Greetings all — please allow me to introduce myself as a new member seeking some basic advice & pointers.
I’ve decided to undertake my first DIY project: updating the crossovers for my c.1989 Dahlquist M-905 speakers. These were purchased new by my brother back in the day and passed along to me as a gift about 10 years ago. They’re in great condition and perfect working order, but I have the itch for an “upgrade” without the budget for a new pair of speakers…don’t suppose I’m the first to find myself in this situation
After doing some research and reading, I settled on the idea of replacing the capacitors as a cost-effective way to gain some improvement in my system’s sound quality. That said, I’m hoping to to benefit from the experience of folks on this Forum who have gone before me and are willing to share their knowledge. Listed below are some of the initial questions I’ve been thinking about…
- What kind of changes (presumably improvements) in SQ might I expect after upgrading the crossover components?
- For those of you who’ve done this kind of project before, what tips, pointers, advice would you offer to someone who’s starting their first project? Looking for anything at all here in terms of tools, materials, process, common mistakes to avoid, etc., which could be of help to a newbie.
- Should I replace other components while I’m in there? e.g., resistors, wires, inductors, etc. I’m basically interested in doing things which will provide the most noticeable SQ improvements.
- Can you recommend suppliers for parts? So far I’ve found Sonic Craft (soniccraft.com) but of course am open to other suggestions. I also know of a company called Regnar which supports old Dahlquist products and sells a cap upgrade for the M-905, but prefer to go the DIY route as I suspect I’ll get better bang for the buck.
- What kind of budget should I expect to need?
- Lastly, is this a lot harder than it looks? I have good mechanical and basic electrical/soldering skills mostly from working on cars & motorcycles, but haven’t gone the DIY audio route before. Red flags?
The M-905s are 2-way speakers, so the XO design is pretty simple (see attached photo) and contain only 4 caps total. The cap values are 10k and 5k mF.
Thanks in advance for your advice!
I’ve decided to undertake my first DIY project: updating the crossovers for my c.1989 Dahlquist M-905 speakers. These were purchased new by my brother back in the day and passed along to me as a gift about 10 years ago. They’re in great condition and perfect working order, but I have the itch for an “upgrade” without the budget for a new pair of speakers…don’t suppose I’m the first to find myself in this situation
After doing some research and reading, I settled on the idea of replacing the capacitors as a cost-effective way to gain some improvement in my system’s sound quality. That said, I’m hoping to to benefit from the experience of folks on this Forum who have gone before me and are willing to share their knowledge. Listed below are some of the initial questions I’ve been thinking about…
- What kind of changes (presumably improvements) in SQ might I expect after upgrading the crossover components?
- For those of you who’ve done this kind of project before, what tips, pointers, advice would you offer to someone who’s starting their first project? Looking for anything at all here in terms of tools, materials, process, common mistakes to avoid, etc., which could be of help to a newbie.
- Should I replace other components while I’m in there? e.g., resistors, wires, inductors, etc. I’m basically interested in doing things which will provide the most noticeable SQ improvements.
- Can you recommend suppliers for parts? So far I’ve found Sonic Craft (soniccraft.com) but of course am open to other suggestions. I also know of a company called Regnar which supports old Dahlquist products and sells a cap upgrade for the M-905, but prefer to go the DIY route as I suspect I’ll get better bang for the buck.
- What kind of budget should I expect to need?
- Lastly, is this a lot harder than it looks? I have good mechanical and basic electrical/soldering skills mostly from working on cars & motorcycles, but haven’t gone the DIY audio route before. Red flags?
The M-905s are 2-way speakers, so the XO design is pretty simple (see attached photo) and contain only 4 caps total. The cap values are 10k and 5k mF.
Thanks in advance for your advice!
Member
Joined 2003
It's fairly simple, replace said parts with newer parts of the same value.
Unless the wiring and inductors looks burnt or corroded, leave them alone.
I would replace the resistors with Mills 12w units. As for caps, Sonic Caps would be a good choice. For large shunt values, Sonic Craft offers AEON caps.
Unless the wiring and inductors looks burnt or corroded, leave them alone.
I would replace the resistors with Mills 12w units. As for caps, Sonic Caps would be a good choice. For large shunt values, Sonic Craft offers AEON caps.
Well, those caps are not electrolytic caps( they will not dry out). so I would not touch that crossover.leave it original!. most the time when you change caps in crossover it is because they have electrolytic caps that with time they start leaking and dry out, those are the ones you change!. in my opinion I would leave them original.
