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If you really are concerned with a quality sound, do not even look at a 6x9 regardless of make or price. I have a acoustic engineer in the family with a enough parchment on his office wall to start a small book company.

Sound generated from a speaker is created in a wave form that travels from its source. (The sound coil in the center of the speaker) and travels in a straight line. If you use an oval speaker you are instantly distorting those vary waves you are hearing. Therefore using a round speaker makes the sound generating much more efficient and will result in cleaner distortion free results.

Quality high end duplex round speakers in the 6inch range will out perform their 6x9 counterparts at all levels.

As far as building a sound system in one of our beloved shoe boxes, a 4 speaker system with a sub woofer will create the happiest noise you can ever desire.

I run a 5 channel system with a dedicated sub woofer driver. I t is all bluetooth so no dash unit, just my smart phone and Spotify to keep me annoying the neighbors.
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Well it's lucky you didn't fall through and into the trunk! ;)
Why is it a package tray anyway, not all cars had left and right side mirrors. It had to be hard to see through the rear view mirrors with the tray full of packages (I'm picturing like Santa was driving).
never understood why it's called a package tray anyway. The trunks are large enough for 5 dead bodies LOL so should store any packages.
 

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If you really are concerned with a quality sound, do not even look at a 6x9 regardless of make or price. I have a acoustic engineer in the family with a enough parchment on his office wall to start a small book company.

Sound generated from a speaker is created in a wave form that travels from its source. (The sound coil in the center of the speaker) and travels in a straight line. If you use an oval speaker you are instantly distorting those vary waves you are hearing. Therefore using a round speaker makes the sound generating much more efficient and will result in cleaner distortion free results.

Quality high end duplex round speakers in the 6inch range will out perform their 6x9 counterparts at all levels.
This may be technically true at a textbook level, probably even measurable with high precision equipment in a perfect anechoic chamber. Cars however are the worst acoustic environments you can ask for, especially our old tin cans with exposed metal inside etc. The reflection of sound off one surface will produce magnitudes more 'distortion' than the difference between a 6" and 6x9" speaker. The harmonics coming off a panel that's not perfectly damped with CLD sound deadening, again a magnitude more distortion. Even our subpar speaker placement options in these things will result in so many reflections before the sound reaches your earhole.

In reality, there is no such thing as an ideal speaker with a perfectly flat response curve, so you will see much more sound quality difference by using a DSP (digital signal processor) and professionally tuning for your speakers and unique acoustic environment, by not using box store quality speakers with passive crossovers, by adding high quality CLD sound deadening to every panel, by not using prefab sub boxes, by using actual component speakers up front with tweeters thoughtfully positioned, than you will by stressing about the minute difference between 6" and 6x9" cones.

I've yet to see a true sound quality setup in a tinny 50s car, even the nicer sound systems on this board would get laughed off any car audio forum if they were presented as a 'SQ' (sound quality) build and many true SQ builds actually use 6x9" speakers. Most people reading this probably aren't going in to SQ competitions, aren't building 5 figure audio systems with $2000 worth of CLD insulation alone, and aren't tuning their DSPs with microphones and a laptop.

I have to add though, the nicer builds here though are undoubtedly very nice sounding stereos that meet the expectations of the driver, and that's what's really important. I'm just saying at this level getting bogged down in minutae like the cone breakup of 6x9" vs 6" doesn't make sense.

Most people likely want a nice sounding stereo they can hear over all the rattles, creaks, and wind noise should feel free to use 6x9s where they make sense for the space you're trying to use. I doubt hardly anyone here could tell the difference between a 6" and a 6x9" in an anechoic chamber, nevermind hanging from the parcel shelf of their car firing straight up in to the back glass.

The front speaker locations we use are even more problematic. The single dash speaker location frankly sucks (I'm using it now with a really nice speaker and still very unhappy with it) so most people do kick panel coaxial (tweeter and woofer together) speakers. Audio directionality increases with frequency, so having your tweeters firing across your feet is very subpar. A simple change that would yield a big improvement would be to switch to a component speaker (separate woofer and tweeter) instead of coaxial and get the tweeters up high and aimed so the highest frequency sounds are not bouncing off anything before hitting your ears.
 

