SE Output xfmrs....who are the current suppliers for not many $$$

[cogitech]

What of more concern to me is the measured output resistance - if that resistance value is correct then around 20% is being lost there (1.8 Ohm in transformer with an 8 Ohm load).

I have an old moving coil meter especially for mesasuring those low ohms as I found that often the modern digital meters do not give a good result.

There's a good chance the measurement is off, then. All I did was hook up my digital MM to the 0ohm and 8ohm lugs and turn it on.

Either way, I am not concerned. They are just something to play with while I wait for my proper OPTs. If they aren't terrible I might put them in another amp some day.

 

[TonyTecson]

OK dimensions of the Chinese Cheapies:

55mm tall x 68mm wide (not including mount flanges) x 60mm (total thickness)

Stack thickness is 35mm.

EI66, slightly bigger than what i have, that is a 7/8 in cl stacked to 35mm....

 

[Bas Horneman]

i need to say, that transformers for 5W are minimum double size of that one..i'm not sure about getting bass below 40,50 Hz with this one...this can be cca 2W OPT .. need to put DC through in real circuit and see

I have transformers that are way smaller than the Chinese Cheapies. They are TO-9105-1 (NOS) that I bought for 10 dollars a pop. They have paper bobbins. 45mm by 45mm by 10mm or so. Probably rated for around 1.5Watt or so. I am constantly amazed that I do not want for bass....Even driving KEF LS51 that a mate of mine has.

 

[AmadeusMozart]

I have transformers that are way smaller than the Chinese Cheapies. They are TO-9105-1 (NOS) that I bought for 10 dollars a pop. They have paper bobbins. 45mm by 45mm by 10mm or so. Probably rated for around 1.5Watt or so. I am constantly amazed that I do not want for bass....Even driving KEF LS51 that a mate of mine has.

When an output transformer is too small (and there is no feedback loop that includes the OPT - eg the RH84) and you push through too low a frequency then you'll get a lot of second harmonics. And a few percent of second harmonic at 60Hz is louder to our ears than the fundamental frequency of 30Hz. But you will not "feel" the bass. This is how they fooled the public in the 50's and "HiFi" was allowed to be used if 50Hz could be reproduced with no more than -3dB loss IIRC.

 

[Bas Horneman]

Hi Amadeus, Guess that explains it. Thanks.

 

[jamesdb]

Tubelab, in post 145 your first photo has a large freestanding console in the background that looks like beautiful workmanship, is that the vintage Zenith console radio you mentioned? What's in them if you don't mind, you have a pair? Can you post a closeup photo when you get chance? I just admire the craftsmanship.

 

[Tubelab_com]

is that the vintage Zenith console radio

Yes. In all my years of speaker building I have never made anything with suitable WAF to be allowed in the main living area of the house for long periods of time. Granted some of my stuff from the 70's and early 80's was pretty rude looking. See the picture of the small speakers I made in the disco era. In the 80's I still used Naugahyde to cover the ugly, but I used real grill cloth instead of crushed velvet from the bean bag chair and waterbed factory.

One day my wife an I were wandering a large antique shop and flea market in Mount Dora Florida when she spots an old radio and says, "Why can't you make something that looks like that." The light bulb went off in my head, and I go buy that old radio.....now where am I going to find another that matches it?

I get home and decide to search Ebay, and by a stroke of luck there is an identical radio for sale about 10 miles from my house....and it supposedly works. I make arrangements to go see the radio and it is indeed playing when I get to the guy's apartment.....to bad, as this raises the price.

So, yes about 15 to 20 years ago I made a pair of HiFi speakers from a pair of matching 1941 vintage Zenith console radios. Knowing that these radios could become collectible some day (unlikely, but...), nothing I did to them in irreversible. The original field coil speakers were an odd size, about 13.5 to 14 inches, so I removed the baffle boards, the speakers and the Wavemagnets (internal rotating antenna). They are safely stored. The original radio chassis are still intact inside the radios, although I did steal the pair of original zenith branded 6V6G tubes out of one for use in a 6V6 based SSE amp.

New Hawthorne Silver Iris (no longer available) open baffle drivers were installed which work quite well in the open backed radio cabinets. They are a coaxial design with an Eminence based 15 inch woofer with a horn tweeter firing through the center of the woofer. The crossover is mounted using the holes for the Wavemagnet.

These have been the living room stereo speakers ever since, even though we have moved twice since I made them. They are 96 dB efficient, so they are plenty loud when driven by the TSE running some now 90+ year old NX-483 globe tubes that were found in a Sparton radio chassis (beyond repair) found in the same flea market as the first radio. Those old tubes make a real nice sounding 1.5 WPC, and still work today. The same speakers can handle over 100 watts, so they are deadly loud when fed by a TV sweep tube amp that makes 125 WPC.

Here are some pictures I took during the final assembly. The time frame can be placed by the CRT TV set and the VHS tapes in the background.

