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6N1P

47.197.10.172
Posted on January 15, 2023 at 07:25:25
Brad225
Audiophile

Posts: 127
Location: Tampa
Joined: December 25, 2006
Contributor
  Since: January 26, 2008
 I am looking for good 6N1P tubes for the rebuild of my ARC 610t amps. Very few available.

I purchased 4 Sovtek from a known dealer and all of them are bad right out of the box.
The only tubes I am finding are Voshkod 6N1P. Some with the Rocket logo some without.

I have read sometimes they are re-branded as Sovtek or Svetlana.

Can any of you tell me if the Voshkod tubes are good quality in general.

Thanks Brad

 

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If you can, find the 6N1P black plate. It is. . , posted on January 15, 2023 at 10:06:45
John PA
Audiophile

Posts: 3990
Location: The lower 48.
Joined: August 27, 2000
 the best sounding IMO and is bullet proof. 1965 was a good year but they are hard to find. I used to see them on eBay from time to time. I bought mine years ago, a full factory box, from a guy that went back to Russia once a year and would bring back tubes.


iBasso DX300MAX Ti. Focal Utopia and Stellia. iBasso SR2. Mr. Speakers, Ether II, Voce stats. Manley, Absolute headphone amp. LTA MZ3, Z10e electrostatic amp. Many other headphones, amps, cables etc.

 

Here is an example of what I have . . , posted on January 15, 2023 at 10:09:38
John PA
Audiophile

Posts: 3990
Location: The lower 48.
Joined: August 27, 2000
 This seller is from Russia but only has one left.

https://www.ebay.com/itm/183915437429


iBasso DX300MAX Ti. Focal Utopia and Stellia. iBasso SR2. Mr. Speakers, Ether II, Voce stats. Manley, Absolute headphone amp. LTA MZ3, Z10e electrostatic amp. Many other headphones, amps, cables etc.

 

RE: 6N1P, posted on January 15, 2023 at 12:27:34
Jonesy
Audiophile

Posts: 3047
Location: Winnipeg, Manitoba
Joined: September 1, 2005
Contributor
  Since: March 1, 2018
 Sorry to hear about the bad tubes. Hope you can return them.

Just curious how you know all 4 are bad. The way they look/sound/test?


"I know just enough to get into trouble. But not enough to get out of it."




 

RE: Here is an example of what I have . . , posted on January 15, 2023 at 12:31:29
Brad225
Audiophile

Posts: 127
Location: Tampa
Joined: December 25, 2006
Contributor
  Since: January 26, 2008
 Thanks John, I did see that.

It also says in big red letters Does Not Ship to United States. My guess is the government there has cracked down on shipping.

I couldn't find any seller from that part of the world that sold anything but the Voshkod 6N1P.

It looks like there is a Voshkod 6N1P-ED that is a bit heavier version so unless I find someone that is selling personal stash I won't have much choice.

I am going to call ARC tomorrow to see if they have any left. They have changed their designs to eliminate that tube from their amps.

Thanks Again, Brad

 

RE: 6N1P, posted on January 15, 2023 at 12:48:29
Brad225
Audiophile

Posts: 127
Location: Tampa
Joined: December 25, 2006
Contributor
  Since: January 26, 2008
 In the amps there are 20 turn variable off set resistors for positive and negative voltage. You need to adjust both to "0" volts in order for the power tubes to bias properly.

With all 4 new tubes in either amp they would not allow the voltage to be adjusted from between 5-6 volts to "0".

When we put the old same manufacturer tubes in, both amps would allow for "0" volt adjustments for the circuits.
It is very strange but no other conclusions than the new tubes are the problem.

Down side is I have had the tubes for 6+ month and can't find the receipt or any email related to the purchase. I will call VIVA Tubes but, I don't hold out much hope of a refund or receiving a credit toward the Voshkod tubes.

It is a good thing my EE friend is incredibly smart and built and rebuilt many pieces of audio equipment.

 

RE: 6N1P, posted on January 15, 2023 at 15:46:41
sony6060
Audiophile

Posts: 1254
Location: USA
Joined: August 8, 2014
 280 listings on eBay.

