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Little Dot Tube Amps: Vacuum Tube Rolling Guide - Page 348

post #5206 of 7503

5691 (6sl7gt) and 5692 (6sn7gt) are premium long life tubes. Rated for 10000 hrs they probably achieve this but under rating the standard tube (hence spec differences) but these tubes are well built with extras supports etc. Originally in the famed red bases, these tubes are highly sort after by audiophiles, especially in Japan after the Roberts Sound Practices article. There were however brown based examples (like CBS / Hytron) in the mid 1950s and later Sylvania / PhilipsECG black based versions 70s / 80s also (as linked to above). All are excellent tubes but I like the brown based ones best and these are still good value for a 5691 / 5692. The balck base 5691 are cheap compared to the red based versions. The 5691 / 5692 are tough little tubes built with massive excess, second only to Bendix. Be careful in purchasing these tubes however as many people try to re label / palm off standard tubes as 5691 / 5692s. These are easily spotted if you know what to look for (5 heavy duty support rods), I have 10 National 5692 from Russia that are...... , well not the same as the US ones!

post #5207 of 7503
Quote:
Originally Posted by mordy View Post
 

Hi i luvemusic 2,

 

After you set up both power supplies I would just re-measure the voltage at the tube socket pins to make sure that nothing changes.

 

Personally, I have a different type of setup with two differently wired breadboards attached to one voltage regulator. I just have to make sure that only one tube is plugged in at any one time. To switch from 6DJ8 to octal tubes I just unplug the Vector adapters and switch to a second set of Vectors, making sure that the voltage is set correctly.

 

(I tried having one Vector plugged into the other, i.e one on top the other, hoping that I would only need to switch the tube and the voltage, but that did not work at all. In retrospect, I should have figured out that that it is a dumb idea to mix two different wiring schemes.)

 

Anyhow, waiting for an upgraded 5A voltage regulator for them power hungry 6SN7 variants...

 

There are custom made Bugatti Weyron level systems out there costing mega bucks:

 

  • VPI Scout turntable + Shelter 501 MkII cartridge
  • Krell KPS 20i/L cd player
  • Gryphon XT MC preamplifier
  • Mandozzi DART harddiskrecorder
  • Nagra ARES harddiskrecorder
  • Self build power amplifiers using 6SN7 - 300B - TB3/1000. These are on the outside of the audio rack. The dedicated power supplies are below; the amplifiers themselves are above
  • Self build tube headphone amplifier using 6SN7's. It is in the middle lower shelf. The dedicated power supply is next to it. It drives a Grado RS1.
  • Self build Avalon Opus Ceramic loudspeakers with external crossovers.

The power amplifiers deliver 70 Watt single ended Class A. The output triodes are pre-WWII transmitting triodes from Philips. The American equivalent is the well known 833A. These triodes are fired through a step down interstage using EML 300B's. I have the 300B-XLS and the 300B-Mesh. And it is a matter of taste what to choose; both perform excellent !. The 300B-driver is essential in these amplifiers for the output triodes want to see a very stable driver.

The amplifiers are fully hard-wired. All needed voltages do have there own power line consisting of power transformer - rectifier - snubber - coil - capacitor - coil - capacitor. This adds up to a total of 32 coils and transformers. And as these amplifiers run on 1200 Volt everything is quite large. The complete amplifier weighs more than 300 kgs.

 

Reinout-de-vries-1.jpg

 

This guy claims that the listening experience is better than listening live in a concert hall.

 

Why I am showing this? Because we have something in common - he is using 6SN7 tubes as drivers. I think we are on to something...

Hi Mordy,

      My setup is only for 6SL7/6SN7 and for 12 volt version. my plan is to use  2 regulators(one is set to 6.3V and the other is  set to12V) and some switches to select from 6V and 12V and from LD 1 to LD MK III or play/used both amps if i want to, once i'am done with these configuration i will take a picture.I want to do it this way because lately i got soo lazy adjusting/reconfigure my setup just to play from LD 1 to LD MK III And hopefully my parts will arrived soon i ordered it 2 weeks ago and i'am still waiting for that SLOW BOAT FRON CHINADA.Those amps on the picture are really nice and THANK YOU for your advised.

post #5208 of 7503

Hi guys - wonder if anyone can put me straight on my search for some nice "coke-bottle" power tubes, better to match (almost visually anyway!) my C3gSs.

Am I way off here, please - viz 6C4C (6B4G/6A3) tubes? 6.3v/900mA - but DIRECTLY heated...would love to hear any opinions/info...

 

Cheers.

post #5209 of 7503
Quote:
Originally Posted by hypnos1 View Post
 

Hi guys - wonder if anyone can put me straight on my search for some nice "coke-bottle" power tubes, better to match (almost visually anyway!) my C3gSs.

