November 21, 2019 at 6:35 am #10380
Hi from San Francisco,
My wife recently inherited a record player/stereo consul from her grandparents. It is huge, it is a terrible use of space in our tiny SF home and it is beautiful! I have poured over the internet and found out all the reasons why it is a terrible setup for a Hi-Fi system but her personal connection to the object and the indelible mark it left on her childhood outweigh the audiophile concerns. That being said I would like to achieve decent sound by rehabilitating it! I should also mention I am a fairly handy guy but have no experience in the world of speaker building.
My approach for the project is to replace the non-enclosed 3-way speakers (woofer, mid, and two identical tweeters pointed in different directions, is that a 3.5-way?) with enclosed 3-way speakers mounted inside the cabinet. I know this will most likely result in a boomy output so I have chosen a bookshelf kit that is specifically designed to operate against a wall (boosted midrange and treble to compensate for room gain). I also plan to build the enclosure using a method outlined in the tech ingredients youtube channel: video titled “World’s Second Best Speakers” starting at the 34:06 timestamp) with the hope that this will drive the base out the front baffle and through the front facing slotted port.
Here is my first question: Is my thinking thus far correct? Will the dampening on the sides and back of the enclosure make the speakers better for this setup or is the real fix in a bespoke crossover? There are many intimidating aspects of this project but designing, testing, and reworking crossovers seems like the most insurmountable challenge to me.
AdministratorNovember 21, 2019 at 7:14 am
First of all, it is a beautiful piece of furniture and I understand the sentimental attachment to it. I honestly have considered redoing on of these myself, so I think it’ll be a really neat project. Can you explain a little more about what you are concerned with. I get you are thinking of adding a constrained dampening layer. Is your concern, since the bass waves wrap around the speaker cabinet, they will become boomy? If it were me, I would enlarge the front baffle to utilize the entire space in the cabinet. That would be the easiest way, to make sure all the waves are radiated forward. As far as dampening is concerned, I don’t think that is the fix.
MemberNovember 21, 2019 at 8:08 pm
Wow, thanks for the quick reply!
I had planned to dampen the sides, top, bottom, and back and to redesign the box so that the front baffle covers all or nearly all of the grill (the added benefit of this is that I can position the tweeter and midrange to project through the slots of the grill). The front baffle would not have the dampening added to it. I have been told to think of sound waves like wind. To my thinking even the longer bass waves would resonate through the front baffle and vent (like wind through a screen door) and be less motivated to move through the dampened sides and back (like wind against a wall) where they would otherwise bounce around and add boom? The kit I have chosen doesn’t have a large enough enclosure volume to warrant the sides to run perpendicular to the grill (thus occupying the space where sound waves might bounce and boom) perhaps I need a larger kit? My current plan was to have the sides angle in to achieve the necessary depth of enclosure.
I was toying with utilizing the space behind the speakers for storage (especially since this takes up such a significant portion of the living room), so the dampening would also be needed to reduce vibrations from shaking the cargo. I may scrap this part of the plan as there is nothing more rattly than bunch of DVDs!
AdministratorNovember 22, 2019 at 6:43 am
It sounds like you’re overthinking this. But I want to point out a few things. First, I would look for a sealed kit versus ported. Looking at the front of the cabinet, there doesn’t appear to be a good area to have the port, where it wouldn’t be obstructed by some wood. Service, if you increase the front baffle, it does not mean you need to change the box size. Keep the box size the same, but increase the front baffle to extend beyond the size of the box. As far as resonance goes, if it is properly designed and braced, you will move your resonance up to where it is inaudible and no longer a concern. I would concentrate on proper bracing in the box and use a sound dampening material in the box to kill standing waves. I hope this helps.
MemberNovember 23, 2019 at 6:47 am
Overthinking it is kinda my thing! But I’m also interested in listening and learning!
Here are the two options as I understand them so far. The one on the left is my tapered idea. The one on the right is what I think you are saying. The second photo shows the driver placement on the grill of the cabinet.
AdministratorNovember 25, 2019 at 5:20 am
That is exactly what I am thinking. Although, if the plan is for it to be ported, you can try it that way first. If it is problematic, you can just plug the port. The only issue I would see with it being tapered, is the crossover takes into account the driver spacing. SO once you alter the driver spacing, you could alter the response.
ModeratorNovember 25, 2019 at 7:25 am
Have you had a chance to listen to the console yet? If not, give it a chance before ripping into it.
Having grown up around this type of musical furniture, my personal preference would be to work with what’s there to start. Given the sentimental attachment, this seems to be prudent.
I must say, I love these old drivers – done up right, they can really surprise you.
