Wednesday, April 30, 2014

SVS Sledge replacement amplifier ordered

I noticed a couple weeks ago that the pilot light on my SVS PB 13 Ultra subwoofer was not on.  I tried turning off and on (I couldn't see which was which bending over the top of the sub, so I tried both).  I also tried flipping the Auto switch.  Nothing happened.  Tracing the cord back through living room snarl was difficult so I didn't check the plug.  Or the fuse.  I vowed to do that ASAP.  But meanwhile, much other stuff was being done, such as fixing security camera DVR, setting up the new video doorbell (took all daytime Friday to finish the job).  And setting up the new pile of components, which I HAD to set up before the party on Sunday, because the RDV-1 needed to be moved off the coffee table, I wanted to put a second FM tuner online, and finally try the extra Sonos box I got from ebay.  Best not to clear stuff out of the living room which ultimately belongs in the living room, I thought.  Better set up the stuff now, which had been waiting the better part of the month of April to get done.  And I did really enjoy getting the second FM tuner online (for now, a Yamaha TX-1000 until I get the KT 6040 eq reset) and listening to KRTU, the local college Jazz station.

It wasn't until the last Saturday in April that I finally got around to better testing.  I unplugged the plug, removed the fuse with a screwdriver (surprised at how much easier this was than the hours I spent to get the Parasound fuse cover off…but not that it was loose or anything, the SVS was just right), and saw the fuse was blown.  I pulled out a Parasound HCA-1000A fuse (did I tell that story, of how I recently ended up with 8 of those fuses trying to get one, because the first Radio Shack store didn't have any in stock, but then I ordered some AND went to another store) which seemed to be the same 6.3A, and plugged in and turned on again.  There was a pop and the second fuse blew.  It was all black.

So this time I traced back the cord, which runs through an orange extension to the Belkin AVU1500.  Well that might not have been a good way to power, but it did work for years.  But for testing I disconnected the plug from the extension and plugged into the closest AC outlet.  I disconnected the input cord.  I turned on the amp then turned on the AC power from a wall switch.  The lights dimmed for a split second, there was a pop, and I blew the third fuse.

At work on Monday I scanned my email to determine that I bought my first SVS PB13 in May of 2008.  I assumed (incorrectly) that there was a 5 year warranty (actually it is 3) but even with 5 years, I would not be covered, unless this was actually my second PB13 (which is still over 3 years old).

I emailed SVS customer support about the blown fuses, asking about repairing the amp, and did it need slow blow fuse.  They emailed back that they did not repair the BASH amps, but would give me $200 off the $599 price of the new Sledge amp.  I wasn't sure I liked that idea, and I read about the possibility of replacing a burned thermistor (but my fuse blowing was likely not merely a burned thermistor) in the PB13 Bash amp.  But also people talking about the Sledge.  At least one person said Sledge sounded better.  Then I looked for pictures, and found this article showing the old and new PB13 amplifiers.  The SVS owner himself says the new Sledge amps are more reliable as well as being better sounding.  They look better made, too, FWIW, though it's hard to tell exactly, since in the new amp the power supply apparently is contained in a big box.  Some online speculated the new amps were cheaper, but it doesn't appear that way FWIW.

By this time I was deciding to get the amp, and I asked for discount code (as SVS suggested) and they gave it to me and I bought the Sledge amp on Tuesday night.  Considering what I spend on other stuff, $399 is not a lot to restore--and actually improve on--what used to be a kind of state of the art sub performance (with one plug, as I use it, PB13 is good on music).  I hope this Sledge amp is more reliable.

After I discovered the non-functioning sub a couple weeks ago, I tried to set the Behringer DCX2496 to play both channels in the other sub.  I could not figure out how to do that without reloading one of the presets.  So I've just been enjoying one channel of bass, but it was well balanced and nothing off center was noted.  I was also thinking of finally hooking up the RDV-1 and did in fact hook it up to the Tact (oops, it has to be hooked to the Behringer, best done with a 110 ohm to 75 ohm converter as I got with the Lavry, but couldn't find two weeks ago).  Then the Behringer gets hooked to the Tact.  But, going full range on the Acoustats, I *could* hook straight to the Tact.  I am tempted.

