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Little Dot Tube Amps: Vacuum Tube Rolling Guide - Page 497

post #7441 of 7455

Don't the C3m's have 20V heaters?

post #7442 of 7455
Quote:
Originally Posted by TrollDragon View Post
 

Don't the C3m's have 20V heaters?

 

Oh! My sleepy eyes didn't catch this! Yes, these have 20V heaters, and so definitely not plug and play!

 

The C3g is plug and play with an adapter.

 

Thanks for catching this!

post #7443 of 7455

Here is a link to a pair of Sylvanias 6SN7GTB (used) for $12.50 incl shipping -  why pay $70/pair? Try them, and if you like them, shop for a NOS pair at the right price if you want new tubes.

 

http://www.ebay.com/itm/Pair-Used-6SN7GTB-Sylvania-Black-T-Plate-Halo-Getter-gm-Good-Match-/131207978618?pt=Vintage_Electronics_R2&hash=item1e8c9ade7a

 

Sylvania sold many tubes under other names, and if the factory code is 312 it is a Sylvania. It is possible to get good deals using other brand names.

 

Here is an offer for 5 used C3m Lorenz tubes for EUR 18.00

 

http://www.ebay.de/itm/Lorenz-Tube-Radiorohre-5-x-C3m-/231308467346?pt=R%C3%B6hren&hash=item35db0f1c92


Edited by mordy - 9/14/14 at 12:36pm
post #7444 of 7455
Quote:
Originally Posted by gibosi View Post
 

 

Sylvania's factory code is 312, so these are genuine. And the date codes are the same 613, so the 13th week of 1956.

Thanks, G!

post #7445 of 7455
Quote:
Originally Posted by mordy View Post
 

Here is a link to a pair of Sylvanias 6SN7GTB (used) for $12.50 incl shipping -  why pay $70/pair? Try them, and if you like them, shop for a NOS pair at the right price if you want new tubes.

 

http://www.ebay.com/itm/Pair-Used-6SN7GTB-Sylvania-Black-T-Plate-Halo-Getter-gm-Good-Match-/131207978618?pt=Vintage_Electronics_R2&hash=item1e8c9ade7a

 

Sylvania sold many tubes under other names, and if the factory code is 312 it is a Sylvania. It is possible to get good deals using other brand names.

 

 

Thanks, Mordy!

post #7446 of 7455

Unfortunately the seller does not ship to Malaysia :( I shall try to ask if he will make an exception.

 

Sorry, where do you see the factory code ? I don't seem to see any markings on the tubes..


Edited by Rossliew - 9/14/14 at 5:17pm
post #7447 of 7455
Quote:
Originally Posted by Rossliew View Post
 

Sorry, where do you see the factory code ? I don't seem to see any markings on the tubes..

 

The tubes you linked to earlier:

 

http://www.ebay.com/itm/Sylvania-1956-vintage-tall-6SN7GTB-vacuum-tubes-matched-and-ultra-quiet-/111330100983?pt=Vintage_Electronics_R2&hash=item19ebca86f7

 

The second picture shows the tube codes.

 

On the first tube, the codes are vertical

 

3  6

1  1

2  3

 

And on the second tube, horizontal

 

312612

post #7448 of 7455
Quote:
Originally Posted by gibosi View Post
 

 

The tubes you linked to earlier:

 

http://www.ebay.com/itm/Sylvania-1956-vintage-tall-6SN7GTB-vacuum-tubes-matched-and-ultra-quiet-/111330100983?pt=Vintage_Electronics_R2&hash=item19ebca86f7

 

The second picture shows the tube codes.

 

On the first tube, the codes are vertical

 

3  6

1  1

2  3

 

And on the second tube, horizontal

 

312612

OK, i see it now! Some tubes do not have these markings so we won't be sure then. Looks like i need to find those with markings to be doubly sure.

post #7449 of 7455
Quote:
Originally Posted by Rossliew View Post
 

OK, i see it now! Some tubes do not have these markings so we won't be sure then. Looks like i need to find those with markings to be doubly sure.

 

If they are labeled Sylvania, then you can be reasonably sure they really are Sylvania. These are way to common to encourage anyone to go to the trouble to make fakes. And there are some construction details that are helpful. Every Sylvania I have seen has black plates. Further, except for a few 6SN7GT's manufactured in the 1940's and early 1950's, the vast majority of Sylvanias, especially the GTA's and GTB's, have chrome tops. The GTB's linked to by Mordy, are classic examples.

 

Search eBay for Sylvania 6SN7 and after looking at a bunch of them, you will soon be able to recognize these tubes, and also be able to differentiate them from the VT-231 types with clear tops, black plates and bottom getters.

 

So when you are looking at rebrands, black plates and chrome tops pretty much narrows it down to Sylvania. And fortunately, rebrands often have the standard Sylvania manufacturer and date codes.

post #7450 of 7455

Here is an update on my excursion into the past, comparing three different pairs of box top getters 6AV6 triodes to a Tung Sol 5687 dual triode. Power tubes for this comparo are a pair of 60's Sylvania 6080WB.

 

All the 6AV6 tubes have very nice mid range and treble, but they seem to be running out of steam in the bass in comparison to the 5687. The best sounding pair is the RCA, followed by the Sylvania and lastly by the Tung Sol. The RCA and Sylvania are musical and sweet, but lack the heft and authority in the bass. The TS sounded slower and had a more woolly and loose bass than the others.

