TUBES

My most recent revelation was a used philips miniwatt ez81 rectifier which I got my hands on. Plugging it into my head amp initially brought out improvements.

Rolling and comparing the same with my other rectifiers I did notice that certain combos of rectifier+output tube had very distinct characteristics. Still can't fathom why a rectifier would make such a diff but it does so I am currently going to leave it at that.

Currently my top 3 fav combos with virens pre/headphone amp are:
1) Philips miniwatt + brimar 6sn7

2) Bel ez81 + kenrad black glass 6sn7

3) Brimar ez81 + hitachi 6sn7

Tube rolling sure breathes new life into your equipment but one needs patience and a very light hand in handling tubes and their sockets. The rewards are very satisfying.

Manek

Tube rolling sure breathes new life into your equipment.

So true, sadly, I have currently shifted to SS amplification, but hold tube, VERY dear..

Ampnut

Your AR would have a tube or two in it ?

Try and get hold of a tube cdp or dac and have fun with rolling.

Manek

Hi Manek,

This is a purely subjective experience! No rules, just new found flavours! Pick and chose what you prefer.

Atleast there is a general level of performance with all these combinations - they all make music. You alter the flavour, the tonality to suit yourself!

Can any other technology offer this user benefit? Not at all. And how long has this being going on - a mind-bogling 70 years!

Regards,
Viren

Agreed, there are no rules, only flavours but lots of them....and thats what is so great about tubes.

Need another flavour? change a tube or two and voila !......a new flavour.

Viren, why don't you tell the folks here abou the 5687 tube you are now using with your amps....and your experience with them over the 6sn7 and the 12au7 and 12ax7 ?

Manek

Manek said :

Viren, why don't you tell the folks here abou the 5687 tube you are now using with your amps....

Hi Viren,

I second that.

Your views and experience on Tubes would be very welcome.

Thanks

Hi,

Nothing like a little bit of history to put things in perspective - something that Lynn Olson does best:

"You might think that really old tubes - designs dating from the early Thirties - sound "vintage" and "tubey." Actually, they don't. Tubes in this family (27, 37, 56, 76, and 6P5) actually sound fast, quick, and incisive, and have very low distortion, along with a favorable distribution of harmonics. If you want a traditional mellow "vintage" sound, you're thinking of a 12AU7, the tube used almost universally in late 1950's amplifiers and many guitar amps - and has distortion many times higher than the early Thirties tubes.

"The universal adoption of feedback in the late Forties allowed electron-tube designers to relax their concerns about distortion and focus on cost, heat emission, and package size instead. Audiophile vacuum-tube amps from the Seventies through today continued with the late-Fifties favorites of the 12AX7 and 12AU7, which are actually considerably worse than the octal predecessors, the 6SL7 and 6SN7, which in turn aren't as good as the early-Thirties tubes.

"The really superior tubes of the mid-to-late Fifties and early Sixties, the 5687, 7044, and 7119, were only used in commercial and aerospace applications, never in high-fidelity electronics sold to consumers."

My experience spans the use of these valves in a relatively short span of time. I started with the 12AU7 and 12AX7 in preamps. Discovered the 6SN7 and 6SL7, and found them to sound far superior. The 12A? series actually give a warm, laid back sound. The 6S? series are more dynamic, more textured, and open.

The 12A? series do have a use - to mate with solid-state electronics - to soften their sound somewhat! And in phono preamps, because of their lower noise performance. When other choices are available, definitely not the ones to use.

My use of interstage transformers brought about another change to the 5687. The 5687 is a very linear triode, with a much lower plate resistance. The plate resistance loads the interstage transformer - a lower plate resistance extends the bandwidth of the transformer, and improves the overall response. With the 6SN7, I was paralleling the 2 sections to lower plate resistance. The 5687 offered lower plate resistance per section. And it proved its worth.

I avoid paralleling sections or valves (shades of Conrad Johnson!), because you lose clarity. No devices are perfect - you get timing and phase errors between sections. Adds some fuzz to the sound. Avoid!

