Trouble with my system- need advice

W

Wsurfn

New Member
I am a novice to this hobby. Forgive me if I am doing something or saying something obviously wrong. I am having trouble with my system powered with a lovely Mac 4100, and I would like some help to fix things.

Problem: Full range of sound seems to be lacking to my untrained ear, especially mid to low. Sounds much better (fuller) at louder volume, but I recently discovered it will cut out (trip something?-the "Power Guard") if volume is dialed too high (dialed about 50% of it's knob range or 50% the height of the amplifier power output LEDs). Highs (strings, horns, vocals, etc.) sound very clear. I am impressed. Mid range to lows are much muted and less clear especially at lower volumes. Certain electric guitar riff lines seem almost missing in some rock songs. It is hard for me to explain.

Story: I am in my mid 40s. I had a bottom off the line Technics component system in HS/college that I struggled to afford. I remember being intimidated looking at high end gear from the early 80s in the specialty Hi-Fi stores since I had no means to afford it. Always thought one day...

I finally moved into my dream home. A modest modern midcentury home in Austin,TX. One feature, was built in shelves for a component stereo with hidden speaker cabinets about head level in main living room.

I decided to get the vintage system I always wanted.

I got a Mac 4100 receiver. I sent it to Terry Dewick. I patiently waited. He serviced it in August, 2011. Full audio update, clean controls, align and test. PG=85W, <0.1 THDat 75W L&R into 8 ohm load. FM Sensitivity =1 uVat 3% THD;Seperation >45 dB

I bought some B&W 685 speakers. I initally wired them with a conventional connection and used the terminal links. I later changed that to a bi-wire connection set up to see it that would help. Maybe a little.

I later added an B&W ASW608 subwoolfer to see if I could fill the sound more. It did help on the very low end, but only there.

The rest of my system is a Nakamichi 680 tape deck (restored by Willy Hermann), Rega Planar 2 turntable, NAD C542 CD player, and iPod in a Cambridge Audio iD50 docking station.


Because access to the speakers is tough, I checked many times to be sure the wiring is correct, although, perhaps there is something obvious I have overlooked.

Any help is welcome.





"Clipping"is caused when the amplifier is asked to produce more power output than it can deliver with low distortion.
 
Last edited:
Register to hide this ad
The biggest single factor in getting good sound is the room and the speaker location in same. How big is your room, where are the speakers located, etc. Got a picture you can post standing several feet back from your best/normal listening position?
 
When I sold B&W speakers there were those who just did not like their sound.....that was Ok we had 3 other brands with different "flavor" to give them a choice.

What speakers have you heard that you liked.......using the MAC4100s built in eq can you fine tune the sound to what you want to hear out of the speakers? The built in 5 band EQ is a powerful tool to learn how you want the sound to be in the end.
 
Sounds to me like it could be a phase mismatch. Unplug one speaker and see if there's more lows and mids. If so, the next step is to switch which wire goes to + and - on one speaker only. If not, then it's something else entirely.
 
Wsurfn said:
Because access to the speakers is tough
Click to expand...

this raises a red flag. Are they in the built in shelves? If yes then that would be my guess as the root cause.
I would suggest moving them out just to test to see if they sound better. I can't imagine them sounding good in there.
 
Thank you to all that took the time to reply.

So, perhaps it just the way these speakers were made to sound. Perhaps it is their location. It is good to know they are an OK choice and compatible with the receiver.

I have the 685s bi-wired. The HF tweeters are to speaker 1, The LF speakers to speaker 2, and the ASW608 to speaker 3 using the speaker level inputs.

Should I have this wired differently (especially the subwoolfer)?

My wife has a pretty good ear. Her Dad has a music degree, and her aunt is a concert pianist. She played the violin until her late teens with success. She was not that happy with the sound, but I think she knows how much effort I put into this project, so she has not detailed what is missing or wrong. She has asked if it is supposed to sound like it does. I will try to get her to try to describe it better.

Here are some phone photos.

The 685s are resting on their sides on 1/4" EVA foam in a wood framed enclosure that is above the windows and below the ceiling of our dinning area at one end of our living room. The side that faces the living room is covered with a thin acrylic speaker cloth and is stapled into the sheet rock. This is covered by wood moulding. It also holds a recessed flood light that project down to the buffet. The original speakers are also enclosed in there (I cannot get them out) and I pushed them to the outer aspect. The ceiling does rise once outside the dining area. It is the largest and main area of the house. 20X40ft?