 

Yes, but I was. . . , posted on January 15, 2023 at 15:57:33
John PA
Audiophile

Posts: 3990
Location: The lower 48.
Joined: August 27, 2000
 showing you what they look like.


iBasso DX300MAX Ti. Focal Utopia and Stellia. iBasso SR2. Mr. Speakers, Ether II, Voce stats. Manley, Absolute headphone amp. LTA MZ3, Z10e electrostatic amp. Many other headphones, amps, cables etc.

 

RE: 6N1P, posted on January 15, 2023 at 18:07:46
Jonesy
Audiophile

Posts: 3047
Location: Winnipeg, Manitoba
Joined: September 1, 2005
Contributor
  Since: March 1, 2018
 That reminds me of certain brands of signal tubes that would never allow me to dial in the DC balance correctly and hence biasing the output tubes. Nothing wrong with them. Just not a good fit in my (40 year old?) but still in use ARC D70.

It may be the same case with the 6n1p.

I came across some medium and high gain 6n1p on the web. I wonder if that would make a difference to making the adjustment. Maybe your tech friend would know and it would help you refine your search.



"I know just enough to get into trouble. But not enough to get out of it."




 

RE: Yes, but I was. . . , posted on January 15, 2023 at 20:28:06
Brad225
Audiophile

Posts: 127
Location: Tampa
Joined: December 25, 2006
Contributor
  Since: January 26, 2008
 Sorry John, if my response sounded unappreciative. I'm thankful for any input I receive here.

So far, no one on any site I have asked on, seems to know anything about the Voshkod tubes.

That seems to be the only tube available world wide at this time. I may have to make a choice between the unknown tube or a tube with 3000 hours on it.

Not a pleasant choice.

Thanks,
Brad

 

RE: 6N1P, posted on January 16, 2023 at 04:22:49
Uncle Mike
Audiophile

Posts: 6164
Location: Southeastern Pa.
Joined: June 20, 2003
 I am asking just for giggles. Have you left the tubes in circuit long enough to warm up nicely and/or burn in? I have seen tubes, especially vintage Russian that are out of spec or will not test unless left powered for an extended time. Once they burn in they are fine. Why not try leaving the tubes in circuit for 8 hours or so and see if you can adjust towards your target voltage.
Another other option is to add resistance to get to the voltage you want. You're EE friend should be able to help with that.
No need to throw out the baby with the bath water yet.

 

RE: 6N1P, posted on January 16, 2023 at 07:42:59
Shep
Audiophile

Posts: 242
Location: Southeast U.S.
Joined: March 13, 2001
 Most Decware amps use 6N1P as an input tube, so you may want to try their site or the classifieds in their forums.

Here's a link to a classified on the forum and I assume the "6P1P" is a typo that that's intended to be for 6N1P...
https://www.decware.com/cgi-bin/yabb22/YaBB.pl?num=1671974744

 

I am really surprised at how . . , posted on January 16, 2023 at 09:46:14
John PA
Audiophile

Posts: 3990
Location: The lower 48.
Joined: August 27, 2000
 hard they are to find now. The 6N1P used to be very common, except for the black plate, and reliable.

I know that some bass players and some other guitarists really like to use the tube, when the rig is set up for them as they last long and they like the tone.

You can message me about the tube. I don't come on here to sell tubes but I have a few.


iBasso DX300MAX Ti. Focal Utopia and Stellia. iBasso SR2. Mr. Speakers, Ether II, Voce stats. Manley, Absolute headphone amp. LTA MZ3, Z10e electrostatic amp. Many other headphones, amps, cables etc.

 

RE: Here is an example of what I have . . , posted on January 20, 2023 at 13:14:43
Akolegov88
Audiophile

Posts: 373
Joined: January 7, 2014
 Re "the government there has cracked down on shipping" - I believe the main reason is that PayPal and SWIFT are blocked by a 'different' government and the seller won't be able to receive the money.