Friday, April 18, 2014

The SL 1000 Mk2 Dustcover

It's been about a month since my SL 1000 turntable system was delivered.  UPS has finally called me to arrange pickup of the packing materials related to the broken dustcover (along with the broken dustcover itself).  I left these outside my front door on Wednesday night.  They did not pick up on Thursday.  This was the last of several phone calls related to the shipping damage claim.  First I was called by the UPS store in Pittsburgh, then by George Heid (both of whom were surprised that I had not heard or seen anything related to pickup attempts by UPS).  I was called by some UPS coordinator, who told me I'd get another call from local UPS.  Finally I was called by local UPS, who set up the pickup, supposedly, for Thursday.  I would have liked to have an inspector come out, but UPS seemed to strongly prefer having things picked up.  I personally hold George Heid responsible for doing a lousy packing job with lousy materials, after we had spent weeks emailing about how it should be done, with him agreeing to do everything as I wanted, then he took two months to actually ship, and when he did he didn't do pack anything like what we had agreed he would do.  I personally thought it would be futile to try to collect from UPS given his lousy packing job and lousy materials, and that Mr. Heid should have taken personal responsibility for his lousy packing job (and/or an attempt to pass off an already fractured dustcover as "shipping damage" which I think is very plausible especially given Mr Heid's experience in the audio field--he must have known better).  But I had waited too long to qualify for eBay Buyer Protection, and his only offer was to send me the proceeds from the insurance.  At this point I don't really care what UPS does.  If I don't get the money, it will prove me right.  If I do get the money, it still won't be easy to find a replacement dustcover anyway (Mr. Heid thinks I should spend even more to get a dustcover with another base, then sell one of the bases).

Before putting the dustcover outside (and I may never see it again, or if I do it may be broken to bits) I made measurements.  It would be very difficult to duplicate this dustcover, however.  It has a shaped lip around the front and two sides which goes over the top of the plinth, probably hugging it fairly tightly, then also rests a bit on top.  In the back, it apparently rests only on the top, so the back is slightly less high.  (I forgot to measure the height, I think it was about 4.5 inches, then the lip was around 15cm.)  And it has trapezoidal shape, with the top making a smaller rectangle than the bottom.  This may have been designed both for cool looks, and for deflecting and blocking sound waves from the outside.  Something that was somewhat unappreciated in reviews of the time in the British audio press, which found that loud enough sound could cause feedback nevertheless.

Anyway, here are the measurements:

554 mm wide
440 mm long

Front face tilts back to top by 50mm
Side faces tilt back to top by 20mm
Back face tilts back to top by 4mm

For a more typical dustcover sitting on the top, it would have to be a bit smaller, so I'm not sure it was even worth making these measurements.  Better to measure the base itself.

Sunday, April 6, 2014

Crossover Settings

These are the settings of my Behringer DCX 2496 crossover as of April 6, 2014.  I worked on these settings over the past few months, primarily to reduce bass boom from room modes that were disturbing outside the listening position especially, and made the walls rattle so it was not enjoyable at the listening position either.  I think the bass may be a bit too attenuated at 45 Hz on music (but on pure tones, it doesn't sound attenuated) but I haven't been able to come up with settings I like better.  It seems any attempt to roll back the -11dB attenuation at 45 Hz leads to boom in a strange nonlinear way.  However my experimentation has been cut short by my fear that I would lose these magic settings, so I also wanted to make sure I recorded them before further fiddling.

