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Tubelab Simple SE with big honkin' Edcors?

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OK, well it is finally assembled. It took longer than I thought to assemble the chassis, as I made of few tweaks to the design since it was painted. This led to a few, inevitable, dings and scratches in the paint but that was inevitable.

tubelab-simplese-6l6gcs-angle-up-300x252.jpg


Wiring also took a while with all of the switches and so forth.

tubelab-simplese-wiring-300x248.jpg


One of the features I added was selectable cathode bias. I was originally going to just swap-out resistors as needed, but I decided it would be a lot more fun to be able to switch them on the fly. These resistors are connect in parallel to 680 ohm resistors. I also added some banana jacks tucked-away behind the cap to measure the cathode voltage with.

tubelab-simplese-cathode-resistor-select-300x229.jpg

tubelab-simplese-cathode-resistor-test-points-300x209.jpg


The recessed-and-covered tube sockets turned otu nice and clean, as I was hoping:

tubelab-simplese-sockets-300x209.jpg


It looks good with KT88s too:

tubelab-simplese-kt88s-angle-300x249.jpg

tubelab-simplese-kt88s-dark-angle-300x175.jpg


More pictures and info is posted here:

http://www.knizefamily.net/russ/electronics/electron-tube-audio/tubelab-simple-se/
 
Thanks all. It was time-consuming and I am a little burned-out on chassis building for now. The Tubelab SE chassis will wait I think. I did draw-up a design for it and it should be much easier to build than this thing was. It will be your typical plate-on-a-wood-box, but with a few twists....

The cathode bias select is simple. I have a spreadsheet that you can use to build a list of resistor values, if you want. The switch just selects a resistor to put in parallel with a 680 ohm that is always there. The actual values are something like: 564, 468, 434, 389, 357, and 340 ohms. Since there is always a 680 ohm resistor there, even when the switch is between contacts, I can turn the switch while the amp is on. The bypass cap slugs-out the switching enough that I don't hear any popping or anything. In fact, it takes some time for the new bias voltage to settle-in. Kinda fun to "hear" the various settings for different tubes.

As to the heatsink, I found that the little sinks ran pretty hot on the breadboard when mounted on the bottom. I think they got to 90^C after a few hours. I felt they would enjoy some additional sinking, so I tied them to the side of the chassis.

Actually, that was the cause of the only snafu I had...a burr on the plate cut through the thermal pad and shorted the CCS to ground. The CCS case is tied to pin 2, which has B+ on it. The 10k resistor didn't like that too much and I smoked it. Once that was fixed, it worked great.
 
The last couple of evenings have been the first time I've been able to do some serious listening since this thing was breadboarded. When it's time to rock, this thing cranks. But for "serious" listening to live stuff, I'm not terribly thrilled at the moment. The sound stage is frustratingly difficult to "get into". I hate trying to describe audio stuff...but with the TSE i could close my eyes, put my head in the right spot, and with some live recordings and I feel like I am there. It's awesome. I don't get that at all with this thing.

Maybe I've been spoiled by the Tubelab SE. I did get better speakers since then and they seem to work really well with that amp. That setup had me hearing things I've never heard before. With this amp it is much less apparent.

Maybe it's those pesky Russian PIOs that seem to sound crappy for a while at first. I have maybe 10 hours on them. The Dynaco definitely needed quite some time for it to sound like it does now. I now have the correct Auriaps to go in that spot (I didn't at the time it was on the breadboard).

Maybe it's the JJ 6L6GCs I am using at the moment. I've tried triode, UL, CFB, all six bias settings, but it doesn't seem to make much difference. They seem to sound the best at lower bias currents in triode mode with no CFB. I'm going to try the SED EL34s next.

Maybe I'll just hook it up to the scope and see if anything is amiss. I don't hear anything obviously wrong. The bass is amazing when rocking hard. It just seems to be lacking in a lot of detail.

Anyone else that has both a SSE and TSE care to comment?
 
boywonder said:
I have both but neither amp is finished yet:xeye:

I'm also finishing Poindexter's EL34 music machine in parallel with those two, so apparently I have ADD.:clown:

I am with you on that. I never seem to have less than 3 projects going in tandem. I do complete projects, its not that they never get finished, just that I don't work linearly.
 
Anyone else that has both a SSE and TSE care to comment?

I have spent more time with both amps than anyone, right?

