300B DIY Tube Amp: ISO-Tango Output Transformer Upgrade!
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- Опубликовано: 8 сен 2024
- In this video I am replacing the 5K 25W Edcor output transformers with some 3.5K 30W ISO Tango units (FC-30-3.5S II). I also explain what was causing the intermittent short circuit issue I ran into with this amp after changing the iron, which was baffling!
Below is a link to the USA distributor for these AMAZING transformers!!
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Well these ISO's busted a glass I had on my table - was listening to "Gravy Sandwich" by Terrence Clark and I had the volume up a little too high and I heard glass break during the song and said to myself I never heard that before then realized the bass in this song had it moving and slid off of table- Thats a lot of bass for a 300B - my speakers are 98% efficient. Wow!
Got my new Tango's installed after replacing the edcors and I have to say my 300B is on a whole other level now! It's really crazy what a difference it made - This 300B IMHO will blow away any other 300B reguardless of price - and Iam not new to tube amps and have many. It's hard to put into words but the lows are more tight and pronounced and the mids are even better than they were and the highs have that wonderful sparkle - it improved across the WHOLE spectrum. It even sounds much better than it shows on paper. Put a smile on my face! I honestly don't think you can find a better amp anywhere- WOW! If you have not built Skunkies 300B you don't know what your missing- you need to use good parts - there cheap anyway but need to pony up and go for the Tango's you won't regret it! I have different 300B tubes to try and see which sounds the best to me - right now I have my Gold Lion's in and it sounds fantastic but will be trying my others but can't see how it can possibly get any better than this! It's not just measuring things and as been stated "Winding technique, materials, and design all play a role in the quality of a transformer. It takes years of experience and practice to design and build high quality output transformers. It is for this reason that output transformer are almost always the single most expensive item in a tube amplifier and their quality cannot be scarified if the goal is a great sounding amplifier."
I know right? It's hard to describe the changes these transformers make, but it's not subtle. Glad you got the build this and hear it!
I’ve come to the conclusion that we don’t necessarily hear the side band harmonics, but we do perceive how the energy is taken away from the fundamental tones and redistributed as side band harmonic distortion, especially on transients where crest factors can exceed +18dB from the RMS level of the signal. Which is why you perceive a softening of bass transients on well recorded music. The loudness wars compress transients into harmonic distortion which is why it’s only noticeable on good recordings.
Awesome Stephe.! Luv your channel. I'm So Glad you got to try the ISO/Tango outputs.!! I knew you were gonna be blown away. I've been doing this for over 35 years and have tried countless other manufacturers transformers, inexpensive ones and very expensive ones. Don't mess around with Any of them, you Will Always be as disappointed as I was. The ISO/Tango's perform like just like there spec sheets Show.! (Most other transformer manufacturers don't even publish the transformers specs Or they are tricky in hiding things within some of the specs) ISO/Tango's Are Wide bandwidth with low distortion and no crappy resonances.! They Are The Only way to go.!
Faaantastic Stephe! EXCELLENT work how you showed the performance differences graphically, using your computer's audio analyser suite! So easy to SEE this! And again, that little patch of yellow on your mouse pointer makes it obvious what you're doing on the screen.
I'm also pleased that YOU are very happy with these ISO-TANGO o.p.t's! You've had enough disappointments, & being 'underwhelmed' with the performance of various amps & their components. This makes me happy too! You deserve some happiness with all the work you put into this.
Mr. Iso-Tango needs to do the right thing & refund you for the cost of your transformers as a reward for your work! I bet their business is going to get VERY busy now after this video gets around. He must just LOVE you now!
Well done on finding that annoying short in your 300B amp too! Stoopid plastic rotating, sharp-cornered capacitor bracket washers ay? It's a mistake that anyone could make, so don't feel bad.
Very good to see that you learned, & helped ME learn about the effects of low frequency T.H.D. on the sound. Fascinating stuff Stephe thank you so much!
