SET 45 Amps

[jcmusic]

Hey Erik,

I won't sweat the small stuff I promise, LOL!!! Thanks for the info I enjoy reading your post about audio. While I have you attention let me ask you a couple more questions. Fisrt what 45 amp would you recomend and why??? Second have you ever heard of Sam Kim or any of the amps he has built? Thanks.

Jay

[Erik Mandaville]

Jay:

Just for the record: That capacitor upgrade I mentioned was in reference to the Transcendent OTLs, only. They just don't seem to change that much to me with more expensive parts. However, caps absolutely can alter the sound or voicing of an amp, and I have done that many times. Sometimes I preferred the more expensive part, other times not. Just depends on the circuit in question.

Best 45? That's a tough one! Best anything is an impossible call for me! I'm not trying to evade your question, I just can't answer it. Cut-Throat has some excellent 45 amps, but I haven't heard the Star Chief. Parallel-feed outputs were really very nice, and MQ makes some very fine transformers for para-feeding. They also sell a grid choke that I loved -- JF Lessard's parafeed amp, the Horus was a truly outstanding circuit, and he used the little choke on the grid of the output stage instead of the usual resistor. Made a big difference to me, which is good, because that little hunk of iron is not cheap.

Erik

[nu2toobs]

Kevin:

I've been doing, but for some reason when I post it looks like one large paragraph.

I bet you're using a mac. This site isn't Mac friendly.

[JBryan]

Kevin:

I've been doing, but for some reason when I post it looks like one large paragraph.

I bet you're using a mac. This site isn't Mac friendly.

I use a MAC and Safari - neither are well supported on this forum. I've read that Firefox is more 'forum-friendly' but haven't given it a try yet. In my case, I've learned to use the the 'less than' key, followed by a 'p' and the 'greater than' key to make a break...PITA!

Have fun!

[Guy Landau]

I've owned Wavelength Gemini PF with cobalt transformers and heard the Yamamoto A-08 (not S) in my system. Both were very good. I tend to favor the Wavelength because it had more speed and slam.

[jcmusic]

Thanks Guy for the reply, I think I have it down to two. The Yamamoto A-08S and Jeff Korneff's 45 amp, right now I am leaning to the Yammy!!!

Jay

[JBryan]

After committing to SET, I heard most of the common triode tubes - from the 845 (at 20w) down to the 10Y/VT-25 (at a half watt) and I think the 45 offers the best of what I listen for in SET while still being practical and accessible. I should qualify 'practical' by saying that while the 45 is capable of driving efficient woofers and presenting even the lowest bass notes, its most impressive dedicated to the midrange and higher frequencies, leaving the bottom-end to be handled by more powerful amps. I've had a few 45 SET amps in my system and I would like to hear the A-08S one day - I've read and heard very nice comments about it. The Korneff amp is one of the very few pieces I've wish I hadn't sold but I picked the Welborne DRD45s over the Korneff after going back and forth for a few months. Both had very nice qualities but I felt the DRDs were a little faster, quieter and more natural-sounding in my system.

I also have a pr of SEOTL amps and find them to be a brilliant compromise offering the speed and dynamics of OTL with near-SET transients and imaging - and they are very quiet to boot. I find that they don't have the soundstage depth or that last ''nth" of the "you-are-there" quality that the better 45 SET designs present, they aren't as analytical as a typical 2A3 amp nor as lush and bloomy as a 300b and have tighter, more impacting bass. Definitely worth a listen - especially as monoblocks.

[jcmusic]

Thanks JBryan that's very helpful and good info, thanks again.

Jay

[Clipped and Shorn]

I have built two "sucessful" (acceptable to me) SET amps. But I have to admit I took a simple go-for-it approach just copying the schematics from online sources getting the parts and assembling. I do have some assembling skills honed by hanging out with Mark Deneen. But I didn't see myself getting into the breadboarding stage, which I probably should have because I could have learned more. It's like working without a net, but I did get lucky, also I triple check all my wiring before firing up on the Very Yak that lives on my table. One amp is a stereo on a single chassis and uses either a 45 or a 2A3, the other is a pair of mirrored monoblocks using the 300B. I think both schematics came from JE labs online suggestions. Both amps worked right out the chute, except I had to do some tube rolling to get the best sound. The 300B amps didn't reallly impress me until I acquired a pair of high quality Sophia Electric tubes, the sound was harsh with the Electro Harmonix. I was planning to build another, but alas, my interests have cycled to other things. It really takes focus and I haven't yet even cleaned up the table where I last worked. The 45/2A3 really sounds fine with my budget LaScalas and Blueberry (NOS tubes).

-Rand Chop Spindle

Hi Mike,

What is the deal with the plastic bags (transformers?).

-Sad Drench Poplin

To keep from getting them scuffed and scratched.

[Clipped and Shorn]

My point is that you don't need to spend a lot or be an EE or even own an oscilloscope to build these simple circuits. There is extensive info on the web and numerous people who have pursued this. These amps work well and one does not necessarily need to go down the path of obsessive audiophile self ambushing. Just build one.

Here is a starting point. Further onlne research will reveal the large club of folks who have done these or similar.

http://members.myactv.net/~je2a3/simple45.htm
http://members.myactv.net/~je2a3/se300b.htm
http://www10.brinkster.com/azcruz/JE_300BDX.html

-Planner Chip Odds

[Clipped and Shorn]

That crazy photo was taken by Mark Deneen. I think he used a special ghosting lens to create the phantom of the opera effect. The large green lights are on the 300B mono blocks.

I just got some lambs to eat the grass here. Now I have to learn about sheep. I may need to bring them up on the Very Yak.

Let's see....what else. Oh, I am getting ready to transfer some new films to digital, and.....

