Can you elaborate on your mod? Did it actually fix your hum?
Where did you add your L/R balance VR?
Pics?
Where did you add your L/R balance VR?
Pics?
I had tried to find the hum noise fo mine.
In result, I removed C15(104, 2ea) like pic..
And add a left-right balance VR..
Very good sound !
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6N6P are pin compatible with 6N1P and ECC88.
I think it depends from amp to amp and even from one mod to another, where you put different pairs of tubes.
Just try one option, and then change position of pairs of signal tubes.
Few mods before, with Shuguang 5881 and NOS russian Proton power tubes from 60ies, excellent choice for my system was NOS Tesla E88CC, with KT77 they just dont show what they show with those and now JJ E88CC are better sonic choice then before.
It is, surely, only on a first sight.
I bought it when i made Yaqin trial in my town and this one was sonically perfect fit for my tube DAC and speakers. Tonewin importer for Slovenija brought them(Tonewin is original factory name for Yaquin and a lot of other brands).
Tonewin Electronics Co.,Limited
Friend of mine brougt to me year ago his Genalex KT77 to try them.
They just sonically wiped off all other power tubes i have.
They sonically "acts" like a hybrid tube between EL34 and 6L6. They have pluses of both, with no minuses.
Only with them i could finish my ribbon DIY mid-tweeter-supertweeter combo with only 6dB crossover. I highs they just bit the **** from any amp for any price, when they are playing on quality ribbons.
They are also perfect match on my amp with 6N1P-EV-6N6P, so, there is no need for more expensive signal tubes..
You guys are talking apples and oranges. As picky and strange as Yaqin's (Yaoin) Chinese engineering is, especially on the VK-2100, it is ONLY ment to handle the 6N1P's on the older models, and the same or the 12AU and AT 7's on the new models. Thats it.
As was mentioned, the stock Shauguang 6N1P are not the best either or any 6N types, which only leaves a good, decent priced 12AU and AT 7 combo. Preamp or not, and regardless of what the MSRP of the VK-2100 is, a set of Genalex Gold Lions would show huge improvements. It's all about tube/valves boys... not just rolling from one crappy set of tubes to another.. it's ONLY for the preamp.
Heck, a great matched set of $10@ JJ's would be a big improvement as long as they were a 12AU and AT 7.
As was mentioned, the stock Shauguang 6N1P are not the best either or any 6N types, which only leaves a good, decent priced 12AU and AT 7 combo. Preamp or not, and regardless of what the MSRP of the VK-2100 is, a set of Genalex Gold Lions would show huge improvements. It's all about tube/valves boys... not just rolling from one crappy set of tubes to another.. it's ONLY for the preamp.
Heck, a great matched set of $10@ JJ's would be a big improvement as long as they were a 12AU and AT 7.
Surely wont.
Now i use them in my very expensive Slovenian Stylos ECC88 tube DAC prototype with great sucess.
After i read Lampizator and Romy the Cat s positive opinion on this tube. I tested it and wrote of it on our SLO forum and a lot of guys tried it. It is safe and it is special piece of gear.
6n1-p is said to be a great small tube in lot of places, why do you think that cheap 12au7 can be better ??
Anyway i'll go the 6n6-p way for testing, soviets left us some great items like tubes and capacitors PIO and teflons, I like to use them,they are great quality items!
Hello !
I think it's a bit hazardous to swap one tube to another, without any changes in the circuit..
6nxx tubes have heater powered vith 6.3v
12xxx tubes are 12.6v powered basically ...But you can use 6.3v if you change some circuitery...connecting to-half parts of the filament //,
Relate to heater voltage, is heater current, you must be sure that the transfo would give you more power when changing from 6n1p, to 6n6p (change from 600mA to 750mA x 4 tubes )
I'm not sure about the schematics : about Q1 ...I think Pin2 is not connected to 3, but would be to 6 (symetrical SRPP)
Would someone would confirm ? and also about R4 and R6 values (colors) ?
Thanks
R.C.
I think it's a bit hazardous to swap one tube to another, without any changes in the circuit..
6nxx tubes have heater powered vith 6.3v
12xxx tubes are 12.6v powered basically ...But you can use 6.3v if you change some circuitery...connecting to-half parts of the filament //,
Relate to heater voltage, is heater current, you must be sure that the transfo would give you more power when changing from 6n1p, to 6n6p (change from 600mA to 750mA x 4 tubes )
I'm not sure about the schematics : about Q1 ...I think Pin2 is not connected to 3, but would be to 6 (symetrical SRPP)
Would someone would confirm ? and also about R4 and R6 values (colors) ?
