Understanding Headphone Specifications, & Home Made Blast Limiters

[Critterhunter]

I've been doing a bit of digging on the net to expand my limited knowledge on headphone specifications since they are a bit out of my field of knowledge. While I was at it, I also have been digging up some limiter circuit schematics and might explore a few of these circuits to see how they perform with my Sony Studio Phones. So far I prefer the audio quality of these headphones and they sure are more comfortable being "studio" size rather than as big as what I normally use. For $20 at Walmart they are the best headphones I've owned so far in terms of comfort and audio quality. I think Crazyman turned me onto those.

The only problem is that I have to keep the volume all the way down on the GT to avoid surface blasts at too high of volume. When that happens not only do I get an ear blasting, but the audio quality distorts badly due to overloading the speakers. I can hear the deepest of the deep in terms of targets fine with these even with the volume on the GT all the way down, but since Minelab recommends full volume on the machine I don't want to risk missing targets.

You are supposed to adjust the volume on the headphones themselves. Well, that still won't solve the problem of surface blasts if I used an in line volume control, so I'm exploring various limiter circuits I might hack together. The sophistication and method in which the circuits work vary and thus so can the audio quality. It might take me building a few different types before I find what I like best. I don't mind a little "cutoff" in terms of a audio "click" or momentary distortion that can be heard when the limiter kicks in. That's a handy way to determine if it's something big or shallow that is being lowered in volume somewhat.

Here's some links. Some of them look to be very interesting reading. I've got a lot to print out again. No matter, always looking for something new to research. Love this sort of stuff...

Some links on understanding headphone specifications...

http://en.wikipedia.org/wiki/Headphones

http://www.practical-home-theater-guide.com/headphones.html

http://www.pcworld.idg.com.au/article/296352/what_do_headphone_specifications_mean_/

http://gilmore2.chem.northwestern.edu/articles/hguide_art.htm

http://www.goodcans.com/

http://www.tomshardware.com/forum/39968-6-help-understand-headphones-specs

Home made limiter circuits...

http://gilmore2.chem.northwestern.edu/projects/limiter_prj.htm

http://www.wa0itp.com/audiolimiter.pdf

Kered, did you say those Sun Ray Golds gave good telling audio in terms of target traits? I've used Grey Ghosts. Somebody wanted to give them to me for free but the audio was so flat from them that I gave them back. Told him they were too expensive to sit on my shelf and he'd be better off selling them to buy something he liked better. I've heard great things about those on some machines but on the GT they sounded real flat to me and somewhat muffled. I've got to dig into this headphone specs more and see which are going to be a good match for the GT's output the most precisely. Then if I can find a commercial pair with limit I may go that route down the road. In the mean time I'll hack together a limiter for these Sonys. I don't see how the audio quality can get any better but you never now. That's why if I find a commercial pair that match the GT well then I'll also pick those up later on. For starters, Minelab recommends 32 ohms for the GT. I *think* older Sovereigns had a different recommendation for that but am not positive. Seem to remember running across that on the web some place a while ago.

 

[synthnut]

Critter,
Shoot a model number of those Sonys that you're using ....There are a LOT of Sony's that are called "Studio Phones" ....Thanks ....Jim

 

[Critterhunter]

Walmart sells them for like $20. I think they are called VM-20 or VM-75 model #. Can't remember, but I'm sure Crazyman does.

 

[otlew]

I will be watching this thread with anticipation. I have the Grey Ghosts and a cheap pair of Sony brand which have a volume control in line with the cord. I suspect that the Grey Ghosts are not a good match for the Sovereign GT. Probably great phones for another machine.

I want to follow Minelab's specs of 32 Ohms Impedance and I want a limiter.

From recommendations and reading the specs I have two choices of readily available headphones so far that fit the bill, at least partially.

Detector Pro Headphones with features as described below.