#1 Subwoofer Left w 10dB balanced attenuator

Channel A -9.0 dB
LR 24 80 Hz
EQ 1.  BP 30 Hz +2.0 Q3.5
EQ 2.  BP 45 Hz -11.0 Q4.0
EQ 3.  BP 39 Hz -3.6 Q 5.6
EQ 4.  BP 32 Hz + 4.0 Q 2.0
EQ 5.  BP 25 Hz +3.0 Q 1.4
Delay 0

#4 Subwoofer Right w 10dB balanced attenuator, level at 1220 (slightly beyond straight up)
Channel B -9.0
LR 24 80 Hz
EQ 1.  BP 27 Hz + 1.8 Q 1.6
EQ 2.  BP 45 Hz - 11.0 Q5
EQ 3.  BP 66 Hz -3.0 Q 3.2
EQ 4.  BP 32 Hz +2.0 Q 1.4
Delay Long 0.1m 0.29mS

#2 Acoustat Left unbalanced via Aragon 8008 BB
Channel A -6.1
LR 24 80Hz (no high pass)
EQ Off
Delay Long 0.85m 2.47mS

#5 Acoustat Left unbalanced via Aragon 8008 BB
Channel B -6.1
LR 24 80 Hz (no high pass)
EQ Off
Delay Short 8mm 0.02mS Long 0.85m 2.47 mS

#3 Elac 4pi via Parasound HCA-1000A no attenuation
Channel A -3.0
Butterworth 48 20kHz high pass only
EQ Off
Delay Short 672mm 1.96mS Long 0

#6 Elac 4pi via Parasound HCA-1000A no attenuation
Channel B -3.0
Butterworth 48 20kHz high pass only
EQ off
Delay Short 678mm 1.97mS

Thursday, April 3, 2014

Do we need audio bandwidth above 20kHz?

Previous post linked to articles related to what has been called "audio objectivism" that all we need is audio equipment with 20Hz - 20kHz bandwidth and other similar easily measurable and long accepted "high fidelity" requirements.  Now, with audio downloads going to 24bit/96kHz and 24bit/192kHz PCM formats and DSD (which also has significantly higher bandwidth than 20kHz, though the upper bandwidth may be more corrupted by noise than PCM formats), a particular question is whether we specifically need audio bandwidth extended beyond 20kHz, and if so, how far?  Here's the article I linked previously which is primarily concerned with this question specifically, and it may be worth reading despite the incredible one-sidedness, condescending tone and over simplistic diagrams.  It is the discussion on digital audio sampling here which is comparatively well presented.


Now I've found a wealth of other information about the bandwidth topic.  And more test material!  Unfortunately, not enough to reach any sort of conclusion, but enough to know this is a serious issue and that many people taking the "higher bandwidth" side are indeed very serious audio engineers and scientists, not the starry eyed kooks and charlatans you would think they were from only reading audio objectivists--who would like you to believe this is an open and shut case and no qualified audio engineer would think otherwise for a second.

Here is one of the best summaries I've found, written by the famous audio reviewer Martin Colloms.  I must say I was very surprised to find him ultimately taking the lower bandwidth side, but his paper is very useful  because he takes the issue seriously and documents many important studies with contradictory results.  I was surprised because of my previous knowledge of reviews written by Colloms, and if you take a look at other articles in his archive, you find that has often not been on the side of the audio objectivists with regards to things like the need for special capacitors (above and beyond what would be required to achieve 20-20kHz bandwidth--for which almost any available capacitors would do fine) and exotic Class A power amplifiers (audio objectivists claim all reasonably well designed audio power amplifiers today, with THD less than 1%, 20-20kHz bandwidth and flat frequency response sound identical, so one might has well have Class AB or D amplifier that meets these specifications than an extremely expensive and high quiescent power consuming equivalent Class A amplifier whose advantages over a well designed Class AB amplifier might not even be measurable in the ways suggested by audio objectivists).

I discovered the Colloms article reading this long and argumentative blog about 192kHz downloads at Steve Hoffman's forums.  This blog is very good reading, once you get past the useless posts, it is full of arguments and evidence on both sides, and having links to articles on both sides.  Unlike many others long blogs I've seen that are often more heat than light.  Just to specifically link some of the things it links, famous audio engineer and scientist (Cal Tech professor) James Boyk has long taken the higher bandwidth side.  In this paper, he merely shows that musical instruments produce significant acoustical energy above 20kHz, and then he simply refers to experiments by others showing this has effects on humans, some of the same studies discussed by Colloms.