Bottlehead Forum
Bottlehead Kits => S.E.X. Kit => Topic started by: i luvmusic 2 on September 15, 2014, 02:15:46 PM
-
Do i need a match pair of tube for the S.E.X.?
Is it important to match the tubes for S.E.X.?
THANK YOU!
-
As I understand it, the 6DN7s are quite common but matching may be a difficult endeavor and is not usually done.
I'm currently using one Sylvania and one RCA selected for their minimum hum during low passages and between tracks. The channel balance seems right and using two different manufacturers doesn't seem to make a difference in overall performance.
-
Good to know i almost got ripoff, THANK YOU!
-
I found lot of 10 6DN7's 2 RCA(NOS),1 Marconi,3 Sylvania and 4 GE(NOS) 6 are NOS and 4 are used.The used ones according to the seller They are tested 92/94,93/90,89/91 and 85/89 what are these numbers mean?$62 including shipping is this price reasonable?
Sorry for all these noob questions.
Thanks!
-
I found lot of 10 6DN7's 2 RCA(NOS),1 Marconi,3 Sylvania and 4 GE(NOS) 6 are NOS and 4 are used.The used ones according to the seller They are tested 92/94,93/90,89/91 and 85/89 what are these numbers mean?$62 including shipping is this price reasonable?
Sounds like a reasonable price to me. I used to buy 6DN7 and other similar tubes for Wooaudio's WA6SE. They are around $7 each on the lower end for NOS.
-
I found lot of 10 6DN7's 2 RCA(NOS),1 Marconi,3 Sylvania and 4 GE(NOS) 6 are NOS and 4 are used.The used ones according to the seller They are tested 92/94,93/90,89/91 and 85/89 what are these numbers mean?$62 including shipping is this price reasonable?
Sorry for all these noob questions.
Thanks!
Those test results depend on the tube tester used. For example on the TV series military testers there is a scale from 0-120 and the spec for 6DN7's says it should test with a minimum of 40. I dont know what a good 6DN7 should test at, but if its 80-90 on one of those testers i would call them perfect.
I think the only time i paid more than $10 a 6DN7 was for some Tung-Sols, they were so rare i just didn't care as i had to have them, and a few others on eBay had the same mentality. As above anything from $5-10 seems to be the norm.
-
I don't see them on ebay for less than $10/tube and THANK YOU! for the info.
-
I don't see them on ebay for less than $10/tube and THANK YOU! for the info.
Tubesandmore dot com has them for $7.50 each. 56 units in stock.
-
Thanks! I will check it out.
-
Is it possible to used a 6SN7 tubes for the SEX amp?
Thank You!
-
The 6SN7 will not work. The 6DN7 is special.
-
If i try it anyway would I see a FIREWORKS and hear a KABOOM?
-
I have never tried it, so there's no way to be sure.
But in theory it might work acceptably - for a while!
The heater voltage will be a little high, and the dissipation in the power section will exceed the spec; both of these will reduce the life of the tube. It should at least be a -GTA or -GTB version, the standard has a much smaller dissipation limit.
-
Go big or go home Paul!! Lol
-
I have both the GTA and GTB so i guess i will be the first one to try these.
THANK YOU!
-
Use ones that you didn't pay much for...
-
OK THANK YOU!
I will be using the 6H8C for now to see how it goes.
-
OK THANK YOU!
I will be using the 6H8C for now to see how it goes.
Make sure to let us know how you get on the Russian 6h8c are inexpensive enough to be regularly disposable.
-
I don't mean they are inexpensive/disposable,It just happened that i paid $3 a piece compare to my other 6SN7's .
I hoped i did not offend anyone.if i did PARDON ME...
BTW You guys should give it a try it does work and sound nice too.
-
I can never tell if PJ is being serious or just trolling us (https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fwww.cr-x.org%2Fgif%2Fsuspect.gif&hash=f0cf7566a00a8343a1f741a9a520c9f82a7fb71b)
6H8C is basically a 6SN7GT and limited to ~300v plate voltage so it may not be suitable.
-
So far still working no unusual things happening i will run it for a little longer and see.
-
So far i run the 6SN7 on the SEX for 6 hrs last night and no issue.I will continue to use these tube until i see/hear something strange.
-
If we assume that this modification drastically cuts down the life of a 6SN7, say by 50%, then you should run the amp for 5,000 hours and see what happens. (Not 6)
-PB
-
Not sure why anyone would want to do that to a perfectly good 6SN7. ???