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Which brings us to solid state amplifiers that can near perfectly reproduce the sound of a record, yet people prefer the sound of the tube amp that isn't so perfect.
Just thought about this now, but I wonder if some of these people who go all out on car audio have tube amplifiers in their cars?
 

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Well, I'm not sure whether I'm going "all out", but my WonderBar has a tube amp. :D
I just need another stock 4 ohm speaker to install in the package shelf.
If you happen to find two small 8 ohm speakers to fit under the two holes and wire them parallel, it will be 4 ohms.
 

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You'll probably want to pick a high sensitivity speaker as well, I don't imagine the factory tube setup puts out a lot of watts.
 

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I love the fact that everyone is weighing in on sound quality of one speaker vs another etc, but I agree with Robert that most true car-audio-geeks would laugh at us debating the sound quality in our 67 year old cars.

I used sound deadener + insulation to try and mitigate some of the tinniness when I was building my car, and I did that for sound quality, road noise and so my doors would not sound hollow and tinny when I close them. I didn't skimp on materials, and I'm really happy with the results.

For my stereo I went with a Retrosound because I like the stock look and options for bluetooth and aux amp etc...because I also have an 800watt kenwood aux amp + powered 10" subwoofer under the package tray. Two 6" round speakers in the afore-mentioned front kick panels I fabricated + two 6x9's in the back. Can't recall the speaker brand but I bought it all at Critchfield and took advantage of their customer support people who are super helpful.

Here's what I told the guy as we were configuring my system: "I want a setup that provides good quality sound, doesn't break the bank and will drown out my singing as I drive down the road without distortion or clipping." (because IMO that was technical enough for this build)

Mission accomplished. I'm happy with the sound and he suggested the 6x9's in back. Since that's what I had in every hot rod I ran as a youngster I figured it would work fine...and it does!
 

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My setup is dead simple like that too. I know a little about building stereos for maximum loudness (SPL) or sound quality, but I have no desire to own the former and the latter is a losing battle in my tin can of a car. I

I've got the Aurora Designs electronics retrofitted in to my stock radio so I can use bluetooth etc, then I'm running 3 6x9s, one in the dash, two in the package tray. And with this simple and grossly subpar by 'audio geek' standards system, I don't lose a minutes sleep wondering about 6" vs 6x9" cone breakup.

That's why I kind of went off at the suggestion that nobody should be running 6x9s because they sound terrible. At this level of stereo, it doesn't come close to mattering.
 
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Did somebody mention Bluetooth?

Have mentioned elsewhere, but I have a small Bluetooth pickup (motorcycle model) in my glove box with a pair of 6x9s in the rear. Of course, I am always telling people in the back to let me know if it needs turning up or down when we are out and about – because of all the road/wind noise!

Am needing to get a small pair of somethings to add into the front. (Don't want to change kick panels ... so maybe something that sits proud?)

(Brand is Boss Audio, btw.)
 

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My setup is dead simple like that too. I know a little about building stereos for maximum loudness (SPL) or sound quality, but I have no desire to own the former and the latter is a losing battle in my tin can of a car. I

I've got the Aurora Designs electronics retrofitted in to my stock radio so I can use bluetooth etc, then I'm running 3 6x9s, one in the dash, two in the package tray. And with this simple and grossly subpar by 'audio geek' standards system, I don't lose a minutes sleep wondering about 6" vs 6x9" cone breakup.

That's why I kind of went off at the suggestion that nobody should be running 6x9s because they sound terrible. At this level of stereo, it doesn't come close to mattering.
Carson, that is not fair, I never said they sound terrible. I said they are a compromised design and a round speaker is more efficient. That means it will produce more sound with less energy. An oval speaker has no place in a conversation about sound performance, none. To say otherwise shows a bias due to a position of pride, ignorance, consumer regret or a combination of all three.

As far as saying the interior of a car is no place to measure sound quality, I have no understanding what that even means. Where else are we going to compare the sound quality of an AUTO STEREO SYSTEM? Simple placement of components and matching and balancing a system with an understanding that high frequencies need short direct paths to the listeners ears and low frequencies need solid mounting in larger spaces with enough power to support the equipment without needing to overdrive it.

