Breaking in.
I recently read where someone at Peerless(?) broke in a speaker and stopped every minute and measured Fs and plotted the change. It initially changed fairly quickly and then after about half an hour was within maybe a percent of it's final value.
I did actually do a break in. I set them on the bench with 50Hz applied so I had about 8mm p/p cone excursion. I left it going for about an hour and a quarter, so if what I read has any validity then it should be broken in. I suppose I should have measured before and after. But 60Hz is a long way from a claimed 39Hz. Maybe the original samples where, and then somewhere along the way the manufacturer just quietly changed something for something else cheaper, or maybe one of their suppliers did with them. Who knows?
Anyway I'm not totally unhappy or anything but it does underscore what Francois said in another thread "I am also a fan of "doing great things with cheap drivers" but I want to remind you one thing: measure your driver with speakerworkshop. The driver alone might sound very good but one fact about cheap drivers is that the spec are not accurate. Try to find the real T/S parameters, you will be surprised how different they are". How true.
Anyway here is a comparison between advertised specs, measured specs, and measured again after I had decorated it with weights.
- Nom impedance: 8ohm
- Power handling: 30 watts RMS
- Frequency range: 31Hz - 3500Hz
- Sensitivity: dB 86 86.81, 79.01
- Voice Coil Resistance (Re): 7.4ohms, 7.05 7.05
- Resonant frequency (fs): 39Hz, 60 35.3
- Mechanical Q factor (Qms): 3.203, 2.89 3.747
- Electrical Q factor (Qes): 1.296, 1.29 1.58
- Total Q factor (Qts): 0.922, 0.89 1.111
- Equivalent Volume (Vas): 40.31Lt, 17.9 17.9
- Cone Area (square metres): 0.0203
I recently read where someone at Peerless(?) broke in a speaker and stopped every minute and measured Fs and plotted the change. It initially changed fairly quickly and then after about half an hour was within maybe a percent of it's final value.
I did actually do a break in. I set them on the bench with 50Hz applied so I had about 8mm p/p cone excursion. I left it going for about an hour and a quarter, so if what I read has any validity then it should be broken in. I suppose I should have measured before and after. But 60Hz is a long way from a claimed 39Hz. Maybe the original samples where, and then somewhere along the way the manufacturer just quietly changed something for something else cheaper, or maybe one of their suppliers did with them. Who knows?
Anyway I'm not totally unhappy or anything but it does underscore what Francois said in another thread "I am also a fan of "doing great things with cheap drivers" but I want to remind you one thing: measure your driver with speakerworkshop. The driver alone might sound very good but one fact about cheap drivers is that the spec are not accurate. Try to find the real T/S parameters, you will be surprised how different they are". How true.
Anyway here is a comparison between advertised specs, measured specs, and measured again after I had decorated it with weights.
- Nom impedance: 8ohm
- Power handling: 30 watts RMS
- Frequency range: 31Hz - 3500Hz
- Sensitivity: dB 86 86.81, 79.01
- Voice Coil Resistance (Re): 7.4ohms, 7.05 7.05
- Resonant frequency (fs): 39Hz, 60 35.3
- Mechanical Q factor (Qms): 3.203, 2.89 3.747
- Electrical Q factor (Qes): 1.296, 1.29 1.58
- Total Q factor (Qts): 0.922, 0.89 1.111
- Equivalent Volume (Vas): 40.31Lt, 17.9 17.9
- Cone Area (square metres): 0.0203
Hi Circlotron,
I've got a 4x12" closed box guitar speaker. You know, the traditional marshall half-stack, but from a must cheaper brand. The problem is a irritation over-pronounced mids and lack of lows. The speakers are the cause I think.
Would this 'adding mass' strategy work for my 4x12" stack?
gr,
Thijs
I've got a 4x12" closed box guitar speaker. You know, the traditional marshall half-stack, but from a must cheaper brand. The problem is a irritation over-pronounced mids and lack of lows. The speakers are the cause I think.
Would this 'adding mass' strategy work for my 4x12" stack?
gr,
Thijs
You could always try the Pete Townshend Method of Amplifier Adjustment. 
If you can't afford that or if you don't have the required negative personality traits, you could perhaps hang a small carpet square about 2 inches in front of the speaker. This will alter the sound quite a bit. I don't recommend you add weight because it will do nasty things to the frequency response as the cone vibrates in an erratic and unco-ordinated manner at higher frequencies. I am not feeding mine higher frequencies, in fact I will start rolling it off at 100Hz or so where it is still behaving itself.
If you can't afford that or if you don't have the required negative personality traits, you could perhaps hang a small carpet square about 2 inches in front of the speaker. This will alter the sound quite a bit. I don't recommend you add weight because it will do nasty things to the frequency response as the cone vibrates in an erratic and unco-ordinated manner at higher frequencies. I am not feeding mine higher frequencies, in fact I will start rolling it off at 100Hz or so where it is still behaving itself.
I quickly unblocked it again!
tschrama said:
IME, fitting appropriate RC networks across the driver voicecoils fixes midrange barkiness, and allows the amp/speaker combination to go harder, cleaner and nicer, and also higher and lower and corrects midrange oversensitivity.
I have not tried this on a "marshall" type quadbox with series/parallel driver connection, but I will probably do this soon to 'fix' the guitar sound of a band I know - after I have sorted the bass rig sound first.
