Lumina speaker replacement specs?

[deton8r]

Anybody know the specs on the speakers in the Sankyo/Bisty Lumina frames? They appear to be square edge 3" drivers. I pulled one on my Jule and it was manufactured by Onkyo and a 5watt driver but I didn't see the usual markings for impedance.

I was thinking if it's a 4 or 6, another way to quiet these down would be to replace the speakers with 8 ohm drivers. One of mine is making some random crackling noises and is probably due for replacement.

I was hoping to just replace the pair with some higher quality drivers probably from Parts Express. I'm an audiophile, what can I say. Any suggestions or part #s?

TIA

[arbycoffee]

I am thinking they are 8 ohm, but I can't find where I go=t that info from.

[fronzdan]

Put a multimeter across the speaker's +/- terminals and measure the resistance. Multiply that by 1.3 and you have a rough measurement of the nominal impedance....enough to tell you if it's 4, 8, 15 etc. Speaker must be disconnected from the audio circuit of course.

[birdbrain]

6.78 x 1.3 makes them 8 ohms

[slothappy144]

I noticed the slight distortion even after trimming the speaker line. We put the factory switch on low to get rid of most crackling and trimmed to get it so it would not deafen us.
I can't hardly believe the amount of sound coming from a tiny 5 watt speaker, crazy loud. Most I have seen are 10 watt??

[arbycoffee]

that be how, can't remember zhit anymore

[Robocourier]

Deton8r. I assume you are using volume controls?? Are you using carbon track pots??

I have a Star Wars and Julie Pinball which had carbon track pots fitted. Putting it bluntly they are crap. The power output from these (and maybe other Sankyo's) seem to kill the pots within a couple of weeks of use. You'll know when they're on their way out as there will be a burning smell and you'll see some arcing inside the pot!! Also, the sound will start to crackle and control will become erratic (full on/full off).

Looking at the other info in this thread re speakers being 5W. We all know how LOUD the games are set in the parlours. Logically, we can assume the speakers are being driven hard and near to their 5W capacity. Standard carbon track pots are capable of handling less than a Watt (often less than 1/2 Watt). Damage is inevitable with the track being burn't.

Incidentally, I have a Pretty Band which is a Heiwa game. The sound doesn't have the guts that the Sankyo's do, with much less bass and general 'oomph'. Bass requires more power to drive the speaker so if there is little bass then there will be less power required to drive the unit. And less demand on the pot to control it.

Has anyone tried cermet trimmers on these games? They tend to be rated higher than carbons. Or even looked at modding the sound board wrt replacing the amp chip with a lower power one?? (I'm sure that's easier said than done). I knew the temptation to take the game apart wouldn't last long!

Oh, and there's nothing wrong with being an audiophile. Some of the pseudo-surround effects from a Julie are awesome when the sound is set up properly. Popping and crackling sounds from the speakers do tend to take that pleasure away!

[daverob]

Or even looked at modding the sound board wrt replacing the amp chip with a lower power one??

You don't need to change the amp, on a lumina game the gain of the amplifier is set by R5 and R6 (both 1k5 and located just above the volume switch). The volume control switch puts other resistors in parallel with these ones to reduce the volume (5k6 in medium level, and 1k8 for quiet), so if you add another resistor in parallel with R5 and R6, you'll reduce the volume level further.

These resistors are 0805 sized surface mount resistors, so a steady hand will be needed for soldering another one on top of them!

[Robocourier]

Thanks!

I'm no whizz on the theory and I'm not sure I'm asking this right, but do the speakers run from a boosted signal off the amp or an attenuated one? By that I'm asking if the 'loud' setting is the 'purest' signal with the 'quiet' setting attenuated or vice-versa??

Also, by adding further resistance, are we likely to create noise in the circuit that a home environment is likely to show up?

This may sound a little pedantic but having had pinballs that have all sorts of sound quality problems when trying to run them quietly (ie not at arcade levels), I think it's relevant!

And as for sm components, I'm not sure I'm capable of holding steady, so I'll look at other options!!!

[deton8r]

That's an excellent point Robocourier. I can't remember the crackling before I added the volume controls but then again my ears were bleeding :lol8:

I took a peek at the speakers in my Cutie Honey and those appear to be much higher end (poly cones and butyl rubber surrounds) than the ones in the julie. Even if the crackling is due to the volume controllers, I wouldn't mind upgrading them to something better since it looks like a pair of speakers will only cost around $20 anyway.

[daverob]

I'm no whizz on the theory and I'm not sure I'm asking this right, but do the speakers run from a boosted signal off the amp or an attenuated one?

The audio signals come out of the sound chip at levels that are too high for the amplifier chip to handle, so they are attenuated by the resistors mentioned above depending on the position of the volume switch. The amplifier then boosts these signals by a fixed amount, and this is fed to the speakers (via an aftermarket volume control if fitted).