Jolly Rogers Ultimate's

Technical Specifications:

* Dual-rotary volume control with "stay put" segmented "click" positioning.
* Limiter Switch for reduction of excessively loud target signals.
* Selector switch for metal detector compatibility with all single-output metal detectors without adapters.
* Heavy-duty muff-to-muff connection cable.
* Heavy-duty coil cable with special 1/4", 90 degree angle stereo connector.
* Compact carry and storage foldable design.
* Heavy-duty polymer muffs with full-ear surround, soft comfortable cushions.
* Adjustable padded headband... no screws, no wire frame, no rust!
* Speakers designed for maximum sensitivity, efficiency, durability, and signal quality.
* Special sound-blocking muff design eliminating environmental ambient noise up to 20 decibels.
* Frequency response: 150 Hz - 20 kHz... only what your detector uses.
* Impedance: 16 ohms nominal.
* Backed by a limited lifetime warranty.

Street Price around $110


Treasure Ears

Technical Specifications:

* Designed in the U.S.A.
* Excellent sound quality for metal detecting
* Separate volume control for each ear
* Comfortable lightweight design
* Adjustable headband with Stainless Steel frame
* Coiled cord for easy extension
* 1/4" right-angle plug
* Built with quality materials
* Speakers designed for maximum sensitivity
* Power Output: 100 milli-watts
* Impedance: 32 Ohms
* Sensitivity: 105 db
* Cord Length: 6 ft. (extended)
* Backed by a 1 Year Warranty

Street Price around $45

If I can make or buy a limiter that is not to clumsy I will buy the Treasure Ears, just because I am locked in on the minelab Sovereign spec of 32 Ohms.

Comments?

 

[otlew]

From Practical Home Theater:

Worth keeping in mind here that the lower the impedance, the more efficient headphones are in converting the incoming electrical energy into sound. On the contrary, the higher the impedance, the more electrical energy is required to drive the headsets tiny speakers.

Maybe the Ultimates with 16 Ohms and a limiter would be a good choice after all for the Sovereign?

 

[deanosaur1972]

Hmm, like many I am watching the headphone discussions with interest................

Previously to Des D's Video thread my main concern on headphones was the ability to keep my ears warm on cold nights..........

My headphones came with the GT - far better than any headphones I have ever had before but.......... haven't got a clue on spec's..... no name or model number......... so then I think well if they came in the package with the new detector then they must have a good relationship with the GT....... then I think, hell they are a shop - in a package they are going to throw in the headphone's with the most profit margin, no doubt they are actually good headphones but optimum??? I doubt it.........

Thanks for all the info so far..............

 

[Tony in FL]

Just a heads up that the spec is between 32 and 100 Ohms, at least per the GT manual. Minelab lists the Koss UR-30's as an accessory for many of their detectors such as the the E-trac, Explorer, and X-terra models and this headset has a 100 Ohm specification.

 

[synthnut]

Keep in mind that the lower you go with impeadence on headphones, the higher the distortion figures will be when running your volume control on FULL aa Minelab reccomends ..... The actual frequency responce of most detectors is not much more than about 200hz to 3200 hz ....That's not a very wide responce, and just about any headphone will reproduce those frequencies ...... You are better off going to a phone with a higher impeadance than 32 ohms as the distortion figures will drop , and you will hear your targets better ..... Try turning your Sovereign all the way up, and then turn your low impeadence headphones al lthe way up ....You will see that you encounter plenty of distortion ... I would venture to say that any set of phones that has an impedence of between 50 and 100 ohms should work just fine ....Any higher than that , and you'll be draining your battery faster on your detector to accomadate the added ohmage .... That's the way I've always known it to be .....YMMV .....Jim

 

[crazyman]

Jim, they are the Sony MDR V-150 and are 28 ohm. I use them for most of my hunting because I can separate the tones better with them than I can with my Killer B's. and the Koss phones they provide You can't beat them for the price.

