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New SET: JE labs simple 45 or tubelab SE?

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Contemplating building an SET for my Fostex FE166s in Austin 166 horns. Intend on getting James OPTs, but need to really establish which design to use. So what do you think? This:
http://www.tubelab.com/se_amp_pc.htm

...or this:
http://members.myactv.net/~je2a3/simple45.htm

plus a brief description on why you would choose one over the other if you wouldn't mind.... feel free to suggest other SETs. I've built many tube amps in the past, this is just my first SET so any advise appreciated. Thanks,

Chris
 
arnoldc said:
It would depend on the size of your room, how loud you listen, and type of music.

Would you mind posting?


Well, I have a mid sized room, but it is heavily acoustically treated with round bass traps against the walls and also mounted on the ceiling. I can get exact dimensions if that would be helpful. Listening level varies, usually at moderate levels, but turning stuff up once in awhile is fun. Music type also varies even more, lots of jazz and some classical.
 
The JE Labs uses a single 6SL7, not a cascode 6SN7, right? At any rate, seems like the Tube Lab is rather more complicated than it needs to be. I have tried a bunch of SET designs for 300B and 2A3s and the one I like the best is a simple one tube driver, direct coupled to the grid of the 45 or 2A3. Sounds outstanding, very little to go wrong, no cap in the signal path, etc... sonic bliss!
Try this one...
http://www.dagogo.com/DIYHeartland/Simple45.html
You can skip the parafeed and go with James, which I've used and LOVE. You can also use a 2A3 but will need to rework the cathode resistor on the output a bit.
 
Silk transformers (from Thailand) did a test of a few transformers (Tango X20 U808
Audio Note Trans 152, and James ) You have to take results with a grain of salt as James is their competition but James OPT tested poorly and they said it ain't any good.Lots of builders like this OPT -it surely look first class.
 
smbrown said:
The JE Labs uses a single 6SL7, not a cascode 6SN7, right? At any rate, seems like the Tube Lab is rather more complicated than it needs to be. I have tried a bunch of SET designs for 300B and 2A3s and the one I like the best is a simple one tube driver, direct coupled to the grid of the 45 or 2A3. Sounds outstanding, very little to go wrong, no cap in the signal path, etc... sonic bliss!
Try this one...
http://www.dagogo.com/DIYHeartland/Simple45.html
You can skip the parafeed and go with James, which I've used and LOVE. You can also use a 2A3 but will need to rework the cathode resistor on the output a bit.

Thank you very much for the link. Looks like a more tweaked version of what I had in mind.

limono said:
Silk transformers (from Thailand) did a test of a few transformers (Tango X20 U808
Audio Note Trans 152, and James ) You have to take results with a grain of salt as James is their competition but James OPT tested poorly and they said it ain't any good.Lots of builders like this OPT -it surely look first class.

Here's a link to the test:
http://www.sacthailand.com/Transformer_TestOutput.html

I don't think a big dip at 80khz is really going to bother me given that I can't hear it........
 
For the price one can't go wrong with James that's for sure . A-Note charges more for copper frame brackets for their transformers (instead of steel ones) than a pair of James Opts :D
Anybody used Hashimoto transformers ?? They supposed to be first class but no reviews so far. Regards, L
 
Don't waste the beauty of the 45. I bought two pairs of Lundahl's C-core OPT for building one new 45 amp and retrofit the 45 amp that I have.

I use Sun Audio's Cascode 6SN7 to drive the 45 with B+ of 400V. It sounds so good with Hammond's 1628SE OPT. Of course, it lacks of the airy highs as the OPT limits the high end frequencies.

I will put the Lundahl's OPT and hopefully it will give me the wideband frequencies.


Johnny
 
Johnny, you put 400v on the plate of a 45? What current are you running at? My data sheet says max plate voltage is 275. As for output transofmers, I'd add that I've tried James, AN, Bartolucci (C core) and ElectraPrint all in conventional air gap designs. Of those, the James has been the favorite, second was AN. But, I'd really encourage exploring the parafeed design where both the choke and the output can be optimized for the tube. Or better yet, use a CCS in place of the choke and then into an optimized OPT (see Gary Pimm's site for more on this).
 
Chris, you'll get tons of opinions in forums like this, which is a good thing, sometimes confusing.

I can even say try my 45 with grid choke and Tamura OPT for a different flavor, but hey, I'm digressing.

To answer your question about the JE Labs Simple 45 only, as I haven't heard a tubelab 45 yet...

The JE Labs Simple 45 sounds good, I have built it among other JE Labs designs - SRPP 2A3, 300B DX, 2A3 DX. Heck, I even had a Gordon Rankin 45 at one point, and I would say it beats the JE Labs Simple 45, in my room, with my gears.

But knowing DIY and based on your background, you may soon outgrow the JE Labs Simple 45. I myself ventured with my own brew and a favorite driver is 417A, which tubelab uses. If I were in your position and I would base my decision on the driver selection, I'd go for tubelab. I'm biased, it shows :D

ps.

There was a post prior that said James OPT tested poorly... I use James JS6113HS and I can say it does not sound poor, in fact it sound GREAT for the price I paid. From someone coming from a MagneQuest DS-025 and Tamura F-475 experience ;)
 
I have an obviously biased opinion here, so I just want to highlight a couple of things.

When I designed the TubelabSE, I spent a great deal of time optimizing the circuitry. The 5842 operates into a nearly ideal load under both the DC and AC conditions. The 45 is driven from a very low impedance source, and all filaments run on DC. That is why the "Tube Lab is rather more complicated than it needs to be." I wasn't trying to design a simple amp, that came later. These "complications" become more evident if the amp is operated near maximum power.

I built several of the popular 45 amps before I designed the TubelabSE. Most had some shortcommings. What is wrong with the direct coupled 45 amp mentioned previously? Think about what happens on power up. The tubes are cold, the solid state power supply brings up the B+ instantly. The CCS has no load yet because the driver tube is still cold, so its output voltage rails, puting a high positive voltage on the grid of the 45. The 45 warms up far faster than the driver tube, so as it begins to warm up, it is slammed into full conduction until the driver tube warms up. If you are going to build this design, use a 5AR4 to delay the startup somewhat.

Ignoring all of the above, the two designs use two totally different construction methods. The TubelabSE is built on a PC board. You assemble the PC board, connect 3 transformers, a choke, and the volume control to the PC board, and mount it all in a suitable enclosure. The PC board is quiet enough so there is no hum even on 106db speakers. Point to point construction requires careful attention to grounding to avoid hum.
 
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