• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Need Help Troubleshooting Bose 601 Series I speakers - tweeters silent.

G

Gabby09

New Member
Hi everyone , first post here. I recently went to show the great direct reflect design to a friend, opening the top cover only to notice no sound from either left or right speaker tweeters. Woofers working fine.

I read around and thought maybe the Tweeter protection Lamps were blown.

I took apart the front speaker to access the crossover network and tested the Lamps
Both show continuity out of the circuit. Is that all you test?
I tried jumping across the lamp and got no tweeter response.
I disconnected one tweeter and drove it with the audio signal and heard the music from it.

I can't find a wiring diagram for the series 1 and it looks different than the series II that you can get a hit on searching google. see... http://www.audiolabga.com/pdf/BOSE601II.pdf

It seems similar to the 1 lamp, three capacitor, 1 resistor design in the three terminal set up of the series II

I see two 3.4uF, 5% 100V Capacitors, one 3.0uF 100V, 5% Capacitor, and a Resistor, 1Ω, 15W, 5%

I found this image that matches mine on ebay..

http://www.ebay.com/itm/Bose-601-se...205963?hash=item58d36c348b:g:wXkAAOSwk1JWgWny

Can anyone tell me what to test next?

I am an old AF electronic technician, turned computer programmer then manager.
So I can understand advice given. It would be cool to resurrect these.
I have done the 8 in speaker re-foaming repair maybe 8 years ago..

Geeze they used to sound great..

Please help.

Gabby09
 
Register to hide this ad
Have you tested ALL of the tweeters?

I believe the tweeters may be paired up in series so make sure all of the drivers work.
 
Gabby09 said:
Hi everyone , first post here. I recently went to show the great direct reflect design to a friend, opening the top cover only to notice no sound from either left or right speaker tweeters. Woofers working fine.

I read around and thought maybe the Tweeter protection Lamps were blown.

I took apart the front speaker to access the crossover network and tested the Lamps
Both show continuity out of the circuit. Is that all you test?
I tried jumping across the lamp and got no tweeter response.
I disconnected one tweeter and drove it with the audio signal and heard the music from it.

I can't find a wiring diagram for the series 1 and it looks different than the series II that you can get a hit on searching google. see... http://www.audiolabga.com/pdf/BOSE601II.pdf

It seems similar to the 1 lamp, three capacitor, 1 resistor design in the three terminal set up of the series II

I see two 3.4uF, 5% 100V Capacitors, one 3.0uF 100V, 5% Capacitor, and a Resistor, 1Ω, 15W, 5%

I found this image that matches mine on ebay..

http://www.ebay.com/itm/Bose-601-se...205963?hash=item58d36c348b:g:wXkAAOSwk1JWgWny

Can anyone tell me what to test next?

I am an old AF electronic technician, turned computer programmer then manager.
So I can understand advice given. It would be cool to resurrect these.
I have done the 8 in speaker re-foaming repair maybe 8 years ago..

Geeze they used to sound great..

Please help.

Gabby09
Click to expand...
I ran into a problem a bit like that once and it too was in a crossover. However it was a fuse... not a lamp. Have you tested the lamp's resistance? In my case a 10 ohm fuse had deteriorated with age and the resistance had increased to 25 ohms. That 15 ohm difference was due to oxygen penetration causing the fuse to corrode. If your lamp has the same problem, remove it and test the tweeter with a jumper.
 
juptonstone said:
I ran into a problem a bit like that once and it too was in a crossover. However it was a fuse... not a lamp. Have you tested the lamp's resistance? In my case a 10 ohm fuse had deteriorated with age and the resistance had increased to 25 ohms. That 15 ohm difference was due to oxygen penetration causing the fuse to corrode. If your lamp has the same problem, remove it and test the tweeter with a jumper.
Click to expand...
I replaced the factory lamp fuses with regular fuses in my 301's. As stated above jump the lamps to see if that's the problem. If it is use a fuse and fuse holder in place of the lamp. Over time those lamps can degrade and effect the sound of the tweeters. Bose used to sell and still might sell fuses and fuse holders as replacements for the lamps. Buying them from an auto parts store is way cheaper.
 
Your problem would seem to be in the capacitors or resistor, especially if you jumped the lamp and still got no response. Do you plan on keeping your speakers, because it appears the crossover network has easy access to the components, so why not rebuild it? The capacitors are probably old and tired anyway. Purchase replacements from Parts Express, DigiKey or Mouser. Parts Express has a good supply of metalized poly axial caps, I'd try them first. Remove and clean the symmetry switch with Deoxit, spraying liberally into the switch inner workings while working the switch back and forth about 30 times. Replace the resistors as well and you'll probably fix the tweeter issue and improve the overall sound quality of the speaker.
 