 

[crazyman]

People using the same model detector can differ on what phones sound best to them so I'm sure an individuals hearing plays a bigger part in how they hear the tones more than the impedance alone. I've always favored lower impedance especially with certain Whites detectors that I used for many years that used 4 filters and had a very wide signal or response. The lower impedance seemed to narrow the signal. With the Sovereigns most of the higher impedance phones I've used just sounded harsher to my ears and didn't have that soft outer edge to them sorta like the difference between foil and gold with the Sovereign with the foil giving a harsher low tone sound while gold gives smoother low tone.

 

[JASONSPAZ1]

Thanks crazyman. I was just about to post a question and you answered it completely. I to have Killer B's and feel as though that it is hard to seperate the tones with the 150ohm impedence. the 28ohm Sony headphones you speak of. Can I get them at Walmart, Target, etc

Thanks in advance
Jason

 

[Critterhunter]

Interesting stuff. Jim, wouldn't a lower ohm rating on headphones note matter, so long as you don't turn the volume real high, or better yet if you are using a limiter to control volume levels. That distortion with these Sonys is what I experience if I go to full volume on the GT and then hit a shallow or large object. I've also noticed very slight audio degradation if I go to full volume and am sweeping over a deeper/not full blast type of target. I suspect what you pointed out might be the issue. Really the audio seems fine at full volume, just sounds a little different in certain ways but still seems to contain all the finer audio detail of a target. It's only when I sweep over something shallow or large at full volume do they really distort on me. Really, like I said if I was running a limiter then I don't think that would be an issue with these headphones. Target volume would never be allowed to rise above a certain level. I think they'd be the perfect headphones in that case. I prefer the smaller size (somewhere between walkmans and full size) of these headphones. Less bulk/weight, and in the summer my ears don't sweat as much. They are also the most comfortable headphones I've ever warned, and I don't really see how the audio quality and detail could get any better. They do lack an inline volume control but that's easy enough to add, and probably not needed with a limiter adjusted right.

Otlew, those Treasure Ears do seem to be a perfect match and the price is right. With a home made limiter they look like the ideal setup. Independent left/right volume control is important. Due to slight differences in tolerances for speaker construction or somebody with bad hearing in one ear that can be a big help. With my Sonys I've got the left ear stuffed with some extra foam because it always seems a little louder than my right ear with these headphones. I'm not sure if that's due to my hearing or if the right speaker is just not as loud. Makes sense that lower impedence (resistance) would allow certain audio signals to break through and sound off easier. That could be important I guess for deep/ultra soft targets or ones at specific frequencies I would figure. If anything that might play a role in power consumption like Jim said. The really high impedence of the Grey Ghosts (can't remember but I think it was well over 100 ohms) is why I feel they had such flat audio which also sounded fairly muffled. Like listening to music through a tin can.

 

[synthnut]

Crazyman,
You are correct ....Everybody hears differently ...This is why I stated in the end ...YMMV ..( Your mileage may vary ) ..... Thanks ...I"m gonna check those Sony's out ....I know what you mean about certain phones just "doing it " for ya ..... I have a set of Audio Technica's that I use that sound similar to why you use your Sony's .... The Sony's are cheap enough that I will give them a try .....I might even like them better than my AT's ......Thanks for the info ... Jim

 

[JASONSPAZ1]

Does the Sony MDR V-150 headphones have an in line volume control?

Thanks in advance
Jason

 

[crazyman]

Sony MDR-V500DJ Monitor Series Headphones. Basically an upgraded V-150. I like the coiled cord better than the straight cord on the V-150. They never put volume controls on thier lower priced studio phones so that will still be a problem for some but I see them for less than $40 so I might pick up a pair.

 

[Critterhunter]

Yes, they are at Walmart. Not sure who else sells them. I did see what looked like the same pair at Radio Shack but they wanted like $40 or $50 for them. Look up the specs for the ones at Walmart, then compare them to the Radio Shack ones. I bet they are the exact same headphones, just with a radio shack model # and higher price on them.

