The Soundfield
Mike Pappas

So did you miss me? Well you have all probably figured out by now that I didn’t make the last issue. Hey! I was busier than a one legged man in a butt-kicking contest! Since September 24th I have been doing College Football for ABC TV, and I have to tell you that it doesn’t’ leave a lot of time for me to scribe these words. So now that I have a bit of time before the start of the ABC TV Golf tour, I figured that I better crank out a couple of thousand words worth and get them in to our fearless editor for his approval.

More On Spectron

Two issues a go, I wrote a review on the Spectron 1KW class D digital power amp. I received that amp back in February of 1996, and since I finished that review I have spent at least twice the amount of time that I spent doing the review listening to the Spectron. Here are my longer term observations:

I am still knocked out with sound of the Spectron ever time I listen to it. I am constantly amazed by the air, focus, and transient capability of this amp. In this day and age of changing gear like underwear, I have had no aspiration to even think about listening to any other amp. This amp does so many things right that I still wrestle to find the words to describe what this amp can do.

As if things weren’t difficult enough already, "something new has been added!" I have been listening to a couple of Spectron prototype monoblocks. Since these aren’t in production, I will refrain from doing a full review, but the sound is pretty amazing. At this point, I expect that the Spectron mono blocks will have a price of about $8,000 list for a pair. As soon as John Ulrick can get me some production units to listen to, along with a case of single malt whisky and three weeks of free time, I will do a full review.

And there’s more: Spectron also makes a pre amp that I have just started to listen to. This baby has so much bandwidth it will pass a video signal! I haven’t spent much time with it yet, but will try to get you a full review soon.

In case you missed my comments the first time (if so, where have you been?!): the Spectron class D digital power amp is one serious butt kicking product! If your system needs a little pick me up (hey, maybe your system doesn’t need a pick me up, but you do) you need to check it out big time....

Note to our readers: I have a pile of things here waiting my ministrations. Thanks to all of the vendors who have been patient with me during my busy season. I promise that I will write up your gear in the near future and get it in to the next issue. Please call off Nick the bone crusher . . . .

Some Other Issues . . .

Let me toss a couple of cents worth on several issues that have been floating around the Positive Feedback clan for a bit.

Modifications: I get really twitchy about modifying hardware. I also have to confess to recently completing an extensive set of modifications (as head of engineering) to the On-Air board at the radio station that I work at. In order to help you understand my misgivings about messing around with the modification of audio equipment, let’s just take a look at what goes into doing mods on radio gear.

Our On-Air board was made by Howe Technologies in 1985. It has been on the air for 11 years, and sonically it wasn’t up to snuff with the rest of the air chain. Since Howe went under about 5 years ago, getting support was impossible. That left us with the choice of buying a new board (financially difficult, since a new On-Air board would run us about $15,000) or reviving our existing board to get us a couple of more years out of it.

I needed to figure out what we could do to improve the sound of the existing board and fix some of the problems we were having with it. I started off by looking at what we could do for the least amount of money that would reap the largest benefits. One area that could be improved were the two VCA’s that are in every input channel. The existing VCA’s were DBX 2050. I knew that there was a pin compatible replacement for them made by THAT Corp. I called their technical sales department and faxed them a copy of the diagram of the input module. They reviewed it and suggested a part that had 10 times lower distortion than the old DBX VCA and was quieter to boot. To use this part, a minor change had to be made to some of the surrounding components. It’s this type of information that I would have missed if I just went ahead and done this mod without their input. The result would have been less than optimal.

As it was, the cost of the new VCAs was $15.00 per input module and we have 12 input modules, so you can see that the parts alone start to get expensive quickly.

Additionally, the microphone preamps in the board were pretty shaky. They used three 5534 op amps per microphone input and there was no trim for common mode. They had a propensity to go into parasitic oscillations at high gain settings and were very noisy. It didn’t make any sense spending money on trying to mod our way out of those problems. We just purchased an outboard mic processor made by Symmetrics, bypassed the mic preamps and all of our mic input problems went away. You have to know when to cut your losses and move on..

The results were worth the effort and station management was very pleased with the results. If you live in Denver dial us up and take a listen: KUVO 89.3 FM.

The whole point of this dissertation is that you have to pick your mods in areas that will give you the most bang for the buck. You can’t get fixated on things that will make you insane and not appreciably add to the results. Also, without technical support from someone with a greater understanding of the devices you are planning to use, you could end up with less than optimal results.

Modifying gear can be a proposition that can waste a lot of time and money if not done with a clear understanding of what’s involved and what are the results you are trying to obtain. In many situations there are easier ways of improving the sound of your system than having your way with your hardware with a soldering iron.

Let’s Talk About The Basics, Sports Fans . . . .

