My used Magnepan 1.6's are missing sparkly treble. Why?

Paul_In_WA · « **on:** 20 Aug 2020, 07:01 am »

Hi. I am new to Audio Circle. I recently bought a pair of used Magnepan 1.6 speakers. Unclear how old they are but they appear to be in good condition and the panels look good when shining a flashlight through. And the speakers sound good except they are almost completely lacking in that bright sparkly treble that I thought they were known for. Something like chimes or a triangle simply isn't in the music played through the 1.6's. If you stand right next to the speaker you can hear those instruments very muted but not at any normal listening distance. I've tried googling to see if this is a known problem with these old 1.6's but without any luck.

The speakers were modified to remove the fuse. Attached are images of the back panel and what is behind it. Could the capacitors have gone bad or is it more likely that there is a problem with the tweeter ribbons?

Does anybody know what might be causing this or if it is fixable?

mick wolfe · « **Reply #1 on:** 20 Aug 2020, 03:29 pm »

Hopefully some Maggie owners will soon chime in, but your statement about the original fuse being eliminated/by-passed sounds a bit suspect. (this assuming the fuse protects the tweeter section) That coupled with the fact you're apparently not hearing any output from the tweeter section. I'd have a conversation with the seller.

JakeJ · « **Reply #2 on:** 20 Aug 2020, 04:04 pm »

I agree with Mick, it sounds like the ribbons are toast and yes that is what the fuse is for. Might call Magnepan and see what the replacement ribbons cost and if you are handy do the labor yourself. I have 3.6r's and it's fairly easy to replace the ribbons in them. Judging from a few pics online it looks about like mine.

Sure hope you didn't pay much for them.

Emil · « **Reply #3 on:** 20 Aug 2020, 04:28 pm »

Well that sucks.

I'm assuming this is the first time you're giving them a listen?

Were the speakers shipped? May want to check all the solder joints. Giggle the wires a bit and see if you hear a difference. That can be an easy fix.

If the quasi ribbon tweeter is burnt, that's not an easy fix like in the 3.6 or 3.7. That may require a trip back to Magnepan

This is also a good place to ask
https://www.audioasylum.com/forums/MUG/bbs.html

kmmd · « **Reply #4 on:** 20 Aug 2020, 05:00 pm »

Sorry to read about this. I agree with everyone that it appears to be the QR tweeter. That being said, the QR is virtually indestructible compared to a true ribbon. However by bypassing the fuse, anything can happen. Unfortunately it’s not an easy remove and replace as the true ribbon models.

As Emil states, check the solder joints and components of the crossover, but also check your speaker cables and connections. I have silver spades on my speaker cables (amp end) and had muted volume as well. Cleaning them with Deoxit cured that issue.

Hopefully you have an easy fix. If not, I’d contact the seller. It’s doubtful that Magnepan will repair a speaker with modified crossovers, but I’d contact them as a last resort.

rollo · « **Reply #5 on:** 20 Aug 2020, 06:28 pm »

Both speakers ? If both it might be the revised crossover for tweeter section. I would talk to seller and ask if tweeters were attenuated. Removing the fuse section should not affect output of such. Both being blown does not make sense to me.

charles

Davey · « **Reply #6 on:** 20 Aug 2020, 08:05 pm »

Since you have easy access to the back, you need to probe the blue and brown wires and see if you have continuity.

Dave.

timind · « **Reply #7 on:** 20 Aug 2020, 08:57 pm »

You can play some music and put your ear near the tweeter ribbon. If one is bad, it'll be noticeable. If there's no sound from a tweeter, check continuity, as Davey says. This will tell you whether the problem is with the ribbon, the wiring, or crossover.

Paul_In_WA · « **Reply #8 on:** 20 Aug 2020, 11:57 pm »

I appreciate all the suggestions. I've found sources for just high frequency sounds like wind chimes or howler fireworks etc. and played those to try and isolate the problem. Both speakers sound identical and do play high frequency sounds similar to but not quite a good as when heard through the Hifiman Ananda headphones which isn't surprising. I also found the XLO Sheffield CD Sweep Frequency Tone online and that stops being audible only 1-2 seconds before you can't hear it in the headphones. https://www.youtube.com/watch?v=wW0BfMuxmos So I think that makes a break in the wiring or ribbons unlikely. However, it continues to be the case that when you play full range music that includes something like high hat cymbals or triangles or chimes etc. then those high frequency sounds are muted or out of balance compared to the same music listened to through headphones. So it is more like the high end is muffled rather than absent.