Guess what, I and other users that have built both amps have come to a similar opinion. The difference between the two amps is not huge, but becomes more evident when you listen to both for a while and with more sensitive speakers. We tested both amps and a bunch of other high end amps at member Korneluk's house with his 106db Lowther based horns. Here the Tubelab SE showed off its true superiority. It has returned to this testing ground again with similar results.

http://www.tubelab.com/Sound Checks.htm

The Simple SE was designed to be "simple". It is an entry level board designed primarily for a high probability of "power up success." This does not make it a bad design. It is similar to, and performs as well (or better due to the CCS) than most other two stage SE amplifiers that use similar tubes. You would likely be quite satisfied with the Simple SE as a major improvement over the sound quality of most SS equipment if you didn't have a better amp (the Tubelab SE). Listen to the comments left by builders that experience the Simple SE for the first time. Especially those who had SS equipment or one of those cheap tube amp kits.

The Tubelab SE was an amp that I designed for myself. I had no intention of selling boards at the time that I designed the Tubelab SE (2003 - 2004). In fact I was still making a few guitar amps when I made my first Tubelab SE. I loaned that one out and never saw it again. The borrower bought it. Then he wanted another, and then one specially made for headphones, then his neighbor wanted one....... The snow ball started rolling so I had a batch of boards made....

The Tubelab SE incorporated all of the things that I had learned about making tubes work their best (even if it meant using some sand) by the time (2003) that it was designed. DHT's PowerDrive, fixed bias DC heating, CCS loading, etc. PowerDrive and fixed bias require a negative voltage supply and bias adjustment which would un-simplify the Simple SE.

What makes the Tubelab SE sound so much better than the Simple SE? I don't know for sure, the DHT "magic"? PowerDrive? Fixed bias? All of these things synergistically combine to give the Tubelab SE its signature sound that makes it work. It is still my favorite amp, and the plastic wonder box that I call the Lexan amp gets the most use (with its 80 year old output tubes).

Am I satisfied with the Tubelab SE? No. I built a P-P amp that uses 300B tubes back in 2002. It has its own characteristic sound. More punchy and dynamic than the Tubelab SE, but not quite as detailed. My ideal amplifier would combine the best traits of both designs. Since those amps were designed I have breadboarded dozens of amps. As of yet I have not come up with anything that beats the Tubelab SE.

I have not found the time to build a completed amp in almost two years. The breadboard that I have been listening to is a Tubelab SE with the "big honkin Edcors" and a pair of those secret tubes that I sent you.

The Simple SE has always been the most popular design. Simple SE boards outsell Tubelab SE boards by a 2 to 3 to one ratio. It typically costs twice as much to build a Tubelab SE and some experience is required to make one work. This makes the Simple SE the right choice for many builders.
 
OK, so I need backpedal a tad. Firstly, I found that someone (probably me) bumped into one of the speakers and moved it. These things are pretty position-sensitive, so that accounted for the complete lack of a soundstage (or whatever you call it). I was able to find the sweet spot.

I was now able to hear more of a difference between the different bias settings on the 6L6s. It sounded the best at 430 and 470 settings in triode. It was still lacking in what I guess you would call "detail", though. I have a few non-live recordings that I noticed what I guess are some really weird mixing techniques that cause really bizarre 360^ panning effects. It really startled me the first time I heard it on the TSE. That's one of the things I've been trying to get to happen, along with some live recordings.

Swapping to the SED EL34s did help a bit. I did an A-B-A-B test and I mildly preferred the EL34s. One thing is that even at the lowest bias setting (560 ohm), these things are running hot. The plates don't glow until I turn it up a notch or two, but I have never seen this much blue coming from these things before. They were pretty, though (is that why I liked them?).

I then decided to try a few other tubes...those KT88s and a pair of 6550s. I was surprised at the 6550s. I had the cathode resistor cranked to 340 ohms and they sounded really great. The KT88s have a lack of detail but awesome bass. The 6550s were somewhere in between, I'd say...kind of how I was expecting the 6L6s to be. It was late and the fam was asleep, so I didn't want to rock the house.

I finally went back to the 6L6s...I was getting tired at this point so I dunno...they seemed similar to the 6550s but not as punchy on rock/pop stuff. The 6L6s don't start to glow until 340 ohms...which I measured/calculated to be about 32W on the plates. They didn't sound any better like that, though.

I tried swapping the input tube and the rectifier, but I can't draw any conclusions from that...maybe the input tube made a slight difference....

I historically have a hard time clearly identifying what I am hearing with audio stuff. What I prefer seems to vary too. In my PP amps, the tube type differences are very subtle. They are less so in these amps, which does make it more fun. I think the fact that I can "hear" the different tubes means that I should probably try swapping the caps. A nice, clean film cap may be just what it needs.

George, your points on the SSE's compromises are taken. It is certainly an easy amp to build (at least until you go overboard with the chassis....) Thanks for the feedback. I was honestly not expecting to notice that much of a difference. My ears historically don't (see above). The amp will have it's place for sure because I love how it sounds with metal/rock/pop/trance type stuff. It has power to spare, especially when I flip the UL and CFB switches. I think I will drag the Dynaco back into the room and do some comparisons with that. I guess I better get the TSE back on the breadboard and get going on that chassis too....
 
