[la_marquise]

Hi:

Does anyone know what the US/European (non-Russian) equivalent to the Chinese 4P1S power tube is? I am trying to completely change the tubes on my LDIII to see if the sound floor and microphonics can be changed.

The front tubes are 1T4/DF91. Does anyone have recommendations as to which brands I should consider?

Also someone suggested tube dampers. Where can I get them and what would be the best way to use them?

All help would be greatly appreciated!!!!!!!!!

Thanks!

 

[la_marquise]

Here are some pictures of the 4P1S (Chinese)/41N1 (Russian) tubes. I would REALLY appreciate it if anyone can recommend the Euro or American names so I can buy the replacements!

THANKS!!!!!!!!!!!!!!!!!!!!

 

[sacd lover]

Quote:

Originally Posted by la_marquise Here are some pictures of the 4P1S (Chinese)/41N1 (Russian) tubes. I would REALLY appreciate it if anyone can recommend the Euro or American names so I can buy the replacements! THANKS!!!!!!!!!!!!!!!!!!!!

I dont think there are any USA or European equivalents.

 

[la_marquise]

I finally found the specs on the *(*&*^*(^ 4P1S tube:

Uf = 4.2V
If = 0.325A
Ua = 150V
Ia= 60 +/- 20mA
Ug1 = -3.5v
Ug2 = 150V
Ig2 less than or equal to 6.5mA
Ug3 = 0V
S = 6+/- 1.5mA/V

PO equal to or greater than 4.2 W

Cin = 8.5pF
Cout = 9.4pF
Cag less than or equal to 0.1pF

Ufmax = 4.7V
Ufmin = 3.9V
Uamax = 250V
Ug2maxp = 250V
Ikmax = 50mA
Pamax=7.5W
Pg2max = 1.5W

Based on the above specs, can someone please help? It's a pentode, octal power tube I believe....

THANKS!!!!!!!!

 

[sacd lover]

The tube you show has a loctal base; not an octal base. Loctals were usually military tubes. The loctal metal base was designed for high vibration environments. In WW2 when planes flew upside down the vibration, plus gravity, could cause a tube to fall out of its socket and they would lose their radio capability. The loctals have a locking mechanism in their base that wont allow the tube to vibrate loose.

The most well known USA loctals are tubes like the 7af7 and 7n7 that are 6sn7 equivalents. There is a USA loctal tube called the 7b5 thats a power pentode .... and a tube called the 7c5 thats a tetrode power tube. You might check and see if the last two could be used as substitutes.

 

[edisonwu]

Is this the little dot 3 amplifier? Why not ask the amp designer for the help? He is a very talking man. He may know such things better than any other people here. I am sure he will provide you better choice on tubes swapping.

 

[la_marquise]

Quote:

Originally Posted by edisonwu Is this the little dot 3 amplifier? Why not ask the amp designer for the help? He is a very talking man. He may know such things better than any other people here. I am sure he will provide you better choice on tubes swapping.

Yes, unfortunately he suggested the Russian 4N1N, which is just as difficult to find.

He helped me with the triodes though, so I now have some 1T4/DF91s on order. Hopefully they will reduce the microphonics by a very large margin. And have cleaner noise floor.

 

[la_marquise]

Quote:

Originally Posted by sacd lover The tube you show has a loctal base; not an octal base. Loctals were usually military tubes. The loctal metal base was designed for high vibration environments. In WW2 when planes flew upside down the vibration, plus gravity, could cause a tube to fall out of its socket and they would lose their radio capability. The loctals have a locking mechanism in their base that wont allow the tube to vibrate loose.

"Roger, roger..." plane has imploded due to exploding (l)octal tubes...thanks for the correction! I guessed at the octal part from the pins.

Quote:

Originally Posted by sacd lover The most well known USA loctals are tubes like the 7af7 and 7n7 that are 6sn7 equivalents. There is a USA loctal tube called the 7b5 thats a power pentode .... and a tube called the 7c5 thats a tetrode power tube. You might check and see if the last two could be used as substitutes.

Will do! Thanks for the tip!

 

[la_marquise]

Quick question: can I still use the 7B5 if the heater voltage is 6.5v, where as the 4P1S is 4.2v or 4.5v?

Current is 0.4A which is .05A higher than the original...

 

[edisonwu]

Quote:

Originally Posted by la_marquise Yes, unfortunately he suggested the Russian 4N1N, which is just as difficult to find. He helped me with the triodes though, so I now have some 1T4/DF91s on order. Hopefully they will reduce the microphonics by a very large margin. And have cleaner noise floor.

What a pity......I wish I could help...

BuMp for you,

 

[sacd lover]

Quote:

Originally Posted by la_marquise Quick question: can I still use the 7B5 if the heater voltage is 6.5v, where as the 4P1S is 4.2v or 4.5v? Current is 0.4A which is .05A higher than the original...

The heater current is close enough but the voltage would need to be upped to 6.3 volts.

 

[viconte]

Quote:

Originally Posted by la_marquise Yes, unfortunately he suggested the Russian 4N1N, which is just as difficult to find. He helped me with the triodes though, so I now have some 1T4/DF91s on order. Hopefully they will reduce the microphonics by a very large margin. And have cleaner noise floor.

Hi pal, so how does the 1T4 sound? One of my local forumers tried the Mullard DF91 on his LD 2 but "I thought that this could get rid of the microphonics but that's not the case and the "upgrade" didn't really improve the sonic performance. There's a slight difference but only if you listen hard enough."
http://www.sgheadphones.net/index.ph...t=0#entry62284

I wondered if the 1T4 is worth getting, yup the 4n1n and the 4pi1pi seems to be non-existent...

Other choices seem to be DF94 or 1s5(which didnt work well wif yours rite?) as suggested by Yang, the maker, below
http://www.erji.net/read.php?tid=168...oread=&page=34
http://www.erji.net/read.php?tid=168...oread=&page=70

The new version, LD3+ is coming out too, uses Mullard EF91
http://www.erji.net/read.php?tid=211982&fpage=1

 

[Csericks]

I use Herbie's Tube Dampers on all the tubes in my ARC units and my CD player; I think that they are the best. I'm not sure that you would get the same results with a headphone amp as it is not subjected to the vibrations that a speaker system is.

 

[Maniac]

Quote:

Originally Posted by la_marquise /img/forum/go_quote.gif Here are some pictures of the 4P1S (Chinese)/41N1 (Russian) tubes. I would REALLY appreciate it if anyone can recommend the Euro or American names so I can buy the replacements! THANKS!!!!!!!!!!!!!!!!!!!!

It may be a bit late, but I just got my LD 3 (not the plus version), and found that it is not 4N1N, but rahter 4P1S... or in Russian

I'm placing an order for 4 tubes, and I kinda suspect that the Russians will have better tubes than the Chinese. Since most of their so called Chinese tubes are copied from Russian anyways.

http://el-tubes.webzone.ru/index1.html

As for the input tube, the circuit can be modified to be more like LD3+, the original circuit is:

and the input tube can be changed to:

Note this is not gonna be a mod that can be done in a snap by anyone, as stuff like heater voltage and stuff needs to be changed, and pinout is also different. but at least it is the same base, and easier than changing the whole damn socket to something else.