Miraphone 1291 and M & M clone comparison

March 8, 2010....   I just received the M & M 1291 clone today and I haven't had much time to do an evaluation yet.  But here are a few images that will just have to do until I get a chance to give it anything more than a quick 'toot'.  An initial quick inspection indicates that this is a VERY good copy in all respects.  The valves move freely and the slides don't show any signs of 'gritty-ness' that I've seen in many of the Asian imports.  The Miraphone is on the right in all of the images.

     

 

Rough intonation check using PT48x with each horn at room temperature.  All slides are pushed 'IN'.  I didn't find any intonation problems within the range noted that could not be corrected.

NOTE

Miraphone

clone

fingering used

BBb

minus 5

ON

open

BB

OK

ON

2 and 4

CC

minus 20

ON

4

CC#

olus 20

plus 30

2 and 3

DD

ON

plus 10

3

Eeb

ON

ON

1

EE

plus 5

minus 5

2

F

ON

ON

open

F#

plus 20

plus 20

2 and 3

G

plus 20

plus 30

1 and 2

Ab

plus 5

plus 30

1

A

plus 5

plus 20

2

Bb

ON

plus 5

open

B

ON

ON

1 and 2

C

ON

minus 5

1

C#

plus 5

minus 30

2

D

minus 25

minus 10

open

So far, I've only found a few small problems with the 'clone':

1)  There is some very mild 'flattening' in the bends of the #3 valve circuit.

2)  A brace between the #2 and the #3 circuit was loose...  a quick solder fix.

3)  The valve guides are plastic and resemble Yamaha guides that have the metal insert.  Problem is...  the metal insert is wider than the plastic part resulting in rubbing the sides of the guide slot and making a bit of noise.

 

Added March 9, 2010

More on the 1291 (M & M) clone... I tooted on it for a while this afternoon and took it to my community band rehearsal tonight. The horn performs great! I plan to alternate between the clone at the REAL Mirafone over the next couple of weeks. Playing the horn, I can FEEL the difference but haven't been able to detect any intonation problems. When I say I can 'FEEL' the difference, I mean the valves aren't quite as smooth at the Miraphone. The slides are typical of Asian horns. The fit and finish of the slide tubes is adequate but not as fine as the Miraphone. I'm going to do a bit of work to make the slides as smooth as I like them. Currently, the #2 slide is stuck and the rest are difficult to pull.

There is a slight flattening of the 3rd circuit where it exits the valve casing and the lower loop of the 1st valve wrap is not parallel and the lower crook is 'over-bent' sort of like a hairpin. Both situations are not 'show-stopper' but look like a little more care needs to be taken during assembly. Apparently the parts didn't fit perfectly and things were forced to make them work. This is the kind of think I've learned to expect from the Asian horn. It's mostly a matter of physical details that will probably improve as the horn builders mature. I'll try to get some pictures of these things on my web page in a day or so.

The valve guides are not copies of the German ones. Jin Bao has chosen to use the Yamaha style plastic valve guide. The didn't get it quite right, though. The metal insert in the guide is as wide as the plastic and the metal 'scratches' the guide slot on the #1 piston. The 'scratchyness' is mainly due to one side of the guide slot not being finished very well. With conventional solid metal guides this might not have even been a problem but the thin metals ones imbedded in the plastic tend to 'grate' along the slot. I've seen poorly finished guide slots on very expensive horns so this doesn't strike me as a problem, either.

At this point... I have to say that the M & M 1291 'clone' represents and excellent value.

And 'no'.... no-one has paid me to say nice things about these horn... not even a T-shirt was involved! :)

Added March 11, 2010

I spent a couple of hours this afternoon cleaning up the tuning slides.  They are were all a bit 'gritty' and I couldn't get the 2nd slide to move at rehearsal Tuesday evening.  Slide alignment was OK so a good cleaning and relubrication worked on everything but the 2nd valve slide.  I had to lap the 2nd to correct out-of-round inner slide tubes.  I noticed a couple more workmanship issue that pictured below.  The 'clone' is on the left and the Miraphone is on the right.  Note the lower 'loop' of the 1st piston circuit.  Instead of the crook 'legs' being parallel as they are on the Miraphone...  they have sort of a 'hairpin' look.  It's difficult to get a good picture of it but there is definitely an 'issue' there.  It's almost like it started out parallel and was 'squished' a bit at assembly to make it fit.  Note that there is a brace on the bell ferrule that does not appear on the Miraphone.  Again...  it's difficult to tell from the picture, but the 3rd valve 'knuckles' have a bit of deformity and slight flattening.  Again...  most likely due to things not fitting perfectly.    