Thanks
R.C.
Thanks for info. I have to ask the author of my tube DAC about this.
Not for 4, only for 2 6N6P. Four of them will silent the amplifier and make sound awful. I tried.
So, there is no need to change the circuitry(because one still use another pair of "prescripted" tubes), but some says(Romy the cat), that the lifetime of the 6N6P will be shorter in non changed circuitry, but. Romy the cat is using much more expensive gold pin 6N6P and i hope that he changed his circuitry.
Russians usually likes cheaper PETP caps over PIOs. PETPs suppose to be quite like Siemens MKLs, very open, detailed, good slam, not so "tubelike" sounding like PIOs.
In my DAC, tube amp, speakers, i use for use Jantzen Superiors(also a pair of Mundorf supremes and SIOs), Jantzens sometimes blended with K42-2 PIOs and then i read this Troelsgravesen article about them.
The Grounded Grid preamplifier
Jantzen Superiors have very good depth and they are very musical, but, they are not so sonically similar to K42-2 PIO, as Troel says.
maybe in his circuitry, in mine K42-2 sounds bit more tube like,and depth of K42-2 also has slightly different character. I use Tempoelectric silver wiring inside all of my components on signal path, inside mids and tweeters-also for speaker wiring for those and for interconnects- and Eichmann Silver and Copper Bullet plugs and Eichmann RCA Phonopods.
In my tube DAC blending of both those caps succeeded, but on supertweeters not.
KT77 Genalex fully detailed character fits like a glove in this wiring-caps combo.
It is very demanding and unforgiving tube, a lot of people dont like it, because it strips and shows system incoherences and result is unmusical harshness.
In fact, it is a bit, transistorlike sounding tube, but that s ok, because we have also tubelike sounding DC and other amps.
I just checked, and gold pinned 6N6P are gone from the market.
For older 6N6P i just look to avoid all boxed ones. They are from eighties.
I look then on EBay for old looking, ugly, almost dirty ones, with non chromed pins.
russians do have year code on the tube, but sellers in Russia have na odd habit, to hide the side of tube with it..
Sometimes they are few, but then sometimes suddenly small merchants in Russia and Ukraine gets big shipment from bigger ones.
Those are from 70ies, typical ugly proletarian, non aristocrats tube...
6N6P = E182CC;5687(WA);6DN7,Russian Double Triode 4pcs - eBay (item 250784078068 end time Apr-04-11 20:36:04 PDT)
This guy is typical- hiding markings..
6N6P - USSR VINTAGE TRIODEs,1977, NOS one or more - eBay (item 180637953102 end time Apr-09-11 11:12:32 PDT)
I think, they are Nevz factory.
Those seems to be, assuming because of the boxes, Reflektor plant.
Reflektor tubes are usually very ok made, like Vostoks.
Year?
6N6P-I = ECC99 = E182CC. Lot of 10 NEW!! - eBay (item 250678955366 end time Apr-04-11 00:46:56 PDT)
6n6p items - Get great deals on Electronics, Business Industrial items on eBay.com!
Only silver OTK stamp means that tube is EV from 60-70ies.
Stamped OTKs are from 80-90ies.
No. They stay slight warm, not hot for some hours, but they are considerably bigger then "ordinary" ECC, so they are an "eye catcher" in pair with ordinary ones.
I think that glowing of signal tubes comes from different voltages of different amps.
When i change factory MKPs for Jantzen Superiors, for quite some time power tubes glowed very blueish. Superiors have 800V, i assume that was the reason.
Guys from Putinland claims that their PIOs are resistant to EM pulse and high radiation level and that comforts me.
It would be nice to have some good music after the nuclear holocaust..
Yaqin vk2100 tubes and a dilemma
Pleased to see this thread has a new life. Thanks Rockford and others.
I took a punt on one of these about 3yrs ago and am very pleased with it. Cold, out of the box, with 6N1's it embarrassed my old Audiolab 8000A - which had itself stood up well against a number of respected more expensive and contemporary SS amps.
I agree with those who raise the issue of heat, this is not unique with valve or even some SS amps. I run mine with the lid off, not ideal, and have often considered modding it as others suggest but haven't gotten 'roundtoit.
That aside my VK is something of a hair pulling enigma to me. No manual or schematic, it arrived with the 6N1's but later I noticed the PCB marked for 12au7's and 12at7's. Perhaps someone here can help with my understanding of this? After reading on.