Am I way off here, please - viz 6C4C (6B4G/6A3) tubes? 6.3v/900mA - but DIRECTLY heated...would love to hear any opinions/info...

 

I hope someone with more expertise will weigh in, but I have no idea what sort of modifications would be necessary to run directly heated cathodes in our Little Dots... But of course, I am hoping that there is a way. :)

post #5210 of 7503

What is the average price you guys paid for 6SN7? i've been looking around and the lowest i found is $20 + shipping (which is some seller will charged arm and a leg)Thanks!

post #5211 of 7503
Quote:
Originally Posted by i luvmusic 2 View Post
 

What is the average price you guys paid for 6SN7? i've been looking around and the lowest i found is $20 + shipping (which is some seller will charged arm and a leg)Thanks!

 

I'm not sure where you are looking, but I see lots of 6SN7s for less than $20. For example, here is a nice Sylvania "Chrome Dome", relabeled as a Raytheon, for $8.50 plus $3.75 shipping within the US. (However, I know that shipping from the US to Canada would be more than $3.75).

 

http://www.ebay.com/itm/1-RAYTHEON-6SN7GTA-Radio-Vacuum-TUBE-Tested-audio-amplifier-Sylvania-/351014736002?pt=Vintage_Electronics_R2&hash=item51ba1bd082

 

One suggestion, when using eBay, go to the left-hand side and click "Worldwide" under "Item Location", and then search for "6SN7". This will give you the largest selection.

 

Of course, if you are searching for tubes that are well-known and in-demand, you might have to pay more. But even then, if you are familiar with the unique construction details of the tube you hope to buy, looking for rebranded tubes can often reward you with significant savings. For example, if you wanted a Sylvania "Chrome Dome", you could purchase the Raytheon linked to above, for cheap.

 

Good luck! :)

post #5212 of 7503
Quote:
Originally Posted by gibosi View Post
 

 

I'm not sure where you are looking, but I see lots of 6SN7s for less than $20. For example, here is a nice Sylvania "Chrome Dome", relabeled as a Raytheon, for $8.50 plus $3.75 shipping within the US. (However, I know that shipping from the US to Canada would be more than $3.75).

 

http://www.ebay.com/itm/1-RAYTHEON-6SN7GTA-Radio-Vacuum-TUBE-Tested-audio-amplifier-Sylvania-/351014736002?pt=Vintage_Electronics_R2&hash=item51ba1bd082

 

One suggestion, when using eBay, go to the left-hand side and click "Worldwide" under "Item Location", and then search for "6SN7". This will give you the largest selection.

 

Of course, if you are searching for tubes that are well-known and in-demand, you might have to pay more. But even then, if you are familiar with the unique construction details of the tube you hope to buy, looking for rebranded tubes can often reward you with significant savings. For example, if you wanted a Sylvania "Chrome Dome", you could purchase the Raytheon linked to above, for cheap.

 

Good luck! :)

Yup to Montreal  $18.48 U.S. shipping for a $8.50 tube incredible !

post #5213 of 7503
Quote:
Originally Posted by MIKELAP View Post
 

Yup to Montreal  $18.48 U.S. shipping for a $8.50 tube incredible !

 

Yes, those of us in the US are very spoiled. I can send a tube from Ohio to California for $2 or $3, with tracking, and it will get there in 2 or 3 days. If I were to send the same package to you in Montreal, it would be around $10, with no tracking, and it would take 10 days to 2 weeks! I find this to be amazing! (>_<) 

post #5214 of 7503

I found a smoked glass RCA 12SN7 for $8 on ebay last week that I bought.

 

http://www.ebay.com/itm/151210735886?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

 

12SN7 are less popular therefore much cheaper, just gotta make sure you have a sufficient external PSU.

post #5215 of 7503

Hi i luvmusic 2,

 

I recently bought a lot of 10 6SN7 tubes for $26 including shipping. Read somewhere (jacmusic?) that he opened a factory sealed box of 50 tubes and found JAN, VT, GT and GTW tubes in the box. Apparently, all the tubes were the same, but they were marked differently.

 

For this reason I don't pay so much attention to what it says on the tube, and as they say, the proof is in the pudding; I'll listen to them and make my own evaluation. There is no doubt in my mind that certain sellers have hyped certain items for profit making reasons. I somebody paid $99 for a tube it better sound stupendous!

 

In this lot of ten I lucked out; there were five winners. I got a Japanese tube, a genuine Sylvania Chrome Dome (not Chrome Top), two late model RCAs and a an earlier RCA that all sound excellent. So I paid $2.60 each, or if I discard the me too's, the cost was $5.20 each incl shipping.

