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Microphone pickups
- Thread starter Squeezy1
- Start date
It's a fairly standard microphone system using (rather expensive) Sennheiser capusules I think.
There are several that look almost identical and that are installed by accordion manufacturers.
They typically have 3 capsules on the treble side and 1 on the bass side.
My experience is that 3 capsules is not enough to get a good uniform sound pickup of all the treble notes.
There are several that look almost identical and that are installed by accordion manufacturers.
They typically have 3 capsules on the treble side and 1 on the bass side.
My experience is that 3 capsules is not enough to get a good uniform sound pickup of all the treble notes.
Caps
Active member
There is an issue with this design in my opinion. The mic pickups appear to be soldered directly to the circuit board leading to unwanted mechanical sounds and resonances picked up from the circuit board. The sennheiser mics are of good quality but should be shock mounted on some kind of foam or rubber insulation to separate them from being solidly mounted to the board. Just my nit picky opinion but I have built a couple of these using high quality panasonic cartridges and found this to be true. Also i would have used shielded cable between the pickups instead of circuit board traces.
I use variants with pins. If you let the mics float a bit above the circuit board, they only pick up solid sound through the pins rather than the case. That is already helping.
Caps
Active member
Interesting -might try stuffing a bit of foam in the space between and see if that dampens it any more. I punch a hole slightly less than the cartridge diameter in a piece of rubber mouse pad. Then use a very thin coax to attach to the cartridge and then glue it to where I want it. Last one I did, I put 4 on the treble side and three on the left. Before gluing them in I used a bit of double stick tape to play around looking for the best locations. Probably two on the left would have been sufficient as i couldn't discern a real difference between two and three.
Thankyou debra
I guess your solution is pretty good for keeping the contact noise down. I don't think the foam would do a lot. I have to admit that my own solution uses the microphones externally in a bar that is rubber-isolated by itself, so the pin separation may be more superstition than anything else. But as an engineer, it feels good to heed one's superstitions.
Caps
Active member
We are talking about reasonably low-impedance high-level signals here (we are behind the buffering JFET right inside the capsules). I've used adjacent circuit traces for this (with the next outward traces grounded), and it worked without getting unwanted hum. And I get to overhaul most amps in my place because of a high voltage overland line 200 yards from our house. If stuff works here without shielding, it will work anywhere.
Though that's hum. Can't vouch for mobile phones.
Alan Polivka
Active member
Any time you use foam rubber inside an accordion, you must select the type of foam very carefully. Many types of foam start to disintegrate after a number of years. This not only negates their purpose, but also makes a mess that can get sucked into reeds. I have had to repair many such messes from old foam in an accordion. There was a time when inferior foam was used in the valve pads on many accordions.
Hammond Organ Co. learned that the hard way. In 1963 they switched from cotton to sticky back foam in the manuals to seal out dust. After 10-15 years, the foam would start to disintegrate and corrode the insulation on the very fine wires (shorting them out) inside the manuals. The foam turned into a black sticky goo that destroyed the manuals beyond repair. It was known as the "black death" for the later model Hammond organs.
There is more than 1000 ft. of fine wire inside each manual that goes to each of the 549 key contacts. Some of the wires were very long as they had a calculated resistance from 10 to 100 ohms. These were "tapering" wires in series with the key contacts to create a volume "compression" over the wide frequency range.
This was a cost saving decision as the cotton cost more to install. It was riveted in place inside the manuals. Sticky back foam installed much easier. In the end it turned out to be VERY costly for the buyer to have the manuals replaced.
Alan Polivka
Active member
This shows exactly why accordions have been built with the same materials and adhesives for more than a half century. Some accordion manufacturers have experimented with alternative materials and adhesives that seemed to work well at first or save cost, but eventually had one or more of the following problems: a) the material did not endure, b) the material did not perform well, c) the adhesive did not retain its adhesion, and/or d) the adhesive was too strong and could not be removed when in need of maintenance or an overhaul.
When repairing or restoring an accordion, I use only traditional accordion materials and adhesives for these reasons. They always work well. I advise others to do the same. It's easy to fool yourself into thinking you've found a better way when it comes to accordion repairs. If you do repairs for others, you're doing them a disservice by using substitute materials or adhesives.
When repairing or restoring an accordion, I use only traditional accordion materials and adhesives for these reasons. They always work well. I advise others to do the same. It's easy to fool yourself into thinking you've found a better way when it comes to accordion repairs. If you do repairs for others, you're doing them a disservice by using substitute materials or adhesives.
Accordion manufacturers were not always that conservative about the materials used. Several decades ago Carini, the main parts supplier started selling self-adhesive felt+leather for the pallets, instead of the felt+leather that manufacturers had to put glue on to attach them to the wooden or metal parts of the pallets. After a few months the adhesive penetrated through the felt and leather and the pallets started to stick to the soundboard. The use of the self-adhesive felt+leather was abandoned immediately but thousands of accordions had already shipped with the faulty pallets. As the Hohner Morino (N series) made by Excelsior was one of the most popular accordions made in Castelfidardo this led to the term "Klebemorino", but other manufacturers also produced many faulty accordions in that time period.
Another problem with not being conservative is the move from leather valves with metal booster springs to (faux?) leather valves with plastic booster springs. When these are used for the low notes in cassotto the force of gravity causes the valves that are hanging down to sag and stay open. Metal booster springs were strong enough to keep the valves closed but plastic boosters are not. Accordions with the plastic boosters result in slow response in the low notes, and some manufacturers went back to using leather + metal springs.
So you are right in sticking to the tried and tested materials and methods, but accordion manufacturers are not that conservative and will try new things that save a bit of production time... sometimes with suboptimal results and some with disastrous results.
Alan Polivka
Active member
Indeed! I have had to fix several accordions with deteriorating foam. e.g., I recently acquired a beautiful LuxFisa accordion (made by CEMEX in the 1960s) with a mano reeds, but its valve pads are badly crumbling. It will be a very nice accordion once I replace all the valve pads, but that's not a trivial job. I don't bother with plastic valves ... all of my accordions have real leather valves and that's all I use for replacements.
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Plastic valves are not the problem. It's the plastic strips used as boosters on leather valves that's the problem. These leather valves come with the plastic booster springs (strips) pre-installed, and it is less work to put them on the reed plates than to first put a leather valve on, then a drop of glue, then the metal booster spring, then the paper or leather disk to better help keep the spring in place, then curl up the end of the spring so it cannot dig into the leather when the valve opens... And less work means lower cost, and as accordion prices never go down it means higher profit. But after 10 years the problems with these valves become evident. (On higher notes leather valves without booster springs also become a problem as the leather's properties change and they either become stiff or they go loose and start making flapping noises much louder than completely plastic valves ever do. I like leather valves (with metal booster springs), but for the highest octave or thereabout I use plastic because they simply work better and last longer than tiny leather ones.
The flapping noise is rarely audible by an audience that sits 10 meters/yards away, but built-in pick-ups will certainly register it.
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