To get at the speakers requires removal of the some of the molding and staples. I have done it twice, but would like to not have to do it again.

I will look for possible shorts with the speaker wire connections at the receiver back since the PG is clipping at high volume. I have played a lot with the EQ controls. I have my old Boston Acoustic A40s somewhere. The speaker foam has disintegrated as they are 20+ years old. I could run them and see what happens as well prior to pulling out the 685s.

Thanks again everyone.
 

Attachments

  • living.JPG
    living.JPG
    77.8 KB · Views: 84
  • BW-ASW608_Rear.jpg
    BW-ASW608_Rear.jpg
    17.6 KB · Views: 63
  • stereo.JPG
    stereo.JPG
    105.1 KB · Views: 81
Last edited:
Not the greatest speaker location ...will compromise sound...but have seen worse.

No need to hook up to spk 1 and 2....just twist together and hook up to 1.

I wish your sub had a line in and out...you could then limit the bass output of your satellite speakers (bandpass) but I would still install a pair of y cords between receiver's pre out and amp in and run the sub off it's line in.....many times the speaker inputs on subs do not have the same access to control functions as line in.

Did you find eq settings that improved the sound toward what you expect? Many audiophile sound benchmarks will suffer because of your speakers installation and the built in design concepts near and dear to B&W which your installation interferes with.....they would not have been my recommendation if I would have been your sales guy years ago.
 
You sure have a beautiful home! But while the location of your speakers may be attractive to the eye, the sound has been compromised. Take those same speakers and place them outside the bookshelf and orient them the way they were designed (not sideways) and just put them (temporarily) on end tables and the sound should improve greatly.
My two cents worth.
Gary
 
I agree with Lotus.
I believe 100% of your issue with the sound has to do with where the speakers are located.
 
Thank you guys. I appreciate you taking the time to help me.

Location, location, location.

So to clarify the sub wiring... Run a pair of RCA Jacks (R&L) from the back to the sub's "Line In" jacks to the back of the 4100's "Power Amp in" jacks after removing the jumpers. Correct?

The advantage of doing this as opposed to using the speaker inputs is? I am sorry, this part is not totally clear to me.
 
Wsurfn said:
Thank you guys. I appreciate you taking the time to help me.

Location, location, location.

So to clarify the sub wiring... Run a pair of RCA Jacks (R&L) from the back to the sub's "Line In" jacks to the back of the 4100's "Power Amp in" jacks after removing the jumpers. Correct?

The advantage of doing this as opposed to using the speaker inputs is? I am sorry, this part is not totally clear to me.
Click to expand...

If you remove the jumpers you'll get no output from the amp.

It's been asked, but I haven't seen you confirm, that all of the speakers are phased properly. I.e., are the + and - wires connected properly at both ends?

What happens if you disconnect the subwoofer entirely?

Here's what I would do. First, extract the system from where you currently have it, and set it up in a smaller, more controlled environment. Put the subwoofer and the bi-wiring aside for the moment, keep things as simple as possible. Wire the speakers to the receiver properly, then see how it all sounds. If everything sounds good, then try the bi-wiring, and lastly add the subwoofer.

If something happens to degrade the sound, then you'll be able to put your finger on it. If it all sounds good at this point, then you can start to look at problems with placement in the room.

I know it sounds like a lot of work to dismantle and move everything, but in my opinion it's the quickest way to isolate the problem. As things are now, you can spend a lot of time trying one thing after another, without really knowing what the actual problem is.

hth,

bs
 
Brian:

I will probably do this. It will answer a lot of questions, and will satisfy my OCD side. I will need to wait at least until the weekend to tear it all down.

I really do not think there is an out of phase issue due to the wiring polarity. I am not seeing this.

I chose to put the HF on speaker 1 and LF on speaker 2 when I went to bi-wire, mainly because the cleanness of the wire insertion in the back of the receiver. When I twist the wires together and use use only speaker 1 for the 685s, I have a hard time cramming the wire into the hole of the 4100s receiver speaker terminals. I am not confident it makes a great connection.

Should I use a connector?

I guess I need to wire the sub, as is, using the speaker connectors on the back of the sub to the receiver terminals of speaker 3 on the 4100.
 
Two 2 male 1 female Y cords can be used to replace the MAC4100 jumpers.

