One of the quickest ways to perk up the sound of a great vintage speaker (aside from replacing rotten surrounds on the woofers), is to replace the tired crossover capacitors with new polypropylene film type capacitors. With a speaker as revealing and downright legendary as the DQ-10, such a freshening up of the crossover can make for very significant improvements. There are kits available for sale on the internet, but the task is simple enough to be done on one's own with superior components for 1/3 the cost with a little care.
The main reason for hesitancy in recapping the DQ-10 crossover is that at first glance, the Dahlquist label capacitors do not have their values printed upon them making their replacement seem to be a wild guess. Fortunately, such is far from the case, for in fact, the capacitor values are printed right on the caps, but in a slightly different fashion. For instance, those caps labeled DQ 1065 are simply 6.5μF and the single DQ 1016 is a 16μF capacitor. The little green capacitors piggy backed on some of the older caps have their values printed right on them, 2μF. Not scary at all to figure out the values. If you're still a bit worried, just refer to the updated crossover schematic.
Something to consider when viewing the schematic is that the DQ-10 crossover did go through a slight redesign about midway through production. In this minor redesign, the capacitor values were changed slightly. In the early models, such as the one pictured, some of the capacitors are DQ 1060s (6.0μF) instead of DQ 1065s (6.5μF) with that for the midbass being two 1060s and a single 2.0μF bypass for a total value of 14μF rather than the later 16μF DQ 1016 (the other capacitors remained the same value). This was an improvement, however slight, and I suggest going ahead and changing your early crossovers to the newer values when recapping.
For capacitors in this particular instance, I went with Solens brand metalized polyprops from the internet supplier Madisound (Parts Express is another popular suppler) as I've used these particular caps in the past and prefer their sonics to the Dayton brand.
The stock crossover:
There are some minor changes -- the midbass wires have been removed for ease of capacitor replacement and several components are disconnected due to troubleshooting several bad capacitors.
The new capacitors fresh from the shipping box and organized by size. All are polypropylene film type capacitors outside of the single 80μF Bennic non-polarized electrolytic per crossover that was selected due to budget constraints.
In the above picture, there are far more capacitors shown than found in two DQ-10 crossovers. There is a reason for this. The exact values desired were not readily located at the supplier, so a slightly smaller value (5μF and 7μF for the 6.5μF and 8.5μF respectively) was chosen along with an additional capacitor of the difference in capacitance value (1.5μF). These capacitors were then soldered together using the leads of the smaller value to act as one larger capacitor. There is an additional advantage to this in that it allows an easy upgrade path in the future -- one need only replace the smaller value bypass cap with one of the same value, but of higher quality to obtain the improved performance at a lower cost and with less effort to install.
A handy trick to make the combination of these capacitor pairs an easier task is to take two medium tie-wraps and use them to hold the caps together firmly for soldering as pictured:
Now comes time to remove the old capacitors and install the replacements. First, take a picture of the stock crossover (top and underside) if you have a digital camera on hand. Should any components or wires come loose during the recapping and you can't remember where the leads went, a picture to refer to becomes vital unless you desire to spend a fair bit of time tracking to track back every lead via the schematic. Then, as mentioned before, it is best to unsolder the two midbass wires initially. This will allow easier manipulation of the Masonite crossover board. Then remove the screws both on the larger coils and those directly on the board. Gently raise the board and peal the foam sheet from beneath. Be careful here as the foam has likely not moved in three decades and so may stick a bit.
At this point it should be apparent that the component leads are soldered inside sheaths lining the various drilled holes. I recommend using a high wattage soldering gun to generate sufficient heat to melt the mass of solder relatively quickly and use a pair of hemostats to pull the leads free and thus make the removal of the old capacitors an easier task. To this, it's a good idea to replace just one capacitor at at time just to make things easier to keep track on. The old capacitors are held in place with a type of globbed epoxy, which is often oozed onto most everything else including the cap. You'll want to remove this to make room for the new, larger caps, but take care chipping it away lest the inductor forms or something else breaks in the process. Also, the masonite is covered with a wax coating, likely to serve as slight electrical insulation, so don't be surprised if it smells like candles while heating up the connections.
The old capacitors (top) and the equivalent value replacements (bottom):
After removing the old capacitor, simply bend the leads of the replacement to fit in the old holes and solder it in. You needn't worry about capacitor orientation as these are non-polarized units, but do ensure that the leads aren't touching anything they shouldn't. Also, don't flex the replacement cap leads too much lest they suffer fatigure and simply break off (something Solens are a bit notorious for). You'll discover that a lot of the old solder was removed in the process, so be sure to refill the hole with new solder -- I used silver content solder, just in case. Be sure that the board is supported in some way so the new leads have room to pass through the hole to ensure a firm mechancial hold and to prevent heat damage to something else such as the cabinet or wires. When done, clip the excess lead length and move on to the next. When all the new caps are installed, reconnect the midbass driver wires, look over everything and compare it to your reference picture to make all the component leads, wires, and jumpers are where they are supposed to be. Then fire up the DQ-10 quickly and listen to make sure all the drivers are producing sound. If so, then congratulations, you can reinstall the crossover board (listen again in case something happened when screwing it back in place) and then install the rear cover again.