This has just been about input and driver valves. Output valves are another story!

Viren

Superb, Viren.

Actually, they don't. Tubes in this family (27, 37, 56, 76, and 6P5) actually sound fast, quick, and incisive

Are these tubes still available ( not in their NOS Avaarat, which will probably cost 2 arms + 2 Legs and my ...

Would love to go down that ally, and hear / built something with them...

viren schrieb:

Hi, Nothing like a little bit of history to put things in perspective - something that Lynn Olson does best: "You might think that really old tubes - designs dating from the early Thirties - sound "vintage" and "tubey." Actually, they don't. Tubes in this family (27, 37, 56, 76, and 6P5) actually sound fast, quick, and incisive, and have very low distortion, along with a favorable distribution of harmonics. If you want a traditional mellow "vintage" sound, you're thinking of a 12AU7, the tube used almost universally in late 1950's amplifiers and many guitar amps - and has distortion many times higher than the early Thirties tubes. "The universal adoption of feedback in the late Forties allowed electron-tube designers to relax their concerns about distortion and focus on cost, heat emission, and package size instead. Audiophile vacuum-tube amps from the Seventies through today continued with the late-Fifties favorites of the 12AX7 and 12AU7, which are actually considerably worse than the octal predecessors, the 6SL7 and 6SN7, which in turn aren't as good as the early-Thirties tubes. "The really superior tubes of the mid-to-late Fifties and early Sixties, the 5687, 7044, and 7119, were only used in commercial and aerospace applications, never in high-fidelity electronics sold to consumers." My experience spans the use of these valves in a relatively short span of time. I started with the 12AU7 and 12AX7 in preamps. Discovered the 6SN7 and 6SL7, and found them to sound far superior. The 12A? series actually give a warm, laid back sound. The 6S? series are more dynamic, more textured, and open. The 12A? series do have a use - to mate with solid-state electronics - to soften their sound somewhat! And in phono preamps, because of their lower noise performance. When other choices are available, definitely not the ones to use. My use of interstage transformers brought about another change to the 5687. The 5687 is a very linear triode, with a much lower plate resistance. The plate resistance loads the interstage transformer - a lower plate resistance extends the bandwidth of the transformer, and improves the overall response. With the 6SN7, I was paralleling the 2 sections to lower plate resistance. The 5687 offered lower plate resistance per section. And it proved its worth. I avoid paralleling sections or valves (shades of Conrad Johnson!), because you lose clarity. No devices are perfect - you get timing and phase errors between sections. Adds some fuzz to the sound. Avoid! This has just been about input and driver valves. Output valves are another story! Viren

Lynn Olson is quite a personality in the audio world & in the DIY world. He is highly regarded. I've yet to meet him but I've cruised thru his website & have spoken to my friend here (who builds tube amps for a living) about some of Lynn Olson's philosophies on tube selection. My friend seems to like Lynn's selections!


From some of the measurements I've seen comparing the 12A?? tubes to the octal 6SN7 tubes I see that the 12A?? tubes do have more odd order harmonic distortion. However, I have to think about the "laid back" sound from the 12A?? tubes! I've heard many 12A?? tube based preamps & many of them are not laid-back!

I believe in tubes. But i believe them only in the signal path.

Try your comparisions using a good solid-state PSU. Your comparisions will yield very different results.

Ampnut

The 5687 tube is available as nos only. No new productions. But the nos is not as expensive as the good 12a? Series nor the 6sn7's. I see that this tube has diy following and is catching up.

If viren says that it is more open and dynamic than the 6sn7 then I guess it definately needs to be heard. One of the head fi forums called it a 6sn7 on steroids !

Once it gets popular I guess new production will start.there are a couple of companies that use 5687 eg audio note, modwright,consonance.

Manek

Viren, did bel make these tubes in india ?