 

[audiowize]

When an output transformer is too small (and there is no feedback loop that includes the OPT - eg the RH84) and you push through too low a frequency then you'll get a lot of second harmonics. And a few percent of second harmonic at 60Hz is louder to our ears than the fundamental frequency of 30Hz.

That is what I refer to as "phantom bass".

 

[bepone]

doesn't matter what manufacturer put on the label. you can judge simple by seeing dimensions. they can also measure it on 1 kHz and there will OPT handle without problem. need to see how OPT behave on 20Hz.. this data they will not provide. because number is very small… to be able to produce low freq. trafo need a lot of turns or big core with reduced nr of turns. here on small OPT there is not enough window to do this. etc etc etc..

 

[bepone]

5W 5K opt you can successfully make with EI96 core (96mm) with stack 46 (mm) to have acceptable losses prim+sec under 8%, with 0.33 GOSS laminations , and weight of the OPT will be maybe over 3, 3.5 kg

 

[cbueche]

Yes. In all my years of speaker building I have never made anything with suitable WAF to be allowed in the main living area of the house for long periods of time. Granted some of my stuff from the 70's and early 80's was pretty rude looking. ...

Engineers favor the function of the form. This is why the "WAF" acronym has been invented.

Here are some pictures I took during the final assembly. The time frame can be placed by the CRT TV set and the VHS tapes in the background.

Oh I'm sure someone somewhere still uses VHS pretending it looks better than 4K TV
I'm always having a good time reading your stories Georges, carry on !

 

[cogitech]

doesn't matter what manufacturer put on the label.

Yes it does. I can find you many examples of popular, mainstream, well-establisghed manufacturers selling 5w transformers that weigh far less than 3-3.5kg. Are they all corrupt?

you can judge simple by seeing dimensions.

No, I can't.

they can also measure it on 1 kHz and there will OPT handle without problem. need to see how OPT behave on 20Hz.. this data they will not provide. because number is very small… to be able to produce low freq. trafo need a lot of turns or big core with reduced nr of turns. here on small OPT there is not enough window to do this. etc etc etc..

Most people aren't using single-ended OPTs to amplify sub-woofers in a home theater, so therefore most people are perfectly satisfied with an OPT that is -3dB at 30Hz at their desired SPL level (forget about 20Hz).

But everyone has their needs. If you think you need a 3.5 kilo OPT for 5 watts so you can get 20Hz, that's fine. Most people don't feel the need for that, from what I can tell. Lots and lots of people out there running 1.5-2kg OPTs and very happy.

For example, most people would trust Lundhal to get the ratings right. https://www.lundahltransformers.com/wp-content/uploads/datasheets/1663.pdf

8 watts at 30Hz into 8ohms - 1.35kg - I haven't heard these OPTs but I am willing to bet they sound excellent.

 

[Tubelab_com]

If you expect your amp to drive a full range speaker that DOES have significant response down into the 40 Hz and below range, then you might need a 8 to 10 pound Hammond or Edcor OPT for 8 to 10 watts.

If you run the subwoofer from the SPEAKER outputs of your tube amp you may get some unusual peaking in it's response due to the impedance effects that the speaker presents to the tube amp's finite output impedance when it goes through resonance.

I made an SSE with 6V6 tubes in triode mode. It made almost 2 WPC. I ran the sub from a crossover placed on the line inputs before the amp and used a pair of the twenty something dollar Edcor XSE OPT's in the amp. It worked real nice.

most people would trust Lundhal to get the ratings right.....1.35kg - I haven't heard these OPTs but I am willing to bet they sound excellent.

I have the 1663 P-P version of the same transformer. Rated for 40 watts at 30Hz. They do make 40 watts at 30Hz when driven by TV sweep tubes running local feedback. There is however some saturation visible on the scope with a resistive load at that level, but none obvious in the speakers at stupid loud volume levels....but my speakers don't do 30 Hz. Yes, they do sound nice, but I bought them for their compact size. The whole 50 WPC tube amp fits in a 2 RU chassis.

 

[cogitech]

For the Canucks out there, I thought I would create this summary of prices (including shipping) for currently available single-ended OPTs. I did not look into James, Electra-Print, Hashimoto, Lundahl, et. al. because my focus has been on relatively affordable options (from dirt cheap to medium priced). Also, my focus has been on 5K OPTs because that's what I need. In descending order, by price (all total prices are for two units):

One Electron UBT-2 - "15w"/6lbs. (at tubesandmore.com) - $129.95 USD x 2 + $57 shipping = $316.90 USD = $422.41 CAD plus whatever you get hit with at the border

Edcor CXSE25-5K - "25w"/9.75lbs. - $94.11 USD x 2 + $111.05 for shipping - Total $299.27 USD = $397.40 CAD plus whatever you get hit with at the border.