Yeah this was instant gratification listening to these transformers for the first time, I knew that this was a nice upgrade!
Gotta be honest: I was hoping the difference wouldn't be so great. Really awesome to see the results, though!
The next video might make you feel better :)
I’m as excited as you are about your amplifier ! I plan on building it too because of this video. I love the sound of 300b tubes!
I like how neat your work is too. Shows lots of pride in your work.
As always thank you for your videos! They have been the source of entertainment and knowledge for me !
Hope you enjoy it!
Really enjoyed seeing you get excited when you looked at the test results. Im going to be building a Tubelab SE with the 45 tubes soon and I think im set on the ISO transformers.
Thank you for proving what I have been saying for 40 years---the quality of the output transformer sets the sound signature of the amplifier. This is especially true today, as most of the "good" transformer builders like UTC, Acrosound, Dynaco, Chicago, Peerless, etc., are either defunct or are not making good iron any more. I have built a few amps using 1950s era transformers salvaged from discarded amplifiers with great results. Enjoy your ISO iron!
Thank you for this episode. This assured me that what I did on my 300b was good. Your project is very successful. I changed the transformers, as I mentioned recently, and switched on Emission Labs 300b mesh tubes. The sound is sweet and you can listen to it for hours without straining your ears.
Thank you again
I’m getting super tempted to build a 300B like that. My speakers are probably not sensitive enough but wow that’s very impressive for a zero feedback triode
Thanks
Amazing measurements Stephe. Really impressive. Thanks for that video
My pleasure!
Just talked to George and ordered some ISO's for this - says he's getting lots of calls for these now because of your youtube channel. The heart of a tube amp has always been the output transformers and this is not where you should do any cost cutting! ISO Tango's have always been "the sought after" OPT's.
Great to hear!
yes Skunkie. The premium amp makers(AR,Mac et al) brag about their output transformers -often wound in house to get the quality sound you describe.
Looks exciting !!
I just can't describe how good it sounds now. :)
@@SkunkieDesignsElectronicsSo the 300b beats your KT120 amp now?
Wow, that's a good question.. I need some more time to answer that one! Likely they are just a bit different.
Considering Sun Valley 300B (Hashimoto iron and NFB) , vs , Sun Audio 300b (Tamura iron and 0-NFB + Sunkie 6SN7 circuit mod)
Hi Stephe, I have been watching your videos for some time now,
I am very impressed at what you achieve, because of that, it has
greatly encouraged me to learn how to build my first ever valve amp,
or any amp for that matter, so a big learning curve coming up, I fully
understand the importance of great output transformers and I have
selected ISO Tango Output transformers. the amp that I plan to build
is a SET 45, my question is this, which ISO Tango output transformer
would you recommend for my build ? I only ask as some people tell
me 7 watts is more than enough, since the SET will only produce 2 watts,
as opposed to a output transformer that is rated at say 20 watts. Thanks.
The FC12S or the FC20-107S would work fine. Contact George at www.tubesusa.com/
Very interesting video. Is important to note that you are comparing 3.5R primary impedance of the Tango vs the 5K of the Edcor. May be comparing vs the model FC-20S? Love your videos btw.
If anything this is easier test for the 5K Edcor and the higher impedance should have lower THD.
@@SkunkieDesignsElectronics yes indeed! thanks for your videos!
Great video. Good to see the OTs giving bang for buck
Stephe, this was such a great episode to watch and it's so great to watch you get excited about huge improvements in designs and/or components. Can I ask you how much you are into your 300b amplifier, money wise? Just a ball park figure? Thanks so much for your videos and all the effort you put into helping us understand tube audio. Love live the tubes!
At this point, around $2k is a guesstimate.
Japanese iron is one of the best. Havent really tried the new ISO, but the older Tango was superb. The other like Tamura also very nice (which unfortunately no longer available). Hashimoto is also good. Edcor unfortunately not at same level... 😅
Thanks for good sharing.
