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Simple SE Tubelab.com

Going to be ordering this PCB. I am completely new to the land of tubes and electronics. I have some experience with electrical but it's limited. Because of this I am going to have a bazillion questions and I will need all of your help. I have a soldering station on order. Aoyue 937+
While I am waiting to order the PCB, there is a transformer manufacturer right next door to my place of work. On tubelab.com he goes into detail about what will be needed for a transformer but he mentions making sure it is SE and not PP, what would be all the info I should give the transformer guys?
Thanks.
 

nightanole

Member
2009-02-28 1:24 pm
A. Move this to the tubelab.com forum here.

B. Only have them roll the power transformers. Tube output transformers is a dark art, and SE are really hard to get right unless they have been doing them for years.

Id stick to the Edcor CSXE25-8-5K or hammond unless you want to get real pricey. You can save half by going to 40hz instead of 20hz with edcor

Hammond Mfg. - "Classic" Single Ended Tube Output Transformers - (1627 - 1642 Series)
EDCOR - CXSE25-4-5K



http://www.diyaudio.com/forums/tubes-valves/83699-edcor-cxse25-8-4k-vs-hammond-1628sea.html
 
How do I move it to tubelab.com forum? I didn't know there was one here, sorry.

B. Good to know thanks.

Those seem to be very pricey transformers. This is my first build and I don't need it to be the best thing possible. 25W is a lot. I thought in the description it said something like 5-14W output from the build? Maybe I misread.
 
Fenn: The Tubelab forum is here:

Tubelab - diyAudio

Another cheaper (and very nice) Edcor alternative is the GXSE series for around $80/pr.......Tubelab George usually uses 5K primary impedance, although depending on your tube choices you may want to consider a 3K (ie with KT88's)

You also want UL taps on the transformer also, allowing UL operation as well as triode if desired.

Other cost effective transformers are the Trancendars on ebay.
 
...there is a transformer manufacturer right next door to my place of work. ...what would be all the info I should give the transformer guys?

As others have mentioned, preferably your manufacturer has some prior experience winding audio output transformers and he should know how to interleave windings. If he doesn't, I'd be tempted to go elsewhere - unless his prices are really good. :) Really, he needs to be able to design a single ended output transformer from scratch. If you have to tell him the design, the results will probably be less than spectacular. If you are capable of creating a good transformer design, chances are you already wind them yourself.

He might need the following specifications from you:
  • Impedance of the primary winding (3K, 5K, or something else)
  • Impedance of the secondary winding (4 ohm speakers, 8 ohm speakers, etc.)
  • Primary DC current (probably 50~100mA) which affects core size and air gap
  • Power handling (5 watt? 10 watt?) which affects core size, wire gauge
  • Desired low frequency extension (30 Hz? 20 Hz?) - affected by primary inductance
 
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That's great I will ask them if they have experience with any audio transformers. If it's cheap enough I may be tempted to let him try it either way. I looked on ebay for trancendar and the search came back with nothing. I think I will be using 6V6, 12AX7, and 5Y3 tubes. As some of these will come in pairs and I will use the left over to build a champ amp when I am done. Will these tubes work with this board? It shows 6V6 on the Tube and Transformer page on tubelab.com. But it shows 12AT7 and 5AR4, I don't know how interchangeable they are. With these tubes how would I go about building the specs for the transformer? Should I start a different way? Thanks
 
Fenn,
IMHO, you can't go wrong with the edcors if your neighbor can't wind them. Transcendors are hard to find.
With the edcors, my favorite are the middle of the road ones. I think they are the GX series. Very detailed and lively with an outstanding soundstage. Upgrading to the more expensive CXE's was not to my liking at all. The amp was slow and compressed. Had a little better bass but the sacrifice was too much.

I used kt88's in mine.
 
The 12at7 is the driver tube. I would stick with the instructions first. The output tubes are to you choice. We can help guide you in selecting the right PT and bias resistor for the output tubes.

Once you get a handle on how to set up an operating point for a given tube then trying different drivers will become easy.
 
I think I will be using 6V6, 12AX7, and 5Y3 tubes. As some of these will come in pairs and I will use the left over to build a champ amp when I am done. Will these tubes work with this board? It shows 6V6 on the Tube and Transformer page on tubelab.com. But it shows 12AT7 and 5AR4, I don't know how interchangeable they are. With these tubes how would I go about building the specs for the transformer? Should I start a different way? Thanks

If you are completely new to tubes and electronics as indicated in your first post, it might be best to do your first build exactly as Tubelab designed it.

Win W5JAG
 
I think I will be using 6V6, 12AX7, and 5Y3 tubes... But it shows 12AT7 and 5AR4, I don't know how interchangeable they are.

You can use the 6V6, just be sure your power transformer provides roughly 540VCT. The 5Y3 should work just fine, especially if you're using 6V6 for the output tubes.

The 12AX7 will not be a good substitute for the 12AT7. I'd guess it will live a short, unhappy life and offer poor performance. The operating conditions enforced by the CCS would result in too much current through the 'X7, exceeding its maximum current and plate dissipation ratings. If you absolutely must substitute, I believe some people have successfully tried the 12AU7. Note that the 'U7 will offer lower gain than the 'T7.
 