I have sort of given up on the usual suspects like 12XX & 6SN7/6SL7 family of small singal tubes. Now mostly experimenting with ancient bulbs like the 27, 76 and modern industrial tubes like 5842, 6DJ8 and 5687, etc

Some of these I have used in recent DIY work in progress experiments

•845 SE Amp: 76>>10Y>>Lundahl LL1660>> 845
•Line stage : DACT 100K>> 5687 >> Lundahl LL1660
•KT88 Push Pull amp: 5842> > Lundahl LL1660> > KT88
•Phonostage: 6DJ8>>27 buffer.

And of course the Santa Clause amp (as described in the DIY thread) that uses E88CC as the input valves.

.Ancient triodes like the 27 and 76 are tremendously linear. You have endless possibilities to choose an operating point and allow an easy, uncluttered sound. Pretty amazing considering they were designed and first built in 1930’s.

My goal is to have a nice reference system in year 2009 that only used DHTs and Interstage coupling. No capacitors in signal path and only oil caps in the PSU.

Aks

You sing the same tune as viren. And that's a good thing as both of you have raised the curiosity in me too to try and hear such tube specimens. The 30's tubes would be hard to find I would assume but the newer ones, would they be too hard to find as well? asuming there are no new production runs by sovtek, eh and others.

Hope u are able to build ur dht system.

aks what would u say about using tubes other than the signal path ?

Manek

Hi,

All topologies in valve circuits work. As has been said before, there is nothing new left in valve design. What's important is how well the selected topology is implemented.

That said, your own thinking and your ears should decide which way to go. About the only way to do that is to DIY. That's why you see so many of us constantly dabling with valves.

Your thinking: what sort of sound do you want in your home? To a lot of us (aks, rajiv - can I include you in this group), who grew up listening to live acoustic music, it is a semblance of that sound that we yearn for. And that leads to the use of the older valves - 26, 76, 2A3 and so on. Purely by elimination - because they are the ones that deliver!

By the way, the power supply is very much in the signal path. It's as important as the rest of the circuit.

Regards,
Viren

Mod-ji
Availability of tubes in India IS a limiting factor. But one can still find older tubes like the 27, 10Y etc with a little bit of foot work. It’s the “modern” tubes like 5687 that are problematic in India. I needed to import 5842 and 5687 from ESRC in USA. Cheap if you have a mule to carry them back to India from US.

On an SE amp EVERYTHING is on the signal path. SS rectifiers are not too bad if you consider how nasty they can actually be. In some application SS is the way to go. I personally feel a tube amp should have a tube rectifier to the extent possible.

Viren-ji has brought out a very important point. We yearn for what is called “Hi Fi” – reproduction of music with complete fidelity. And if simple, time tested methods can achieve this, then why not?

My preamp (ARC Ref3) uses the 6H30P tubes. The stock tubes (Svetlana) took about 80 hours to start sounding better.

After reading a lot of opinions on NOS tubes, specially the 6H30P ones, I changed to NOS 6H30P-DR's from Sovtek and out of the box these were better than stock. After about 100 hours, it was like a different preamp. The NOS tubes are very smooth with excellent bass response and a liquid top end.

I changed only the 4 in the signal path and not the 1 in power supply as the person/company I bought them from didn't think it would make much of a difference in the sound quality.

The pre also has a 6550C in the power supply. I experimented with a couple of tubes here but did not find a difference.

Hi msb1

Thanks for sharing...

I use the Ref-3's little brother : the LS26

Has set me thinking....

Hi,
Does the LS26 use 6H30P's? If yes, you will definitely benefit from a NOS tube.
PM me for names of suppliers.

Another question for you, does the LS26 have individual gain controls? They left this out in the REF3 for some reason and I find the gain very high.

Does the LS26 use 6H30P's?

The LS26 uses the 6H30 not sure the diff between the 6H30 and the 6H30P.

Can some Tube Guru help ?

Another question for you, does the LS26 have individual gain controls? They left this out in the REF3 for some reason and I find the gain very high.

