases.
 

Looking at tube specs the 5V3/5AU4 is the most powerful of these type tubes has a transientplate current of 6.6 amps. dam I have a couple of these
and never tried one.
John this tube might slightly beat the 3DG4

 

[PanamaRed]

Only two rectifiers i've tried in those Decware amps was the 6106 and a NOS RCA 5Y3G. I have quite a few other rectifiers to roll in there but I never felt compelled to.
 
Quote:

Bendix 6106, the original rec or rolled-in these two amps? If the latter, what did you have in prior?