-
Haha - "smoke 'em if you got 'em"
How does the sound compare?
-
I'am not good at describing sound but i will try,The 6H8C sounds more relaxing than the 6DN7 a little less Bass and smoother treble.
To my ears there are times that the 6DN7 can be harsh on my ears but so far i did not experienced these with the 6H8C.
IMO when it comes to music/audio gear it's most likely a personal taste,Sounds that is good to my ears might not for others it's like one of those cable/capacitor debates but lets not go there.
-
. . . IMO when it comes to music/audio gear it's most likely a personal taste, Sounds that is good to my ears might not for others it's like one of those cable/capacitor debates but lets not go there.
So true and you are the only one that matters in this.
-
So I fired up an old spreadsheet and looked more closely at the 6SN7-GTB. It should work just fine, and within spec. Output is about 3/4 watts, damping factor 1.0.
A speaker with a very low QT could work really well with the low damping factor; for example an FE-206E Fostex in a 1 cubic foot box tuned to 50Hz or a bit lower. Try a 2.5-inch ID tube 4" long. Parts Express has ready-made 1.0 CF boxes.
-
So I fired up an old spreadsheet and looked more closely at the 6SN7-GTB. It should work just fine, and within spec. Output is about 3/4 watts, damping factor 1.0.
A speaker with a very low QT could work really well with the low damping factor; for example an FE-206E Fostex in a 1 cubic foot box tuned to 50Hz or a bit lower. Try a 2.5-inch ID tube 4" long. Parts Express has ready-made 1.0 CF boxes.
THANK YOU For the INFO!
-
Late to the conversation, but thetubecenter.com has 6DN7s and will match them if you want. I got a pair of GE 6DN7s matched that got rid of the channel imbalance I had with the stock tubes. http://www.thetubecenter.com/vacuumtubes_tubelist_tubes_6d4-6jz8.html
-
I just got 10 pairs from a auction.THANK YOU!
-
Did i miss an eBay bargain? :o
-
Alright, I'm going to try 6sn7 GTB's in my SEX with Stax earspeakers and report back. I've got more 6sn7's than one needs in a life time. Smoke em if you got em right!
-
I did not get mine from ebay it's from a guy at my town.
-
I'm listening to GE 6sn7 gtb's in my SEX as I type this. So far I'm really enjoying the sound! I've got some hum that needs tracking down but otherwise, so far so good!
-
My amp is actually quieter with the 6SN7's.
-
It's partially tube related and something else in my amp as it's a hot mess under the hood. I've got too much stuff wedged into that small chassis.....
-
I just tried a pair of Toshiba 6SN7GTB I have lying around. I'm really enjoying the sound too. It's more chill than the 6DN7 (usually have Sylvanias in there).
-
I just tried a pair of Toshiba 6SN7GTB I have lying around. I'm really enjoying the sound too. It's more chill than the 6DN7 (usually have Sylvanias in there).
I'am Glad that you are enjoying it too as i do.
-
I'am Glad that you are enjoying it too as i do.
Thanks to you, I got to try them! I have more usable range on the volume control now. Attached is a picture
-
Thanks to you, I got to try them! I have more usable range on the volume control now. Attached is a picture
You are most welcome!BTW i'am still using the 6H8C i bought more for spare.
-
From my limited understanding, the 6H8C has max plate voltage 330V while the SEX has 375V on section 2's plate. Are you sure that's going to be OK?
-
Maybe not but i like the sound of it,I have plenty of this anyway so it doesn't bother me.
-
One of the great things about building a kit is that you can probably fix it if something breaks ... :^)
-
To sum up it means that 6sn7gt cannot be used but the gta and gtb can. This would be a shame as I have six cryoed mullard 6sn7gt with me, which I have no use for. I was hoping I could use it here.
Shreekant :)
-
You would not want to use premium 6SN7's in this application. This is experimental, and likely will reduce the effective lifetime of the tubes used.
-
I finally replaced my 6H8C that i've been using for some time with this SYLVANIA 8SN7GTB i was not expecting much from this Sylvania 8SN7GTB but WOW!Sound smooth i'am loving it so far. ;D
-
8SN or 6SN? If its an 8 its going to be running cold with low emission. I ran a frequency response test on mine with a 6SN7 and i was not impressed with the results...
-
It's 8SN7GTB........I like it.
-
I haven't tried the 8SN7GTB, but I've gone back to the 6DN7 tubes a while ago.