 

RE: 6N1P, posted on January 20, 2023 at 13:26:29
Akolegov88
Audiophile

Posts: 373
Joined: January 7, 2014
 Please see the link below:

https://www.nosvacuumtubes.net/product/6h1n-eb-6n1p-eb-voshkod/

 

RE: 6N1P, posted on January 21, 2023 at 01:49:43
mondial
Audiophile

Posts: 880
Location: S.E. ASIA
Joined: January 14, 2007
 I bought them from Jim McShane and from ARC . No DOA . My ARC power amps use them as well as input tubes .

 

RE: 6N1P, posted on January 21, 2023 at 12:59:10
Brad225
Audiophile

Posts: 127
Location: Tampa
Joined: December 25, 2006
Contributor
  Since: January 26, 2008
 Thanks, but, neither of them have any.

 

RE: 6N1P, posted on January 22, 2023 at 05:49:56
zacster
Audiophile

Posts: 2054
Location: NYC
Joined: November 22, 2003
 Don't assume that. A 6P1P is a EL90, 6V6, 6AQ5 near equivalent that is also used in audio and not the same at all. It is a tetrode. A 6N1P is a dual triode of course.

 

RE: 6N1P, posted on January 23, 2023 at 09:18:09
Brad225
Audiophile

Posts: 127
Location: Tampa
Joined: December 25, 2006
Contributor
  Since: January 26, 2008
 I'm now happy to say that I have working 6n1p tubes in the amps.

After bringing all of the good and bad tubes back home arranging them to go to a vintage repair company on Tuesday that tests tubes.
I was surprised to make a discovery with the tubes that were in the amps.

The 6n1p tubes that we removed from the amps were installed by Audio Research when they went back to get a clean bill of health by Echo Audio in 2015 prior to my purchasing them. The amps were shipped directly to me from ARC.

When I looked closely with a magnifying glass to make out what was left of the original cables all 4 had rockets on them signifying they came from the Voshkod factory. Only one of the of the tubes was marked Sovtek. Two of the tubes had identical markings from the Voshkod factory and the fourth had the rocket and markings from another company the labeled Voshkod tubes with their name. The latter 3 tubes have the exact markings as some of the tubes I ordered from different sellers.

The 4 6n1p Sovtek tubes I purchased from a known dealer, that were no good had the rocket and the same markings as the current tubes I have been receiving. I was surprised Sovtek used their tubes for many years or someone is putting Sovtek on old tubes.
The only difference is they charged almost 3 times as much. That's my fault for not knowing enough about the tubes currently available.

I explained the rebuild of the amps and missing the warranty time and I accept I did. I even offered to pay to ship them back and if they found they were in perfect condition I would be happy with some credit toward other tubes or I would pay to ship them back to me and I would attempt to sell them. They suggested it my EE fault and had no interest in anything I offered.
I understand being in business I was self employed for all but 2 years of my working life but there is a thing called customer service.

Just interesting ARC has no tubes that fit their specs but there are obviously 1000's of 6n1p EV-EB tubes that they have used. I realize they have high standards but surprised none are their standards. We will see in time.

The EV-EB tubes are said by other ARC owners to have the factory rating of 5000 hours in their amps.

Oh well that is part of owning older tube equipment. At least my wife hasn't taken away my credit and debit cards.

Can't wait to get them home. Hopefully by the weeks end.

 

RE: 6N1P, posted on January 30, 2023 at 14:14:37
Jonesy
Audiophile

Posts: 3047
Location: Winnipeg, Manitoba
Joined: September 1, 2005
Contributor
  Since: March 1, 2018
 I finally got a chance to dig around and found a quintet of 6N1P I had purchased as part of a complete retube set for an ARC VS110. I actually bought it for the SED Winged C 6550 output tubes I like to use in my ARC D70. So the 6N1P's have just been sitting in their boxes.

When I looked at the actual tubes they are a bit of a scramble deciphering the apparent relabelling. Looks like these are actually 6H1N EB. Note that EB military designation is by design more rugged but with that comes a difference in their data sheets.

Again, similar to my earlier posted reply regarding apparent equivalent tubes that have medium or high gain, it's possible you are not running across defective tubes but tubes that are not ideal to your unit's needs.

