[longbowbbs]

No...I think Ken should send me some cables....

 

[PAM005]

Hi Tomsix, for speaker use with S6 - can you use 1pc. Left channel cable and 1pc. Right channel cable (2outputs / 6.35mm jack (L/R - mono) on S6) or do you have to use a stereo output cable / 6.35mm jack ? And starting what efficiency (dB) for speaker use? It sounds very easy and tempting to try !

 

[bcschmerker4]

...BTW: have you tried connecting the Studio Six directly to efficient loudspeakers? You might really be surprised at how BIG and full that one triode watt can sound in an average-size listening room.

As in a Western Electric® 555W compression driver feeding a 15A horn on each channel?  Those were among the very first successful PA speakers ever, and they HAD to be sensitive due to the extremely limited output from the Type 30 direct-heated triodes of the 1920's.  Early cinema houses paired the 555W/15A with the 597A high-frequency compression tweeter/horn assembly.

 

[TomSix]

Yes, If you'd like to try driving speakers with the ST-6 there is a "quick and dirty" way to do it:
 
One can obtain a quality 1-meter long or so patch cord with 1/4" stereo phone plugs on the ends. then get a small metal project box (perhaps 2" x 4") and drill it to install a pair of speaker binding posts of one's choice, and a 1/4" stereo phone jack, and maybe four rubber "feet". This box can be placed out-of-sight in back of the amplifier. And then the speaker speaker lines can be connected and also the patch cord can be plugged-into the box and routed underneath the amp and looped so that when loudspeaker listening is desired one can simply plug the patch cord into any headphone jack. Of course, any clever variation on this idea would work also.
 
On suitable sensitivity speakers: It really depends on how close you want to be when listening, what size room you have, and how loud you really want to play. Let me tell you what I've found:
 
For desktop listening within a 1.5 meters or so it really is not important how sensitive the speaker is, as it will play at quite satisfactory  loudness with even low sensitivity (low 80dB, Watt, Meter) speakers such as the classic BBC LS3/5A variants. In fact, such small speakers as the BBC LS3/5A I find sound really good from anywhere in the room when used inside a small to modest size listening room. 
 
HERE IS THE MOST IMPORTANT NOTE:    Be careful not to confuse a speaker's sensitivity rating with it's ability to accept drive from an amplifier. As long as a speakers's impedance curve and reactances generated by the crossover circuitry are not too difficult of a load, i.e, demanding of heavy current, then tube amplifiers such as the ST-6 will work well. Fortunately, many people are using tube amplifiers these days, and so there are a good number of suitable new manufacture loudspeakers to choose from. Also, reviewers and users generate a lot of references online so one can get some idea whether a certain loudspeaker is generally known to be "tube friendly" or not.
 
On suitable impedance ratings: the ST-6 will drive well any otherwise suitable loudspeaker with a nominal impedance rating of 6-ohms or higher. 16 ohm speakers will  drive just fine. 
 
Final word on sensitivity: though good speakers with low 80s dB sensitivity can work well as mentioned above, if you really want to "rock out" in a larger listening area, then speakers of 90dB or more would probably prove to be more satisfying for you. Speakers of about 95/96 dB and above will really allow strong dynamics to be more fully expressed at greater SPL, and very much fill the room. Again though, don't assume automatically you require super- sensitive loudspeakers to fully enjoy the ST-6. The triode circuit of the amplifier delivers it's watt of power very effectively to suitable loads, and so will likely surprise you with how subjectively full and forceful the sound is.
 
Let me know of your experiences!

 

[TomSix]

PAM005,
 
Oh yes, forgot to comment: Yes, if desired you could use two separate mono cables: one with a 1/4" stereo phone plug having only the Left connection soldered, and a second mono cable with a 1/4" stereo phone plug having only the Right connection soldered. This way you could plug this pair of Left and Right channel cables into any two headphone jacks on the ST-6 when loudspeaker listening is desired. No shortage of phone jacks on a Studio Six!

 

[PAM005]

@TomSix - thank for the clear explanation - it couldn't have been said more tempting ! Let's find out (in near future) how this already gorgeous amp for headphones will drive our speaker setups... For sure to be continued!

 

[goldendarko]

Hey guys, so I just received the NOS tubes I ordered and I installed 4 of them (Red Base RCA 6SN7, 2 Bendix 6v6s and one Mullard 5AR4) and something seems to have gone wrong. The OB2s which I didn't change seem to be flickering and getting really hot. I've turned it off after taking the following video but I'm just wondering have I done something wrong or is this normal? I double checked and all the tubes are in correctly but since this is my first foray into tube rolling I'm not sure what to expect. Any advice would be appreciated.