I've rolled an number 6dj8/699/PCC88's. All were an improvement - to me in my system - over the Chinese valves. The usual suspects generally supported their reputations/characteristics but there are many I haven't tried. One I'd encourage rollers to try is the Russian Volkshad 6h23, particularly if your system sounds too bright or forward in the mid-range, lacking good bass, and you can get them at a reasonable price as I believe they are getting harder to find.
Discovering the the PCB markings for 12XXX's led to a trial of a few, e.g. Brimar, Mullard, Philips, Tele's, RFT, Tungsram. Without exception these proved unexceptional. Seemingly the failure to light these valves points to heater current, which without any technical knowledge beyond a very vague understanding of serial vs parallel circuits and pin compatibility is about as far as I go and I don't know how this works. Hence my comment above re the enigma of this amp. Starve or overcook?
Possibly the answer to my own question is in what I'm currently using. 4 x RCA 6fq7/6gc7 used cleartops. I've a few other versions I haven't tried yet including nib Australian Mullards. Don't really want to get into the subjective of comparisons of types within families or between them. These satisfy pin compatibility and heater current requirements compared, I think, with Chinese 6N1's. They are very much cleaner with better apparent linearity, I find - possibly in part a factor of lower gain except that AU7's don't cut it and I've bh7's untried. Uncovered the amp shows no sign of stress. Transformer is the circular one, own covered box.
There are many tubes this amp can handle, ECC85/6aq8's have been mentioned, close to 6bq7's are another, both are similar and have been run together, give me good results - and there are a number of others still cheap which I haven't tried yet.
What I've found in a general sense is the ability of the amp to reflect other system changes whether 'major' components, connects or tubes is its measure and charm. The ability to 'tailor make' sound without major component cost.
I have quite a bit of gear but this is used mostly with an Arcam DV79, Technics ST-8077k tuner, Castle Stirling 3's or Proac Super EBT's. A Linn Sondek went with marriage.
Thanks, keep it going, I'd welcome any comments re my dilemma..
.
Pleased to see this thread has a new life. Thanks Rockford and others.
I took a punt on one of these about 3yrs ago and am very pleased with it. Cold, out of the box, with 6N1's it embarrassed my old Audiolab 8000A - which had itself stood up well against a number of respected more expensive and contemporary SS amps.
I agree with those who raise the issue of heat, this is not unique with valve or even some SS amps. I run mine with the lid off, not ideal, and have often considered modding it as others suggest but haven't gotten 'roundtoit.
That aside my VK is something of a hair pulling enigma to me. No manual or schematic, it arrived with the 6N1's but later I noticed the PCB marked for 12au7's and 12at7's. Perhaps someone here can help with my understanding of this? After reading on.
I've rolled an number 6dj8/699/PCC88's. All were an improvement - to me in my system - over the Chinese valves. The usual suspects generally supported their reputations/characteristics but there are many I haven't tried. One I'd encourage rollers to try is the Russian Volkshad 6h23, particularly if your system sounds too bright or forward in the mid-range, lacking good bass, and you can get them at a reasonable price as I believe they are getting harder to find.
Discovering the the PCB markings for 12XXX's led to a trial of a few, e.g. Brimar, Mullard, Philips, Tele's, RFT, Tungsram. Without exception these proved unexceptional. Seemingly the failure to light these valves points to heater current, which without any technical knowledge beyond a very vague understanding of serial vs parallel circuits and pin compatibility is about as far as I go and I don't know how this works. Hence my comment above re the enigma of this amp. Starve or overcook?
Possibly the answer to my own question is in what I'm currently using. 4 x RCA 6fq7/6gc7 used cleartops. I've a few other versions I haven't tried yet including nib Australian Mullards. Don't really want to get into the subjective of comparisons of types within families or between them. These satisfy pin compatibility and heater current requirements compared, I think, with Chinese 6N1's. They are very much cleaner with better apparent linearity, I find - possibly in part a factor of lower gain except that AU7's don't cut it and I've bh7's untried. Uncovered the amp shows no sign of stress. Transformer is the circular one, own covered box.
There are many tubes this amp can handle, ECC85/6aq8's have been mentioned, close to 6bq7's are another, both are similar and have been run together, give me good results - and there are a number of others still cheap which I haven't tried yet.
What I've found in a general sense is the ability of the amp to reflect other system changes whether 'major' components, connects or tubes is its measure and charm. The ability to 'tailor make' sound without major component cost.
I have quite a bit of gear but this is used mostly with an Arcam DV79, Technics ST-8077k tuner, Castle Stirling 3's or Proac Super EBT's. A Linn Sondek went with marriage.
Thanks, keep it going, I'd welcome any comments re my dilemma..