The last time I picked up a pair at Walmart (as a backup to my first pair), I couldn't find them at one local store. Had to head over to another nearby Walmart who had them on the shelf. This was last year. Not sure if they were phasing them out or if the first store just ran out of stock. So far I've had no issues with the cord on these things, and I've put them through a ton of abuse, snagging them on branches in the woods and such. I have the excess length of the cord tied up into a bundle with a twisty tie off of a bread bag. The original pair I cut the cord on to shorten the length (trying to save that extra once or so with my light weight GT), and then realized they didn't have all the wires visible inside the cable. Some cables for things like headphones do a sneeky thing and use the shielding that keeps out the interference as a "wire" for one of the connections. That stuff is usually some form of foil and so is a real pain to solder to. It can be done, but on that day I didn't feel like tackling it. That reminds me, I should go ahead and finish that project. Some times I lose the twisty on the cord due to branches and then I'm dragging cord on the ground all day long.

Besides the audio's telling subtle telling audio traits of these Sonys I just love how compact and comfortable they are. Very light as well. I always hated certain headphones that would start to make your ears sore or were so big and bulky and killed so much noise that I couldn't hear what was going on around me. After having a few dogs on different days sneak up behind me in the woods and stick their wet nose on the back of my leg I decided enough was enough of that. Rarely am I hunting where it's important to drown out the surrounding noise. Only at the beach, and even then I don't really have an issue.

 

[crazyman]

Yes I've seen them at Walmart and Target and no they don't have a volume control.

 

[crazyman]

Jim, besides what I already posted another reason I like them is their comfort and size. I get sweaty ears with the big phones even in the winter and these are smaller and don't block the air and as Critter said they are the most comfortable phones I've used and pretty rugged. Also I live and detect in prime bear and mountain lion country and I can hear whats going on around me when in the woods. At less than $20 they are worth a try and still make a good backup if you don't like them.

 

[otlew]

Otlew, those Treasure Ears do seem to be a perfect match and the price is right. With a home made limiter they look like the ideal setup. Independent left/right volume control is important. Due to slight differences in tolerances for speaker construction or somebody with bad hearing in one ear that can be a big help. With my Sonys I've got the left ear stuffed with some extra foam because it always seems a little louder than my right ear with these headphones. I'm not sure if that's due to my hearing or if the right speaker is just not as loud. Makes sense that lower impedence (resistance) would allow certain audio signals to break through and sound off easier. That could be important I guess for deep/ultra soft targets or ones at specific frequencies I would figure. If anything that might play a role in power consumption like Jim said. The really high impedence of the Grey Ghosts (can't remember but I think it was well over 100 ohms) is why I feel they had such flat audio which also sounded fairly muffled. Like listening to music through a tin can.

I am one of those people who has a deficit between ears, I discovered that at 17 years old. So I guess I have been defective for most of my 63 years

With that said I need to be able to boost volume to my "bad ear" and need the separate volume controls, so that is one of my must haves. The Sovereign GT certainly has a learning curve and I don't want another impediment.

I hope your able to arrive at a good homemade limiter as I just can't seem to move off of the recommended optimum of 32 Ohms and would like to give the Treasure Ears a go.

 

[Critterhunter]

You can buy an inline volume control from Radio Shack for like $5 if you wanted that. I don't think it would really be important if you had a limiter on it. Even at full volume targets at normal depth (not super shallow or super big) don't sound too loud to me. It's only when I run over something right near the surface or large like a pop can do they give you an ear blasting at full volume on the GT. I think a limiter would fix that. You can also lower the volume slightly more to fit your comfort by stuffing the ear muffs with some foam.

Here's some info I dug up on various things. Those Treasure Ears are looking better and better...

Treasure Ears for $45. Take the "X" out of the name in this link. Find Mall wouldn't let me post it otherwise.

http://www.dXetectordepot.com/gray_ghost_headphones.htm#treasure%20ears

This looks to be a limiter for $76 at Kellyco