By design the B&W speakers radiate very broadly...therefore they are affected greatly by nearby obstructions...speakers that project their sound field more into the room would better better choice for this type of installation

Check your sub owners manual to see if the upper cutoff frequency and phase control are active while using the speaker level inputs...on many only the level control is active.
 
The Low Pass Frequency control knob, I believe, works with both set ups.

The Phase switch (0 or 180 setting) works with both set ups.

The Low Pass Filter switch (in or out setting) applies only to LINE input. The filter is always in circuit with SPEAKER LEVEL input.

Both Speaker and line inputs have separate Volume control knobs.

So, I am still unclear, IS there still an advantage of using LINE over SPEAKER input on this particular subwoofer?

Final Question: If bi-wiring the speakers, IS it advantageous/disadvantageous to wire the low and high frequency speaker wires to separate receiver speaker terminals--- or not (all to Speaker 1 vs. separate them as Speaker 1 for HF and Speaker 2 for LF)?
 
Depending on the load the sub's speaker input presents to the receiver, the Mac4100 could be seeing speaker impedence loads below 3 ohms....it is typical for B&W speakers to drop below 6. This might cause the receiver to go into PG earlier than you want it to.

It is an amplified sub....line in is the correct input.
 
Disconnect your speakers at the amp and using a 9 volt battery, pulse the 865 speakers and make sure the woofers move outward with the positive wire of the speaker touching the positive terminal of the battery momentarily while the negative is connected to the negative of the battery. Then do the same thing to the sub woofer and make sure the woofer is moving out word. If not reverse the polarity of the offending speaker wires until all the woofers are moving outward. With your speaker locations the bass should be predominant. The windows may be acting like large baffles that flex and absorb your bass frequencies. Try moving your speakers closer to the primary listening position and away from the windows. The speakers are rated at 88db a 1 meter 1 watt. And with approaching 100 watts thats only 108 db at one meter distance from the speaker. With all the professionally trained musicians in the house thats about 10 db short of what you really need to produce live levels with a 10 db peaking factor safety margin. I would go look for Hersey's by Klipsch if you want small speakers, and Corn walls for full range live level reproducers with the available power you have. If you want to stick with the B&W line, such as 802's, then you had better be prepared to to increase your available power 6 to 8 times.
 
And also for reference, OSHA considers hearing protection necessary for exposure to 90dB sound for an 8 hour day. Higher volume, less time. Not that I never turn it up, but listening to 110dB routinely isn't good for the ear.
 
108 db at one meter is would be 96 db at 12 feet and subtract 10 db for peaks would be 86 db. The spoken voice is 75 db at 2 feet so 86 is a very marginal level at best. Professional musicians, Sound and Studio engineers listen at an average of 90 db. So your speakers fall short at 12 feet in the size of room you have.
 
Sorry, I'd missed the size if the room and the ceiling rise. If you're sitting on the other side of the room, the volume would drop quite a bit, and a clean 90dB would be a challenge.
 
Thanks to all.

I did not get the 685's out of the sub-ceiling cabinets this weekend, because we had people over.

I did buy pin connectors that allowed the 2 (bi-wired) 14g wires to be connected to the speaker 1 receiver terminals more securely. I also disconnected the subwoofer completely. The clipping still occurs at 50% volume on the dial or 1.0 on the LED power meter.

I wired the subwoofer using Line Input as opposed to Speaker Input. No difference. Same clipping issue.

I tried a different pair of non-bi-wired speakers (my old Boston Acoustics A40s) by themselves as well. Still same clipping issue at same point. That said, WOW, how the B&Ws sound infinitely better. I guess I had under-appreciated how good they sound.

No out of phase wiring. Double checked this.

So, I guess it is an sound issue with the speaker placement, and a separate clipping issue with the receiver.

The receiver issue is a bummer, since I had Terry check it out, and he did not find an issue.

To make matters worse. I went to put it all back together in the shelf (I decided I would limit my volume and play with the equalizer knobs), and the receiver dropped a bit (I caught it) when the shelf tilted, Unfortunately, the speaker wire connector pins sheared off in the speaker receiver terminals. I cannot get them out. They are stuck in there. Also the RCA plugs of my Rega turntable also separated off, and they will need to be replaced.

I am so frustrated. Bad luck with High Fidelity.
 
You must log in or register to reply here.
Back
Top Bottom