Hammond 1628SEA - "30w"/11lbs.- the cheapest way to get some is from A1parts.ca - $174.78 CAD x 2 + $16.90 (flat rate) to ship a pair = $366.46 CAD (not sure if tax is added after because I did not choose to go through the full paypal checkout)

Transcendar TT-338-OT - "10w"/4lbs. - $95 USD x 2 + $49.60 shipping (flat rate) = $239.60 USD = $319.35 CAD plus whatever you get hit with at the border

Edcor GXSE15-5K - "15w"/2.75lbs. - $42.34 USD x 2 + $64.50 for shipping = $149.18 USD = $198.05 CAD plus whatever you get hit with at the border.

Edcor XSE15-5k - "15w"/1.6lbs. - $21.76 USD x 2 + $57.85 shipping = $101.37 USD = $135.11 CAD plus whatever you get hit with at the border

Hammond 125CSE - "8w"/1.3lbs.- the cheapest way to get some is from A1parts.ca - $58.17 CAD x 2 + $16.90 (flat rate) shipping = $133.24 CAD (not sure if tax is added after because I did not choose to go through the full paypal checkout)

Laidy's (Chinese Cheapies) - "8-10w"/2.2lbs - $80 CAD per pair, shipped to your door (no border hit).

There are more models available from most of these vendors, of course, but this should give you an idea (as a Canadian) what it will cost you for the middle and low end of the market.

 

[kodabmx]

Tax will be added to the purchases from A1.

Also, I found a listing for the "Laidy's" transformers for only 50$ on ePay.

 

[cogitech]

Note: I chose the Transcendars because a) they were at the top of my budget and b) I believe they are considerably better than anything below them on the list. I chose to buy the Laidy's because - why not? I bet they are as good as (or better than) the two immediately above.

 

[cogitech]

Tax will be added to the purchases from A1.

Also, I found a listing for the "Laidy's" transformers for only 50$ on ePay.

$50 for a pair?

My price is for a pair. Shipped.

 

[cogitech]

If you expect your amp to drive a full range speaker that DOES have significant response down into the 40 Hz and below range, then you might need a 8 to 10 pound Hammond or Edcor OPT for 8 to 10 watts.

I suspect I could put a line-level 35Hz high-pass filter into my system and not notice the difference for well over 95% of the music I listen to, and my max desired SPL is not much more than 80-85dB (89-91dB peak) at the listening position. I am typically pulling about 1-3 watts from any given amp in my system and don't expect expect to run my SSE at more than 6 watts except on very rare occasions. If I "need" more power than that for some unexpected occasion, I have a 25w EL34 P-P and various SS and Class D amps I can use.

Unsurprisingly, I'm not building a SET for "power".

 

[bepone]

Yes it does. I can find you many examples of popular, mainstream, well-establisghed manufacturers selling 5w transformers that weigh far less than 3-3.5kg. Are they all corrupt?



No, I can't.



Most people aren't using single-ended OPTs to amplify sub-woofers in a home theater, so therefore most people are perfectly satisfied with an OPT that is -3dB at 30Hz at their desired SPL level (forget about 20Hz).

But everyone has their needs. If you think you need a 3.5 kilo OPT for 5 watts so you can get 20Hz, that's fine. Most people don't feel the need for that, from what I can tell. Lots and lots of people out there running 1.5-2kg OPTs and very happy.

For example, most people would trust Lundhal to get the ratings right. https://www.lundahltransformers.com/wp-content/uploads/datasheets/1663.pdf

8 watts at 30Hz into 8ohms - 1.35kg - I haven't heard these OPTs but I am willing to bet they sound excellent.

why bigger transformer? because to have wide frequency response, you need to have a lot of interleavings and insulation. this takes space. higher insulation distance = low capacitance P-S. more interleavings, low parasitic inductance. those are main variables to keep low.
also you need to fit a lot of wire in the window to have good inductance for good bass. if your goal is -3dB on 30 Hz by measuring frequency response you will find out that amplitude is starting to drop below 200 Hz, or maybe 300 Hz and you can hear that. you dont need filter there with S.e. amp which usually has problem with the damping factor and high output resistance. you need to move problems out from the hearing spectrum.

and there are also a losses, usually 10%, better less. you need to go with thick wire to keep them low. thick wire also takes space.. so it is clear .
all of mentioned variables you cant do with small transformer...speaking from experience...and need to see besides fr also how "nice is 1KHz " square signal under full power! you can see the ringing. etc etc
many aspects which you cant find in manufacturer label .
in attachment you can find something of my work, bigger ones 10W S.E. 5 kg each.. smaller one is cca 50mm brick, 10W PP guitar. the same output power.

 

[TonyTecson]

the bigger the core area of the traffo, the lower the saturation frequency consistent with power....
power handling is a function of traffo weight....

the bigger the winding geometry, shunt capacitance rear its ugly head, and high frequency takes a hit..