YES. Each input has Low / Medium / High gain settings. ( each step has a 6 dB change, and ideal for A/B comparisions sometimes, where 1 CD player has a 6 dB high output because its a Balanced output, and the other CD player unbalanced.

These can be set from the remote, and also show up on the display. I think this facility is also available on the Ref-3.

Let me know...

Amp_Nut schrieb:

The LS26 uses the 6H30 not sure the diff between the 6H30 and the 6H30P. Can some Tube Guru help ?

I would not consider myself a tube guru but I have an answer:

There is no difference between the 6H30 & 6H30P tube - they are the same - the name has been shortened to 6H30.

As is well-known, the 6H30 tube is a Russian tube so the non-numeric characters are written in Cryllic. So, what is written as "H" in Cryllic is really a "N" in English.
In Russian, the tube's name/number is 6H30n. When translated into English it is 6N30Pi. The "n" is Cryllic for "Pi" & signifies a miniature construction.

So, people in non-Russian counties refer to this tube as 6H30P or 6H30.

Further, there are different designations of the 6N30Pi tube such as
* 6N30Pi-DR, which is supposed to be most rugged military tube.
* 6N30Pi-EB, which is a notch below in ruggedness from the -DR variety.

Thanks, Bombaywalla, that was Very informative.

Bombaywalla is right.
Here's a clarification on this from Victor Khomenko who was the first to use this tube in an audio application:

http://db.audioasylu...c+Victor+Khomenko&r=

He also considers the DP/DR as the best version.

Some Russian tubes are easier to source in India. Most of these tubes were used in earlier MiG fighter planes and Air Defense (Pechora, etc) systems. Forces modernization programme rendered a whole inventory of tube obsolete.

Desi tube sellers are increasingly trying to peddle odd ball Russian tubes.

Aks-ji

Would you please tell us who these desi sellers are and where would we find them say in delhi, mumbai, bangalore, chennai or any other place you know of ?

Manek

This question is for the tube gurus

Brimar made a tube called the 13d5. Some say it is the industrial equivalent of the 12au7/ecc82/cv4003. Its the new fad on the internet for 12au7 compatibles.

There are some who have tried to search in the tube book of brimar but couldn't find a mention. So its been touted as a drop in replacement without hard evidence.

Any of you used one ?

Manek

Manek schrieb:

This question is for the tube gurus Brimar made a tube called the 13d5. Some say it is the industrial equivalent of the 12au7/ecc82/cv4003. Its the new fad on the internet for 12au7 compatibles. There are some who have tried to search in the tube book of brimar but couldn't find a mention. So its been touted as a drop in replacement without hard evidence. Any of you used one ? Manek

I'm afraid not, Manek!
all my tube gear uses 12AX7, 12AT7, 6992, 6N23 type tubes.

Hmmm
Apart from tubemonger and a few ebay guys I don't think anyone else sells these tubes.
Manek

Manek schrieb:

Aks-ji Would you please tell us who these desi sellers are and where would we find them say in delhi, mumbai, bangalore, chennai or any other place you know of ? Manek

2 shops in Jamshedpur. A few in Kolkata. And one called something like “Delite Radio & Electrical” in chandni chowk area of delhi.

Besides I have bought tubes from places like Varanasi, Patna, Cuttack, Ranchi, Raipur and Bhopal.

Tk u sir aks.

Aks, viren and other tube gurus.....


On power tubes....are there any hidden gems like the 5687 preamp tube ?

The run currently seems to be kt88/66, el34 mostly.

In a pushpull config which dishes out approx 40 watts per side would you guys use any other tubes besides the above ?

Manek

807 Tetrode
6BG6GA Tetrode
6B4G Triode
and to some extent 811A Transmitting Triode

All tremendous VFM. All (exept the 6B4G) can easily output more than 50 watts under certain operatong condition.

807 is a very sweet and powerfull tube. Some people say much better than EL34 and I tend to agree with that.

HOw about the 6L6 series ?

Manek,

aks has a lot more experience in this than I have, and I value his suggestions.