My stereo is mostly invisible and sounds remarkably clean and full, rich even. It was not built to make my ears bleed, just wanted a good solid system that entertains me when I grow board of hearing my big block rumble.
 

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Well it's lucky you didn't fall through and into the trunk! ;)
Why is it a package tray anyway, not all cars had left and right side mirrors. It had to be hard to see through the rear view mirrors with the tray full of packages (I'm picturing like Santa was driving).
Well, look at it this way:

Back in 1955-57, they didn't have cell phones to be texting on while driving. Drive-thru windows in fast food restaurants were still pretty rare, so eating your dinner while driving wasn't really viable.

So, stacking piles of packages on the package was the dumbest thing they had to work with. :)
 

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You'll probably want to pick a high sensitivity speaker as well, I don't imagine the factory tube setup puts out a lot of watts.
If you're curious about the details of the factory radios, this is the service bulletin for the '55 Wonderbar - the primo factory radio available in '55:

A list of all radios can be found at Old Chevrolet Radio Information.

The factory radios are fine for what they are. What they aren't is anything close to a decent stereo system from a big box store in terms of power or sound quality.

A typical 1950s home stereo system (a "hi fi", as they used to call them) couldn't hold a candle to the kind of sound systems you're talking about.

The original tri-five AM radios were for listening to a little music while you were driving. Or listening to a baseball game. Or listening to the news. The '55 speaker placement and level of sound deadening just wasn't a big deal. If you wanted a quieter car, you went and bought a Buick or Cadillac.

And, you had to listen to the buzzing of the mechanical vibrator tube while listening to your music on this radio. I've done so, and it's mildly annoying even if you're not anything close to an audiophile.

And don't forget - these radios were AM ONLY. Have you tried listening to music on an AM station lately?

Car sound systems that offered perfect acoustic fidelity at a volume that'll shake the paint right off the car simply weren't on anybody's radar. Never mind the super-duty generator it would take to run all those tubes in the amplifier.
 

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For a stock rear speaker installation, I'd leave the two holes in place and install a factory size 4 ohm 5x7 rear speaker (if you can find one) along with a factory style grille.
Do you have a stock radio (which one?) and the stock rear speaker control?
View attachment 365634 View attachment 365633
Do you have the grille and switch for sale?
Stan
480.662.0767
 

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Do you have the grille and switch for sale?
No, those were pictures I copied from ebay listings.
I do have a rear speaker control that I bought on ebay, but it has one of the connecting lugs broken off, so I soldered directly to one of the rivets to test it with an ohm meter.
And I found some beige cloth-covered wire to try to match the original design rear speaker wiring.
I won't be able to properly test the control until I get my WonderBar working and get my hands on two speakers.
 

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Carson, that is not fair, I never said they sound terrible.
If you really are concerned with a quality sound, do not even look at a 6x9 regardless of make or price.
That is what I got from your statement above. I'm sure you can see how I got there.

I feel the need to respond to this point in case someone who didn't know a thing about stereos wandered across your post and took it the same way I read it, saying a 6x9 shouldn't even be an option as of course nobody goes out seeking poor quality sound. You're a respected member here, very knowledgeable on these cars, and I believe people hold your advice in a high regard. On this point however, you're off base.

As far as saying the interior of a car is no place to measure sound quality, I have no understanding what that even means.
What I mean by this is if we get in to an audiophile level discussion of the waves coming off a 6" round speaker vs. a 6x9" speaker, any distortion due to cone shape etc, that discussion is frankly irrelevant when the audio environment is this poor with subpar speaker placement and so many reflections. Of course this is the environment we have to work with, so we do the best we can. Car audio, like everything else, is full of compromises. Anyone building an audiophile stereo to the level to notice any minute difference in the distortion of waves between the 2 speaker shapes is not doing so in a 50s car interior.

I said they are a compromised design and a round speaker is more efficient. That means it will produce more sound with less energy. An oval speaker has no place in a conversation about sound performance, none.
Here's where you seem to have a misconception. The 6x9" has a larger cone area and is often just slightly more efficient. As a very important bonus, the larger cone area lets it hit significantly deeper bass notes which is a definite plus if a person is not planning to install a subwoofer to fill in the low end.

