Help! How to make bulb-backlit same brightness as newer gear?

Johnny_Law

Johnny_Law

AK Member
Subscriber
Proud new owner of a C32 pre-amp - which I'm using with my MC7300 - both thanks to huge generosity of AK members.

I love how they both look, but the C32 is a bit dimmer than the MC7300. I would love any ideas to help get the C32 to brighten up to match the MC7300's brightness levels.

Would LEDs in place of bulbs increase the brightness considerably? I have also been looking at LED sheets that I could apply directly behind the glass instead of using the piece of light diffraction plastic.

Thanks in advance for any ideas / pics / comments!

Ryan

(I'm also having some difficulty to align the back-panel to get the light to come through evenly ... to be fiddled with once I get my replacement glass in the mail ... yeah, already broke it, learned that lesson REAL quick!)

6DUWgREl.jpg
 
I think using LEDs instead should brighten it up for you and yes, maybe a stip of the leds you can get very cheaply now. I'm not sure about properly powering those strips inside the unit. I know they need 12v DC to run usually. Would be interesting if anyone else has done something similar.
 
Color and brightness consistency between components has never been a strong point of McIntosh, even on the newest models.
 
Once you change the illumination, chances are it'll be brighter than the amplifier and you'll be back to where you started.
 
One thing I've learned is that the mounting of the clear plastic diffuser behind the glass makes a difference. Later models were held in place with double sided tape. The thinner the tape, the closer the plastic is to the glass and the brighter it will be. Unfortunately, once it is mounted it would destroy the black paint if you tried to remove it. I believe the C32 uses the same 6v lamps with pigtail leads as the C33. Not a standard item. Either buy them from Mcintosh or make them yourself.
 
Well, it's certainly worth playing with. Having some experience with back-lit automotive gauge clusters, I'm hoping that experience can translate over. The gauges work in much the same way, even with the clear plastic diffusion panel and the colored tint on the back of the gauge faces themselves. Some have had success with EL sheets which, and I don't yet know how much they cost, but which might be a plausibly effective solution, with some fine tuning.

A random picture from the internet of EL sheets purportedly used in a gauge cluster:

66ChargerDash2.jpg
 
62caddy said:
Shouldn't happen if the LEDs are green.
Click to expand...

I tried the green LED’s inmyMC2105, and I felt that they made the amp look cheap, and the green didn’t match my other McIntosh gear. I then tried the white LED’s, and they were too bright. I went back to the stock lamps, and with the new glass it was just exactly perfect!
 
So one issue with EL sheets is that they emit an audible buzzing noise. Depending on how close you are to the unit and how quiet the room is (and your ears) you might notice it. I actually bought two strips for this exact purpose to experiment with but have not yet actually tested them. Now that I fixed my MX120 I might get around to messing with the sheets on my C28.
 
Searing75 said:
I tried the green LED’s inmyMC2105, and I felt that they made the amp look cheap, and the green didn’t match my other McIntosh gear. I then tried the white LED’s, and they were too bright. I went back to the stock lamps, and with the new glass it was just exactly perfect!
Click to expand...

Was the green "washed out" or did it simply not match the other equipment?
 
I'd go with the warm white LED's (color temperature at 2700K) and use 2 layers of polarizing gels set between the LED's and the panel.

The 2 layers of gel allow different amounts of light to pass, depending on their rotation versus each other. Experimentation (fix one gel, and rotate the other) will get the right light level. Color will be the problem then.
 
62caddy said:
Was the green "washed out" or did it simply not match the other equipment?
Click to expand...

The green LED’s in my MC2105 did not match the green lettering in my C32 with stock bulbs. They also looked cheesy in my opinion. The white LED’S made the lettering too bright and washed out. Looking.
 
Searing75 said:
The green LED’s in my MC2105 did not match the green lettering in my C32 with stock bulbs. They also looked cheesy in my opinion. The white LED’S made the lettering too bright and washed out. Looking.
Click to expand...

Depending on the color temperature, white LED's lack the red component, leading to a sterile glaring color. Another problem is the light projects off the top of a LED, where light projects from the side of the filament on a lamp.

Super bright LED's are simply too strong IMO, if you want to experiment with color, you'd need gel's from Lee Filters, if you want to explore luminance; you'd need a PWM controller, or my polarized filter idea. But if you start at the lower Kelvin LED's the color could work from the outset. I wouldn't count on it, but it could. Digikey has 2500K and lower, but I didn't look any further, after finding a 6 volt LED. And I'd use the PWM controller to just get the light correct, and put filters in after; a PWM controller is an oscillator, and nobody wants an oscillator in a low-voltage device.

From Digikey, I set filters for 170 degree viewing angle, and 2700K color temperature. If I was looking, I'd start with a bunch of 1214-1361-1-ND; 170 degree/6.2 volt surface mount LED's in 2700K. CRI doesn't matter here as you're behind a massive filter (the faceplate)

I'd start with the service manual, it looks like the lamps are GE 634, taking 6 volts, making the LED above at 6.2 volts a good match. Maybe use my polarized filter idea to damp the light coming off the top of the LED, so you get more light from the sides of the LED than the top.
 
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The main reason for the LED substitutions I made were to correct color irregularities between the meters in a stack of three McIntosh amplifiers.

If they were used separately in different systems I wouldn't have touched them but since they're all together, the difference was definitely annoying. They are quite bright however. (I wish they could have been made not to be so bright).

Otherwise teal-green lettering I left alone but I have seen a warm-white LED conversion on a C26 posted here which I thought look very good.

Only other replacement I did was green LEDs for the dial on an MX110 after seeing the results of another AKer posted here which I thought looked spectacular.
 
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Ordered in a handful of LED's to start the process for myself. The C 29 uses 5.3 volts for the lamps, I have 4 different groups of LED's coming in from Digikey, and some polarized film. I've also got some blue gel's from Lee filters that look good.

I don't have any lamps out on my C 29, but I see a few on one of my 2255's. All LED's are 3.3 volts, and all but one are at 2700K. I have one at 2200K I'd like to look at. Dispersion and damping will get a little taxing, the lamp power on the C 29 is A/C (thanks for the service manual, Davy!) so reverse current might be an issue. I'll probably use 2 in one location, one high, the other low.

This will likely wind up on a back burner as my C 34v will probably come out of its box in a week; the wife is out of town, and I can set up a system above sea level for the first time.
 
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