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Little Dot Tube Amps: Vacuum Tube Rolling Guide - Page 170

post #2536 of 6925

Hi kvtaco 17,

 

Other people tried to solder wires to the pins and had a hard time. Could you please tell us how you did it? Did you file off the coating or use some special equipment?
 

post #2537 of 6925

I cleaned the pins with sand paper (800 grit) and the sprayed some electronic contact cleaner on a rag and wiped it down. I stress using stranded 28/30 awg wire and tinning the ends lightly so they keep their form while soldering... other then that I didn't do anything special.
 

post #2538 of 6925
Quote:
Originally Posted by jaywillin View Post

ok, i must be doing something wrong, the seller that i bought the cbs hytron 6cs6 , sent me a set of rca  6cs6

they made an even worse noise than cbs tubes, a loud steady hum

the tubes construction appears a little different

i tried ef95 and 91/92 ,

i put the rca 5915's in, they sounded fine, so the amp seems ok, headphones ok

i double checked the jumper placements, and the 5915 is playing now

am i missing something ?

 

 

The one with the shiny ribbed plates is actually a GE 6CS6. Evidently, RCA contracted with GE for some 6CS6, and then simply rebranded them. I have one of these RCA/GE tubes too..lol

 

The noise may go away after burn-in.... In my experience, if the noise appears immediately upon turning on the amp and becomes louder as the volume control is increased, it is likely a defective tube. If the noise appears gradually, as the tube warms up, and the amplitude does not change as a function of the volume control, then it is likely the noise will disappear after burn-in.

 

Good luck!

post #2539 of 6925
Quote:
Originally Posted by MIKELAP View Post

Well gibosi your Westinghouse 6av6 are coming along nicely (24 hours)similar to the other 6av6 nice treble clean sounding tight bass nice crisp sounding good soundstage using the Senns hd800 and Conductor's Dac .                                                                                                                                                                                     

 

I am glad to know that my Westinghouse tubes meet with your approval. lol   As I recall you have a number of EBC91/6AV6... Do you have a favorite or two?

post #2540 of 6925

Also to add I use NO-OX-ID A-special electrical grade to keep the pins from corroding after I clean them (really should be used on any connection) It's something I use for work on everything for telecom/data center on cable ends, lugs, termination points ext. It works very well with the small pins on these tubes I use a very thin layer (feel it can't see it) like in a telecom application. This stuff is greasy (don't use it where you'll end up touching it) and will get hard kinda over time so caking a bunch on a connection just makes it stick a bit.  


Edited by kvtaco17 - 8/22/13 at 8:40pm
post #2541 of 6925
Quote:
Originally Posted by kvtaco17 View Post

I have the 6DT6A and its just as you described (I like my sparkle and as the bass tightens the treble comes out more) so far so good!

 

I have about 20 hours on a pair of RCA 6HZ6 and these too are the same as you and Mordy describe the 6DT6. Great tubes for cheap!! :)

post #2542 of 6925

Hi Gibosi,

 

I am sorry to tell you that personally I did not find the RCA 6HZ6 tubes as good as the RCA 6DT6. Below are my previously prepared comments:

 

 

Here is a comparo of the pentodes RCA 6DT6 (hereafter dtox) and the RCA 6HZ6 (hereafter Herz) tubes. According to Gibosi's estimation both tubes are the same, but the Herz should sound louder because it has higher grain. Maybe they are twins, but not identical twins. It is more like the big bully brother Terz and the sweet sister Deetx, but I am getting ahead of myself......

 

The Herz was a brute to break in. Firstly, as soon as I turned them on there was a loud hum. Oh no, what did I do? Luckily, it dissipated after a few seconds. In the beginning the tubes did not sound anything special. This continued for over 40 hours until the tubes finally opened up.  In addition, they ran very hot; too hot to touch.

 

Another peculiarity: All my tubes I play with the LD volume setting at 3 o'clock. With these tubes I had to turn it down to around 1-2 o'clock to avoid a strange kind of "hollow" distortion.

