P80 Speaker test box - Guidance required!

[scot850]

Those from the P80 forum may have read I am trying to build a simpl-ish test rig to test P80 audio head units and speakers if needed.

I am ok with the head unit testing and now want to build a test rig for the audio out put so I can test the operation of the head units but also the speakers as well.

I was hoping to build a box to house a full set of speakers from a P80 wagon, and maybe later to check sedan shelf speakers and C70 speakers as well.

I have attached a picture of the speakers:

P80 speakers

PXL_20230213_212744895.jpg (542.1 KiB) Viewed 4344 times

First thing I realised was building one board/box to include the C70 front speakers was going to be too heavy, so I am going to build one for the 8 speakers from a P80 wagon as a separate unit and them maybe one for the C70 front speakers and sedan rear parcel shelf speakers if I can figure out how to get them out!

1) So on the understanding that I am not looking for audiophile quality, is there a suggestion as to what is the best order to lay the speakers out. I have laid the top 8 speakers as they would be in terms of a P80 wagon. Would I be better putting the small rear pillar speakers between the larger rear speakers and the front larger door speakers?

2) I plan to build a box with a removable top and bottom so that I can easily access the speakers to swap them out to test others if needed. The covers are to limit dust/dirt getting into the speakers when the test rig is not in use. I plan to have a box as thin as I can make to prevent damage to the speakers. The rear door speakers have a plastic housing on the rear which is about 3" deep so I need to allow for that, but then the front speakers sit proud of the door so I will have to allow for that. I want to be able to test the balance of the head unit as well as the fader option front to rear in the car. Anything I should worry about?

3) Lastly, to me a strange one, I recall that you should have speaker impedance's balance, but notice the dash panel small speakers are 8 ohm, as are the rear door speakers and rear tailgate pillar speakers. So why are the front door speakers 4 ohm?

I thought that might be a mistake, but the C70 DyAudio front speakers are also 4 ohms? I am not sure what the small speaker for the C70 is as I can't read the label.

Is that correct?

Any help or guidance is much appreciated!

Neil.

[precopster]

Hi Neil. It's been a while hasn't it?

The setup in your photo looks truly ominous

I would imagine that the lower impedance of the 4 ohm speakers (and therefore resistance) allows the amplifier to automatically output more power to those lower impedance speakers.

The amplifier is probably designed for 4ohm loads and produces more volume to those speakers at the front doors. Because of this factor the amp has fading biased toward front door speakers. Are the tweeters in the doors mated with a small capacitor and coil (simple crossover) or are they in parallel with the door speakers?

Does this make sense Neil?

[MrAl]

Those from the P80 forum may have read I am trying to build a simpl-ish test rig to test P80 audio head units and speakers if needed.

I am ok with the head unit testing and now want to build a test rig for the audio out put so I can test the operation of the head units but also the speakers as well.

I was hoping to build a box to house a full set of speakers from a P80 wagon, and maybe later to check sedan shelf speakers and C70 speakers as well.

I have attached a picture of the speakers:

PXL_20230213_212744895.jpg

First thing I realised was building one board/box to include the C70 front speakers was going to be too heavy, so I am going to build one for the 8 speakers from a P80 wagon as a separate unit and them maybe one for the C70 front speakers and sedan rear parcel shelf speakers if I can figure out how to get them out!

1) So on the understanding that I am not looking for audiophile quality, is there a suggestion as to what is the best order to lay the speakers out. I have laid the top 8 speakers as they would be in terms of a P80 wagon. Would I be better putting the small rear pillar speakers between the larger rear speakers and the front larger door speakers?

2) I plan to build a box with a removable top and bottom so that I can easily access the speakers to swap them out to test others if needed. The covers are to limit dust/dirt getting into the speakers when the test rig is not in use. I plan to have a box as thin as I can make to prevent damage to the speakers. The rear door speakers have a plastic housing on the rear which is about 3" deep so I need to allow for that, but then the front speakers sit proud of the door so I will have to allow for that. I want to be able to test the balance of the head unit as well as the fader option front to rear in the car. Anything I should worry about?

3) Lastly, to me a strange one, I recall that you should have speaker impedance's balance, but notice the dash panel small speakers are 8 ohm, as are the rear door speakers and rear tailgate pillar speakers. So why are the front door speakers 4 ohm?

I thought that might be a mistake, but the C70 DyAudio front speakers are also 4 ohms? I am not sure what the small speaker for the C70 is as I can't read the label.

Is that correct?

Any help or guidance is much appreciated!

Neil.

Hi there Neil,

What exactly are you looking to test here, what aspect of the speakers.
If you just want to know if they work, you can just connect them up with alligator jumper wires. It sounds like you want more than that though so maybe you can describe in detail what exactly you want to test about these speakers, and if you need to test the base amplifier or radio or something like that too.

If you are looking for sound quality, that's a little harder to do. In theory the speaker enclosures are matched to the speaker so not sure if there is a perfect match for multiple types of speakers, and that's like an entire science in and of itself. Again though, i am not sure what you are after exactly yet so maybe you can describe what you want to do in more detail.

