FD9: 1959 Fender Deluxe Tweed: 108 Output Transformer, Frequency Response

This amp is not as loud as expected for 15W. The frequency response curve shows why. I do not recommend replacing the output transformer because in the 300-1K Hz range the harmonics are quite significant (perfect for a blues player).
Original Work, Copyright 2022 James D. Whiteside, II all rights reserved, For consideration only, no reproduction without prior permission.

[@deeem-tee799]

Hello Jim, very informative! I plan to build a 5B3. 10 watts output. I would really like the 108 blues hump in the output that you talk about here. Blues wonk if you will. I found a Soursound 108 or Mercury Magnetics “ Woodie” ouput but have no idea if that 108 honk is there. Can you recommend what trans specs i ask for to replicate the 108 bogey honk? What is a wound trans ( not off the shelf type ) that you talked about? Thank you for your time and help! What do i ask for getting it wound? I will be happy to pay you handsomely for your time and effort. Ive looked high and low for a Triad 108 but nothing available.

[@deepblueharp]

I am working on your request. Please give me a few days and I hope to have you a source, reference number and cost for a "108" that is wound and built as a near clone. I have sent him the measurements for this 108. Thank you for watching my video series.

[@deeem-tee799]

@@deepblueharp ​ ​ THANK YOU so much!! You seemed like such a nice helpful person in the vid!! Where do i contribute to you….Patreon? I cant tell you how helpful this is!! I was looking hard at Soursound SST 108 and Mercury Magnetics FTDO-15M Do i have a 4 and 8 ohm option with your source Jim? Thank you so very much! Pls let me know where to show appreciation and support channel! Have a nice weekend. Take as long as it takes! Mike

[@deeem-tee799]

@@deepblueharp the lesser volume is perfect for what i am looking for. So glad i came across your site. Ill leave you be now…. thanks again

[@deepblueharp]

@@deeem-tee799 The trick to a blues output transformer is to have it saturate (keep the laminations as thin as possible), have either a 4 or 8 ohm output and load the plates right at their the recommended loading on the plates. The larger the load, the more fidelity there is. The thicker the lams the more fidelity there is. On the downside of a blues output transformer is that they overheat. There is a balance. Remember, the amps folks like for playing blues were made on the cheap. They were not intended to last long. Sort of a "throw-away". Universal transformers with multiple taps on the primary and/or secondaries are not suited for blues.

[@Echo_III]

How do you know and measure (%) what is 2nd, 3rd and 4th order harmonics, sir? Is there some calculations involved or the option on the oscilloscope to chek it out? Thank you!

[@deepblueharp]

I import the waveforms from the oscilloscope to my PC and run my Fourier Signal Analysis. The analysis program confirms the fundamental frequency and calculates all the harmonics along with their magnitude. From the analysis I can then recreate the signal on my PC for use in tube design.

[@deeem-tee799]

Hi Jim, i thought i would mention- what I ‘m looking to clone is a 1953 5B3. I think the 53 had much more earlier break up than a 59. According to the transformer manufact’s the 48-53 OT’s had a primary of 14K? Whats your opinion on this? Thanks again!

[@deepblueharp]

The 6V6GT P-P tubes would need between 8K and 10K loading. A 14K is a heavier load and a heavier load is better for fidelity.

[@deeem-tee799]

@@deepblueharp ok, got it. Pls keep me posted onvhow the manufacturer sourcing is going . By the way , would 55’ iron be better to custom wind OT on? Or doesnt it matter. If so, i have a 1955 deluxe size OT they can wind on.

[@deeem-tee799]

@@deepblueharp pls keep me posted on how the 108 sourcing is going. Pls excuse the typos. Do you need tubes ? I guess you dont have a patreon page…i do have a decent tube stash. I d gladly share. Pls take a listen to : 1957 Les Paul played by Joey Landreth on youtube. Thats the wonk im after ….hope your 108 source can get close or nail that lovely Blues tone for me. I REALLY appreciate your time and help Jim!! I have a couple Sangamo tone cap if you re interested.

[@deeem-tee799]

@@deepblueharp i meant : according to Mercury Magnetic’s early tweed OT is 14K. I think a 108 clone from your source will sound stellar! Im not swimming in $$$ but i may order more than 1 being that you mention they tend overheat creating the sought after tone. How many hours can i expect to get out of the OT your source ? If they are approx $50 or so….i may order a back up depending on how long i can expect them to last.

[@deepblueharp]

@@deeem-tee799 Please email me. My email is on my channel under the About tab.

[@deeem-tee799]

Another point: Soursound and Merc Mag claim the 108 was not in the early 50’s tweeds. I am building a 5B3. 1949-53 i think. I cannot seem to get a straight answer from research on what Leo had in them. But Im sure a 108 will sound just fine. This will be a guitar amp. Not for harp. Thank you again Jim!

[@deepblueharp]

I limit my comments to equipment that I have actually worked on in my shop and can validate the parts as being original. The '59 I had in my shop was 100% original in parts (except the preamp tubes). I haven't worked on a 5B3 yet. It would not be out of the realm of possibility for Fender to have also used Stancor or Thordarson, because they were the "big guns" and marketed heavily in all areas of consumer and military electronics.

[@deeem-tee799]

Thank you!