I looked on ebay for trancendar and the search came back with nothing. Thanks

The Transcendars are a little tricky to find on Ebay, since Gery from Transcendar does not put the word "Transcendar" in the auction title........do a seller search on Ebay for ggaet. It appears that he is selling a bunch of HP test equipment presently; the last Transcendar auction was in January. You could always email him.......The Trancendars are available with and without UL taps in 3K & 5K flavors. I would get the UL taps (for $5 more) since that will allow ultralinear operation. They usually sell for around $120-$130 or so.
 
Fenn,
IMHO, you can't go wrong with the edcors if your neighbor can't wind them. Transcendors are hard to find.
With the edcors, my favorite are the middle of the road ones. I think they are the GX series. Very detailed and lively with an outstanding soundstage. Upgrading to the more expensive CXE's was not to my liking at all. The amp was slow and compressed. Had a little better bass but the sacrifice was too much.

I used kt88's in mine.

Bigger is better doesnt work as well with output transformers. The gx are only rated to 40hz at full power, but will go lower then 20hz with less power. Upping to the cxes means they want 25 watts, which is a bad match for the amp unless it can provide at least half that. If your running the kt88 (HUGE) in triode mode your only putting out like 7 watts. So ya the smaller guys would sound better.
 
Wow. Loads of info. Thanks so much guys. Some have mentioned to stick with the original build, but it's a little pricey and the reason I was looking at this PCB was because it said I could go with cheaper stuff. Also, it's kind of hard to tell what the real build is because he has done like 50 billion experiments with them. It seems some people are saying go with the $100+ transformers, but this is my first amp and my wife would kill me if I spent that much and then had to buy everything else.
Ty_Bower: Thanks for explaining about the X7's and T7's. I'll go with the T7's since they are about the same price anyway.
Nightanole: I spent last night searching through tubelab.com on my phone. I don't have the internet at home. I saw that he mentioned the Edcor XSE15-8-5K for that price I am ready to order if people think it would be good. I would see about making my PT order from them as well. I've decided not to limit the tubes too much. The 300B's will probably be too much for me. I will call a local tube shop and see what price they would give me. If there is a tube that seems like it would work better than another one in the Edcor please let me know. And please explain the reasoning to me. I really am interested in learning the why's. Lastly, I appreciate your guys kindness. Thanks everyone.
 
The Transcendars are a little tricky to find on Ebay... do a seller search on Ebay for ggaet.

He seems to be selling off unused test equipment under the ggaet username, but the transformers seem to sell under the username "transcendar". Of course, there isn't a whole lot of activity recently. I think Gery is in a state of semi-retirement, and makes transformers only occasionally. You might try contacting him directly.
 
I did look him up and I got the same results Ty. I will search out the Transcendars more at a later date. $120 is a bit steep for me right now.

I looked at the PT specs on Tubelab.com and it seems like the XPWR002 will match up close enough. If I go with something that requires less power can I just use resistors or something to adjust this? I want to start ordering soon. :)
 
I looked at the PT specs on Tubelab.com and it seems like the XPWR002 will match up close enough.

I once did a little searching and also thought the XPWR002 might fit.
http://www.diyaudio.com/forums/tubelab/159971-simple-se-build-costs.html#post2070070

Keep in mind that all the XPWR models I noted (002, 033, 035, 048, 059, 134) are 700VCT or higher. They will work great for EL34, 6L6, or larger types. They are no good for 6V6. If you want to run the smaller tubes, you need a PT that makes about 540VCT.

Don't forget the Allied power transformers:
Allied 6K7VG, 750VCT
Allied 6K56VG, 540VCT

If you get an Allied PT, pick up a Triad C-14X choke while you are there.

If you buy a PT that can supply more mA current than you require, you should be OK. No adjustments should be necessary. If you buy a PT that makes a higher voltage than you need, you will likely be in a pickle. It can be awkward to try to drop the higher voltage down to a lower level. Cemented resistors can work, but they will dump a lot of heat. You can also try choke loading the power supply (instead of cap loading).
 
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Wow. Loads of info. Thanks so much guys. Some have mentioned to stick with the original build, but it's a little pricey and the reason I was looking at this PCB was because it said I could go with cheaper stuff. Also, it's kind of hard to tell what the real build is because he has done like 50 billion experiments with them. It seems some people are saying go with the $100+ transformers, but this is my first amp and my wife would kill me if I spent that much and then had to buy everything else.
Ty_Bower: Thanks for explaining about the X7's and T7's. I'll go with the T7's since they are about the same price anyway.
Nightanole: I spent last night searching through tubelab.com on my phone. I don't have the internet at home. I saw that he mentioned the Edcor XSE15-8-5K for that price I am ready to order if people think it would be good. I would see about making my PT order from them as well. I've decided not to limit the tubes too much. The 300B's will probably be too much for me. I will call a local tube shop and see what price they would give me. If there is a tube that seems like it would work better than another one in the Edcor please let me know. And please explain the reasoning to me. I really am interested in learning the why's. Lastly, I appreciate your guys kindness. Thanks everyone.

the xse is very plain looking with no endbells, it also will not have much bass and isnt a good match for a kt88. Id go for the gxse for like an extra 25 bucks a pair unless your going to run something really low wattage in UL mode (kt88 is as big as it gets)


For cheap power transformers check out antek. They are about half as much as edcor or less.

Kt88's are expensive, you could try a el34 in UL mode. If you want more power you can switch to kt120's but you will need to up your voltage and change all the electrolytic caps to something that can handle the voltage.


Not to thow a monkey into the wrench, but have you thought about the simple PP? You can get russian el84 (614p or something) for a like a buck each. And the output transformers will be half as much.