.
Pre-amp output for subwoofer VK-2100?
Folks -
I'm the plowed new owner of a VK-2100, which sounds really quite nice & tasty driving an older pair of Metronome 3's.
But, since I cannot stop myself from tweaking - I'd really like to add a preamp output to this poor, inoffensive piece of HiFi kit to allow for a subwoofer to kick my ribs about.
I poked about on the amp's mainboard, and found two 5mm jumpers labeled 'ROUT' and 'LOUT' - and since routing louts is ALWAYS a good thing, I had some hopes that these jumpers were going to offer a quick and dirty solution.
Sadly, it looks like these jumpers aren't at line-level, but seem to be unfiltered signals headed towards the output transistors - the waveforms there look pretty dirty and full of ripple on my scope.
From a cursory look at the main board, it looks like these two points are just ahead of the air-wound inductors that couple to the final stage. I suppose one could grab signal from the jumper points, or after the inductors, but I think that you'd need to build a buffer stage before feeding anything out into the Real World.
Any ideas or comments - anyone already done this mod?
Alternatively, I did run across another post on the tubes forum that shows a simple, and apparently effective little resistive network which, when taken off the main output provides a fairly low-level signal to drive the subwoofer amp. This solution should be a reasonable hack until a more permanent, or at least more elegant, solution is hit upon.
Cheers & TIA for your comments
Jim
Folks -
I'm the plowed new owner of a VK-2100, which sounds really quite nice & tasty driving an older pair of Metronome 3's.
But, since I cannot stop myself from tweaking - I'd really like to add a preamp output to this poor, inoffensive piece of HiFi kit to allow for a subwoofer to kick my ribs about.
I poked about on the amp's mainboard, and found two 5mm jumpers labeled 'ROUT' and 'LOUT' - and since routing louts is ALWAYS a good thing, I had some hopes that these jumpers were going to offer a quick and dirty solution.
Sadly, it looks like these jumpers aren't at line-level, but seem to be unfiltered signals headed towards the output transistors - the waveforms there look pretty dirty and full of ripple on my scope.
From a cursory look at the main board, it looks like these two points are just ahead of the air-wound inductors that couple to the final stage. I suppose one could grab signal from the jumper points, or after the inductors, but I think that you'd need to build a buffer stage before feeding anything out into the Real World.
Any ideas or comments - anyone already done this mod?
Alternatively, I did run across another post on the tubes forum that shows a simple, and apparently effective little resistive network which, when taken off the main output provides a fairly low-level signal to drive the subwoofer amp. This solution should be a reasonable hack until a more permanent, or at least more elegant, solution is hit upon.
Cheers & TIA for your comments
Jim
Attachments
I think one of the reasons this amp sounds so good is that the SRPP is a very dynamic and musical stage, and it appears to have two in series.
In theory the SRPP is non-ideal and purists insist their CCS stuff is better, but I suspect into a real load the SRPP performs in a better way for the music. I have a SRPP driver on my tube amp and it sounds awesome..
Additionally the feedback loop doesn't have an output transformer inside it - never a good idea IMO.
Am I right in thinking that the SRPP in this amp is the voltage amplifier stage (VAS) and the output transistors are basically configured as followers with a voltage gain of about unity?
In theory the SRPP is non-ideal and purists insist their CCS stuff is better, but I suspect into a real load the SRPP performs in a better way for the music. I have a SRPP driver on my tube amp and it sounds awesome..
Additionally the feedback loop doesn't have an output transformer inside it - never a good idea IMO.
Am I right in thinking that the SRPP in this amp is the voltage amplifier stage (VAS) and the output transistors are basically configured as followers with a voltage gain of about unity?
Hello, everyone!
I apologize if I am going to sadden some of the people with my comments but I think you should know some facts about this amplifier; they will come from somebody, who is working with analog electronics for last 20 years and at least it will bring some technical clarity on a number of topics here. Or so I hope.
I bought one about 2 years ago with the idea of having a workbench for trying some ideas in hybrid sound amplification. Upon opening I found immediately that the design is not really friendly to major mods, so I will need to think of something more creative than just adding a web of wires to the amplifier.
As far as architecture is concerned, it is indeed a gain stage with current buffer and global negative feedback. Now, some numbers. 2x 6N1 back to back are producing a gain of app. 1,200x and very deep NFB reduces it to app. 30x. So, we have >30dB NFB in the amplifier, which means it does not matter if it is the tube or a solid state design - you are listening to NFB. Also, circuit diagram has a major error in 6N1 section, good thing the PCB is routed properly.