I agree, there is not much to be done here. You could bypass those capacitors (the yellow things) with some .22uf film and foil polypropylene caps from parts express. The existing caps are film type, not electrolytic which would really benefit from upgrading. It is possible that those caps are polyester, though, and could potentially benefit slightly from upgrading to polypropylene caps. Dahlquist fanatics would probably know if that was the case. Find another project, no huge gains here from tampering, in my opinion.
By the way, those caps are not "10k and 5k"... the smaller one is 6uf.
By the way, those caps are not "10k and 5k"... the smaller one is 6uf.
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Member
Joined 2003
Perhaps somewhere that would be of some benefit to improve is the cabinet. Can you post some photos of that? How thick is the material? How much bracing is there? Does it sound hollow when you knock on the side with your knuckle?
You can always cut some dowels and insert them into the cabinet to improve bracing, as well you can always add some more damping material. These are simple and cheap tasks.
You can always cut some dowels and insert them into the cabinet to improve bracing, as well you can always add some more damping material. These are simple and cheap tasks.
This is your best advice and the adding of extra damping material if what is there is degraded (or non-existent)
Thanks for all the replies and helpful info. It seems there’s a consensus forming that I should leave the XOs alone…Guess I’ll have to find some other project to play with!
I’ll try to provide answers here to the questions some of you’ve asked:
- Yep, those are the original XOs. Definitely not electrolytic caps, though I haven’t been able to find any detailed info on their composition. I do know they were manufactured by Dahlquist. In the upgrade kit Regnar sells for ~$100 the included caps are made by SAS. So, new caps wouldn’t really provide better SQ then?
- So, what am I trying to improve? Excellent question. I dunno, probably just a case of upgrade-itis. My setup sounds pretty good to my ears, given budget and room constraints. If there’s anything I would try to improve upon, I would say perhaps the soundstaging, depth especially. Maybe someone can see improvements in placement or room setup based on the attached pics of my listening space? (Obviously it’s a living space, don’t have a dedicated A/V room.) FYI, the associated gear is: Parasound HCA-1000A amp, Parasound P/LD-1100 preamp, Logitech Transporter digital music server (using lossless source files).
- One of you asked about the drivers — the M905 has Vifa drivers, 8” woofer and 1” tweeter. They’re in excellent shape. Rubber surrounds on the woofers so no worries there. See attached pics.
- As for the cabinets, they have a nice walnut veneer over I’m not sure what base material (MDF? some kind of ply?) — Perhaps one of you can tell by looking at the additional pics I’ve attached? They don’t sound particularly hollow when I rap on the them with a knuckle, but neither is the sound completely “dead.” Walls are ~1/2” thick and there is some bracing inside (2 vertically placed dowels) and also some ~2” thick white material which looks to me like fiberglass insulation positioned to cover the entire rear wall of the speaker (I pulled it out of the way when I took the photos so it’s not in the pics).
- Any suggestions for improving the way the speakers sit on the hardwood floor? The floor actually is uneven in places so the speaker stands are not resting perfectly flat on all four corners. Problem?
- @DreadPirate (great handle, btw): You mentioned the smaller cap looks like 6uF to you. I ended up calling the guys at Regnar about this one, because it’s not marked except for the cryptic “Dahlquist 1060 Mexico” you see in the photo. They told me it’s 5-5.5uF (allowing for 10%tolerance). What makes you think it’s 6uF, or is this close enough not to matter? FYI, the larger cap is clearly marked “10k / 100V”.
Thanks again, any more ideas you can offer are appreciated!
I’ll try to provide answers here to the questions some of you’ve asked:
- Yep, those are the original XOs. Definitely not electrolytic caps, though I haven’t been able to find any detailed info on their composition. I do know they were manufactured by Dahlquist. In the upgrade kit Regnar sells for ~$100 the included caps are made by SAS. So, new caps wouldn’t really provide better SQ then?
- So, what am I trying to improve? Excellent question. I dunno, probably just a case of upgrade-itis. My setup sounds pretty good to my ears, given budget and room constraints. If there’s anything I would try to improve upon, I would say perhaps the soundstaging, depth especially. Maybe someone can see improvements in placement or room setup based on the attached pics of my listening space? (Obviously it’s a living space, don’t have a dedicated A/V room.) FYI, the associated gear is: Parasound HCA-1000A amp, Parasound P/LD-1100 preamp, Logitech Transporter digital music server (using lossless source files).
- One of you asked about the drivers — the M905 has Vifa drivers, 8” woofer and 1” tweeter. They’re in excellent shape. Rubber surrounds on the woofers so no worries there. See attached pics.