Last edited:
Good Morning,

Maybe a tip. If you have problems with woofers, these have different batches, sometimes 4 ohm or 8 ohm and connected different. For testsignals: http://www.repairyourspeakers.com/manuals/Testsignals/
Take note to be very careful with testsignals. Above the hearing in practice is about 40 - 15000 Hertz, and below or above you hear nothing, but the speaker takes the power. So do not increase the volume if you hear nothing. First test with about 1000 -5000 Hetz to set the volume.

Best regards, Fred B.
 
Wow, thanks for the great options and advice!
1) I will make my own diagram.
2) I will test each tweeter, checking the ohms test and if ok, I'll try a weak audio signal.
a. Is there a simple way to disconnect reconnect these wrap on connections?
b. Maybe add (crimp on) spade connectors? I assume using a soldering iron near a tweeter speaker connection is a bad idea.
3) (rebuild crossover) If all the tweeters are ok, I'll start by testing the resistor. I'll check part prices on the caps and resistors.
 
I made an initial wiring diagram for this crazy crossover / symmetry capability.
I don't get the filter but mostly a series C & R & concerned the 8 inches seem to be are in parallel.
Not sure how they get overall 8 ohms impedance.

Bose 601 Series 1 Draft Wiring Diagram.jpg
 

Attachments

  • Bose 601 Series 1 Draft Wiring Diagram.jpg
    Bose 601 Series 1 Draft Wiring Diagram.jpg
    54.1 KB · Views: 45
If you choose to replace the crossover components with parts from Parts Express, DigiKey or Mouser, use their links in AK so AK can get credit for it.
 
Ok Ill learn to do that..

I have used the ohm test and tone test and driven the tweeters individually.

Left Speaker has 2 bad tweeters (open), Lf in and Rt out. So the symmetric driven path was open for all four (red to green).

The Right Speaker seems to have come to life given that I now used the test tones, tweeters all seem to be working now.
I noticed that you can't really see or feel the tweeters moving but you can hear for sure using the high end > 2K test tones.

So bad left made me think bad right too.

Any suggestions on reconnecting these wire wrap connections?
 
Oh,, measured 13 Ohms on the woofers. and ~ 7.5 Ohms on the good tweeters.
On Over all Impedance....
So looks like two 16 ohms woofers in parallel = 8 ohms and two 16 ohm tweeter pairs in parallel = 8 ohm impedance
 
That's odd, to be honest. I have Series II, which I'm pretty certain used the same/similar drivers. Mine are 4-ohm (3.1 using DATS software) each. However, mine are in series so they are seen as 8-ohm to the network. If you are correct than I can't use First Gen woofers in mine. I'm currently using a 301 woofer in each cabinet due to one speaker missing a "correct" driver. Wanting to keep matched pairs I settled on 301 drivers. They sound great. If you like you can check out my 601 II post here http://www.audiokarma.org/forums/index.php?threads/bose-601-ii-journey.617839/

I detected issues with a couple tweeters on mine. What it eventually turned out to be was the stupid twisted wire. The wires had broken right at the terminal, so no signal. I tested the tweeters AT the terminals and discovered they worked. Then grabbed a wire and it pulled away from the driver. Thankfully they left long leads on these buggers. These are the only speakers I've ever worked on that had plenty of lead wire, but maybe because they anticipated the wire to break since it's solid core. Not a good idea in my opinion, but it works.
 
Gabby09 said:
Any suggestions on reconnecting these wire wrap connections?
Click to expand...
If you unwrap the the stud, you'll have to solder the wire back onto the stud. You'll need a wire-wrap tool in order for the wire and stud to fit together perfectly.

I have experimented with wrapping the wire by hand around one of my jewelers' screwdriver which has about the same diameter as the stud. After wrapping the wire about 4 times around the screwdriver, I slide the wire off and place it onto the stud. I then solder the connection together. Hope this helps!
 
Copa1934, Ill recheck (ohm out) the tweeters at the terminals, thanks for the advice.
Yes for sure, I see 2 woofers in parallel set up for the woofers. input has two yellow leads going one to each woofer and 2 green leads, one to each woofer.. that's it. Parallel
 
Thank you Bose. In any case I love mine. Have two pair of 901 as well with EQ. Had a pair of 501 II, but sold those. Had an RS woofer (considered by many to be a good replacement). They sounded OK, but clearly liked the 601 and 901 better.
 
Hey Jim, just checked my T/S from DATS and those replacements are bloody close. Really close. I might have to consider those. Good price. Only real difference is the Qes and Qts, but don't recall what the impact is when those are different.
 
Copa1934 said:
Hey Jim, just checked my T/S from DATS and those replacements are bloody close. Really close. I might have to consider those. Good price. Only real difference is the Qes and Qts, but don't recall what the impact is when those are different.
Click to expand...

The Qms. could be slightly different?
I assume your test is being done from a driver that has been in use?
 
You must log in or register to reply here.
Back
Top Bottom