If you relax the power requirement, that opens up a much wider range of power valves - 45, 50, 2A3, EL84, 6V6, 6L6. And the better sounding topology of SE designs.

If you were building a system, I would advise selecting high sensitivity speakers, and looking at these low powered amps, where a few watts in enough to enthrall you!

Viren

viren schrieb:

aks has a lot more experience in this than I have, and I value his suggestions.

And that is the overstatement of year

I thought Mod was looking to “discover” tubes beyond that excellent list of 6L6, EL84, 45 etc

6L6 is my favourite tube. The Santa Claus amp started around that. The 807 & 6BG6GA tube belong to the 6L6 tube family and maintains the same audio quality. Just that these are relatively cheaper and more plentiful available. In India the 807 is still available as military packing for little money, but the 6BG6GA needs a little searching. The only drawback is the Anode Cap but I think that looks cool. That also ensures that it can take upto 700volts/100mA type of abuse without complaining. This tube is already “discovered” in the west and waiting for a similar treatment here.

Viren-ji has mentioned the 2A3 tube. 6B4G is in the same family albeit with an octal base and 6.3volt filament. Lately 2A3/45 seem to have dried up in India but I still see 6B4G triode at times.

The 811A is a cheap triode. It was made for the defence forces and just like the 807 can take up incredible amount of abuse. Should you want a Class A2 DHT SE amp than this is the tube to go. From my side I will gift you a pair of NOS 811A as a starter kit . Just that I am not too sure if you are very crazy about class A2 operation and a tube with Anode Cap

Viren-ji
What is your opinion on 801/10Y triode? I am using them as driver tube for my 845SE project but it seems people are using them as power triodes and getting a whopping 1watts of clean DHT power. Its still cheap.

Viren,

Aks is right...I am in the discovery phase. The reason I mentioned 40 watts cause most speakers today are not very tube friendly and if tubes were to catch on with the current run of speakers then methinks 35-40watts would be what's called for at the minimum ?

Aks, you mentioned 807 is better but can you expand on that ? In what way better ?

Manek

807 belong to the 6L6 family. It is electrically similar (accept plate voltage) to the 6L6-G type which is the earliest version of 6L6. Some people say 6L6G is the best sounding of the 6L6 family and I am in agreement.

Now the 6L6G is getting expensive and hard to find. The 807 on the other hand was made in millions to support the WWII and it is still affordable. I paid Rs. 50 ea for them about 4 years ago. Just the military grade packaging is worth more than Rs 50! So in that way it’s a much better tube

807 are sturdier than 6L6G. The major difference is on pinout and plate voltage handling. 6L6G is limited to 300volts on anode while the 807 easily take 700volts due to the top cap design. The screens for both the tubes are, however, still limited to 250volts though in practice it can safely take 300volts. Thus the higher anode voltage of 807 doesn’t mean a lot purely from an audio point of view. It is still limited to 300volts if you are planning to build a triode or ultra linear tapped amplifiers. But if you are looking at purely tetrode operation it can easily delivery excess of 50 watts into a 6K load. I am just giving approx figures off my head. Look up the 807 datasheet for more details.

In Push Pull UL mode you will get about 18watts of clean Class A power. Those who know and look for better solution will likey prefer the 807 tetrode.

Edit later : What is cooking mod-sahib with this sudden "discovery" phase ?

Hi aks

I'll tell you what's cookin....beer marinated
t-bone steak bathed in southern barbecue sauce, hash browns and carrots ! Very down to earth yet delicious.

Actually, viren got me thinking some time back with his usage of those russian valves....there are so many different types of vales made and we are still stuck on a few. Non avialability or high prices of many popular ones are going to push the manufacturers and consimers to look for alternatives. Just wanted to know what else could be used that would be as good or better.

For eg. I caught on the 5687 from virens website. Lo and behold, its one of the very good preamp tubes around.

Another thought that came to mind was that tubes are again getting fashionable with the philips boom box using it and a computer motherboard manufacturer using it. What better chance than to give tubes their much deserved moment in the sun ?