This is where most modkeeters go wrong. They are messing with things like power supplies in their gear while forgetting things like getting clean AC power in to their listening room in the first place. Another area that never seems to get much attention is acoustics. ‘Philes will drop thousands of cubic bucks on the latest hardware, spend months (or years) modifying it, and then use it in a room that has the acoustics of a concrete sewer pipe.

So let’s talk about your AC power. When you turn on your power amp do all the lights dim in your room? When the ‘fridge kicks in do you hear a click in your system? Does one circuit breaker turn off all of the outlets in your listening room and your microwave? If you answer yes to any of the above questions, your AC power is hosing up your sound.

And you know what, campers? All of the plug-in power fixes in the world can’t completely cure power that is contaminated from the start. Having an electrician install dedicated outlets with isolated grounds in your listening room won’t cost you an arm or a leg (thousands less than buying all new gear after you fry it doing some mods) and will result in much better sound. Hey, you won’t even have to worry about voiding the warranty on your gear with this one!

Now let’s talk nasty. Room acoustics are like weird Uncle Lem. You know, the one nobody mentions since he did time on a morals charge. Something to do with farm animals.... So, how are your room acoustics? Maybe a little weird? Got the guts to check it out?

Sit in your listening position and clap your hands together. Do you hear flutter echoes, hard returns and or other nastiness come back at you? If the answer is yes, your room acoustics are screwing up the sound of your system. You should put away your soldering iron and do something about it. Listen, if your hand clap came back as a fluttery mess of hard returns, that stuff coming out of your speakers will be coming back to you the same way.

The solution for these types of problems run from easy to expensive. ASC and RoomTune (along with others) make all kinds of products to help you out of these jams. I use ASC products in my room and they do a great job. Hell, if you are having withdrawal symptoms from not having modified anything in the last couple of hours, you could even make your own.

Try building a frame from some 1" x 2" and filling it with Owens Corning 703 Fiberglas mats. Cover the whole shebang with some nice looking close weave fabric (how about plaids?) and — presto!! — you have a broad band absorber. You could even cover it with some black velvet and you will have a canvas for your next mural! Place this bad boy on the wall that is giving you a hard return or flutter echo and odds are it will make a bigger improvement to your system than anything you could do with a wire cutter and a bail bondsman.

If you want to get even more creative, you can build diffusers from Sono Tube concrete forms. These come in various diameters from 8" to a couple of feet. I suggest using the 10" size and cutting it in half length wise using a circular saw (wear eye protection, hearing protection, and have a helper, lest you have to start counting in base 8). Screw them on the walls at first reflection points in your room using drywall screws. If you want you can even use these as low frequency traps by closing the tops off with plywood (leave the bottom open) and stuffing the tube with Fiberglas. If you are part of the save the earth society, use dacron fiber instead of Fiberglas; you will itch less afterwards. Cut the length of the Sono Tube to the 1/4 wave length of the frequency you are trying to absorb and you’re in hog heaven.. I know, I have fixed a couple of recording studios this way, and this work like crazy..

So let me close out our little talk today by saying that sometimes the most obvious mods that will give you the most bang for your buck don’t involve you gaining an intimate carnal knowledge of your gear’s internal workings... So there!

The Power Of The Press

Here’s some other serious stuff for you to think about:

Do you know who is one of the largest company in the audiophile business? I will give you a hint — it isn’t a manufacturer! Still guessing? It’s Stereophile magazine! Surprised?

Now I have to figure that there is something wrong with this business when one of the largest concern in the industry is a magazine that writes about it. I can’t think of a single other industry that has a magazine as one of the largest enterprise in the industry. Could you imagine Road & Track being as big as General Motors? I can’t.

I suppose this shows that audiophiles must be spending more time reading than listening, a situation I think has to change for the long term good of this industry.

Hey but what do I know? Perhaps in the not too distant future we won’t listen to music any more — we’ll just read about how good it was in Stereophile...

Until Next Time!

Well you survived another one of my columns with only a few more gray hairs to show for it. As always your comments are welcome. You can write me care of Positive Feedback or email me at [email protected] As always anything you send me is potential fodder for my next column.

Mike Pappas’ Current System:
Speakers: Avalon Radian HC
Power amp: Spectron 1KW, Spectron Prototype Mono Blocks
CD Transport: Vimak DT-1000
D/A Converter/Preamp: Vimak DS-2000 MKII
Preamp: Spectron Preamp
DAT Transport: Sony PCM-25000
A/D Converter: Vimak AD-500
Acoustical Treatment: ASC
Digital interconnects: JENA Labs Trinity II AES/EBU
Analog interconnects: JENA Labs
Speaker cables: XLO Type 5 Bi-wire

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