 

About settings:

 

NS EF95 (P&P) : Fairly pleasant but light weight bass and sharp treble. Mid range harshness. Not especially wide sound stage

                         

EF95  1/7 strap:  Sharp treble, mid range harshness, monster bass that goes very low. Sound stage average

 

EF95  6/7 strap (simulated EF92):  Thin, sibilant sound, exaggerated treble, bloated bass - forget about it

 

EF95  2/7 strap:  Pentode/heptode magic! Detail, monster bass, pleasant treble, very good instrument separation. Sound stage average. But:

There is a strange mid range coarseness/harshness and a slight treble sibilance. It is not a mid range coolness, but rather the opposite of sweetness. Tartness? Harshness? Terseness? Coarseness?

 

Perhaps these tubes will match somebody else's equipment better than mine, but these Herz 6HZ6 tubes are not among my favorites because of the mid range aberration. It must also be pointed out that the tubes came from two different production runs. The construction looks almost identical, but one tube has a copper post and one not. I could not detect any difference in sound after burn in.

 

But what about the 6DT6 little sister dtox?

 

Well, this tube can compete with the best! What can I say? Beautiful, detailed strong bass, the sweetest mid range, and treble with the right amount of shimmer and great detail. A really satisfying, full bodied sound with the widest sound stage. On a good recording the sound stage and instrument separation is just amazing. Toe tapping index 5+.

 

All of the above pertains to EF95 1/7 strap setting. The other settings (6/7, 2/7, NS) were all OK, but the sound was thin. Good bass, sibilant treble.

 

G, amazing how different similar tubes can sound!

 

post #2543 of 6925

Hmmm... I think I need to get a pair of RCA 6DT6.....

post #2544 of 6925

Just in the door this afternoon are 10 NOS NIB 6J3P-E from the Ukraine.  These are much taller than the usual compatible tubes for this amp, and the gain is much higher than the Voskhods I had in previously.  Just out of the box though... must be time for cooking. :)

post #2545 of 6925
Quote:
Originally Posted by gibosi View Post

 

The one with the shiny ribbed plates is actually a GE 6CS6. Evidently, RCA contracted with GE for some 6CS6, and then simply rebranded them. I have one of these RCA/GE tubes too..lol

 

The noise may go away after burn-in.... In my experience, if the noise appears immediately upon turning on the amp and becomes louder as the volume control is increased, it is likely a defective tube. If the noise appears gradually, as the tube warms up, and the amplitude does not change as a function of the volume control, then it is likely the noise will disappear after burn-in.

 

Good luck!


the cbs, gradual and noise doesn't change, i'll burn this in longer

the rca, instant and the noise doesn't change with volume change,, and it appears to be just one tube after switching sockets

i have to get another power cord , the LD and the schiit are having to share ! lol


Edited by jaywillin - 8/23/13 at 5:28am
post #2546 of 6925

Hey mordy do you have a link for those RCA 6DT6 cant seem to find much on ebay maybe there sold out. thanks

post #2547 of 6925
Quote:
Originally Posted by gibosi View Post

 

I am glad to know that my Westinghouse tubes meet with your approval. lol   As I recall you have a number of EBC91/6AV6... Do you have a favorite or two?

i tried to have a listen to all 6 pairs of 6av6 SYLVANIA, G.E. ,JAN.GE, WESTINGHOUSE ,LORENZ,HIT RAY,and man its hard to tell them apart personnally they all sound good to me and similar as i commented before.if theres differences i cant ear them  with these olden ears and i mean olden !

post #2548 of 6925

Trying the G.E. 6DT6A  TUBES warmer sounding than the 6av6 tubes more laid back to me less agressive in the treble department this is out off the box impressions if they would stay the same i would be happy another good sounding pair imo                                                                                                                               .Processed By eBay with ImageMagick, R1.0.1.M1

post #2549 of 6925
Quote:
Originally Posted by MIKELAP View Post

Trying the G.E. 6DT6A

 

Seeing those CGE "Japan" tubes, I once again think that the mystery Siemens "foreign" tubes might be Japanese.

post #2550 of 6925

Hi Mikelap,

 

Looks like you are right, can't find much in RCA 6DT6. I have not heard the RCA 6DT6A, perhaps it sounds the same. Maybe somebody out there has compared both?

 

The other avenue to find these tubes is to be pro active. Contact the sellers that you have dealt with in the past that were cooperative, and ask if they have this tube. Many times it works, but I found that at times the seller suddenly jacked up the price because now you are asking for something.

 

Based on experience, a little patience always pays off. Just check Ebay often, and new items always come up.

 

I myself only have one pair of these, so I have to follow my own advice....

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