Let's look at popular reasonable budget speakers from Crutchfield, all coaxial/triaxial (without separate tweeters). I promise I haven't cherry-picked these examples after looking at the specs, I picked the speakers before looking at the specs. 2 of these speakers I own personally, one in 6.5" (but component), one in 6x9" (but triaxial), I have no strong preference either way, whatever fits the application.

How to use the data below:

dB - Sensitivity - A higher dB number means more efficiency (more measured sound per watt at 1m, except Morel).

Hz - Frequency range. look at the lower Hz number as an indicator of how low the speaker can go. I'm less concerned with the high end as long as it's over 20,000Hz or so as that's usually 'high enough' for most music and most people over 18 start to lose high frequency above 17,400Hz, above 12,000Hz by age 50.

Infinity Reference Series
6.5" Round Coaxial Infinity Reference REF-6532ex 93dB sensitivity, 57-21,000Hz range
6x9" Oval Coaxial Infinity Reference 6x9 REF-6532ex 94dB sensitivity 46-20,000Hz range

Morel Maximo
6" Round Morel Maximo Coax 6 - 91dB sensitivity 55-20,000Hz range
6x9" Oval Morel Maximo Coax 69 - 90dB sensitivity, 45-20000Hz range
(note: Morel measures sensitivity at 2.87v @ 1m, rather than 1w @ 1m)

Polk DB series
6.5" Round - Polk Audio DB 652 6.5" 92dB sensitivity, 40-22,000Hz range
6x9" Oval - Polk Audio DB 692 6x9" 93dB sensitivity, 30-22,000Hz range

Alpine S
6.5" Round - Alpine S-S65 88 dB sensitivity, 70-22,000Hz range
6x9"Oval Alpine S-S69 90dB sensitivity, 65-22,000Hz range

Alpine R
6.5" Round - Alpine R-S65.2 88 dB sensitivity, 65-40,000Hz range
6x9" Oval - Alpine R-S69.2 90dB sensitivity 60-40,000Hz range

Kicker CS
6.5" Round - Kicker 46CSC654 - 90dB sensitivity, 40-20,000Hz range
6x9" Oval (3 way) - Kicker 46CSC6934 - 92dB sensitivity, 30-20,000Hz range

Kicker KS
6" Round - Kicker 47KSC6504 - 90dB sensitivity, 43-21,000Hz range
6x9" Oval - Kicker 47KSC6904 - 92dB sensitivity, 30-21,000Hz range

Summary: All but one speaker has better sensitivity (efficiency) in the 6x9" size of the same model. Every 6x9 has significantly lower range, which will be crucial if someone is not planning on installing a subwoofer, as many owners of trifives seem to choose.

This is why I choose to strongly dispute your statement

If you really are concerned with a quality sound, do not even look at a 6x9 regardless of make or price.
Someone following your advice would end up with a less sensitive speaker that can't hit the low notes. That isn't efficiency or quality sound in my book.

To say otherwise shows a bias due to a position of pride, ignorance, consumer regret or a combination of all three.
Well, here I am still saying otherwise. After looking up and posting the data, I don't think I'm being ignorant, do you?

And I don't think it's pride or consumer regret as I have both sizes in my last 2 stereos. I actually spent significantly more on the build that has the round speakers so if I was going to be proud of one of my stereos, it would be that one. I have the Infinity Reference Series (but the 3-way) in 6x9" in my '55 (chosen for the fit, and that I won't be running a subwoofer) I also have the 6" Morel Maximo components in my pickup (chosen for excellent SQ, along with a 12" Sundown subwoofer @ 500w RMS to fill in the lows). I regret neither purchase, or wish I'd have bought either in the other size. Both are a good choice for their application.

I do always enjoy a good technical debate, especially with someone with some technical chops, so if you want to post up the data for a bunch of popular 6x9s that are grossly less efficient than their equivalent 6-6.5" round counterpart, or some data showing that despite hitting significantly more of the audible range, their sound quality is somehow worse, I'll gladly be proven wrong, always happy to learn something new.

Bottom line, you buy what fits the application, and avoid blanket statements like "do not even look at a 6x9 regardless of make or price".
 

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Congrats.