I just figured out a new lazy way to start my own blog. Right, you guessed it.

-Hands Cold Nipper

[mike stehr]

I just figured out a new lazy way to start my own blog. Right, you guessed it.

-Hands Cold Nipper

Keyboard Pondering...

Joe Roberts said it's hard to make a real bad sounding SET amp. Being simple circuits, they are hard to mess up.

Breadboarding is not a difficult thing to do. It's quite the opposite actually, and can be more of a lazy approach to building a circuit of one's desire.

You can use a external tube DC regulated power supply. That takes care of the power supply B+ for the circuit under test, and a heater winding to use as well. Then it's just a matter of connecting the circuit together, either using all clip-leads or a combination of clip-leads and terminal strips.

I purchased a pair of James 6123HS universal ouput transformers, with 2.5K, 3.5K, 5K primary taps, and a (35%) screen tap. These things lend themselves to breadboarding.

The circuits I have experimented with using these OPTs were, SE 6L6, SE 6V6, RH84, ( SE EL84) 829B, (over my head) 71A, and 45. I pinched schematics for these circuits offline as well, I'm no designer. I used a schematic from online for SET 71A, and then just swapped it over to 45.

RH84 and SET 45 would be two tube based circuits I would like to make completed amplifiers from. You can breadboard up a circuit, and if you hate it or can't optimize, then you rip it apart and that's that.

My retired EE audio friend always mentioned you troubleshoot/optimize things on a oscilloscope a lot quicker than you would using one's ears or voltage measurements. He considered those who tweak and fiddle by ear, the "tune for maximum smoke" approach.

I'm still stuck in that mode... But I'm working on using a scope properly.

I have a 2A3 SET stereo amplifier of his own designed circuit. 6EA7 with a cap bridged Allied 1:1 10K IT to the 2A3's. I just bought a pair of Sylvania 5930/2A3W tubes from him, so the amp is set...

But I like this Scott LK48B I just got going. It's the rock n roll integrated amp.

[Clipped and Shorn]

Mike, thanks for the encouragement. I think I will use a breadboard approach for the next project utilizing the more economical 46 tube. And, I should buy some probes for that Oscilloscope sitting on my kitchen table and learn how to use it.

I think I have stockpiled some of those James Xfrmrs too.

Is that an Oscar Peterson LP I see in your photo?

-Land Ciphers Pond

[jcmusic]

I want to thank all who posted in this thread, I have decided on a Korneff 45 SET amp. Thanks again Mike L.

Jay

[Cut-Throat]

I want to thank all who posted in this thread, I have decided on a Korneff 45 SET amp. Thanks again Mike L.

Jay

Please post your impressions of this amp, when you get it.

[jcmusic]

I want to thank all who posted in this thread, I have decided on a Korneff 45 SET amp. Thanks again Mike L.

Jay

Please post your impressions of this amp, when you get it.

Cut-Throat,

I for sure will as soon as I have a little time with them!!! Would you please tell me your impressions of all the 45 type tubes you have tried!!!

Jay

[Cut-Throat]

I for sure will as soon as I have a little time with them!!! Would you please tell me your impressions of all the 45 type tubes you have tried!!!

Jay

I can say that I love every 45 tube that I have ever tried. And every 45 tube I have tried, I prefer more than any 2A3 or 300B tube I have tried.

What I am saying, is that I don't find a huge amount of difference between various 45 tubes. I have quite a stash of 45 tubes, and plugging and unplugging them to listen to various music passages is a time comsuming and tedious process. And is also a process that I don't quite trust myself with; in that it can be quite subjective. With that said the RCA Globe 45s that I have plugged in currently sound superb. I also like the fact that they are from the 1930s and look very cool with their Globe Shape.

Whether they sound better or worse than the TJ Meshplates from current day production, the nuances of the sound differences are small enough that I should not comment. The differences in sound between SS amps and Push Pull amps, and SET amps (2A3 vs. 45 ) are obvious to me. The differences between tubes are not. Except for the fact that I beleive that Old Stock tubes are more robust and may last longer than new production.

So no golden ear comments from me on Tube brands, Let alone Capacitor brands. And when you get to interconnect and speaker wires that are all made with copper with different colored sheathings - You can pretty much forget asking me!

Here is a picture of my Welborne Starchief amps in Bubinga Wood, with the RCA UX-245 Globes in Action !

[JBryan]

The Korneff amp is an excellent choice. Cut-Throat is right in that the differences between various 45 tubes are subtle but for my money, the globes offer more of what makes the 45 special. On the Korneff, I liked the Cunningham/RCA globes for 'air' and the Emission Lab solid plate 45s for "punch". Jeff Korneff designed his amps with fairly low gain so the power tubes have less of a signature than with other 45 amps. Actually, the 6SN7s have more of an impact on the amp's sound and I'd suggest rolling them first. Its been awhile but IIRC, the Sylvania Chrome Domes (yellow GTB) are a good starting point. For a more delicate presentation, I'd recommend trying a Tung-Sol (tall bottle) and if you want to hear something on the darker/heavier side, try the Sylvania VT-231. You can't go wrong with any of these tubes but each will sound pretty distinct from the other. Have fun!

[jcmusic]

Cut-Throat, Thanks alot for all the info I didn't ask for!!! I just wanted your opinion on the 45 tubes you have tried no big deal.

JBryan, Thanks you for the info on the 6SN7 tubes thats good to know that they will have a say in the final sound!!! I have alot of expirence with this tube as my pre-amp uses them!!!

Jay

[Cut-Throat]

Cut-Throat, Thanks alot for all the info I didn't ask for!!! I just wanted your opinion on the 45 tubes you have tried no big deal.

Jay

Yeah, I just got rambling.