It's kind of like some output tubes that aren't recommended for auto biasing amps but ok for amps that have manual biasing.

These are my observations anyways and wish I knew more on the subject.

In any event, to make a long story short, I did find a company that sells the 6H1N EB, for consideration while you continue to research the situation. And they appear to have a lot in stock. I have never dealt with them though.

Jonesy


"I know just enough to get into trouble. But not enough to get out of it."




 

RE: 6N1P, posted on January 31, 2023 at 10:35:25
Brad225
Audiophile

Posts: 127
Location: Tampa
Joined: December 25, 2006
Contributor
  Since: January 26, 2008
 Thanks Jonesy. Well as any normal rebuild of, well, virtually anything goes more issues discovered and being dealt with.

When the 3 group of 6n1p tubes still had some problems, my EE friend decided to investigate a bit closer. He found that the 2 Field Effect Transistors in the bias circuit would test fine one moment and then test wrong moments later.
He changed the 2 of them in both amps. Tubes were reinstalled and 3 of the Variable Resistors would allow him zero out the voltage in the + & - side of the bias current worked perfectly but one was still very unstable. 4 new VR's should arrive tomorrow or Thursday and we will attempt to be finished with the amps.

Our new assumption is that the tubes I have are more than likely fine and it was the inconsistent parts that made us think they were bad.
The odd thing is that with the old tubes that had 3000+ hours on them were always stable. Who knows.

On another note. I purchased the amps used from a known seller in the US. The amps had gone back to ARC for a checkup and new tubes throughout before being shipped directly to me from ARC. I was given copies of the bill showing what was done and new parts installed in the amps.

I had never looked closely at the 6n1p tubes ARC had installed until the perceived problem with the new tubes.
I took a magnifying glass to clearly see the markings. All 4 tubes had the Voskhod Factory rocket on them. 1 of them was labeled Sovtek and said 6n1p-EB. 2 of the tubes had different markings but labeled as 6n1p-EB and the last one had a different company logo with the 6n1p-EB markings.
It was surprising that ARC used those tubes to re-tube the amps in 2015 but not now.

They were obviously good quality as they had many hours on them.

One interesting thing, on the day we listened to them for 3+ hours in his system. With the KT120 tubes the heat output had dropped by almost 3/4 from what the 6550 produced. You could hold your hand 1" above them and it was nothing like the 6550. If you tried that previously, you would be bandaging up your burns.

 

RE: 6N1P, posted on January 31, 2023 at 11:31:52
Jonesy
Audiophile

Posts: 3047
Location: Winnipeg, Manitoba
Joined: September 1, 2005
Contributor
  Since: March 1, 2018
 Ah, always seems to be something. But at least the trouble shooting is going in the right direction.

I replaced all trim pots in my amp some years ago and it really helped stabilize any measurement readings.

The octet of power tubes in the set I purchased consisted of 7 6550 Winged C and 1 6550WE. They are all matched extremely close and I believe originally came from ARC. Due to availability I suspect they chose the best options available to make up the sets. That may explain the different tube brands you likewise have come across.

Glad you are able to use the KT120 instead of the 6550's. That is a lot of tubes and I can only imagine the heat. I only have 5 6550's total and it is indeed very hot. Unfortunately ARC says I cannot run the KT120's in my amp. It would have been nice to have that option as tube supplies diminish.

While doing some research on your amp I came across your rebuild on another forum. I don't usually spend much time anywhere other than Audio Asylum but looks like you've been at it for some time. I admire your passion and especially your patience. Quite the journey. Thank you for sharing some of it here.

Jonesy


"I know just enough to get into trouble. But not enough to get out of it."




 

RE: 6N1P, posted on February 3, 2023 at 10:49:30
Brad225
Audiophile

Posts: 127
Location: Tampa
Joined: December 25, 2006
Contributor
  Since: January 26, 2008
 Repair comes to a standstill... again.

The variable resistors were to be shipped out last Monday. The company in Texas had computers down and nothing could go out.

Then the ice storm pretty much handcuffed everyone in the state.

Oh well nothing to do but dream of music.

