Valve compression issues on new instruments?

bassguy · Veteran Member Joined: 25 May 2016 Posts: 336

Specifically how is valve compression measured? How quickly can valve compression diminish on a new indtrument? I just ordered an instrument & a credible THF messaged me about his experience with the same product, describing low valve compression & premature lacquer wear around the valve casing

Richard A

Richard III · Posted: Thu Apr 20, 2017 2:31 pm Post subject:

Ignore this if it is too annoying, but I play instruments all the time that are 40-60 years old with fine compression. Any brand that has that bad of valves is not worth having at any price. Oh wait, any price seems to be little silly. If some guys says, hey man, here's a horn for a dollar that you just have to use 30 weight motor oil to make the valves work, I might be tempted.

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Richard

King 1130 Flugabone
King 12C mouthpiece

rufflicks · Posted: Thu Apr 20, 2017 2:41 pm Post subject:

How does it play???
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James Becker

Thank you Richard for mentioning our ability to quantify valve seal.

Under a load of 1 psi of static air pressure our test can detect the "blow by" or pressure loss of piston and rotor valves. Keep in mind the sound pressure you produce inside a wind instruments does not exceed 1 psi, so this is a realistic amount of pressure.

When new, top end manufacturer's valves will typically score 95% air tight with 5% pressure loss, while student models typically score 85% air tight with 15% pressure loss. Instruments that loose greater than 20% from when new are candidates for rebuild.

Longevity of seal is improved when valves are fitted to closer tolerances to begin with, are cleaned regularly, and oiled daily. The purpose of oil is not only for lubrication but also to displace the damaging effects of trapped condensation from your breath. As with any unprotected brass, oxidation will occur allowing copper carbonate deposits to build up inside your instrument. Corrosion removes zinc from the alloy and copper carbonate will act as an abrasive accelerating mechanical wear.

This diagnostic test is provided free of charge for our repair customers so we can more intelligently advise them as to whether a rebuild is needed or not.

FWIW we've witnesses a Bach Stradivarius C trumpet that was played daily for seven years need a valve rebuild and replacement leadpipe due to "red rot" (de-zincification). So you'd do well to keep up your instrument's maintenance.

I hope this is helpful.
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James Becker
Brass Repair Specialist Since 1977
Osmun Music Inc.
77 Powdermill Road Rt.62
Acton, MA 01720
www.osmun.com

Our workshop is as close as your nearest UPS store https://www.ups.com/dropoff?loc=en_US

Richard III · Posted: Fri Apr 21, 2017 5:46 am Post subject:

I do a plug the bell test and blow. This is how I found out that an old cornet had an issue with it's tuning slide water key. It seemed okay. The cork wasn't bad. But the spring was weak and it wasn't sealing completely. Easily fixed as part of my tech person's fixing of all issues. The first valve has some blowby also that was made worse by old valve guides. Still an issue that thicker valve oil doesn't fix, but the horn plays fine. I may have it rebuilt in the future.
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Richard

King 1130 Flugabone
King 12C mouthpiece

Paladin53 · Regular Member Joined: 27 Sep 2015 Posts: 34

James,
Could you please explain how you go about the compression test?

What gauges do you use?
Assuming two gauges, where are they placed?
Where do you apply the 1psi air?
Where do you measure the leakage?
How do you measure the leakage?
Is it a certain amount of time, then check loss?
Or is there a measure of blow by flow?

I am familiar with compression test on engines but having a hard time understanding how one would go about it on trumpets.

Pictures would really be nice.
Thanks,
Floyd

James Becker · Posted: Fri Apr 21, 2017 2:07 pm Post subject:

Thanks Floyd for asking about our leak tester.

To be perfectly honest I'm not comfortable listing details on a public forum. Our tester was developed specifically for wind instruments and is not the magnehelic popular with woodwind technicians. We feel it's more effective than the "Mag" machines in providing us the data we need to perform our jobs.

Anyone is welcome to come in our shop for a compression test and evaluation free of charge.
_________________
James Becker
Brass Repair Specialist Since 1977
Osmun Music Inc.
77 Powdermill Road Rt.62
Acton, MA 01720
www.osmun.com

Our workshop is as close as your nearest UPS store https://www.ups.com/dropoff?loc=en_US

Bflatman · Heavyweight Member Joined: 01 Nov 2016 Posts: 720

It has to be said that some manufacturers in some countries produce scrap metal and sell it as trumpets.

These instruments are worthless and many purchasers buy them simply because they are cheap and shiny.

Stories of valves wearing out within 12 months or unplayable instruments that are not even worthy of being made into a lamp abound.

If you buy a trumpet and out of the box it has low compression it cannot be fixed no matter how much you want it to be.

All my instruments have good valves and play wonderfully and sound great. I paid around 30 dollars for them and the most I have paid is 80 dollars, they are all between 50 years old and 90 years old.

Its not a one off fluke I have bought 9 instruments all of them incredible players for the price paid and in my view they are all incredible players at any price. There is not one bad instrument among them, all were bought blind on ebay without playing them first.

There is no excuse in my view for owning a 100 dollar instrument that sounds crap and has crap valves when for 50 dollars you can buy a wonderful instrument that will last you 50 years.

Are we seeing a revolution thanks to the internet crap is being widely distributed.

James Becker · Posted: Thu May 04, 2017 4:32 am Post subject:

I'd like add to Bflatman's contribution, when purchasing either new or used, you're more likely to have a better outcome when sticking with quality name brands known for valves that meet industry standards. Rolling the dice and purchasing unproven brands based on price alone is something to be avoided.

As my grandmother was fond of saying "A fool and his (or her) money are soon parted."

My 2 cents.
_________________
James Becker
Brass Repair Specialist Since 1977
Osmun Music Inc.
77 Powdermill Road Rt.62
Acton, MA 01720
www.osmun.com

Our workshop is as close as your nearest UPS store https://www.ups.com/dropoff?loc=en_US

Dale Proctor · Posted: Thu May 04, 2017 6:43 am Post subject:

Informative thread - I've enjoyed reading it so far.
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Louise Finch · Posted: Fri May 05, 2017 8:50 am Post subject:

lipshurt · Posted: Fri May 05, 2017 10:20 am Post subject:

you can do a simple vacuum test which will tell a great deal. Almost as good as a 1psi pressure test.

1) remove the 1st valve slide and plug the top tube with your left thumb.
2) press all three valves down and suck on the mouthpiece to make a vacuum.
3) seal the vacuum with your tongue and time how long it takes to have ZERO vacuum in the instrument.

If it takes 20 seconds the horn is like new.
15 seconds = good
10=you will feel looseness
8=possible playability issues. Loose slots, weird notes
5=playability issues, flat low register, some upper notes way sharp, looseness
3= bordeline not playable. I've know LOTS of guys that play gigs on horns holding 3 to 5 seconds of vacuum
2=much worse than 3. probably more leaks than just valves
1= drastic problem

This test checks all of the horn except the bell tail/casing joint which can also leak. It does check the valves, slides, water keys etc. What it doesn't do is tell you where the leaks might be. Under water pressure test show where leaks might be.
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