 

[goldendarko]

Hmm not sure how to upload the video but I forgot to mention it seems to be making a low humming noise also. I'm very disconcerted right now and hoping these tubes haven't damaged the Studio Six

 

[TomSix]

goldendarko,
 
sounds like you have a bad tube perhaps. I just sent you a Private Message with my phone number.
 
You should probably power down the amp for the time being.
 
give me a ring and we can probably troubleshoot that in 10 minutes.
 
More than happy to help!
 
-Thomas

 

[goldendarko]

Tom thanks for the quick reply. I was actually able to isolate it to the Bendix tubes. Not sure if I bought the wrong tube or something but it said they were a matched pair of Bendix 6V6GTs (5992?) luckily I also bought a pair of brimars too and they seem to be working fine so everything is warming up now and I'll give them a try. Bendix set will be going back unfortunately

 

[TomSix]

An important set of friendly suggestions on replacing or trying new tubes in the Studio-Six (or any other vacuum tube equipment as well):
 
When wanting to try out new tubes in a tube amplifier, it is always wise to install new tubes only one-at-a-time,  and then verify the new tube's correct operation for at least a few minutes be for proceeding to turn-off and unplug the amplifier again in preparation for the installation and operation verification of the next new tube, and so on.
 
ALWAYS turn off an amplifier and unplug the amplifier from the AC wall receptacle before removing or reinstalling ANY tubes.
 
ALWAYS first  make absolutely certain an amplifier is allowed to sit for at least 2-minutes after it has been turned off and unplugged from the AC mains BEFORE removing or installing tubes.  Failure to do so could damage the equipment and/or cause FATAL ELECTROCUTION!
 
ALSO: TUBES CAN  GET DANGEROUSLY HOT AND CAUSE SERIOUS BURNS!   It is wise to always allow at least two minutes or more after power is removed from an amplifier before removal of a tube is attempted. Be careful, as even after two minutes some tubes may still be too hot to comfortably touch or handle.
 
NEVER plug in or turn on an amplifier unless there are tubes (of the correct type) installed in ALL of the amplifier's tube sockets.
 
I suggest you strongly consider all of the above suggestions carefully if you are new to changing tubes in amplifiers and/or simply perhaps not fully aware of such standard precautions. I only offer these suggestions as a friendly helpful suggestion to fellow enthusiasts. You alone are responsible to decide if you are comfortable and competent to work on vacuum tube equipment yourself.  I accept no legal responsibility for any personal injury or property loss resulting from anyone attempting to change vacuum tubes and/or otherwise undertaking any similar or related amplifier servicing tasks.
 
IF YOU HAVE ANY DOUBTS ABOUT YOUR KNOWLEDGE OR ABILITY TO CHANGE OR OTHERWISE HANDLE VACUUM TUBES AND ASSOCIATED EQUIPMENT SAFELY, THEN IN THE INTEREST OF SAFETY I STRONGLY SUGGEST YOU SEEK THE ASSISTANCE OF A QUALIFIED ELECTRONICS TECHNICIAN.
 
 
Whew!...

 

[goldendarko]

Now you tell me! I broke about 3 of those rules, lol. Oh well all seems well and I'm still alive. Who needs instructions...pfff

 

[TomSix]

goldendarko,
 
good show! the Studio Six is purposely overbuilt and so fairly electrically rugged, and so there should have likely been no harm done. If the fuse has been weakened, then you will know that soon enough if it blows. If it does, fuse replacement is no big deal.
 
A quick work on the Bendix Tubes: The Bendix 6V6 is *normally* a very mechanically rugged tube, But... (I may ruffle feathers with this comment) I have never been all that too keen on their sound signature and find them a bit "overrated" by some enthusiasts.
 
As I have hinted previously, expensive does not always and automatically equal sonically superior as far as tubes go.
 
Personally, I'd lean towards the Brimars, and likely take my refund for the Bendixes and buy some more music instead
 
Keep my number, and feel free to call or message if/when you need help.

 

[goldendarko]

Ok thanks for the help. Great amp by the way. Love your guys work, I've owned about 4 ALO products over the years and they are always top notch.

 

[TomSix]

Thanks goldendarko, for the kind words. I can't take too much credit however, as my involvement with ALO was limited to my work on the Studio-Six project -- including the matching phono stage.
 
I do agree though, ALO has produced some very innovative products over the years, and they were an early player in the high-end personal audio world.
 
Always glad to help