Let’s start with the existing design of the speaker enclosures. I cannot see, but my guess is that the back baffle is perforated hardboard / pressboard. If so, then these are a very common design of modified open baffle, similar in example to open back guitar speakers. These were designed to use the wall that the console sits against as a part of the system, adding gain in the bass region. About all you can do is some sort of bracing to reduce or eliminate enclosure resonance. You’d have to do a visual analysis to determine what would be needed, if any at all.
Next, I see that passive crossover is rather lacking. The (12″?) woofer is run full range while the (3×5?, 4×6?, 5×7?) mid-range has a cap across the terminals while the paralleled tweeters have a single cap in-line. A proper crossover network would most likely clean it up rather well. As old and hi-Qts as these most likely are, I wouldn’t really worry about anything other than 1st order. To do this you’d need the impedance of the drivers and an idea of where to cross them over.
Now, I don’t see any real markings, except for something on the woofer that ends in a -8. Not to fear, just disconnect the leads and measure the DC resistance. An 8 ohm speaker will measure near 6 ohms DC. A 4 ohm speaker will measure somewhere near 3 ohms DC. A 16 ohm speaker should be somewhere between 12-14 ohms DC.
If you don’t have a DATS (if you did, you wouldn’t be doing the last step above) then use a FM car transmitter (buy online, big box stores like Walmart, or if you have something like a 5 Below or Big Lots, check there) and your computer to transmit test tones to the FM section of the console using something like Audacity. Try with the individual units hooked up, ie, just the woofer and run test tones in 100 Hz increments up to maybe 2500 Hz. Then do just the midrange doing a 300 – 5000 Hz test, and then the tweeters running 1500 – 6000 Hz. Make each step at least 1 – 2 seconds long and listen for when the tones get strong at the bottom and weak at the top. If you run with those numbers in a conservative fashion, the crossover should be fairly close to correct, plus you’ll have already started the tuning by ear process.
Just my thoughts.
MemberNovember 25, 2019 at 7:01 pm
Thank you for all that info!! Even without any experience I had thought (based on the videos that I have seen) that the crossover was seriously insufficient! It’s nice to hear that confirmed!
There is only one side of the consul that puts out sound. The other side either has a wiring issue or something in the amp or control panel. The biggest issue with using the existing setup is that my wife’s family all report back that it never sounded great, even when it was younger and fully functional! I don’t know if that is because of the crossover, the open baffle, the quality of the drivers, the turntable they had, or the fire hazard of an amplifier! I suspect it is all of the above. I don’t think I have the time or expertise to tweak the existing setup to try and find its potential. I am considering either purchasing speakers for it or building some that are based on somebody else’s expertise. It is becoming clear to me that I need to get my hands on a dats. Is there anyone who rents these out since I don’t have plans to build speakers full time?
ModeratorNovember 25, 2019 at 10:47 pm
Ah, I thought it was, as DATA from Star Trek TNG once said, “Fully Functional”. Being as you are in SF, you might be able to contact YouTuber Shango066 to maybe fix the tuner/amp section.
Until then, if you have some other type of amp to test the speakers, or jumper the wires from the working side speakers to the non-working side speakers to verify their condition, you could make a plan on what you find.
I understand if you would rather upgrade everything to work within the cabinet. After all, it is yours (well, the little lady’s).
Do you intend to keep “a record player” in the cabinet? Not necessarily what’s in there, but maybe a more modern unit. And would you want to keep the “radio” section? If these aren’t really part of the plan, then by all means, go for whatever fits your needs and plans.
To go for new speaker drivers or a “box in a box”, look for a good sealed (acoustic suspension) design. I would think you could go with a good 8″, or better, 10″, and still have room left over. That way, you could just frame out some cleats in the existing enclosure to screw a back onto at the appropriate distance back to get the correct interior volume.
(I don’t want you to think I’m badgering you into using the old drivers, it’s just I don’t like to waste perfectly fine “things”. Maybe they are just junk from the get go and should be relegated to the dustbin. Or if the one side is blown, then “make new”. 😉 )
AdministratorNovember 26, 2019 at 5:15 am
Part of the issue with those “crossovers” is they were merely guessing on a lot of this when that cabinet was built. They hadn’t really figured out T/S specs yet, even the box design was lacking (ie I bet all three share the same airspace…whoops). 😀 But that is okay. I am glad they experimented, helped us get to where we are today.
Part of it is the acoustic offsets, as well as the phase response. But you are headed in the right direction for sure.
I like reusing the old drivers, like @tvor-ceasar is saying. But I think in your case, that might be biting off more than you can chew right now. I would definitely keep the drivers. They might even be able to be used as parts for someone that is refurbishing an old one to original specs.
MemberNovember 29, 2019 at 10:54 pm
So there is a Black Friday deal for a Sonos amp and a pair of Sonance in-wall speakers that I could install inside my cabinet. The amp would cost $530 from Costco. The speakers would cost me $435 for the pair from Best Buy. I know the speaker quality won’t be as good and the analog signal coming from the turntable will be converted to digital (so i’m losing the purity of the signal), not to mention I’ll be missing the opportunity to build my own speakers but a deal is a deal!! Talk me down! What are your thoughts?