A very very long time ago i designed two speaker boxes for some friends and they were very happy with the design, at least on paper. It had a feature of using a very nice patterned front grill that they loved. After a lot of wood cutting and screwing and gluing, we found out that the front grill choice was anything but optimum except in appearance. The problem was, it absorbed too many of the highs in the sound so everything sounded muffled. We had to rethink that part of it.
There is even more to it than that though with the speaker box size, shape, and base port and resonant frequency and stuff like that.
Last but not least is the electrical connector type.

[scot850]

I thought I was fairly clear, but obviously not!

The rig is not to provide studio audiofile quality. It is purely for testing the operation of the components and the head units, amplifiers and the likes associated with the audio system:

I plan to use banana plug posts so that the speaker box can be disconnected, and connected banana plugs to each of the output wires on the head unit harness. I will make it eventually to be able to also work with the amplifiers and their harnesses and I have a serviced sedan electric aerial for radio signal connectivity.

All I guess I really need to know is does it make much of a difference how far the speakers are apart? Is there a minimum separation they need to have to operate correctly. If they are too close will they cause any interference with each other?

The box I build needs to be reasonably light for moving and storage, but I plan to make the top and bottom removable and a simple set of pivoted legs to stand the unit up when testing (so I can hear if each speaker is working). I will align the right speakers to one side and left to the other of course. Fronts to the top and rears to the bottom.

If there is anything else I should consider then please let me know. I hope to get started on this tomorrow. Less talk, more action!!

Neil.

[MrAl]

I thought I was fairly clear, but obviously not!

The rig is not to provide studio audiofile quality. It is purely for testing the operation of the components and the head units, amplifiers and the likes associated with the audio system:

I plan to use banana plug posts so that the speaker box can be disconnected, and connected banana plugs to each of the output wires on the head unit harness. I will make it eventually to be able to also work with the amplifiers and their harnesses and I have a serviced sedan electric aerial for radio signal connectivity.

All I guess I really need to know is does it make much of a difference how far the speakers are apart? Is there a minimum separation they need to have to operate correctly. If they are too close will they cause any interference with each other?

The box I build needs to be reasonably light for moving and storage, but I plan to make the top and bottom removable and a simple set of pivoted legs to stand the unit up when testing (so I can hear if each speaker is working). I will align the right speakers to one side and left to the other of course. Fronts to the top and rears to the bottom.

If there is anything else I should consider then please let me know. I hope to get started on this tomorrow. Less talk, more action!!

Neil.

Hi Neil,

Well if you are only testing for basic functionality, why do you need an elaborate box? I would think you could just lay the speakers down and jumper them to a radio or amplifier and run it up for a minute. Are you planning to bolt the speakers into the box?

[scot850]

Yes I plan to bolt/screw them into the box more for safety as it reduces handling and likely damage of the cones. Also in a box I can have banana plug quick connects so the main parts can be broken down into smaller components sizes for storage. It also means quicker set up and finally if the box is stood up it takes less desk/workbench space when in use, a lot less and easier to work with than 8 speakers and associated 2 wires/speaker which are likely to get damaged or the speakers themselves.

It is a good and fair question. I do have a habit of 'over-engineering' simple tasks!

Neil.

[scot850]

So I have been in procrastination mode on this project as I had something bugging me in my mind. It finally dawned on me that I need to check the speaker impedance of all the speakers and also the wiring diagram again.

What my subconscious mind was nagging was that the wiring diagram for the speakers had the rear door and parcel shelf speakers in parallel. However, the front door speakers are direct feed as are the small dash speakers (tweeters?).

I knew the front door speakers were 8 ohm impedance, and the rear door and parcel shelf were 4 ohms. What confused me was I thought the dash speakers were also 4 ohms. Now I am not very knowledgeable on this stuff, but do recall from years ago that you have to have matched speakers or you can damage them or some will draw more power than others.

The re-checking of the dash speakers I discovered they are actually also 8 ohms like the front door speakers.

Now it all makes sense. That means the speakers are as follows:

1) Dash (tweeter) small speakers - Direct feeds from head unit - 8 ohm impedance
2) Front Door speakers - Direct feeds from the head unit - 8 ohm impedance
3) Rear Door + Rear parcel shelf (sedan)/rear D pillar (wagon) - Joint feed to speakers (so I assume 4 ohm + 4ohm = 8 ohm) These have a common feed from the head unit and the signal is split into parallel feeds to the speakers.

That is good as I had only bought 12 banana plug connectors by mistake, but now I realize that is all I need. Phew!

Now I can get back to assembling the speaker box now I have the wiring clear in my head.

Neil.

[BlackBart]

...I plan to use banana plug posts.....

Now if your alligators eat your bananas, you’re gonna have trouble.


You should make cool walnut or teak boxes, pick an exotic brand name, tell everyone you’re an acoustical engineering genius, and sell them for $5000.

[scot850]

That might be version #3...................!

Neil.

[MoVolvos]

*
How many different factory head units are there for the P80?

How do the plug(s) differ or just the number of wires?

How many different speaker set up or quantity are there in the P80?

Is there a factory amp(s) that factors into this and how is that wired in?

Perhaps just put known working speakers back in the car, wire in additional plugs for the various units if that's how it's set up and use the car as the test bed. Since the wiring to each speaker is already in the car you don't need reinvent that and just use the acoustical environment Volvo already created.

Need to compare plugs and wiring diagram of the various head units. You need to do this whether you create your own test bed or use the car.

*