And Edcor is 20% of the price. Sometimes folks can't afford top shelf stuff!
@@SkunkieDesignsElectronics yes... Edcor, Hammond are fraction of the price. Not a fair comparison, but if can afford, good OPT is a must.
After all of the KT120 tube performance false claims and the dead-short at 20 KHz Willsenton 300 output transformers, it's great to see how the Iso-Tango transformers exceed their specs.
Amazing results and sound upgrade:)Thanks and have a nice day:)
That's so kool 😎. L👀ks like the build quality of your Tango's gets the very last drop of goodness out of your 300Bs. Another advsntage to having top tier output transformers is their ruggedness. One of my AVVT 20SL monoblocks had a parafeed cap short out that killed all the iron except the Magnequest OPT. I get a -3dB BW of 12Hz to 45KHz at 4W.
BTW, have you tried adhesive nylon zip tie mounts for keeping film caps in place? Seem to be more benign in my experience :)
3:23 That is a really freaky mistake! I mean it beggars belief that such a minor error could ever lead to a failure like a shorted cap, especially a plastic film cap! I guess you live and learn - I would've never seen this coming.
New to your channel
watched a good dozen vids b4 i subbed.
Im just a rando lurker that doesnt leave comments, generally speaking
a few of my thoughts and encouragement:
Life is too short
ignore your haters
keep following your muse
your content and designs are top notch
you share the small details
like the why fors and when to's and what happens when we do's
you dont need my validation, but human to human
you kinda kick ass
and those tangos are really slutty
Thank you for the note :)
Wow Stephe.. You’re going full on Deluxe with OPT’s.. I have seen too many Solens fail tbh..
Yeah I think I'm gonna pull them out.
Hi, I see a few viewers questioning the power rating of the transformers say 25 watt, 30 watt vs say 40 watt... It's Not the transformer power rating we're primarily concerned with, it's the inductance of the primary windings.! That's what gives the transformer/tube combination great bass response and low distortion.. It's all a balancing act, the lesser transformers have core saturation showing up sometimes as high as 200hz.! As the tube is being driven to pull current the transformer primary Must Be Able to absorb the magnetic flux, Store it, then release it as the tube is turning off.! None of the transformers I've ever tested can do this nearly as well as ISO Tango's And I mean NONE of em
Hi, Thank you for all this information, following you from Sweden. I would like to upgrade my 300B with these transformer but could not find them. You call them ISO-Tango, is the model the XE-20S? I built my 300B wiring my own power and uotput transformer. Greate fun but have since replaced output transformer and want to upgrade again. Thanks again for your work!!
No the model is FC-30-3.5S II
That's great news - I have built your 300B and love it!! you really need to stop all this - now Iam thinking on replacing my Edcors. Did you need to make any other changes with the Tangos (bias resistor) or anything else?
Nothing, just wired them up!
Would just a touch of negative feedback take care of the square wave rounding distortion and improve the frequency response above 10khz? Might be a game changer on the top-end performance of the amp...
What you are seeing on the leading edge of the 10K square wave is outside of human healing.
I'm gonna get around to building this some time or other but, I seem to remember that a Hammond 1828SEA transformer being thrown out there as a replacement for the Edcor. Did you ever try the hammond's in this amp. The hammond 1830SEA at 3.5K might be a better option. Just looking for a cheaper option than $900 before shipping.
Never tried hammond OT. Sorry can't comment on them. Someone else did email they bought a pair of these ISO Tango units are were as impressed as I was.
I built your 300B amp about 18 months ago, and now want to do the output transformer upgrade. Are these a direct drop in, or does the 880 ohm cathode resister need changing as well? I have not found a video on your site that shows the swap out.
Thank you!
Keith
It's a direct swap, no other changes needed.
Thanks!
Thanks for this video. Yea I have a bunch of those Solen caps in my stuff. Will add them to the checklists! So for the 300b amp would you recommend a 3,5k opt or a 5k? I’m using 4.7k lundhals and have been happy, these are higher end. That said am I missing something?