The KT88s have a lack of detail but awesome bass.....I did an A-B-A-B test and I mildly preferred the EL34s.

I have come to the same conclusions. On my big speakers (15 inch woofers) the KT88's especially the EH tubes cranked up to 100 mA have the most awesome wall shaking bass, but give up the most detail. Loud rock, techno works the best with EH KT88's in UL with CFB. The EL34's have the most detail and imaging but give up the most bass. Simpler music, vocals, deserve triode mode without feedback. The 6L6GC falls somewhere in between these extremes.

The EL34 in triode without feedback comes the closest to the Tubelab SE's sound, but doesn't quite get there.

In the Tubelab SE the 45 and its derivatives have the most detail, imaging, or "magic". They also only make about 2 watts so there isn't going to be any wall shaking. The 300B ups the power and gives up some (but not much) of the "magic". The 2A3 has a sound all its own. I can't describe the 2A3 sound, but others call it "sweet". I am not so fond of it.

What I prefer seems to vary too.

My preferences vary with the type of music being played. Yes I will crank Metallica through the Tubelab SE, but it just sounds better through a Simple SE so does Pink Floyd, Depeche Mode and a lot of similar music. Norah Jones or Diana Krall is only singing in the same room with me if she is singing through a Tubelab SE though.
 
Originally posted by tubelab.com ...the KT88's especially the EH tubes cranked up to 100 mA have the most awesome wall shaking bass, but give up the most detail.

Do you have any Reflektor 6550s (Sovtek, EH, Tung-Sol, etc)? I'd be curious if you think they are any different than your KT88s, which are also Reflektor.

In the Tubelab SE the 45 and its derivatives have the most detail, imaging, or "magic".

I have to agree. I definitely lost something with the 300Bs. I haven't tried the ones you sent me yet, but part of the re-breadboarding includes validating the layout of the upcoming chassis that will be capable of using them....

My preferences vary with the type of music being played. Yes I will crank Metallica through the Tubelab SE, but it just sounds better through a Simple SE so does Pink Floyd, Depeche Mode and a lot of similar music. Norah Jones or Diana Krall is only singing in the same room with me if she is singing through a Tubelab SE though.

Conversely, I find the TSE with my sensitive speakers (horn tweeters) to be a poor combination for hard rock/metal or anything that uses a lot of guitar distortion and/or electronic music. "Death" metal is the worst (Dark Tranquility, In Flames, etc). Having "detailed distortion" seems to be very distracting and I literally can't hear anything else. The SSE does much better here. Other types of rock/pop are fine on the TSE where the electric guitar is not so dominant. Having the extra power of the 300B is nice for that.

I think the lesson I'll take from this is that there probably isn't any end-all-be-all of amps. What is good for one type of music may be a detriment to another. I can think of no better excuse to own more than one amp! ;)
 
I think the lesson I'll take from this is that there probably isn't any end-all-be-all of amps.

I have been searching for that amp for a while. About the time I think I am close I find some new music, or something that sounds best on one of my older amps. At one time I had about 10 working amps all on a shelf that could be easily connected up. I have cut that number down to 4 working amps now. Two TSE's, one SSE, and the 845SE which has not been used in over a year. My old friend the 300Beast has died, but I will not canabalize it until I make a new one. This is my motivation for the "universal driver board". Some amps like the 845SE were my favorite when I made them, but I lost interest after I got used to the sound. A few like the SSE and TSE's and the 300Beast just keep me interested, but I have learned to listen to the breadboard for a while before investing the time to build the chassis. The second TSE is still a breadboard after over a year, so its time to build a box.

I built an SSE, the "Fisher cabinet amp" shown on my web site but after listening to it for a few months I lost interest, and it gets too hot in a non ventillated wall unit, so it is now partially dismantled. The big old CRT TV finally died, so a flat panel went in its place. I now have all the space behind it to put a tube amp, but what kind? I keep changing my mind.

Do you have any Reflektor 6550s

I have one EH 6550 which looks, and sounds exactly like the EH KT88's. I am convinced that they are the same tube. I bought them all used, and then matched up some pairs and the 6550 was a good match for one of the KT88's. They play well together in a push pull amp.

I have some older Sovtek 6550WA's that were my favorite tubes in guitar amps years ago. I have tried them in the SSE. They do not have quite the bass that the EH tubes have. I also have some Svetlana 6550's which may be Reflector sourced, some Winged C 6550s, and some new Chinese 6550's, and some vintage GE 6550's. All of these sound reasonably good with subtle differences. I can't pick a real preference, but the die hard tube rollers can. The EH tubes are my first choice for anything loud or bass heavy. This may be due to the monster winged plate that lets me turn up the current to 100mA without worry.
 
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