  

The pictures below show what I consider to be a problem with the transition from the leadpipe to the 1st valve.  The image of the 'clone' on the left shows what appears to be an odd angles where the leadpipe meets the casing.  The ferrule covers up what's really going on there but one can assume that the end of the leadpipe and the end of the knuckle are not square.  It's obvious that the leadpipes are not bent the same.  The Mirafone is on the right.  It sports some 'lacquer craze' from a previous repair.

 

I also worked on the valve guides a bit.  The problem here is that the metal insert in the Yamaha-style guides are as wide as the plastic and the metal is making contact in the guide slot.  The guides cannot be reworked without sacrificing the correct width for proper alignment.  This is something JinBao needs to address.  REAL Yamaha valve guides would work except the small 'nub' on the bottom side of the guide is a bit too far away from the outside of the piston.  My fix for the situation would be to elongate the alignment hole in the top of the piston to allow the Yamaha guide to extend a bit further.  The guide would be held firmly in place by the valve stem and washer.  Again...  the 'clone' plays very well.  The timbre is as identical to the Miraphone as my ear and amateur playing can determine.  Most of the things I've pointed out here are simple workmanship issues that can be corrected with minimal time. 

Added March 13, 2010

Spent about three hours today working on the problem of the 'raspy' valves.  The problem here is that the metal inserts in the plastic valve guides were the same width of the plastic.  When the guide rode up and down in the slot...  the metal rubbed the inside of the slot.  The fix is for Jin Bao to reduce the width of the metal insert in order for the plastic to do its job.  The picture at the left below shows the four clone valve guides...  two from the bottom and two from the top.  And...  a top and bottom view of a Yamaha valve guide.  Note that there is plastic exposed on either side of the metal insert on the Yamaha guide while the clone guides show the metal flush with the plastic.  The picture on the right is a view of a single clone guide and a Yamaha guide.  It's quite obvious of what Jin Bao tried to do here...  they just need to go back to the drawing board and do it right.  (Hey guys...  if you are reading this...  send me four new guides after you make the required corrections!)

As a temporary fix (until I hopefully get corrected guides from the factory)...   I modified DEG valve guides to work on the clone pistons.  I could have used Yamaha guides but I close the DEG ones because they are ALL plastic and don't have the metal insert that I would have had to drill through.  The DEG (or Yamaha) guides fit on top of the piston but the little pin on the underside needed to move away from the tip of the guide about .080" to put the guide in the right place to fit into the guide slot in the piston casing.  I drilled a .077" diameter hole through the guide in the new location and cut the old pin off.  A piece of #12 copper wire serves as the new pin.  With this set-up...  I can just pop the 'improved' version in when (if) it becomes available. 

 

Finally, I opened up the back portion of the slot in the guide with a .216" diameter drill to fit the piston stem and also reduced the outer diameter of the washer to fit into the recess in the valve guide.  The picture below show the modified DEG guide ready to fit to the casing and guide slot.  Only a small amount of sanding of the plastic was necessary to make the guide fit the slot.  The total time to modify the four DEG guides and complete the installation was about three hours.

   

While I had the pistons out working on the new valve guides...  I did make a few 'discoveries'.  In a port of the #2 piston, there is some epoxy or solder...  apparently covering up some sort of defect.  Maybe a hole in the port??  Dunno.  It wasn't leaking and was fairly smooth so I didn't scratch around on the stuff.  The workmanship on the pistons is nowhere near the quality I see on the REAL German 1291.  Take a look at the chamfer around the ports.  This transition between the inside of the port and the outside of the piston should be as sharp as possible.  A bevel like this will interrupt the smooth airflow through the horn.  You can also see this same condition on another picture a bit up the page.  You can actually see where the cutting tool 'chattered' while the operator tried to put a bevel on the edge.  No bevel is best...  with a nice sharp corner.

       

Unless I stumble across more problems...  this will probably be my last entry.  I've spent maybe a total of six hours so far fiddling mostly with 'scratchy' slides and valves.  If a person is willing to put up with these small details that are mainly just poor craftsmanship...  they could end up with a horn that plays very well.  This one does.

Sequel....  3/24/2010....   I've been alternating playing the REAL Miraphone 1291 and the M & M 'clone' for a couple of weeks now.  The performance of the two horns is amazingly the same.  One person who has heard me play both horns volunteered that the Miraphone sounds a bit more resonant and darker than the 'clone'. 

 

Page created on March 8, 2010

Updated on March 24, 2010