My guess is that You mis read / misplaced a bias resister in the amplification stage of the 834.
You might be missing a watt or so of power using a 4.7K. I was all ready to put the 8ohm load on the 6 ohm taps until I saw these results.
@@SkunkieDesignsElectronicsthanks! I am not concerned about power as much as response. Reflected impedance confounds me..I have 8 ohm and 5 ohm taps and 8ohm full rangers. The amp sounds good !
I doubt you left much, if anything, on the table.
Question, if I may. Last I checked, there was a blue Edcor choke by the Skunkie sticker. It's black now! Did it get replaced by a Hammond choke? I watched the 300B power supply vid, saw the Edcor XPWR134 die and get replaced by a Hammond 274BX; maybe I missed a choke replacement somewhere. Confused...
I just painted all the iron to match. Hammond Power transformer, Edcor choke but I believe Hammond makes an identical choke as well.
@@SkunkieDesignsElectronics Nice! Looks sharp with the matching paint, ISO OPTs, tube rings, logo and all. Would Hammond 193J 10H-200mA *82Ω* be close enough? BOM has Edcor CXC125 10H-200mA *75Ω*.
Yup, that will work fine.
Now the question is if I am going this far do I keep going to the 40 watt transformer for even better bass or will that start rolling off the high frequencies? 30 watt is probably already overkill and best when I think about it .
I think that is a real issue but not sure with these ISO tango units?
Actually, the Edcor is comparing extremely well, considering they are much cheaper.
They are not bad at all, but we are in a "diminishing returns" area and it's easy to spend this same money on audio gear that doesn't give this improvement. The audible difference is more than these measurements show IMHO but that's all subjective. And yeah I did listen to it before I measured it :)
What budget tube amp has good OTs such as the ISO Tango’s? Or are they only used in really expensive amps?
They are probably only going to be found on $$$$ amps is my guess.
Don't mind my comment. I see ChengX caps are used, which are highly unreliable capacitors! They will fail and short out over time!
Yeah, I should probably upgrade some of those caps. Think I'm gonna swap that solen for a wimma too.
im confused. As you were talking about the distortion and response curves a little bubble keeps popping up that says they are for the Edcors? Which is it?
When the bubble comes up, I have overlayed the previous Edcor measurements.
Oh I see it now. Early senility.🤪
LOL!
I would like to see the difference in primary inductance of the 25w.edcor and the iso.would it be possible to share that? values may differ in actual operation, but still useful.im thinking that the iso has more inductance and or it doesn't drop off more at low frequencys,so the impedance the plate sees stays high enough to keep the distortion in check at lf.this would support your findings of using slightly higher impedance than desired inexpensive transformer ? some one please inform me if I'm way off . good charts at the iso link you provided.they show impedance at various frequency.
The Edcor is already a higher impedance than desired, it's a 5K vs the ISO 3.5K which is why the Edcor has lower power output. The low frequency THD is where the magic is happening IMHO.
I understand the impedance difference, just trying to understand characteristic difference in those two transformer that led to measured and sound performance of those transformer.was thinking maybe inductance on primary, from turns or the iron.
Or how the interleaving is done or the quality of the metal used for the core or... So many variables!
True the interleaving affects the capacitance and the hf which can limit amount of inductance used.quite a balance in design.your testing is helpful for any one selecting an ot
Can i use their FC-40S since this is the lowest price for the 300B?
The FC-40-3.5S cost more than these FC-30-3.5S II I used. They have a cheaper FC20, but honestly I would find a way to buy the slightly higher cost FC-30 for this application. And not sure what extra an FC-40 brings to the table unless you are planning on using those special higher power rated 300B tubes.
ooops i should have said fc20s
i am planning to build this amp soon, after the color preamp which i already have the materials shipped.
thank you Skunkie.
I also got a pair of the FC-20S at the same time that I plan to use on a 2A3 amp.