All New KA Series Commercial Backbores

Austin Custom Brass
"I loved the A2 because of the great core sound it gave me. The KA1 takes my me to another level. The sound is crisp yet full with sparkle. Incredible!" -Tim Evans
(5 reviews)
1.00 LBS
6.00 (in)
6.00 (in)
6.00 (in)
Free Shipping
Current Stock:
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ACB KA Series Backbores - The Commercial Sound You've Been Waiting For!

Having the right backbore is a huge component of finding your perfect mouthpiece, especially in high pressure lead trumpet/commercial settings. Our KA Series backbores are designed to help you customize the sound and feel of your mouthpiece when matched with your favorite high-compression mouthpiece top.

If you want help choosing a backbore for your particular playing needs, please call our Mouthpiece Hotline at (781) 816-9664 and we'll be happy to assist you!



Here are some general descriptions of the KA Series backbores:

  • KA1: opens up ok, but stays tight through almost to the end.
  • KA2: opens up much more quickly after the throat.
  • KA3: opens up like KA1, but then opens up again like the KA2 at the end. It has for me, the most compression of the three backbores making it feel about one throat size smaller overall.
You might also want to check out the A2 and T backbores from our Standard backbore line.

If you have additional questions, please send us an email! 

Prior to ordering please check our Shipping and Returns policy.

Also note weight indicated in the ad is shipping weight not actual weight of the item.


Austin Custom Brass,  ACB, Trent Austin, For sale, custom brass shop, custom trumpet,  Kansas City, kc, kcmo, Trumpet, Cornet, Flugelhorn,We have mouthpieces equivalent to the Laskey 84D, Warbuton 2D, Denis wick, wick, Laskey 84B, Warbuton 2MD, Laskey 84C, Warbuton 2MC, Hickman GW, Bach 1X, Monette B1-1, 30's Bach NY1, Vincent Bach 1 mouthpiece, Laskey 80B, Haefer, Yamaha 16C4, Schilke 16C4, Bach Mount Vernon 1 1/4C, Curry 1.25BC, Bach 1 1/4C, Bach 1/4 C, Tilz 1 1/4CE, Monette B2, Monette B2S3, ACB 1.25C, MV 1-1/4C, Monette B2LD, Tilze 1 1/2E, Bach 1 1/2B, Monette B3, Curry 1.5BC, Warbuton 3MD, Bach 1.5C, Monette B3, Curry 1.5C, Warbuton 3MC, Bach 1.5C, Monette B3, GR 67, Monette B3L, Bach 1.5D, Mount Vernon 3C, GR 66.5, Mount Vernon 3B, BH3, Monette B4, Bach Mt. Vernon 3, Monette B4S, Bach Mt. Vernon 3D, Monette B4L, Bach 2 1/2C, Bach 3D/E, Curry 3DE., Monette B5L, Bach 3, Bach 3B, Monette B5, Bach 3, Warbuton 4MC, Schilke 14B, Monette B6s1, GR 65M, Pickett 5D, Monette BLM, GR 65M/S, Monette BL, GR 65S, Pickett 5E, New York Bach 5B, Pickett 5B, GR 74.7 MX, Bach 5B, Pickett 5C, Curry 5C, Monette B6, Giardinelli 7M, Bach 7D, Monette B7, Bach 7E, GR 64S, Giardinelli 7S, New York Bach 7, New York Bach 7B, Giardinelli 10M, M Shew 2, New York Bach 10 1/2C, Shew Yamaha Lead, Marcinkiewicz Shew 1, Giardinelli 10S, Schilke 14a4a, Monette B4L, Bach MV 3D, Marcinkiewicz Shew 1.75, Vintage Gustat Heim trumpet mouthpiece, Al Cass 1-27, Cat Anderson trumpet mouthpiece 


  • 5
    Great Piece

    Posted by Jason Lizotte on 16th Apr 2021

    So I bought a top online (TA Screech) thinking I had bought a whole mouthpiece. So now in need of a backbore I reached out to Trent and his team. Josh was awesome! He walked me through all the differences and how they translate to playing. This one will do "X" this will do "Y" etc. He took the time to walk me through all the different options and educated me without making me feel dumb for not knowing these things despite 30+ years of playing. We landed on the KA1. I wanted something that had a little tightness since most of my horns have huge bores. The difference from what I was playing previously was almost instantly noticeable. Not only did this set up sing in the middle registers, it really sang in the upper register as well with great slotting. My first go, a double D zipped out of the horn and I was loving it. Like everything else, it's going to take more time with it to hone it in and make it my regular piece but super impressed so far.

  • 5
    KA3 Backbore

    Posted by Tim Evans on 30th Dec 2019

    I really liked the A2 backbore. Then when the KA backbores came out I went with the KA1. Surprisingly my sound had more brilliance and sparkle and my range increased two notes. Then I went with the A3. The added resistance is incredible. Again I moved up an additional two notes from the KA1 and to my notes are cleaner and faster. Also I have more core in the sound without sacrificing any of the brilliance. The KA3 is a lot of fun!

  • 5

    Posted by Keith Felkner on 1st Jul 2019

    The KA2 is a very versatile commercial backbore. The compression is excellent all the while maintaining and even blow and a good sound from top to bottom; not too tight and not too big.

  • 5
    KA3 w TA-z

    Posted by Doug Zimmerman on 24th Mar 2019

    Trent's comments about the sizzle are spot on...this backbore really sparkles, but it is not so bright as to be annoying...there's still a real good core to the sound. The TA-Z top doesn't work for me, so I will be experimenting with other sizes.

  • 5

    Posted by Tim Evans on 17th Mar 2019

    I loved the A2 because of the great core sound it gave me. The KA1 takes my me to another level. The sound is crisp yet full with sparkle. Incredible! Oh and it gave me two more notes to my playable range just to show off it is the complete package. You have to try it!