Adding mass will 'kill' the attack sounds of the guitar, and is likely not applicable here.
The purpose of the RC networks is so that the box presents as a reasonably purely resistive load to the (NFB) type amplifier.
A highly inductively reactive load represents stored and delayed energy, and this flings back at the amplifier, and because of NFB loop causes ringing, which can manifest as ear bleeding and barky mids.
With correct RC compensation, your guitarist will I expect have a rather tamer and much more articulate rig, that the guitarist and all audiences will prefer.
A further improvement is to run low inductance speaker cable.
Canare 'Star Quad', or 10/20/25 pair telephone wire works a treat.
Paiting the cones and dome with several coats of diluted PVA wood glue can also be useful to 'quieten' noisey cones, but of course is irreversable.
Eric.
It'd be interesting but the financial controllermrfeedback said:
would probably notice the different colour and ask difficult questions. It sounds not too bad in actual fact, although I sort of wish I hadn't been in such a rush and waited till I got some of those WES drivers like I originally wanted, but seeing Jaycar is only 20 minutes away the temptation was too great. What I have to do now is work out what I need in the way of a mid and tweeter. WES has some good Peerless 5" and 6" bass/mids for $60 to $90 which is not too bad seeing how good they probably are. I want someting that will work from about 100Hz up with a box size of max 20 litres, preferably sealed and max power input of 50 watts. I'm open to suggestions of course.
Circlotron,
Wouldn't the added mass of the coins be enough to cause the cone to sag due to gravity and eventually cause the voice coil to rub against the magnets?
As an owner/builder of Klipsch Corner Horns I stand behind you in the bigger is better theory.
I think you had a great time on this project.
Wouldn't the added mass of the coins be enough to cause the cone to sag due to gravity and eventually cause the voice coil to rub against the magnets?
As an owner/builder of Klipsch Corner Horns I stand behind you in the bigger is better theory.
I think you had a great time on this project.
Hi Doctor_Ssyko! Yeah, maybe they might sag eventually but I think it would take many years. I suppose I could face it upward for a year then downward for a year etc. Or just rotate it 90 degrees every 3 months. Or have it motor driven...
BTW, how do you pronounce your surname, like Sicko, or Psycho?
Or just rotate it 90 degrees every 3 months. Or have it motor driven...BTW, how do you pronounce your surname, like Sicko, or Psycho?
Graham, you might be able to convince 'She Who Must Be Obeyed' that paper cone 8"' 's make really good 8" 2 way satellite cabinets, and that PP cones make more ideal subs cabinet drivers.
WES have DT-500 tweeter for $13.00, and they are quite good, especially if you put a shunt RC network across them.
I have not tried any WES mids, but the better ones are likely to be reasonably ok, especially for a budget HT setup.
I do not have their catalogue to hand, but I expect the DM-500 to be worth a try.
In my experience, correct electrical tuning/compensation goes a real long way in turning ok-ish drivers into nicely acceptable ones.
The WES range of PP caps are sonically fine enough too, and without paying silly prices for the exotic variants.
Good luck with your new system.
Eric.
WES have DT-500 tweeter for $13.00, and they are quite good, especially if you put a shunt RC network across them.
I have not tried any WES mids, but the better ones are likely to be reasonably ok, especially for a budget HT setup.
I do not have their catalogue to hand, but I expect the DM-500 to be worth a try.
In my experience, correct electrical tuning/compensation goes a real long way in turning ok-ish drivers into nicely acceptable ones.
The WES range of PP caps are sonically fine enough too, and without paying silly prices for the exotic variants.
Good luck with your new system.
Eric.
Black Plastic Sounds Fine To Me.
Hi Dave,
That comment was suggested as a way that Graham may be able to convince his 'Financial Controller' that another pair of 8" drivers is justified - he already bought the paper ones, so they could be diverted to a pair of 2 ways, and a new pair of PP 8" drivers for the bass cabinet.
In my experience paper cones can and do get peaky towards high mids, and PP drivers can be much better in this respect.
The main point of my post was to assure Graham that these cheap PP drivers are bloody good, especially for the (budget)money.
I belted the hell out of these with my 150W amp after I fitted them and they sounded very fine and did not break or smoke.
I intend to build a pair of line source cabinets, and these drivers look like good budget candidates, especially for the money.
One of my systems is 8" 2 way in large tall cabinets, and the PP woofers in those work very nicely too.
In a sub cabinet, I would be inclined toward PP drivers also.
Eric.
Hi Dave,
That comment was suggested as a way that Graham may be able to convince his 'Financial Controller' that another pair of 8" drivers is justified
- he already bought the paper ones, so they could be diverted to a pair of 2 ways, and a new pair of PP 8" drivers for the bass cabinet.In my experience paper cones can and do get peaky towards high mids, and PP drivers can be much better in this respect.
The main point of my post was to assure Graham that these cheap PP drivers are bloody good, especially for the (budget)money.
I belted the hell out of these with my 150W amp after I fitted them and they sounded very fine and did not break or smoke.
I intend to build a pair of line source cabinets, and these drivers look like good budget candidates, especially for the money.
One of my systems is 8" 2 way in large tall cabinets, and the PP woofers in those work very nicely too.
In a sub cabinet, I would be inclined toward PP drivers also.
Eric.
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