-
The 8SN7 wants 8.4v heater power; it might be prudent to measure the voltage at the socket. If it's less than 7.5 volts, the cathode is not likely to last long.
That same voltage for the 6SN7 may be a little high due to the reduced current demand - worth checking if you are running these tubes long-term.
The low frequency extension (-3dB at 35Hz if I read the plot correctly) is probably affected by the higher plate resistance; experimenting with a larger parafeed capacitor might prove interesting. Was this measurement made with an 8-ohm load on the 8-ohm tap?
-
All tubes were tested on the 8ohm tap into a 32ohm dummy load.
-
So I fired up an old spreadsheet and looked more closely at the 6SN7-GTB. It should work just fine, and within spec. Output is about 3/4 watts, damping factor 1.0.
A speaker with a very low QT could work really well with the low damping factor; for example an FE-206E Fostex in a 1 cubic foot box tuned to 50Hz or a bit lower. Try a 2.5-inch ID tube 4" long. Parts Express has ready-made 1.0 CF boxes.
Alright, I'm in - I've got a pair of TS 6SN7GTB, and feel like experimenting.
You'll not find any measurements here - I'm a drummer, not an engineer - and, lack the necessary skills and equipment (fairly certain hitting the SEX with sticks will not help), but I'll log the hours and sound quality as I go.
-
Alright - after about 24 hours of play time on these new prod Tung Sol 6SN7GTB...
This comes out of extended listening, while working.
I perceived slightly more gain than the RCA 6DN7 I've been using. Kept the volume set while testing. More air/sparkle and perhaps more touch and presence in the mids. This may just be new vs old tubes? Or, maybe there's a subtle upper and mid forward shift combined with rolled off low freqs, with these 6SN7.
At times, I heard an unnatural edge (tizzy) on cymbals - not great. Over hours of listening, they generally sounded too lean and bright. This is something the amp excels at in its stock form, and in my system - natural sounding acoustic instruments. Could be this bright edge would subside with more time.
The low end is less extended and defined with the 6SN7. Pretty significant loss there.
Went back to the stock pair and it reminds me how much I like this amp.
All good. For me, this is the point - perspective.
I'll keep playing with the 6SN7 off and on - maybe more play time will help.
I am more interested in the coming cap upgrades.
I should add that the 6SN7 sounded good in general - not all bad.
Finally - the hum I'd battled with a minor mod recently was louder with these tubes.
-
You pretty much nailed it, have a look at the frequency response chart i posted further back in this thread, the low end with the 6SN7 drops off pretty dramatically from 300hz down.
-
You pretty much nailed it, have a look at the frequency response chart i posted further back in this thread, the low end with the 6SN7 drops off pretty dramatically from 300hz down.
Ah, maybe I'm learning! Regardless, I am trusting my ears more as I go on.
Doing this little test drove me to purchase a couple Sylvania 6DN7 off Ebay.
-
The most rewarding is when you hear X, then measure it and find the same result :)
The Sylvanias (provided they are the real Sylvania and not rebrands) are the best sounding for mid/low end. You sacrifice a little bit of high end response vs the others, but depending on your setup that may be just what you are looking for.
-
How do I ID the tubes as true Sylvania? codes?
-
Look at the construction, if the plates and mica spacers look like these they are Sylvania,
(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fbottlehead.com%2Fsmf%2Findex.php%3Faction%3Ddlattach%3Btopic%3D5316.0%3Battach%3D5121%3Bimage&hash=75c3de065a6c0fbab513c8caf21e196a978803d6)
GE/RCA/TS look like this,
(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fbottlehead.com%2Fsmf%2Findex.php%3Faction%3Ddlattach%3Btopic%3D5316.0%3Battach%3D5115%3Bimage&hash=e015779abdeac9d64c506c3482b6c4a6bbcbc4f2)
-
Thank you!
I bought a couple - separately - as I only have 2 pair today.
I've been holding off because based on all yours and others posts, there's not much sonic variety there.
-
There are really only the two types, Sylvanias, and everything else. They have slightly different characteristics, Sylvanias are slightly better on the low end, the rest are better on the high end. Its worth trying both for yourself to find which you prefer. I also find the Sylvanias to have a nicer midrange.