This (from both of you) is how to throw opposing views and argument around in a manner of decency* – even when one or the other (or both) might be getting a bit upset.

* I would have said 'gentlemanly', which it is, but I want to cover also women around here too.
 

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If you're curious about the details of the factory radios, this is the service bulletin for the '55 Wonderbar - the primo factory radio available in '55:
Wow, I read here something to make me think, What? A two tube amplifier? Well yes it is indeed according to the schematic! The rest is the tuner. I would guesstimate the output to be under 6 watts. BUT, they can and still do make extremely efficient speakers that can make those 6 watts seem to be much much more. The thing is though, that the more efficient the speaker, the worse the sound quality is. There is always a give and take. I work on 12 watt (RMS) tube amps on a regular basis and they sound darned good to me and to most people, and very loud when mated to their 15" Full Frequency Range speaker! Yes, 16" full range. It's really amazing how well they can sound for what they are. But in the same token, audiophiles laugh at them, (or maybe cringe). I thought I had good ears but evidently not. That's why I use the standard 1K square wave input and check the output (and between stages) for distortion, clipping, and more with a oscilloscope.

On a slightly different note (no pun intended), the direction of the speakers does play a big role. That's why they make raised/angled speaker housings for the rear and for the front that aim the sound so it's a little bit of a straighter path to the listener. And on the subject of speaker housings, take notice that not only cheap speaker/cabinets are made of particle board, but the high end ones also use particle board. It doesn't resonate nearly as much as plywood does.
 

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Congrats.

This (from both of you) is how to throw opposing views and argument around in a manner of decency* – even when one or the other (or both) might be getting a bit upset.

* I would have said 'gentlemanly', which it is, but I want to cover also women around here too.
So, we have two men who are clearly intelligent, strong personalities, and well-versed in their facts, but have opposing viewpoints. They debate the topic by presenting their facts - and without getting nasty.

I would say they're behaving like gentlemen, in the classic sense of the word.

(Note that I've stayed out of that portion of the discussion, as I have nothing of value to contribute. Fact is - if I'm driving somewhere and the radio is on, it's because my wife turned it on. I can tell a good-sounding stereo from a crappy one, but that's about the extent of it.)
 

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Wow, I read here something to make me think, What? A two tube amplifier? Well yes it is indeed according to the schematic! The rest is the tuner. I would guesstimate the output to be under 6 watts. BUT, they can and still do make extremely efficient speakers that can make those 6 watts seem to be much much more. The thing is though, that the more efficient the speaker, the worse the sound quality is. There is always a give and take. I work on 12 watt (RMS) tube amps on a regular basis and they sound darned good to me and to most people, and very loud when mated to their 15" Full Frequency Range speaker! Yes, 16" full range. It's really amazing how well they can sound for what they are. But in the same token, audiophiles laugh at them, (or maybe cringe). I thought I had good ears but evidently not. That's why I use the standard 1K square wave input and check the output (and between stages) for distortion, clipping, and more with a oscilloscope.

On a slightly different note (no pun intended), the direction of the speakers does play a big role. That's why they make raised/angled speaker housings for the rear and for the front that aim the sound so it's a little bit of a straighter path to the listener. And on the subject of speaker housings, take notice that not only cheap speaker/cabinets are made of particle board, but the high end ones also use particle board. It doesn't resonate nearly as much as plywood does.
Tony, you are correct. I recall hearing these referred to as a push-pull amplifier, where one tube amplifies the positive portion of the output wave and the other the negative portion.

The tri-five Wonderbars and pushbutton radios used this same circuit. (The main difference between them is the signal seeking portion of the Wonderbar.) The manual tune radios used but one tube to drive the speaker.

Some '57 pushbuttons (like the one in my '57) used a single transistor to drive the speaker. They also use an unusual group of tubes in the remainder of the circuit that use a plate voltage of 12 volts instead of roughly 100 volts. These radios are a single piece unit (instead of 2 piece) and do not require the mechanical vibrator tube and transformer.

FWIW, I also have a '57 pushbutton radio that is all tubes in my stash of goodies, so I have examples of both '57 pushbutton radios.

As far as output power - 4.5 watts sticks in my mind, but I can't remember where I saw it. I might have that in a paper copy book on these radios.
 
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