Double Bass Gallien-Krueger 200mb speaker replacement

[Francois Blais]

Good call.
I was unsure about the colors at the terminals.
With only one speaker and no external cab, there's not much problem if the phase is reversed, at least with a BG I guess. (I don't see a DB in your posts profile)
If you can plug another cab, put them in front of each other.
If you hear low-end cancellation, then reverse the wires on the speaker.

 

[Grooveman]

The speaker in the 200 mB is a fairly common Celestion speaker. The only problem is getting to it. In the 200 mB you have to pretty much take the cabinet completely apart. There are 30-40 screws. Use an electric screwdriver and keep track of your screws as you go. It took me a couple of hours to take it apart, switch out the speaker and put it back together. It's doable but a bigger job than with any other cabinet.

mark

Hello sir this is an old post but I'm going to ask you question hoping that you'll get this and reply . I'm about to replace the speaker in my GK 200MB, before I start disassembling the unit I wanted to ask you about the material used to seal the joints of the cabinet when you disassembled it is it a foam or is it a kind of glue type of substance -does it need to be replaced or if it is heated with a hair dryer, soften the sealant to help pull the cabinet apart without destroying the seal? Kind of like taking apart aa iPhone, I guess
Many thanks For your attention
Alan

 

[Ric Vice]

Hello sir this is an old post but I'm going to ask you question hoping that you'll get this and reply . I'm about to replace the speaker in my GK 200MB, before I start disassembling the unit I wanted to ask you about the material used to seal the joints of the cabinet when you disassembled it is it a foam or is it a kind of glue type of substance -does it need to be replaced or if it is heated with a hair dryer, soften the sealant to help pull the cabinet apart without destroying the seal? Kind of like taking apart aa iPhone, I guess
Many thanks For your attention
Alan

Groove Man,
First question, what are you using for your replacement? GK sells the only speaker that I know of that's suitable for use in that sealed cabinet. Second suggestion, find someone who's a quallified
technican and let them do it, unless you cannot affort the cost. You'll be glad you did.

 

[Grooveman]

Hello Rick,
I have a new speaker from GK.
I have disassembled the unit. Not so difficult.
40 years old tape two sided tape.?
Does anyone have information on what the tape is? Is it sticky due to age?
I worry its compression is gone, before I reassemble, I wonder is there a official sealing tape.
And,
Which is the positive terminal wire, purple or red, the original speaker had purple attached to the red painted dot on the basket.
Thanks GM

 

[Grooveman]

I got my old speaker out, does anyone know what the polarities are on this old one? Red and purple wires, no markings on connections.

The old speaker has the red dot connected to the purple lead, but the new replacement speaker from GK shows the + terminal on the right terminal??
Any positive way to know the polarity of the out put leads?

 

[DoubleMIDI]

Maybe the leads are wrongly connected?
The red point means positive, the new speaker is clear, but the leads need to be checked.
Is one of them connected to ground? If yes, the other is the positive one, but that does not need to be the case.

You can also connect a 1.5 volts battery to the speaker and look in which direction the speaker jumps. If both jump in the same direction, see where which battery pole is connected to the speaker and do it the same way with the new speaker. This should not damage the speaker, but the battery might get discharged quickly.

 

[Grooveman]

Thank you
right after I posted this I remembered the one and a half volt battery trick. seems like on the website eminence speakers are all marked with a red dot for positive so the answer to the question is the purple lead from amp is positive the red is the ground.
Also a word for the wise do not tighten the speaker too tight to the body or else the rubber dampener pushing against the magnet and rear of the cas will have nothing to push against .

 

[B String]

Groove Man,
First question, what are you using for your replacement? GK sells the only speaker that I know of that's suitable for use in that sealed cabinet. Second suggestion, find someone who's a quallified
technican and let them do it, unless you cannot affort the cost. You'll be glad you did.

I completely agree with this post. After much experimenting and time consumption, I found out that the speaker in that combo is made for THAT application. It was well worth sending the the combo to GK and letting them fix it correctly. Or.... Buy the speaker directly from GK and get detailed instructions on reassembly. Or.... have a tech who knows this issue do the reassmbly. jmho

 

[Grooveman]

I took my time with the project going step-by-step organizing my parts using a hair dryer to heat up the taped parts so I didn't have to bend aluminum to open the box .ordered the speaker from Gallien Krueger ,the speaker is made by eminence, found out that the speaker leads from the amp are red and purple the purple is the positive lead .
Took some part cleaner to remove it is much of the tape from the aluminum then wiped everything with alcohol to get all the oil off . I found some neoprene tape , 30 mm wide, 2mm thick, I cut it into 10 mm strips and replaced the foam making sure to cover the screw holes so the screws would seal tight.
Recaulked the corners with new silicone putty . You can see where the possibility of air leakage is with the light.
It sounds amazing total success .
And disassembling the unit I recommend removing the sides first , I would even suggest heating it up a little bit -like screen replacement on new iPhones is done) because it's most likely really glued tight due to the foam turning to a sticky mess over time.
I offer this video as a form of reference to ever attempt this . Contact Gallien Krueger and get the correct driver unit don't waste your time with anything else .
I did this because I was quoted $250 to have this replaced by the authorized repair shop in Tokyo, and because it's 40 years old I was given a speech about how to give up and buy a new one so I jumped into this project. Total two hours to disassemble and clean another hour to cut foam and then another hour to slowly reassemble I might add that be careful that how you took the speaker inside the cabinet because I tightened it too tight and I noticed the flat facing begin to distort when disassembling noticed the amount of tension on all nuts and screws there's also probably some type of glue attached to the screws to keep them from coming out because they are not torque very tight.

I paid $100 for the speaker and $25 for foam, a graphite scraper and parts cleaner.
I plan to copy the cabinet design and re-foam the old driver and use it.
Cheers.
I have attached the movie of some of the photos .

Dropbox - Movie.mp4 - Simplify your life

 

[68bassman]

Very helpful. Thank you. I will attempt this soon.