 

If you look at the left column on Ebay of 6SN7 listings (or whatever) you will find a check box that says sold listings. When you check it you will see what the items actually sold for. Usually, but not always, there will be desirable tubes that sold very cheap. This overview gives you an idea what to pay and how much you should bid. If there is a best offer feature, don't hesitate to make a shamelessly low offer. A decent seller will not ignore you, but come up with a counter offer. Sometimes it's ridiculous, and sometimes reasonable. Or they may bite on your original offer...

 

What you a are looking for are the non professional sellers that are selling off what they picked up at an estate sale or inherited from an old uncle. Don't forget that the 99c tube somebody is selling is the same as someone else is asking $29.99 for.

 

Scroll down this list to see what 6SN7 tubes sold for the last couple of months:

http://www.ebay.com/sch/Vintage-Electronics-/14998/i.html?_from=R40&_sop=15&_nkw=6sn7&LH_Complete=1&LH_Sold=1&rt=nc

 

Now, type in 6SN7 and click on lowest price incl shipping from the drop down menu on the right:

http://www.ebay.com/sch/Vintage-Electronics-/14998/i.html?_from=R40&_sop=15&_nkw=6sn7&rt=nc

 

I counted a dozen auctions starting on under $1 (don't know where the price will end), and four Buy It Now tubes for less than $6 incl shipping within the US

 

Unfortunately, shipping to Canada is a bummer...

 

Now I have given away my buying secrets....

 

PS: Don't forget to check the feedback score. Anything under 99% I would be leery of. You can actually go in and read the negative feedback to see what the problem is - sometimes it is trivial.

post #5216 of 7503
Quote:
Originally Posted by hypnos1 View Post
 

Hi guys - wonder if anyone can put me straight on my search for some nice "coke-bottle" power tubes, better to match (almost visually anyway!) my C3gSs.

Am I way off here, please - viz 6C4C (6B4G/6A3) tubes? 6.3v/900mA - but DIRECTLY heated...would love to hear any opinions/info...

 

Cheers.

Those directly heated could be very very difficult to get work with LD. I could suggest next tubes:

http://www.radiomuseum.org/tubes/tube_6j5g.html Half of the 6SN7, so you need 4 tubes to replace two 6N6P.

http://www.radiomuseum.org/tubes/tube_6f8g.html Like 6SN7, but needs different adapter

http://www.radiomuseum.org/tubes/tube_ecc32.html This could be the best candidate.

post #5217 of 7503
Quote:
Originally Posted by Artsi View Post
 

Those directly heated could be very very difficult to get work with LD. I could suggest next tubes:

http://www.radiomuseum.org/tubes/tube_6j5g.html Half of the 6SN7, so you need 4 tubes to replace two 6N6P.

http://www.radiomuseum.org/tubes/tube_6f8g.html Like 6SN7, but needs different adapter

http://www.radiomuseum.org/tubes/tube_ecc32.html This could be the best candidate.

 

I've been considering trying the 6F8G (VT-99) if i can find an affordable one, especially since i'll need to buy an adapter.

post #5218 of 7503
Quote:
Originally Posted by Artsi View Post
 

Those directly heated could be very very difficult to get work with LD. I could suggest next tubes:

http://www.radiomuseum.org/tubes/tube_6j5g.html Half of the 6SN7, so you need 4 tubes to replace two 6N6P.

http://www.radiomuseum.org/tubes/tube_6f8g.html Like 6SN7, but needs different adapter

http://www.radiomuseum.org/tubes/tube_ecc32.html This could be the best candidate.

 

Many thanks Artsi (and everyone else!) for not calling me mad/sad/stupid (as I did the moment I posted that shot-in-the-dark!). Suppose I was hoping against hope there would be some way of using direct-heated tubes....ah well...

 

Re.your best candidate - wish I could afford them!! I have in fact been browsing a cv181 substitute - a rather nice-looking Sophia '6SN7', which actually looks nothing like a 6SN7!. But even these are not cheap...WHY did I pay so much for the 6N30P-DRs??? These Sophias would look SO much better...and probably sound just as good, if not better? (Mind you, of course, we had no idea we would end up in such tube territory many months ago, lol!).

 

But who knows - Santa Claus just might come early...

 

Quote:
Originally Posted by gibosi View Post
 

 

I hope someone with more expertise will weigh in, but I have no idea what sort of modifications would be necessary to run directly heated cathodes in our Little Dots... But of course, I am hoping that there is a way. :)

 

Yes g, so was I hoping...but alas against hope it would appear!

 Never mind, at least Artsi has come up with some possible alternatives...to spend or not to spend?, that is the question...

post #5219 of 7503

Those Tennis Ball CV181's look amazing.

 

These don't look too bad either, but not as nice.

post #5220 of 7503

Don't be fooled by marketing, guys. The tubes look purdy, but they are CV181s in name only.

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