Announcement

Collapse
No announcement yet.

How to spec replacement OT?

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • How to spec replacement OT?

    I would like to give the owner the option to upgrade a failed output transformer in an Orange Tiny Terror 7/15 to a Hammond. What are the key parameters when specifying an OT? Thanks.

  • #2
    The simple answer is to look at that the output tube complement is in the amp. One EL84? Two or four of them? A 6V6? Maybe a pair of those? Or a couple 6L6, whatever.

    Whatever the amp might be, the tubes will want the same basic impedance environment. So if the amp has a pair of 6L6, look for transformers intended for amps with a pair of 6L6. Usually the number of tubes pretty much tells you the power, so a pair of 6L6 probably means a 50 watt amp, more or less. Of course there are exceptions. FOur EL84s could be 30 watts or even 50. SO pay attention to stated power handling. And match the tube set.
    Education is what you're left with after you have forgotten what you have learned.

    Comment


    • #3
      That amp's output (I believe) is a pair of EL84's at 15 watts. It should be similar to the Vox AC15. Assuming that scenario is correct, the Hammond 1750Y would be a valid replacement. That said, there are other things to consider like size, mounting hole pattern, etc. The specs are on their website.
      "I took a photo of my ohm meter... It didn't help." Enzo 8/20/22

      Comment


      • #4
        Oops, just realized that transformer only has an 8 ohm tap. Since this is a head- not a combo, you probably want more taps for whatever cabinet somebody wants to use. The 1650E would probably be a better choice.
        "I took a photo of my ohm meter... It didn't help." Enzo 8/20/22

        Comment


        • #5
          I have a Fender Pro Junior sitting here, needs an OT. One pair EL84. Puts out 15w. Factory has them in the factory, but not in parts stock. Got an 8 week backorder. PLus they are limiting them to replacement only, meaning I have to give a serial number for the amp to even order one. NO extras to go on my shelf. To help the customer I started idly looking around for alternates. I not long ago had a Peavey Classic 20, same tubes, and PV no longer has those transformers.
          Education is what you're left with after you have forgotten what you have learned.

          Comment


          • #6
            I have found the Hammonds to be good value for the money. Much cheaper than say the Mercury Magnetics and some others and seemingly just as well built. I've yet to spend the time to try comparing transformers in the same amp to see if it's worth the extra dollars for the "higher hyped" transformers, but customers seem happy with the Hammonds. Much of the time they are cheaper than the original part and an improvement.
            "I took a photo of my ohm meter... It didn't help." Enzo 8/20/22

            Comment


            • #7
              Key parameters? Primary Z, secondary Z, power handling capacity, frequency response are the big four.

              I was looking at OT specs when I was planning to build an OTT-15 from scratch. The Hammond that I'd choose for the application is small -- a 1608. It's a 10W HiFi transformer with an 8k primary and4/8/16 secondary. But sit down, the price for that little guy is about $80. That's similar to the 1750Y but nowhere near the stupid price for a MM OT.

              If that price bothers you, other options would include the Hammond 1760E guitar-type OT which has similar specs but is about half the price.
              Last edited by bob p; 07-06-2013, 05:20 AM.
              "Stand back, I'm holding a calculator." - chinrest

              "I happen to have an original 1955 Stratocaster! The neck and body have been replaced with top quality Warmoth parts, I upgraded the hardware and put in custom, hand wound pickups. It's fabulous. There's nothing like that vintage tone or owning an original." - Chuck H

              Comment


              • #8
                Those trannies that I mentioned are all "textbook" primary Z of 8k. Some people (Matchless) intentionally choose a lower Primary Z to select a different operating point. Doing that opens the door to a lot of other Fender OT.
                "Stand back, I'm holding a calculator." - chinrest

                "I happen to have an original 1955 Stratocaster! The neck and body have been replaced with top quality Warmoth parts, I upgraded the hardware and put in custom, hand wound pickups. It's fabulous. There's nothing like that vintage tone or owning an original." - Chuck H