- As for the cabinets, they have a nice walnut veneer over I’m not sure what base material (MDF? some kind of ply?) — Perhaps one of you can tell by looking at the additional pics I’ve attached? They don’t sound particularly hollow when I rap on the them with a knuckle, but neither is the sound completely “dead.” Walls are ~1/2” thick and there is some bracing inside (2 vertically placed dowels) and also some ~2” thick white material which looks to me like fiberglass insulation positioned to cover the entire rear wall of the speaker (I pulled it out of the way when I took the photos so it’s not in the pics).
- Any suggestions for improving the way the speakers sit on the hardwood floor? The floor actually is uneven in places so the speaker stands are not resting perfectly flat on all four corners. Problem?
- @DreadPirate (great handle, btw): You mentioned the smaller cap looks like 6uF to you. I ended up calling the guys at Regnar about this one, because it’s not marked except for the cryptic “Dahlquist 1060 Mexico” you see in the photo. They told me it’s 5-5.5uF (allowing for 10%tolerance). What makes you think it’s 6uF, or is this close enough not to matter? FYI, the larger cap is clearly marked “10k / 100V”.
Thanks again, any more ideas you can offer are appreciated!
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Member
Joined 2003
Sounds like adding a few more braces and some extra stuffing would help. It's cheap and simple. If you're still not satisfied, then I would look at finding a different speaker that you like better. The drivers and crossover look good, the crossover design may not be optimal (who knows), but without some fancy measuring equipment you're SOL for a crossover redesign.
By the way, that's a real nice home you have there.Good luck with your project.
By the way, that's a real nice home you have there.Good luck with your project.
Thanks DcibeL. The place is great, should last us until it's time to have kids anyway!
I'll do some research on bracing and stuffing...might find myself coming back to the forum with more questions! As for new speakers, the Dahlquists sound pretty damn good -- I don't know what I'd have to spend to better them, but I suspect it would be a pretty large $$$ number. I've been toying with the idea of adding a sub...
My immediate thought on seeing that tweeter is that a "Vifa D27TG05-06 1" Textile Dome Tweeter" from Madisound ($21) MIGHT be a drop-in replacement AND actually work OK with the same XO. I remember playing with both of these tweeters about 15 years ago....
A brace from the weakest point between the tweeter and woofer to the rear panel is probably the most effective single shot.
Some feet -- two in front and one center in rear -- might work for stabilizing them? Maybe even make them adjustable if you want to play with the tilt and height. The height is important, as already stated.
For more image depth, pull them away from the front wall (and perhaps also move your listening position closer).
DIY speaker cable is cheap and easy. (Surplus CAT5 available?)
A brace from the weakest point between the tweeter and woofer to the rear panel is probably the most effective single shot.
Some feet -- two in front and one center in rear -- might work for stabilizing them? Maybe even make them adjustable if you want to play with the tilt and height. The height is important, as already stated.
For more image depth, pull them away from the front wall (and perhaps also move your listening position closer).
DIY speaker cable is cheap and easy. (Surplus CAT5 available?)
Room is nice, can't see the back wall but a few bass traps may work to improve over-all sound.
One thing that may work well is a cheap Bi-amp set-up with a pair ( or more ) of subwoofers, taking the LF ( Sub 100 Hz ) out of the main speakers could give a lot more clarity in the midrange and add to the overall SPL so you could actually turn the volume down a notch or two
One thing that may work well is a cheap Bi-amp set-up with a pair ( or more ) of subwoofers, taking the LF ( Sub 100 Hz ) out of the main speakers could give a lot more clarity in the midrange and add to the overall SPL so you could actually turn the volume down a notch or two
Reviving this old thread, I have a question about replacing electrolytics in my JBL 250Ti crossovers. In my case, there are two 24uFs in each crossovers. One is on the woofer shunt and the other is on the 108H lower midrange shunt.
My buddy replaced the corresponding 24uF woofer shunt electrolytic caps on his 240Tis with film caps, and we A-B'ed it against a pair of L250s (not the Ti version) and his 240Tis (same woofer and effective cabinet volume) had a lot more bass. It was dramatic, and it remained even when we moved the speakers to take each others' places in the room.
What effect does a dried-out cap have on a woofer shunt or Zobel? Would it decrease the bass or decrease it? Would it increase capacitance or decrease it? Just curious.
My buddy replaced the corresponding 24uF woofer shunt electrolytic caps on his 240Tis with film caps, and we A-B'ed it against a pair of L250s (not the Ti version) and his 240Tis (same woofer and effective cabinet volume) had a lot more bass. It was dramatic, and it remained even when we moved the speakers to take each others' places in the room.
What effect does a dried-out cap have on a woofer shunt or Zobel? Would it decrease the bass or decrease it? Would it increase capacitance or decrease it? Just curious.
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