 

Time for a change again. Pulled out the the tubes and changed the jumpers from EF92 to EF95 settings no sweat, plugged in the Vectors and the 5687 with the 12.6V voltage regulator and PS. With this tube it sounds like you added a sub woofer; it goes so much lower in the bass, and the bass is much better defined with great slam and attack. The treble also has more sizzle and power.

 

I figured out that I must have spent around $120 or more on adapters (two Vectors, two octal to 6N6P, two 9pin socket extenders), two voltage regulators 5A and 15A, a laptop power supply and a PC 430W 12 V PS, two computer fans and a 9pin breadboard. It is well worth it because of the tremendous upgrade in the sound.

 

So long 6AV6 - the 5687 is the clear winner in this comparo.

post #7451 of 7455
Quote:
Originally Posted by mordy View Post
 

Here is an update on my excursion into the past, comparing three different pairs of box top getters 6AV6 triodes to a Tung Sol 5687 dual triode. Power tubes for this comparo are a pair of 60's Sylvania 6080WB.

 

All the 6AV6 tubes have very nice mid range and treble, but they seem to be running out of steam in the bass in comparison to the 5687. The best sounding pair is the RCA, followed by the Sylvania and lastly by the Tung Sol. The RCA and Sylvania are musical and sweet, but lack the heft and authority in the bass. The TS sounded slower and had a more woolly and loose bass than the others.

 

Time for a change again. Pulled out the the tubes and changed the jumpers from EF92 to EF95 settings no sweat, plugged in the Vectors and the 5687 with the 12.6V voltage regulator and PS. With this tube it sounds like you added a sub woofer; it goes so much lower in the bass, and the bass is much better defined with great slam and attack. The treble also has more sizzle and power.

 

I figured out that I must have spent around $120 or more on adapters (two Vectors, two octal to 6N6P, two 9pin socket extenders), two voltage regulators 5A and 15A, a laptop power supply and a PC 430W 12 V PS, two computer fans and a 9pin breadboard. It is well worth it because of the tremendous upgrade in the sound.

 

So long 6AV6 - the 5687 is the clear winner in this comparo.

If you want to sell your adaptors, voltage regulators, PS, breadboard, etc...i may consider taking them off your hands :D

post #7452 of 7455
Quote:
Originally Posted by mordy View Post
 

Here is an update on my excursion into the past, comparing three different pairs of box top getters 6AV6 triodes to a Tung Sol 5687 dual triode. Power tubes for this comparo are a pair of 60's Sylvania 6080WB.

 

Very interesting, but I am not at all surprised. My 1950's GE 6AV6 were my favorite tubes up until I started to roll double triodes. But after my first session with an Amperex Orange Globe, there was no turning back. In my opinion, the GE 6AV6 is superior to the GE/Mullard 6HM5, but no match for a good double triode.

post #7453 of 7455

Concur - the allure of the 6HM5 is that it is a straight plug and play tube, and it doesn't require any modifications to use. The superior box top 6AV6 require cutting off and taping pins 5&6, and changing the jumpers from the EF95 to the EF92 setting.

 

The dual triodes require much more extensive modifications with a breadboard and adapters + external power sources in some cases. However, the efforts are rewarded with superior sound. There is no turning back....

post #7454 of 7455
Quote:
Originally Posted by hypnos1 View Post
 

Hi guys.

 

A while ago I decided to give a real cheap job a try just for fun, remember?...ie the Little Bear P8 (with metal case and toroidal transformer).

 

Well, with 2x '50's TS 5687s (separate heater power supply and different pin-out to the stock 6N3P) driving a single Chatham 6AS7G, all I can say is... unbelievable!.. Better than the MKIV SE with any tubes up until the latest magical finds...I kid you not...CRAZY!!

 

However (there's always a catch, no?) - even with just one 6AS7G, it gets far hotter than the LD...volume knob is at 3 o'clock as opposed to the LD's 10 or 11. And it obviously doesn't really like the higher external heater power supply - pretty bad hum, which I can actually minimise by using myself as ground, via a wire attached to the tubes' centre tap, and completely by finger also placed on the amp's metal front plate...unconventional, but it works lol! (Better be careful I don't brush the pos., though!:eek:)...Next step is to attach said wire direct to said metal front, and see what happens...

 

Anyway, these niggles notwithstanding, for anyone prepared to do the necessary this represents tremendous value-for-money, methinks...

 

Here she is, next to big brother...and as per gibosi and mordy, giving new meaning to "flying by wire"!! (might get round to making some proper adapters later - all depends on the Feliks project...).

 

(To eliminate the need for external power supply, I might just have a go with some nice 6N23Ps...)

 

.

 

Edit...Correction...the 5687s in at present are the Raytheons...and very good they are too :D.

 

I know this is VERY unfair, but there isn't quite the 3D 'holographic' sound of the modded LD, nor same level of detail...but hey, you want blood?!! :wink_face:

Did you hard wire your HEADPHONE into your AMP?

post #7455 of 7455

One of my Favourite Plug and play tube is the GE JAN 5654W but IMO not better than 6HM5,How i miss those days using those tubes now they are Dust Collectors.:biggrin:

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