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Welcome to Austin Custom Brass 

New mouthpiece Comparison chart for 2026

New mouthpiece Comparison chart for 2026

Austin Custom Brass 

Mouthpiece Equivalency Chart

Standard Series Updated 2026

info@austincustombrass.com

(816) 410-0826

www.austincustombrass.biz



Well you've asked for it and you shall receive it!   We'll have a PDF  version up soon on our standard mouthpiece page as well but this is a quick reference for anyone interested in our Standard series mouthpiece line!

*Our inner mpc diameter is measured at 42/1000ths of an inch

Model

Inner Diameter*

Cup Depth

Throat

Backbore

Closest Equivalent

1B

.684

Deep Cup

26

A1

Laskey 84D, Monette b1-1, Bach 1x

1C

.684

Medium C Bowl Cup

26

A1

Laskey 84C, Monette B1-1,  Bach 1C

1CS

.684

Medium C bowl with more aggressive entrance into throat

26

MO

None (new design)

1 Studio

.684

Shallow bowl

28

KA3

Bach 1E,  B1-1L, 84S

1.25BC

.675

Hybrid
B/C  deep 

25

A1

Bach MV 1 ¼,  Monette B2,  Stork 2, Warburton 2

1.25C

.675

Medium C Bowl Cup

26

A1

Bach MV 1 ¼c,  Monette B2-7,  Stork 2c, Warburton 2MC

1.25CS

.675

Medium C bowl with more aggressive entrance into throat

26

MO

Bach MV 1 ¼C,  Monette B2S3,  Stork 2d, Warburton 2MV

1.25 Studio

.675

Shallow bowl

28

KA3

Monette B2L, Warburton 2S, 

1.5 BC

.668

Hybrid
B/C  deep 

25

A1

Bach MV 1.5B,  Bach 1.5B,  Warburton 2B, 

1.5C

.668

Medium Cup

26

A1

Bach MV 1.5c,  Bach 1.5c,  Warburton 2mc, Stork 2C 

1.5CS

.668

Medium C bowl with more aggressive entrance into throat

26

MO

Monette B3sf7,  Stork 2C+,  Laskey 68C 

1.5 Studio

.668

Shallow bowl

28

KA3

No real equivalent but rim is same ID  as Schilke 14a4a  where we measure

2BC

.664

Hybrid
B/C  deep 

25

A1

Bach MV3C,  Monette B4

2C

.664

Medium C Bowl Cup

26

A1

ACB old MV3C, Bach MV 3C,  Monette B4-7, 

2CS

.664

Medium C bowl with more aggressive entrance into throat

26

MO

ACB  Legacy MV3CS, Bach MV3D,  Monetts B4S

2 Studio

.664

Shallow bowl

28

KA3

Legacy ACB Ta2,  Monette B4LDS, Schilke 14a4a

3B

654

Deep B Bowl 

25

A1

Bach 3C, Monette B5, 

3C

.654

Medium C Bowl Cup

Bach Corp. 3C,  Warburton 4MC,  

3CS

654

Medium C bowl with more aggressive entrance into throat

26

MO

None (new design)

3 Studio

654

Shallow bowl

28

KA3

Warburton 4S,  Bach 3e, Reeves JH,  Monette B6LDS1

4BC

.650

Hybrid
B/C  deep 

25

A1

Monette B6, Warburton 4MD, Bach 3B 

4C

.650

Medium C Bowl Cup

26

A1

Monette B6S1,  Bach 3C (newer ones)

4CS

.650

Medium C bowl with more aggressive entrance into throat

26

MO

Monette B6S1,  Bach 3

4 Studio

.650

Shallow bowl

28

KA3

Bach 3E,  Reeves JH (Jerry Hey),  Warburton 4S,

5B

.644

Deep B Bowl 

25

A1

Old NY  Bach 5b with a more comfortable rim

5C

.644

Medium C Bowl Cup

26

A1

Old Bach 5C with a more comfortable rim 

5CS

.644

Medium C bowl with more aggressive entrance into throat

26

MO

No Modern Equivalent

5 Studio

.644

Shallow bowl

28

KA3

No Modern Equivalent

Ta1B

.635

Deep B Bowl 

25

A1

Bach 7B, otherwise no real modern equivalent 

Ta1

.635

Medium V Cup 

26

KA1

Giardinelli CT (but fairly different from that original)

Ta1CS

.635

Medium C bowl with more aggressive entrance into throat

26

MO

No Modern Equivalent

Ta1 Studio

.635

Shallow bowl

28

KA3

No Modern Equivalent

10.5C

.628

Medium C Bowl Cup

26

A1

New York Bach 10.5C

10.5CS

.628

Medium C bowl with more aggressive entrance into throat

26

MO

Marcinkiewicz 10.5C

10.5DS

.628

Medium shallow bowl

27

MT

Schilke 13A4A

10.5 Studio

.628

Shallow bowl

28

KA3

Yamaha 14A4A

Here is a list of our backbores in order of tightest to most open:

  • KA3: our newest commercial backbore and it is amazing! Feels almost like the throat is one size smaller due to the compression.

  • KA2: a very nice backbore with good zing.

  • KA1: more core than the A2 and a bit tighter as well.

  • A2: The A2 is a weapon! Designed to be mated with compression mouthpieces.

  • T: Tight: commercial backbore which provides the most resistance and "zing" to your sound

  • MT: Medium Tight: Provides great resistance, especially for players who tend to "backup."

  • S: Standard: Provides the best balance between resistance and sound spread for most players.

  • MO: Medium Open: A great slightly open symphonic shape produces a rich, warm tone but still gives ample resistance when needed.

  • A1: This backbore is a very large, symphonic backbore that is in between the MO and O – a

wonderful backbore suited for the classical player or jazz soloist wishing for a large sound!

  • O: Open: This is a very large, open backbore designed for the orchestral musician to provide the feel and sound spread that most orchestral players prefer

  • OO: Very Open: Huge backbore for enormous, rich sound (takes a lot of air)

8th Jan 2026 Trent Austin

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