As far as quality is concerned it's a bit of a balancing act. If the levels fed into the amplifier are too high, then the amplifier will distort. If they are too low, then the background noise (hiss/hum etc) introduced by the amplifier will be more noticable.

Volume controls after the amplifier (ie the aftermarket ones fitted to the pachi) will reduce the background noise by the same amount as they reduce the overall volume, so you might think that the best quality would be to set the volume switch to max, and reduce the volume with the external controls. However an external control is effectively changing the impedance of the speaker connected to the amplifier, so may cause the amplifier to distort more than it would with the speaker impedance it was designed for.

It's something that really needs a few experiments done by someone with better ears than I have.

This may sound a little pedantic but having had pinballs that have all sorts of sound quality problems when trying to run them quietly (ie not at arcade levels), I think it's relevant!

You've got a Stern machine as well then

That's an excellent point Robocourier. I can't remember the crackling before I added the volume controls but then again my ears were bleeding :lol8:.

Cheap underrated volume control pots will heat up quite significantly under load (it might not be enough for you to feel it, but there will be a significant temperature shift). As everything expands and contracts as it heats and cools, there will be a small amount of movement in the volume control that could combine with a poor contact on the control and cause the crackling noise.

[arbycoffee]

daverob
What about cutting the pos wire and soldering a 5k resistor on each speaker than use the back for control ?

[Robocourier]

However an external control is effectively changing the impedance of the speaker connected to the amplifier, so may cause the amplifier to distort more than it would with the speaker impedance it was designed for.

In that case I'll give these a whirl then.

http://www.ampmaker.com/vr02x.asp

My games are in cabinets so I'll have somewhere to fit them onto OK. I'll let everyone know how I get on with them in a couple of weeks.

[Robocourier]

I took a peek at the speakers in my Cutie Honey and those appear to be much higher end (poly cones and butyl rubber surrounds) than the ones in the julie. Even if the crackling is due to the volume controllers, I wouldn't mind upgrading them to something better since it looks like a pair of speakers will only cost around $20 anyway.

But then if the problem is still the volume controls you'll simply get a better quality crackle!

I'd look at both parts of the equation. It looks like Parts Express in the US do L-pads at a reasonable price if you can find somewhere neat to fit them on your game (as they are likely to be too large to fit inside the front door).

Click on the volume links in your own post and read logicprobes post from 2004 (!) for some more info (if you haven't already).

When you've sorted it let us know as I'm all for quality sound.

[daverob]

daverob
What about cutting the pos wire and soldering a 5k resistor on each speaker than use the back for control ?

A 5k resistor is quite a large value compared to the original speaker impedance of 8 ohms, so is going to make it pretty quiet. In the original volume control thread (which is autolinked to the word volume), logicprobe suggests 50 ohm resistors. It might be worth trying a few different values in the range of about 30 ohms to 200 ohms, to see if there's a value that fits it nicely with the range of control on the original volume control.

The lower the resistor value, the higher wattage it needs to be. Based on the lumina frame speaker rating of 5 Watts, A 100 ohm resistor needs to be about 0.5W, a 50 ohm resistor needs to be 1W, and a 30 ohm resistor should be at least 1.5W. At these minimum power ratings they will get quite hot in use, It's probably a good idea to use a resistor with a rating of at least double these values to keep the temperature down. If the speaker rating in your pachi is higer, then you'll need an appropriately higher wattage resistor.

[birdbrain]

I have a group of 5 L-pads from parts express in the auction right now even cheaper.

[johntofva]

I have a group of 5 L-pads from parts express in the auction right now even cheaper.

Okay ........Where? Don't see them.

[birdbrain]

sold to england. robocourier

[arbycoffee]

A 5k resistor is quite a large value compared to the original speaker impedance of 8 ohms, so is going to make it pretty quiet. In the original volume control thread (which is autolinked to the word volume), logicprobe suggests 50 ohm resistors. It might be worth trying a few different values in the range of about 30 ohms to 200 ohms, to see if there's a value that fits it nicely with the range of control on the original volume control.

The lower the resistor value, the higher wattage it needs to be. Based on the lumina frame speaker rating of 5 Watts, A 100 ohm resistor needs to be about 0.5W, a 50 ohm resistor needs to be 1W, and a 30 ohm resistor should be at least 1.5W. At these minimum power ratings they will get quite hot in use, It's probably a good idea to use a resistor with a rating of at least double these values to keep the temperature down. If the speaker rating in your pachi is higer, then you'll need an appropriately higher wattage resistor.

Thank you for the info

A second question:
can you use a LED to work as a resistor, On some machine from Japan that are Made into Desktops and Cyclic Machines they do ?

[drcrippen324]

no LED can be used to suck of a tiney amout of current but not as a resistor usualy a resistor is placed in line to lower the power sorce to a level tolerable by the LED so as not to blow the LED