CanadIanGeek
New Member
Short Version: I want to know what basic measurements I should take (before and after making changes) to get a decent picture of how a given speaker is performing beyond what my less educated ears tell me.
Long Version: I have 4 sets of vintage speakers from the 1970s that really should get a re-cap (and some need box repairs) to ensure they play long into the future. Over the years I've bought all the equipment and parts I need to do the job, but every time I take a step closer I get cold feet and walk away. This is mostly because of the complexity of a system where a single change can have unforeseen consequences. Being that the re-cap work is pretty reversible I want to be able to check my work by taking measurements before and after. I'm pretty sure I have enough equipment to do the measurements I need, but I just need to know what measurements I should take so that I can then educate myself on how. I don't have access to an anechoic chamber, and can't easily do the measurements outside.
Equipment:
For those who are about to scream about me ruining a bunch of precious old artifacts of a bygone age, I will cut you off at the pass. None of my speakers are models that are revered for their audio perfection. I love them and intend to stay true to what they are, but they are in need of some love. The better the condition they are in the less I intend to do. I'm not striving for perfection or trying to flatten their response curve nor do I expect night and day differences. I'm just trying to stabilize things and sand any rough edges. If no one notices a difference that is a success, if I notice a tiny improvement that is a huge bonus! If things get worse, I want to know right away, so that I can roll back the changes or go a different direction.
Long Version: I have 4 sets of vintage speakers from the 1970s that really should get a re-cap (and some need box repairs) to ensure they play long into the future. Over the years I've bought all the equipment and parts I need to do the job, but every time I take a step closer I get cold feet and walk away. This is mostly because of the complexity of a system where a single change can have unforeseen consequences. Being that the re-cap work is pretty reversible I want to be able to check my work by taking measurements before and after. I'm pretty sure I have enough equipment to do the measurements I need, but I just need to know what measurements I should take so that I can then educate myself on how. I don't have access to an anechoic chamber, and can't easily do the measurements outside.
Equipment:
- DATS V3: I bought this because it gave me a tool for measuring components(capacitance, inductance) check drivers, and bonus it can be used to measure speakers and check for box issues etc.
- MiniDSP UMIK-1: Calibrated measuring mic. I caved and bought this when I realized I could use it for my various speaker repairs and modifications, but could also use it to calibrate my Pioneer surround receiver.
- Multi-Meter: Might as well list this here since it does measure and I do have it. It's a basic digital unit, nothing fancy.
- What software should I be using?
- What measurements should I be taking?
- What checks should I be doing with the individual drivers?
For those who are about to scream about me ruining a bunch of precious old artifacts of a bygone age, I will cut you off at the pass. None of my speakers are models that are revered for their audio perfection. I love them and intend to stay true to what they are, but they are in need of some love. The better the condition they are in the less I intend to do. I'm not striving for perfection or trying to flatten their response curve nor do I expect night and day differences. I'm just trying to stabilize things and sand any rough edges. If no one notices a difference that is a success, if I notice a tiny improvement that is a huge bonus! If things get worse, I want to know right away, so that I can roll back the changes or go a different direction.
- Two pairs of Celestion Ditton 25: One of these is a later model they were my first Hi-Fi equipment(high sentimental value). They need some major box repairs(I lived in a bus for 6 years), but they still sound fabulous. The other set is in VERY good condition, but the capacitors look sketchy as hell! These have a reputation for having very sensitive, much praised and sought after, tweeters that blow if the the crossover sends it too low a frequency. The two sets are from different build generations, they have the same drivers but the later model(with the damaged boxes) have MKP caps where the other ones have hard to identify caps that are covered in a white precipitate. So the fact that Celestion upgraded feels like it gives me full license to do the same
!! These are going to be the first ones that I work on because I don't want them in service until those caps get changed. Right now they are a waste of space in my living room so no procrastination allowed! - Leak 2060: These are on my desk(it's a big desk)! These get used every work day. Love them, but the whole crossover is electrolytic caps that are VERY old. They also have almost no stuffing in them, so I might experiment with changing that, but I want to change as little as possible.
- Akai SW175: These are in my big room(kitchen/dining room). These have the cheapest looking crossovers and they have only a bit of fiberglass less than a cm thick stapled to the sides of the box. The box also has a hole through(from the factory) where there is a 1/4" headphone jack(I guess they used it as an alternative quick connect cable). These also have a reputation for having too small a box for the big 15" woofer, so it could probably be improved with some proper stuffing work and maybe seal the hole! They sound shockingly good, if a bit weak on the bass side.