BTW, the heater circuit is wired separately at the back of the board with thick yellow wires, I am quite sure switch between 12.6V and 6.3V heater supply is done by just wiring it differently but in any case, there is no automatic selection between different heater voltages!
Also, TOSHIBA is not manufacturing the output transistors of that type for, maybe 10 years now. What is used in VK-2100 is Chinese knock-offs.
VK-2100 sounded noticeably worse comparing to entry level BRYSTON solid state amplifier.
I would definitely recommend before investing into silver wiring and audiophile capacitors to make some other basic improvements to the amplifier if it is itching to get the sound improved on VK-2100. Note that my guinea pig ended up quite different from the original architecture and it will take time, some skills and patience to make all the changes, would you decide to follow my route.
FAIRCHILD manufactures replacements to 2SC5200/2SA1943, they are FJL4215/4315, they are quite inexpensive and they also have better linearity. I purchased a handful from DIGIKEY, matched two pairs and replaced the output transistors. That greatly improved the stability of DC offset with temperature and now it is running at 3-5 mV of DC offset at all times.
If you are planning to still have deep NFB, adjust the output stage quiescent current to app 50 mA. The pots used could drift away during the transportation stresses and it takes literally single degrees of rotation to misbalance the transistors.
6N1 or 6N1P (note that 6DJ8 is not a direct replacement to 6N1P!) simply can not produce any decent sound at something like 2 mA of plate current, wich is a factory setting. Power supply does not have a lot of room for improving on that, so I left only one tube per channel and increased the plate current to 5.5 mA. That was the single best improvement I had from all the mods. Note that in this case the existing NFB loop is useless as the gain stage has become inverting, so you would need to come up with the decision on either to keep the NFB but modify it or not to have NFB at all. I opted for the latter and had to deal with amplifier instability caused by the poor topology of the PCB. NFB hides that problem of VK-2100.
Indeed all 0.47 uF capacitors need to be replaced; mine were from a Korean manufacturer, who makes no secret that these are from low cost computer grade family.
Well, I think I would better fast forward to the end and describe what I ended up with.
With new power transformer and 18V power rails I have AB output stage with 0.8 A quescent current (that is maximum the heatsinks can handle without going to dangerous temperature. Replacing heatsinks is something I did not have courage for - it is really complicated), no NFB, 1975 6N1P-EV from VOSKHOD factory runing at 5.5 mA. Output impedance is at app. 1 Ohm, maximum output power is close to 6W at 8 Ohm.
It sounds really pleasant now, I compared it to 6C4C SET with HAMMOND output transformer and it is not losing it by large margin if loosing it at all; I am switching between them from time to time just for fun. Source is MARANTZ CD player and NAD turntable with CAMBRIDGE audio phono stage. Speakers are open baffle 15’ MAGNAVOX with horn tweeters, both from 1970s production.
BTW, my original idea was to use transformer feed of solid-state output buffer from a tube gain stage but that will have to wait for better times.
My conclusion is VK-2100 is not worth attention as a component in a stereo system as-is, extensive mods to architecture and component selection indeed could help stepping up quite significantly. It is actually not expensive to make those changes but it would take time and I would not recommend doing them without prior experience of repairing or modifying audio equipment.
Thanks.
VK2100 - preamp section as AIKIDO
Today I finnished with last mod of my VK-2100. I rebuilt the tube section in TUBECAD AIKIDO. I used 6N23P tube. I replaced all the resistors. Also removed the NFB. I replaced the 0.47 uF capacitors with Jantzen Audio Superior. The Rk of first tube is 300 Ohm and of second tube is 680 Ohm.
Also modified the power supply. I add RC filter. The Va is around 260Volts.
Now VK-2100 plays realy very very sweet and good.
The costs of mods: 4 tubes - around 60$ - 6N23P reflector (y. 70-71 black anode),
resistors - around 5$
Caps - around 50$
I need about 4 hour to this mod.
Today I finnished with last mod of my VK-2100. I rebuilt the tube section in TUBECAD AIKIDO. I used 6N23P tube. I replaced all the resistors. Also removed the NFB. I replaced the 0.47 uF capacitors with Jantzen Audio Superior. The Rk of first tube is 300 Ohm and of second tube is 680 Ohm.
Also modified the power supply. I add RC filter. The Va is around 260Volts.
Now VK-2100 plays realy very very sweet and good.
The costs of mods: 4 tubes - around 60$ - 6N23P reflector (y. 70-71 black anode),
resistors - around 5$
Caps - around 50$
I need about 4 hour to this mod.