 

RE: 6N1P, posted on February 4, 2023 at 20:22:35
Jonesy
Audiophile

Posts: 3047
Location: Winnipeg, Manitoba
Joined: September 1, 2005
Contributor
  Since: March 1, 2018
 Variable resistors always work better when there's an ice storm delay! Hope they arrive safe and get you back into music soon.

Jonesy


"I know just enough to get into trouble. But not enough to get out of it."




 

RE: 6N1P, posted on February 5, 2023 at 08:31:08
Brad225
Audiophile

Posts: 127
Location: Tampa
Joined: December 25, 2006
Contributor
  Since: January 26, 2008
 Maybe, it will help them stay cooler in the midst of all of those tubes, Jones.

Phil found unused holes in the traces when he removed the resistors.

He said its not good for current flow when they heat up and cool down over and over again.
He solder filled them all.

I learn something new each time he replaces a part.

 

RE: 6N1P, posted on February 5, 2023 at 08:54:34
Jonesy
Audiophile

Posts: 3047
Location: Winnipeg, Manitoba
Joined: September 1, 2005
Contributor
  Since: March 1, 2018
 Filling unused holes is new to me as well. Makes sense though as you say. I suppose it's possible especially narrow traces may even crack at thise points. Barely visible and enough to drive a tech crazy.

Thanks for sharing this.

Jonesy



"I know just enough to get into trouble. But not enough to get out of it."




 

RE: 6N1P, posted on February 5, 2023 at 09:09:16
Brad225
Audiophile

Posts: 127
Location: Tampa
Joined: December 25, 2006
Contributor
  Since: January 26, 2008
 Funny you mentioned that as I forgot to include it.

He did spicily say after many heating and coolings the chances of cracking the sides of the trace are very good.

 

RE: 6N1P, posted on February 10, 2023 at 07:19:06
Brad225
Audiophile

Posts: 127
Location: Tampa
Joined: December 25, 2006
Contributor
  Since: January 26, 2008
 So, the parts came in and the install commenced. They are a major improvement in their ability to adjust + & - current to "0" without fluctuating up and down a few tenths or hundredths.

One of them still doesn't want to "0" out so Phil is going to start tracing back through some parts he didn't test. He believes that that are going to be a couple of weak resistors to replace.

I again, told him I was sorry for the problems the amp was giving him. His response, again was.
No, its fine. I love figuring these things out.

Says the guy that woke up at 2:24AM Thursday and was thinking about the amps. He got up and installed all of the new parts he had prepped for, went back to bed at 5:45 and fell asleep till 10AM.


*Another learning session for me. I asked him "Is it detrimental to the amps if that one doesn't "0" out?" He said no, but.

Think of the wave the electricity as it makes sweep from + to - up and down.
If it is not able to zero out then it will cut off the top or bottom of the wave depending whether it is the + or - that is not zeroed out.
As the wave is cut off so are the dynamics of current, hence, the dynamics of the sound you hear.

I have learned a lot. I just don't have the ability to apply it. That is what the professionals are for.

 

RE: 6N1P, posted on February 15, 2023 at 06:08:41
Brad225
Audiophile

Posts: 127
Location: Tampa
Joined: December 25, 2006
Contributor
  Since: January 26, 2008
 Swing and a miss, yet again. Phil has cleaned all of the boards and cleaned all connections that are detachable for that one side of the amp. ARC suggested it may be something in the main control board on the front panel of the amp.

After a thorough check, he removed the front of the good amp and installed it on the non zeroing amp and the problem still exists.

I spoke with him last evening and he is going to remove all of the parts related to the KT120 upgrade path for that side of the amp. Possibly one of the parts has issues.

More to follow in the story of.... Phil & Brad verses the 610t.

 

RE: 6N1P, posted on February 16, 2023 at 08:46:16
Brad225
Audiophile

Posts: 127
Location: Tampa
Joined: December 25, 2006
Contributor
  Since: January 26, 2008
 It looks like the problem has an answer.

Yesterday Phil did a diagram of the entire bias circuit with values large enough to make notes on it.

