Archive for the "tech" Category
Feb5

DIY Speaker Modifications / Tweeks

Posted at 12:36 PM • 2 Comments

Always in a quest for getting a little bit better sound out of the equipment that I have on hand – for as little money as possible – I turned to the internet looking for any advice on tweeking my speakers.

I have a pair of Radio Shack “RCA” branded Linaeum tweeter equipeed speakers. They used to be sold as “Optimus LX-5″ speakers from Radio Shack. with the name change they replaced the driver with a much better driver than the LX-5′s original driver – and thats about it.

These speakers sound pretty good, but have way too much upper bass emphasis. I found several tips online – one of which was to fill the speakers port hole with drinking straws.

I tried this, and did not notice enough of a difference to make it worthwhile.

So; I opted to add some mass to the drivers and to the speaker face to dampen unwanted resonance and also to add some poly-fil to the cabinet.

Adding polyfil to the cabinet, in laymans terms, essentialy makes the driver think that it is in a bigger box.

So, here is the speaker:

After popping off the grille you need to remove the rubber cups on the front panel and remove the four screws that hold the plastic front to the aluminum cabinet:

And, here is the inside of the cabinet as it was manufactured:

And the driver board:

First thing I did was to add some mass to the driver basket to reduce resonance.

I used Ideal brand “DuctSeal” which is available in one pound bricks, it is a non hardening putty designed to seal around air ducts, outside electrical boxes, etc.

I used it to smooth the transition between the basket and the magnet; and also on the basket itself.

then I tapped all over the driver board to listen for areas that resonated “wrong” and applied DuctSeal in the apropriate areas to eliminate the reasonance.

Then I turned my attention to the cabinets themselves:

Following along with the straws inside of the port holes; I tried adding foam to the port holes as well:

But, these pieces of foam were promptly removed after the speakers were reassembled; as in my opinion it was just too much, and made the speakers sound far too “nasaly”

Having had sucess with my speakers; I turned my attention to the absolutely worthless Radio shack RCA branded subwoofer that I am using.

First off; I removed the driver:

Then to stiffen up the cone I “painted” it with “Mod Podge” – which is a sealant / glue / finish product that is available in most craft stores. One of its intended purposes is to “seal” jigsaw puzzles together after they have been assembled.

While the “Mod Podge” was drying I applied some DuctSeal to the subwoofers driver:

For the heck of it; I applied some Mod Podge to the cardboard tube in the subwoofers enclosure:

Then I also added some poly fill to the subwoofer enclosure. Typically this is not needed in subwoofers; but this subwoofer was exceptionally “honky” with an emphasis in the upper mid-bass.
My additional reasoning was that this subwoofer is only worth about $10.00; so even if I screw it up- no big deal.

And; reassembled:

The improvements gained by these modifications were nothing short of amazing.

These speakers sound like something easily costing two to three times what these speakers initially cost.
I noticed when I was working on them that I could probably notice even more of an improvement if I were to swap out the ferrite core inductor for an air core inductor and replace the caps with better quality caps.

That will probably be my final upgrade to these speakers before I ultimately upgrade to a better overall speaker.

All in all though; this took me about an hour start to finish and its like haveing a brand new system.
I would say that it was well worth it.

Feb3

DIY Speaker Stands

Posted at 10:17 PM • 2 Comments

OK; before I even get into the project let me get something out there:

I probably could have purchased some speaker stands for the same amount of money that I spent on this project.

But they wouldn’t have been EXACTLY what I needed, and most likely they wouldn’t have been as well built.

When all was said and done this project cost me approximately $130.00 – although I have enough materials that if I spent another $25.00 on lumber I could have easily made one more set – and still had other materials left over.
All materials were purchased at my local big box home improvement store (Home Depot)

For this project I used

-A plank of Red Oak
-Some 3″ PVC pipe
-2 sections of All-Threaded rod
-Various Nuts, lock washers, and cut washers
-Metallic Silver spray paint
-Stain
-Rope caulk
-Sand

Since Home Depot’s lumber selection is nothing short of AWFUL, the only Red Oak that I could find was a stair tread.
But; if you ask nicely you can most likely find a Home Depot associate who is so desperate to avoid doing some type of an assigned project that they’d be willing to cut the lumber for you. (if you pre-measure and mark the lumber; and teach the Home Depot employee how to use their saw) Which will save you a bunch of time at home.

For my stands I decided to use 11.5″ squares for the base and 8.5″ squares for the top.

I also picked up some cheap-o drill bits since I don’t have any good bits left that aren’t out for sharpening.

After marking the center points on each piece of lumber I used my drill press to make a recessed hole for the all-threaded rod and the nuts:

After making the recess the appropriate depth for the washers and nut to rest flush I swapped the bit and drilled the hole all the way through for the all-threaded rod.

What it should look like -

Recessed side:

other side:

Then you mark and cut your PVC so that the speakers will be at ear level when you are in your listening area – in my case it was 27″ – To get a straight cut I used my chop saw – but I didn’t take a pic of that.

After I cut the PVC to length, I marked the all-threaded rod to the appropriate length and then cut it with my dremel and cutting wheel – which I also didn’t photograph ;but I will share my embarrassment. The cutting wheel broke while I was cutting the rod and it spun back and hit me in the face; cutting my cheek. But “I’m good”

Next I sanded the lumber to a nice finish with 220 grit sandpaper and stained it with a semi transparent white stain to match my other furniture.
Again, to match my IKEA TV stand I painted the PVC with a metallic silver spray paint. I prepped the PVC by rubbing off any sharpie, etc with an acetone soaked rag – sanding it with 150 grit sandpaper to take off the gloss – and then cleaning again with acetone before painting.