                Comment


                • #9
                  I have a Hammond 1608 in my own amp. It's a proto of a design I did for someone else. When sourcing parts we found the guys at Heyboer were competitive and we knew the name was respected. So the production accurate proto's had custom Heyboer OT's. The Hammond sounds better IMHO. Vote two for the 1608.
                  "Take two placebos, works twice as well." Enzo

                  "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

                  "If you're not interested in opinions and the experience of others, why even start a thread?
                  You can't just expect consent." Helmholtz

                  Comment


                  • #10
                    Thanks for the good info. We can get a replacement for 25 bucks from Orange...but I dont have a good feeling about the quality of their transformers, from
                    what I have read and what I see...

                    Comment


                    • #11
                      At 25 bucks each buy 3.

                      Comment


                      • #12
                        Originally posted by The Dude View Post
                        I have found the Hammonds to be good value for the money. Much cheaper than say the Mercury Magnetics and some others and seemingly just as well built.
                        +1 for Hammond. Traynor has been using them since Pierre Trudeau was Canada's Prime Minister, the first time. And probably before. Nothing second rate here. Prices have taken a hike upwards lately but so has everything else. The only thing that bugs me about Hammonds is the large OT's have a hinky secondary winding arrangement that either requires a special switch to access 4, 8 and 16 ohms or simply select two impedances then you can use a toggle switch.

                        Meanwhile Mercury's prices and sliding price scale keep me from ordering any. Also found one Mercury PT failed for no good reason, and another OT that had a screechy bright output in an otherwise stock Bandmaster. Color me unimpressed with Mercury, except for their sideshow-barker style of salesmanship. Let's hope Hammond never starts carrying on like them. I can say I've worked on a couple of Two-Rock amps that had Mercurys specially developed for them, and those amps sounded terrific no matter where you set the knobs. I'll credit TR's engineering for that, not the iron supplier.

                        Edcor transformers made in USA - New Mexico - seem to have some respect from the hi fi builders. A small family business with quality products. I haven't used any - yet - but thought I'd pitch in a good word. Seen them mentioned favorably on Audio Asylum. Most recently see the Tube DIY column. Perhaps they don't have bandwidth to satisfy some "golden ears" but perfectly adequate for guitar/bass amp duty.
                        Last edited by Leo_Gnardo; 07-06-2013, 01:52 PM.
                        This isn't the future I signed up for.

                        Comment


                        • #13
                          I haven't used any Edcor OT's yet. But I'll second the vote based on quality and customer service. One of their standard model PT's met all my criteria except one. It used a different primary. I called them to ask if I could get that model in the primary I needed, even if they had to bump the price. They said they could and there would be no price bump. They said they would be happy to add the new model to their available line up for future orders. You see, Edcor carries very little inventory. They make their iron when it's ordered and then ship. So you can expect a four to six week wait. But the specs were dead on and the quality is excellent. Real pretty paint too.
                          "Take two placebos, works twice as well." Enzo

                          "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

                          "If you're not interested in opinions and the experience of others, why even start a thread?
                          You can't just expect consent." Helmholtz

                          Comment


                          • #14
                            What about Classic Tone Transformers?
                            They are American made in Chicago.
                            Their prices are reasonable.
                            ClassicTone Transformers By Magnetic Components, Inc.
                            "If Hitler invaded Hell, I would make at least a favourable reference of the Devil in the House of Commons." Winston Churchill
                            Terry

                            Comment


                            • #15
                              I've been using the Classic Tone units as replacements for a few years now. US made, price is right, paper bobbin. I think they sound great. Triode Electronics in Chicago is the main distro for them.

                              CLASSICTONE Transformers by Magnetic Components, Inc. - MADE IN USA -
                              The farmer takes a wife, the barber takes a pole....

                              Comment

                              Working...
                              X