There is a third variation, the holy grail tube as i call it, of which i only have one set. They are marked as Sylvania Export in gold writing, coin base bottle, with the tall skinny Sylvania plate for the 1st section, regular GE/RCA style secondary plate in grey, and GE/RCA Mica spacers. They have the low end response of the regular Sylvanias, and the high end response of the GE/RCA/TS. The best of both worlds if you like, and they also measure insanely low THD distortion levels. Where most are 2-3%, these measured below 1%. They are a bit of a mongrel in there build, and out perform everything else in every measurement i have done on them.
Other trends i have noticed that are worth noting, coin base tubes measure lower distortion than regular tubes. And Sylvania tubes measure a higher transconductance than regular tubes. There doesn't seem to be any difference between grey or black plate RCA/GE tubes. Tubes with series heaters tend to be noisier. You can tell i have tried a few ;)
-
Appreciate all this insight - thank you.
I'll keep an eye out for some of these elusive beasts.
Seems cap rolling is a more effective (potentially expensive) and accessible means to tweak. Based on available parts, etc.
-
There are really only the two types, Sylvanias, and everything else. They have slightly different characteristics, Sylvanias are slightly better on the low end, the rest are better on the high end. Its worth trying both for yourself to find which you prefer. I also find the Sylvanias to have a nicer midrange.
There is a third variation, the holy grail tube as i call it, of which i only have one set. They are marked as Sylvania Export in gold writing, coin base bottle, with the tall skinny Sylvania plate for the 1st section, regular GE/RCA style secondary plate in grey, and GE/RCA Mica spacers. They have the low end response of the regular Sylvanias, and the high end response of the GE/RCA/TS. The best of both worlds if you like, and they also measure insanely low THD distortion levels. Where most are 2-3%, these measured below 1%. They are a bit of a mongrel in there build, and out perform everything else in every measurement i have done on them.
Other trends i have noticed that are worth noting, coin base tubes measure lower distortion than regular tubes. And Sylvania tubes measure a higher transconductance than regular tubes. There doesn't seem to be any difference between grey or black plate RCA/GE tubes. Tubes with series heaters tend to be noisier. You can tell i have tried a few ;)
I've been absent from these forums for a while and coming back to see such awesome information only confirms that I shouldn't have strayed so long. Thanks for the amazing information, mcandmar - now I have to go tube hunting! ;)
-
Welcome back ;)
-
Found a couple coin based RCA - grabbed them on Ebay. Should have them next week.
One of my current RCAs gave up on me.
-
Got the RCA coin based tubes in tonight. Letting them play for a bit.
Construction appears to match my other RCAs.
-
I have been listening to my new 6DN7s for about 10 hours and I forced myself to put down the headphones to post this.
I had previously used the best pair I had: one RCA and one Sylvania because of their combined low noise floor and best sound. I tried many combinations of RCA, GE, and Sylvania.
But now.... I have found the best 6DN7 tube yet.
These tubes have the lowest noise of any I have and they are better matched, channel-to-channel.
They are damn-near holographic.
I am currently using them with a pair of NAD VISO HP50s and I am now hearing imaging that was never there before.
Here are these new tubes that have found a home:
-
Yeah the Tung Sols are a little bit better than the other 6DN7s. I had some in my own SEX amp for many, many years. But I wouldn't say it's enough of a difference to pay exorbitant money for them.
-
Dan
These Tung Sols are head and shoulders above what I have found to date.
Perhaps I have not been fortunate enough to have better sounding Sylvanias, etc.
Anywho, I do not have the desire to do tube rolling in the S.E.X. for now!
I will be prepping some parafeed caps to try but I will get a couple of months on these tubes before I do.
-
Interesting findings. I measured the TungSols for frequency response and distortion and i couldn't see any difference between them and the regular RCA/GE tubes, yet for some reason my ears told me they sound slightly cleaner. I just put that down to my imagination and moved on.
One thing you do not want to do is mix regular GE/RCA tubes with Sylvanias as they have a fairly different frequency response, i would imagine it would sound a bit disjointed mixing them.
Happy holidays all!
-
Thanks mcandmar
I tried many combinations of the tubes on hand with the lowest noise (I wanted the S.E.X. to be as dead quiet as my Crack/Speedball).
I fell upon the RCA/Sylvania combo that sounded the better of the various combinations.
Measurements do not tell the whole story - I believe that subjectivity is King in this hobby (or maybe I'm just blissful in my ignorance).
-
I love the tung sol tubes. They have great balance and detail. The sylvania black plates are very close, a little less deatail but deeper bass. I have a matching date code pair of sylvania grey plates that sound very very good as well but different than the tung sols and the black plates. It comes down to using the pair that sounds best to you.