Then I assembled the bases by threading two nuts, a lock washer and a flat washer on the top side of the base plate and a flat washer, lock washer and nut on the bottom side. I also coated the rod with blue loc-tite.

Next I used a cut-off section of PVC to mark where the PVC for the stands should sit on the base plate – and then wrapped rope caulk around the all threaded rod and the base plate in order to create a seal with the PVC and keep the sand inside.

Oh, this is rope caulk – you pull it off the roll and press it into place.

Then applied another bead of rope caulk on the PVC pipe and pressed the PVC into the base

Time for sand!!!

Once the stands were “filled” to the top I temporarily finger tightened the top in place and then picked up and dropped the stands several times to “tamp” the sand down and settle out any air.

Before settling:

After Settling:

Then I topped the columns off with sand until it would not settle anymore and capped it off with rope caulk.

Lastly I put loc-tite blue on the all threaded rod, slipped the top plate on and bolted it down with a flat washer, lock washer and a nut.

lastly – and MOST IMPORTANTLY – i applied stik-tak to the speakers (for isolation) and pressed them into place.

Done!!

I am astoundingly happy with these stands. When the music is really cranked up I cannot feel any vibration in the base of the stand, or in the floor.

After placing the speakers on the stand everything sounds much more defined and the bass is much tighter.

If you make some of your own – let me know about it!!

Jan30

Ultra cheap upgrade for an ultra cheap phono stage

Posted at 12:19 AM • 2 Comments

I will confess now that my stereo gear at home is ultra sub-par bargain basement stuff; but I try to do the best that I can with it.

After working at a dealer myself that sold VPI and Rega tables, Conrad-Johnson, etc – I wanted an at least mildly respectable turntable.

So, a few years back I picked up a B-stock Pro-Ject table and fit it with a pretty nice GRADO MM cartridge; and left it at that.

My garbage A/V receiver doesn’t have a phono stage; so I picked up the ultimate of all ultimate pile of crap phono stages.

The MCM Electronics 40-630 Piece Of Crap phono stage:

widely available on eBay for anywhere around $10-$20; you get exactly what you pay for.

Although I do not own the appropriate gear to measure it and tell you; I can say that the RIAA EQ curve is VASTLY off base; the sound stage is ultra flat and narrow. Everything is very brittle sounding and it sounds almost like your records have been placed under running water while using this phono stage.

But the most noticeable flaw with this phono stage is the INSANE 60hz hum. This unit is A/C powered and has the transformer inside of its chassis.

The hum is so bad that the reciever has to be turned up quite loud to get over it; and in many cases the hum just drowns out any recorded sound on the record.

So; time to rip it apart.

After unfolding two tabs; the bottom plate can be slid right off

Just look at that quality!!!! And the “Fully isolated” transformer is a piece of state-of-the-art wonderment!

We are going to solve the hum problem by replacing the transformer with a DC Battery power supply.

After checking it out with my multimeter I determined that the transformer was putting out a somewhat fluctuating voltage range of 15.5VDC-17VDC.

Awesome; the solution is easily within reach at this point.

Proceed to remove the transformer – it is mounted to a plate that is held to the chassis with two screws.

There is the offending pile of crap:

Make sure that it goes DIRECTLY into the trash

All in all; still a pretty low quality piece – but lots of room

(with the “isolation plate” back in place)

And; the ultimate solution to the problem.

I had this stuff on hand; but if you wanted to purchase it – here is what I used:

-(2x) “Heavy Duty” 9V Battery Snap Connector Radio Shack Part Number 270-324 (pkg. of 5)
-(1x) SPST Mini Toggle Switch – Radio Shack Part Number 275-634
-(2x) 9V Alkaline Enercell Batteries – Radio Shack Part Number 23-463 (pkg of 2 batteries)

…Actually; if you haven’t got this stuff on hand – it may not be worth purchasing – since the parts would probably cost you about $15 – and for a grand total of $35 you could probably find a better phono stage than this MCM Electronics piece. :)

The rest is fairly self explanatory; I’ll let the pics talk…

Test fit

Cut the pigtails to the appropriate length:

Mr. Dremel:

Test fit switch (and cover hole for A/C cable with electrical tape):

Solder and shrink wrap the battery connectors:

Add a Positive lead to go from the phono stage to the battery power switch:

Connect battery pigtail negative lead to phono stage:

Solder switch in place:

Cover the switch and bottoms of the batteries with tape to protect against shorting; then put it all into the chassis:

Put the bottom cover back on it and make appropriate labeling for the new switch:

I also marked the date of when I installed the current set of batteries on the side of the chassis.

Finished!!

And the results…

Was it worth it? ABSOLUTELY!!

The hum is GONE the phono stage is 100% silent!!

Additionally; the soundstage is wider and not quite as flat; the phono stage is now also a great deal warmer; instruments no longer sound like they are buried – and the EQ curve sounds like it is a WHOLE lot closer to where it should be.

Swapping out the transformer for batteries isn’t going to make this shining turd sound like a $50000 phono stage; but it WILL make it sound kind of like a $50.00 phono stage.

I am almost positive that replacing the crappy components with some quality components will make a MASSIVE difference – but I don’t see myself actually investing any money into this thing.

Given my average listening habits and the current draw of the transistors I would estimate proposed battery life somewhere around 1YR. But – I think that I am going to be buying a new phono stage tomorrow anyway; so I don’t think it matters.