AdministratorNovember 30, 2019 at 8:22 am
a deal is always a deal. I bought a whole Definitve Technology surround sound once for $500. I t was too good to pass up. I mean each tower had a 15″ powered sub in it, how could I pass up that deal? That deal would definitely simplify your project. The only caution I would mention, is if you are using the built-in turntable it probably does not have a preamp built into the record player. So you may need to get one. Something like this should work just fine.
ModeratorNovember 30, 2019 at 5:16 pm
Doing a little guesstimating, the volume inside one section of wall is approximately 3.16 CuFt (standard 2×4 stud on 16″ ctc, 9′ ceiling is 14.5″ (1.21′) x3.5″ (0.29′)x9′)+-, while just using a WAG at the dimensions inside the speaker cabinets is probably close to 3.5 CuFt. So the plate speakers would work, more or less.
But (there’s always one if those), the major problem I see is that of not destroying the furniture in order to a remove the old baffle and place a new one. Plus, you are limited in how high you can place them in order to get good dispersion. Additionally, for the price of the plates, I could probably get individual drivers and crossover components to do both sides. For less. (If the original drivers are okay, you would only have to spend $ on xover parts) And you wouldn’t have to tear the cabinet apart.
To the amp, RCA stuff was pretty good. The electronics were usually better than the speaker systems available. It would be easier all around to get it fixed if possible, since it was designed for that cabinet and setup. You would be surprised at how loud these systems get.
Personally, if I were to get the amp and speakers, I’d use them on their own. As much as the sound would be improved over the stock console, I’d have a hard time reconciling the expense and rework that would have to go into the retrofit where in the future, if you’d want to change out components, you’d have to go through it all again, and at that point, the sentimentality may have worn off with all that trouble. Besides, changing things up too much strips away the sentimental attachment.
Now, if you could do some basic troubleshooting to verify where the bad channel starts, then there are options that could upgrade the amp section of the stock receiver. I’ll leave that for the future should that appeal to you.
MemberNovember 30, 2019 at 9:04 pm
I am super grateful for you thoughtful responses!!
I haven’t purchased anything yet because the deals last for a couple more days!
I do have a new turntable with a preamp built in. The old turntable gave up the ghost. I can turn off the preamp if I ever want to upgrade that component but for now I have it switched on (baby steps). The front baffles come off of the grill with about 10 screws. So it won’t destroy anything to go that route. I could definitely build boxes around the in-wall speakers if I felt the volume negatively affected the sound.
I have definitely decided to replace the amp and speakers instead of trying to rehab them. I don’t like the idea of wasting the components but I also don’t feel qualified to chase down problems when they will inevitably arise. There is no nostalgia for the components and if my fixes stopped working then all the magic of the cabinet will melt away in frustration!
The deciding factors as I understand them are as follows:
1- the signal will be digital instead of analog. I doubt if I would know the difference without a side by side comparison but I have a romantic notion of analog being more pure.
2- I won’t get to optimize the placement of the drivers on the grill the way I could if I designed my own front baffle/enclosure.
3- I don’t think the speakers are as good a value for money as what I could build with your guys help.
1- the speaker design and crossover are done.
2- I can also plug my tv into the system and get home entertainment out of it. Although some other amps will do this as well. It’s not ideal to play tv sound from a two speaker setup but I can upgrade that in the future as well.
3- I don’t have a lot of time to design the speakers.
4- sonos has a room calibration feature that works with these speakers (for whatever that is worth).
any thoughts would be appreciated. Are my thoughts incorrect? Are there any things I am missing?
ModeratorDecember 1, 2019 at 6:16 am
Well, you did ask us to talk you down. I guess I wasn’t persuasive enough. 😀
*Puts on best used car salesman voice*
Why didn’t you say so in the first place?!
I could see replacing the turntable and using the original equipment, but knowing the baffle is so easily replaceable makes this more of a game changer. Before I get into the baffle, let me make this one point.
If you are going to mount the new amplifier / receiver in the same way as the original, you’ll want to think about adding forced cooling since the orientation changes the direction of airflow – pushing the heat back inside the case. If the fan creates electrical interference, you’ll have more than enough room to create a duct that will allow you to move the fan away from the amp case, reducing the interference.
Okay, to the baffles and speakers. If the plates give you a box size, go for it. If not, a solid sheet of 3/4 ply would probably work well enough sealed on the back. Remember the bracing to reduce unwanted resonance, if you go that way. Also, you may want to tilt the baffle back a degree or more to better align the tweeter with the desired listening position. Don’t forget to try to find a similar grill cloth to the original.
There you go, blessing given. 🙂