The crossover with new capacitors installed.
After the second DQ-10 passes the ear -*test*-('"). Congratulate yourself and kick back to enjoy the improved sound.
- JP
The main reason for hesitancy in recapping the DQ-10 crossover is that at first glance, the Dahlquist label capacitors do not have their values printed upon them making their replacement seem to be a wild guess. Fortunately, such is far from the case, for in fact, the capacitor values are printed right on the caps, but in a slightly different fashion. For instance, those caps labeled DQ 1065 are simply 6.5μF and the single DQ 1016 is a 16μF capacitor. The little green capacitors piggy backed on some of the older caps have their values printed right on them, 2μF. Not scary at all to figure out the values. If you're still a bit worried, just refer to the updated crossover schematic.
Something to consider when viewing the schematic is that the DQ-10 crossover did go through a slight redesign about midway through production. In this minor redesign, the capacitor values were changed slightly. In the early models, such as the one pictured, some of the capacitors are DQ 1060s (6.0μF) instead of DQ 1065s (6.5μF) with that for the midbass being two 1060s and a single 2.0μF bypass for a total value of 14μF rather than the later 16μF DQ 1016 (the other capacitors remained the same value). This was an improvement, however slight, and I suggest going ahead and changing your early crossovers to the newer values when recapping.
For capacitors in this particular instance, I went with Solens brand metalized polyprops from the internet supplier Madisound (Parts Express is another popular suppler) as I've used these particular caps in the past and prefer their sonics to the Dayton brand.
The stock crossover:
There are some minor changes -- the midbass wires have been removed for ease of capacitor replacement and several components are disconnected due to troubleshooting several bad capacitors.
The new capacitors fresh from the shipping box and organized by size. All are polypropylene film type capacitors outside of the single 80μF Bennic non-polarized electrolytic per crossover that was selected due to budget constraints.
In the above picture, there are far more capacitors shown than found in two DQ-10 crossovers. There is a reason for this. The exact values desired were not readily located at the supplier, so a slightly smaller value (5μF and 7μF for the 6.5μF and 8.5μF respectively) was chosen along with an additional capacitor of the difference in capacitance value (1.5μF). These capacitors were then soldered together using the leads of the smaller value to act as one larger capacitor. There is an additional advantage to this in that it allows an easy upgrade path in the future -- one need only replace the smaller value bypass cap with one of the same value, but of higher quality to obtain the improved performance at a lower cost and with less effort to install.
A handy trick to make the combination of these capacitor pairs an easier task is to take two medium tie-wraps and use them to hold the caps together firmly for soldering as pictured:
Now comes time to remove the old capacitors and install the replacements. First, take a picture of the stock crossover (top and underside) if you have a digital camera on hand. Should any components or wires come loose during the recapping and you can't remember where the leads went, a picture to refer to becomes vital unless you desire to spend a fair bit of time tracking to track back every lead via the schematic. Then, as mentioned before, it is best to unsolder the two midbass wires initially. This will allow easier manipulation of the Masonite crossover board. Then remove the screws both on the larger coils and those directly on the board. Gently raise the board and peal the foam sheet from beneath. Be careful here as the foam has likely not moved in three decades and so may stick a bit.
At this point it should be apparent that the component leads are soldered inside sheaths lining the various drilled holes. I recommend using a high wattage soldering gun to generate sufficient heat to melt the mass of solder relatively quickly and use a pair of hemostats to pull the leads free and thus make the removal of the old capacitors an easier task. To this, it's a good idea to replace just one capacitor at at time just to make things easier to keep track on. The old capacitors are held in place with a type of globbed epoxy, which is often oozed onto most everything else including the cap. You'll want to remove this to make room for the new, larger caps, but take care chipping it away lest the inductor forms or something else breaks in the process. Also, the masonite is covered with a wax coating, likely to serve as slight electrical insulation, so don't be surprised if it smells like candles while heating up the connections.
The old capacitors (top) and the equivalent value replacements (bottom):
After removing the old capacitor, simply bend the leads of the replacement to fit in the old holes and solder it in. You needn't worry about capacitor orientation as these are non-polarized units, but do ensure that the leads aren't touching anything they shouldn't. Also, don't flex the replacement cap leads too much lest they suffer fatigure and simply break off (something Solens are a bit notorious for). You'll discover that a lot of the old solder was removed in the process, so be sure to refill the hole with new solder -- I used silver content solder, just in case. Be sure that the board is supported in some way so the new leads have room to pass through the hole to ensure a firm mechancial hold and to prevent heat damage to something else such as the cabinet or wires. When done, clip the excess lead length and move on to the next. When all the new caps are installed, reconnect the midbass driver wires, look over everything and compare it to your reference picture to make all the component leads, wires, and jumpers are where they are supposed to be. Then fire up the DQ-10 quickly and listen to make sure all the drivers are producing sound. If so, then congratulations, you can reinstall the crossover board (listen again in case something happened when screwing it back in place) and then install the rear cover again.
The crossover with new capacitors installed.
After the second DQ-10 passes the ear -*test*-('"). Congratulate yourself and kick back to enjoy the improved sound.
- JP
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