This morning he started unsoldering some parts to test values and found 5 resistors on the "non zeroing" side of the amp that were nothing like the schematic or the resistors on the other side of the amp. Their values or markings were not there on any of them. Phil mentioned other parts that they had removed any identifying marks in the past, probably for proprietary design reasons.

He texted today me and said the believes he found the problem being, the 5 resistors.



An hour later he called to tell me that he had received an email from Greg at ARC. Greg said that he found an engineer that had been there long enough that he remembered an issue they encountered with the bias circuitry.

Apparently during production they ran out of the parts that were originally designed to be used and changed the 5 resistors in different places (with no markings) and never put it on the original schematics. So, the only people that ever knew were the engineers and the person installing the parts.

The weeks Phil has been trying to figure this out is a design change with no public record. Pardon my language but, that is F-ed up. I guess, the only good news is that they owned up to the unrecorded change and gave us the correct information.

They do have the original correct parts and will sell them to us so Phil is ordering them today.

As one of my pair of amps has both configurations I asked Phil to find out what year my amp was assembled. It would seem, it was possibly the first one, hence, the different design on each side of the same amp.


I am so thankful for Phil. I don't think I could find anyone else that would have the patience and curiosity to make this happen. To say nothing of the labor bill if I didn't trade my furniture making skills for his EE skills.

Hopefully my next post will be confirmation of the problem being corrected.

 

RE: 6N1P, posted on March 13, 2023 at 09:40:36
Brad225
Audiophile

Posts: 127
Location: Tampa
Joined: December 25, 2006
Contributor
  Since: January 26, 2008
 I am ecstatic to say the amps are home and functioning properly. I can't say I was excited at 69 years to be moving them to my second floor listening room but I guess you have to pay to play. Nothing that ibuprofen and wine couldn't fix.


I will try and make this short. The last 2 months Phil spent trying to figure out why one amps, 2 adjustable resistors would not zero out, turns out to be surprising and frustrating at the same time.

Apparently during the production of the 610t amps ARC received more orders than they ever expected for the time. They ran out of some resistors and chose to make a design change to the board and not include it on the schematic. The change was only used until more of the original parts arrived.

We found this out because one of the engineers that Greg at ARC spoke with, as Phil encountered more dead ends with the amp remembered they changed it.

ARC offered to send us the proper parts at no cost, which was great. The problem is when Phil put the new resistors in, the amps + and - voltage at the 2 zero out resistors was still too far off to adjust properly.

Phil next decided he had to eliminate the chance of a problem tube socked or something under them that was unseen. We ordered 6 sockets, as he wanted to keep both amps the same for base line readings. Under the sockets he found some ugly soldering but nothing he thought would be the problem. He did though find more ground loops under sockets 19 & 20 and he eliminated them on both amps.
He installed the new sockets and the amp that had been problem free was still just that. The amp with the issue still had that.

He decided that the new replacement parts ARC sent to fix the issue had to be the problem.

On the side of the amp that the voltage was to low he, through best guess measuring and trial and error added different value resistors in series until it was at a value that was within specs to be able to zero out.
On the side that was to high he did the same thing but in reverse and lowered it to be within spec. That side also zeroed out.

We were both ecstatic and frustrated that was a long 2 months trouble shooting the problem that was an unpublished design change.

So, the end result was they sent 2 different design 610t amps to the original owner.

From the 1 1/2 hours Phil and I listened to them yesterday evening they are going to be amazing in more than one way once broken in some.

I was stunned that even after 1 1/2 hours I could actually put my hand on 4 or 5 tubes and they were hot but you could have never gotten close to the 6550 tubes with your hand. We found that the room was much to cold to be comfortable listening to music at the same thermostat setting when the 6550 tubes were in and running.

 

RE: 6N1P, posted on March 13, 2023 at 09:42:32
Brad225
Audiophile

Posts: 127
Location: Tampa
Joined: December 25, 2006
Contributor
  Since: January 26, 2008
 Back home and ready to be enjoyed again.






 

RE: 6N1P, posted on March 15, 2023 at 02:37:12
mondial
Audiophile

Posts: 880
Location: S.E. ASIA
Joined: January 14, 2007
 Wow ! Congratulations , happy listening !

 

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