Is it possible that the volume the 1.6's tweeters put out simply diminish with age? They are probably at least 20 years old. Or do the capacitors age in change the sound quality?

dB Cooper · « **Reply #9 on:** 21 Aug 2020, 01:15 am »

I hope you have a return option, because it sounds like you were sold a bill of goods. You should not have to replace drivers on speakers you just bought, just because somebody decided that the fuse didn't 'sound good'. Blown tweeters don't 'sound good' either.

Davey · « **Reply #10 on:** 21 Aug 2020, 01:48 am »

I think it's unlikely both tweeters are burnt out here. However, you don't know until you do a little troubleshooting.

Bypassing the fuse is fine but it's unfortunate the speakers were modified like this, because it precludes adding an attenuation resistor into the tweeter network.

Dave.

Hifilisten · « **Reply #11 on:** 18 Dec 2021, 11:46 am »

Paul,
I’m having the same problem with my modified 3.7i’s…. What was the fix for your speakers?
was it a new tweeter?
There doesn’t seem to be any output above 16K?
To test the tweeter I Tried running the amp directly to the tweeter and it played mids but was still rolled off above 16K?
Although the midrange on my tweeter did sound choppy? but that may have been a poor connection?

Elizabeth · « **Reply #12 on:** 18 Dec 2021, 06:14 pm »

My guess is the capacitors are wrong for the tweeter. It looks like the caps were also replaced. just tossing in a pile of capacitors will probably end up screwing up the crossover frequency and may also be responsible for cutting the highs off.
Buying modified stuff may become a nightmare, and you got the nightmare version.
What I would do is figure out the caps values. try to get an original schematic with the correct values. Which you might have to search for, I think Magnepan will not give it to you?
They may not be worth the bother. Uness you can find a skilled techie who is willing to help you for free. (or you can figure it out)
Anyway I think it is the caps that are messed up. wrong values dead cap,(particularly any for the tweeter) wrong wiring hard to say. I suggest threatening to sue the jerk who sold them to you. Ask for a return and refund. they will cost you more than they are worth to fix.

SteveFord · « **Reply #13 on:** 18 Dec 2021, 06:21 pm »

Hifilisten,
A popped ribbon is easy enough to diagnose visually.
Did your modification involve bypassing the fuses?
If not, try some new fuses.
If so, you'll need to contact whoever did the modification.

dwmaggie · « **Reply #14 on:** 18 Dec 2021, 09:02 pm »

You might check out Magnepan Users Group site, aka MUG. Schematics for various Magnepan models can be found there, plus, a lot of very knowledgeable Magnepan Fanatics. It is a great site for repairs and modifications.

I.Greyhound Fan · « **Reply #15 on:** 19 Dec 2021, 01:01 am »

I agree with Elizabeth that the crossovers are wrong. You can contact Magnepan and see if you can purchase new crossovers for the 1.6's.

Another option is to contact GR Research. Danny has a crossover mod for the 1.6's-

https://www.gr-research.com/store/c24/Magnepan_Upgrades.html

Davey · « **Reply #16 on:** 19 Dec 2021, 05:29 am »

Quote from: Hifilisten on 18 Dec 2021, 11:46 am

Paul,
To test the tweeter I Tried running the amp directly to the tweeter and it played mids but was still rolled off above 16K?

I suggest to not do that again.

The crossovers here are a series configuration and you shouldn't be fooling around unless you know what you're doing.
You certainly shouldn't be sending a full range signal to the ribbon tweeters of a 3.X speaker.

Dave.

Elizabeth · « **Reply #17 on:** 19 Dec 2021, 06:20 am »

Quote from: I.Greyhound Fan on 19 Dec 2021, 01:01 am

I agree with Elizabeth that the crossovers are wrong. You can contact Magnepan and see if you can purchase new crossovers for the 1.6's.

Another option is to contact GR Research. Danny has a crossover mod for the 1.6's-

https://www.gr-research.com/store/c24/Magnepan_Upgrades.html

I did not know about Danny at GR Research having Magnepan crossover replacements. yes I would highly recommend him. He is a great guy and this probably is your best chance to fix the issue.
I would highly recommend contacting him

Letitroll98 · « **Reply #18 on:** 19 Dec 2021, 11:44 am »

Paul made four posts in August of 2020, I don't think he's checking in to read your replies.

Hifilisten posted yesterday about his 3.7i model which has a completely different tweeter and he didn't mention any crossover modification.

🤔

timind · « **Reply #19 on:** 19 Dec 2021, 03:10 pm »

This seems like an obvious question to me: what exactly do you expect to hear when playing a 16khz signal? Are you using your ears to measure this? I know I would hear nothing.