....And yes, the more I listen to my tube headphone rig the more I feel the need to explore the beuatiful world of tubes.

Like rajiv from lithos mentioned the other day, "nothing can put all the music together and present it as beautifully as tubes can, but they lack slam !" Rajiv needs to hear a tube amp or two with slam. Any pointers ?

Manek

Manek said :

Rajiv needs to hear a tube amp or two with slam. Any pointers ?

The Prima Luna Prologue-2 with its KT88s gets my vote !

Leben CS-600...

After comparing them one after the other in succession, I greatly prefer the Shindo Aurieges+Montille to the Leben CS600 with stock tubes. With NOS tubes the Leben might be better. Stock, the Shindo pre-power is a far better amp.

yeah the stock sovtek 6L6GCs have an edge to it making them slightly bright and hard...awaiting my WingedC 6L6GC. apparently the Golden Lion Reissue KT77 are ultimate but too much $$$

NOS (or even EL34/KT66/KT88) with the Leben makes them lush in the midrange but it loses its bass slam

But Manek, last time you showed a lot of interest in cables and ended up cooking some cables up ! so this "cooking" would be really interesting

Cooking cables is fun. I have cooked many more since then and now use home cooked @ower cords and interconnects in my gear and am happy. Doing a bit of research on spkr cables.

As far as amps....currently don't have time for that but god willing will get to that as well. In the mean time am wanting to find the hidden treasures.

Who better to ask than viren and aks....

I think all of us toobies are lucky to have such fine and knowledgable gentlemen on the forum.

I can see em blushing already :-)

Manek

When a baawa gets cooking anything other dhansaak or patranimacchi, it gets interesting

I believe we bring an Indian perspective into the tube scenario to this forum. Otherwise if someone is looking to enhance his tube knowledge, there are excellent forums like audio-asylum.

Russian valves were discovered after the demise of SU. Some of their own developed tubes are simply out of this world. Some of their electronic companies have been designing and building tubes for ages. In future I want to try out these modern tubes.

Talking about slam, nothing matches SE845. You DON’T need a subwoofer.

aks ji,

Haven't worked with the 10Y, though I've heard a lot of good things about it. These DHTs provide such a sense of presence in their sound, that other valves can't match. And you really need a small power valve to drive those monster 845s!

Have to make another attempt on a preamp with 26 valves. I have a pair sitting with me. The first time around, I did have difficulty getting hum levels down.

Another big power valve getting to be known is the Russian GM70. A DHT, could be an equivalent to the 845. Readily available at reasonable prices off ebay stores from Lithuania and Russia.

Viren

viren schrieb:

.. Russian GM70..

Sometime ago I got a list of military dispoable tubes from a shop in kolkata. That list came to him from the party who actually participated in the auction and lifted some LOT of stuff (tubes included) from army. The list had GM70 and other russion tubes. These will turn up at usuall places.

I bought some Russian caps from a lithuanian ebay seller. Quite happy with the experience. Per peice they were cheaper than what I would have paid for film foil cap in India.

Aks

De havilland make single ended monoblocks with the gm70 tube to dish out 50 watts ! Wouldn't that be operating them at their max limits ? Or is the rating a bit optimistic.

Other diyers seem to limit themselves to around 40watts max for stable operation.

Pretty encouraging reading on the gm70 performance but I believe the iron used with it is just too expensive for most diyers.


Manek

Hi Manek,

Yes, there are no off-the-shelf items available for designs such as these. You almost have to order custom wound transformers.

When you are pushing 150mA at 1200V through transformers with air gaps, and you want 50 watts out, you are talking about big monsters!

Just like when you want 30 hertz out at 95 dB out of speakers in your living room, you have big drivers and monster cabinets!

Time to step back, and re-examine your system building.

Viren

I guess this tube will remain in the realm of diy and a very few production units.


Manek

Another thing that people have been using with vacuum tubes are amorphous core transformers.

Why and how are they better for audio than the standard ones ?

Manek