Hello, fellow Audiolics, welcome to another meeting of Audiolics Anonymous, our support group for the insatiably TWEAKED. Well, the past couple of monthís columns were pretty boring as I reread them, as I had several projects cooking, but none of them had fully materialized. Now I have a number of goodies to share, and will try to fit as many as possible into this monthís column.
Our fearless leader, Steve Rochlin, several months ago, had me build the above amp ( see Audiolics Chapter IV), and the damn things turned out so well (smoked everything else I had ever heard in my system) that I refused to give them back to him, and happily coughed up the price of the pair. After negotiations, he talked me into building another pair for his use. Actually, it didnít take much talking on his part, as I had had some ideas on how to improve the amp, and wanted to try them out. So Steve contacted Mr. Schmalle of Electronic Tonalities, www.bottlehead.com, and ordered another set. Unhappily, they had some parts supply problems, and it took about 5 months to get the kits. Happily, this gave me some time to further think about the tweaks I wanted to do. Also, by going to their web site, they have a link to a discussion group on the AUDIO ASSYLUM web site www.audioassylum.com/forums/bottlehead/bbs.html on single ended amplifiers, where there is much discussion about tweaking these beauties.
When building the original kits, I first noted that the chassis was too small for easy work. Second, the setup was such that power supply wiring crossed close to signal wiring at several points, and third, the ground buss and some of the signal wiring was overly long. This was so because the Paraglow amps are actually an upgrade of an upgrade of an upgrade of the Parasex amp. Mr. Schmalle has been very clever in keeping parts costs down by using many of the same parts and the same chassis with all of his amps, but this made for the above problems in construction. Then I decided to replace all of the signal wire with Allen Wrightís silver foil, www.vacuumstate.com and the power wire with silver bezel from MYRON TOBRACK, INC., of New York. The chassis was expanded to 12x16Ē, and, as I didnít have any metal plate, I replaced the top with a 3/8 inch sheet of oak plywood. As there was no grounding connection then between the parts, I added a length of copper wire connecting all of the transformers, inductors, and tube bases to the AC ground. The cheesy AC wire was replaced with an IEC plug, and series 1 ohm 10 watt resistors paralleled with 0.1uF caps were run between the IEC and power transformer for some line noise control. Similar 10 ohm/0.1uF setup was used after the power diodes to cut down on switching noise. Per Mr. Schmalleís instructions, a spst switch was added to the B+ to allow the power tube to warm up before being hit by B+.
Then I spent several hours bread boarding the parts for close to ideal layout, so that all of the power supply was on one side, the driver stage in the middle, and the output tube and transformer on the other side, with no crossover of wires, using the shortest runs possible. As I like the look of a clean chassis, only the two tubes were placed on top of the plate, with all of the other parts either screwed or hot melted to the underside. Finally, in the interest of minimalism, no power switch or speaker posts were used, with Allen Wrightís speaker foil hot wired to the output transformer. Total work time, including chassis construction was about 12 hours for the two units, not including the time for staining and polyurethaning, which I havenít gotten around to yet.
On testing the unit out before playing, I was surprised to find that the tweaked units were running voltages about 15% higher than the originals. Whether this was due to the layout, the use of the silver bezel, or the power transformers, I have no idea, but everything was pretty balanced among the various voltages. I therefore decided to leave well enough alone, and run everything a little hotter except for my VAIC 2A3 mesh tubes, for which I used the lower resistance 2500 ohm plate resistor, that is recommended for NOS and Chinese tubes. This did the trick.
1. Noise- Almost none. The noise floor is almost non-existent. With my 112 dB efficient horns, the ear has to be in the bell of the horn to hear tube hiss. And there is absolutely no 60 or 120 cycle hum, and no sign of RFI, which is surprising since I opted for an all wood chassis without shielding. A Radio Shack sound level meter at its highest sensitivity with the microphone in the bell of the horn just registers at its lowest reading.
2. Sound- Almost perfect. When mated with the TAD 4001 driver-Edgar horn combo, from 400 to 20K, the clarity and quality is even better than with the originals. I am hearing things in records and CDís only hinted at before; those subtle hall sounds that make the presentation real. The sound stage now envelopes, with hall and record sounds going out beyond the walls, to the height of my 14 foot ceilings, and actually to about 2 feet behind me on certain records. I donít know whether this is due to the lowering of the noise floor, the routing of and the quality of the silver wire, or any of the other changes I have made, but it is significant. I canít talk about its qualities below the mid range, since I donít have any way at present of running them full range, but boy am I happy with what these amps can do in my system.
3. Looks- Almost minimalist. With only two tubes, the input plug and the B+ switch rising over the tops of the amps, and with the VAIC mesh tubes allowing the orange glow of their filaments through, in a darkened room, they add a glow which Iím sure ads to the aural pleasure.
4. Price- Almost a steal. At $ 1150, one of the least expensive and best sounding amps availableÖ and fun to build to boot. And tweakable. And the tweaks do work.
5. Power- Almost too much, at least for sensitive horns. At 2.5 to 3 watts, not muscle amps, but youíd be surprised what these things will do.
Back in the early 90ís, Dan Schmalle and a group from Poulsbo, Washington, formed the VALVE magazine. From the beginning, they wrote up the minutes of their get togethers for those who couldnít be there, and this over the years evolved into the magazine. From a few pages, at first, it has grown into a 20 to 30 page web site which can be accessed through his site, www.bottlehead.com/valve/valve.html. Instead of paper, one can now download each month the minutes of their meetings, but also several articles related to tweaking, kit building, and repairing equipment, both new and old. While long to download with a 56K modem, about 5-6 Mbytes per month, with a cable line it takes two to three minutes and is very informative.
Dan has also come out with a set of two CD-ROMs that contain all of the previous Valve magazines using Adobe 4.0. They are very interesting reading, as they show how the group has progressed over the years from tinkerers to serious hobbyists and even professionals. While the first two years worth hold little in the way of new knowledge, from about the third year on, most of the articles are very informative, especially on methods for repairing and updating tube audio equipment. While I must confess that I have only come to the end of the first CD-ROM, which covers 1995-98, I have gleaned several bits of knowledge, and find the price of $65.00 very reasonable considering what this would cost if done on paper. They even have several articles showing the evolution of the PARAGLOW AMP, which I found very informative. Definitely worth the money if you are into antique audio.
Gray's Power Company
Clark Johnsen, TWEAKER of all Tweaks, brought these over to my house the other day for evaluation, and I was pleasantly surprised what they did for my system. Remember, I run all of my equipment off of 5 AC-DC-AC power supplies, and am theoretically almost completely isolated from the power system. Thus, my jaw fell to the floor when we attached just two of them to the low power equipment, and heard the sound stage open up and the grunge factor bottom out. So much so, that I immediately put in an order for four of them for my system.
Then, horror of horrors, in came the latest Stereophile with a review of them by Jonathan Scull, he who has loved every piece of equipment heís ever gotten for free in his system, and gives the worst review since the debacle years ago with the infamous Bob Carver put down. Obviously, they werenít expensive enough for Jonaten. Trusting in my own ears, I kept the order open, and I was correct in the first place. They are in my system, and working up to expectation, so I donít know what happened in Jonathanís system. Anyway, for the price, they do as advertised. Recommended. www.audiolinesource.com.
Steven R. Rochlin's Listening Room
Happily, two weekends ago, I took a trip over to the western end of New Hampshire with the family, and was privileged to be able to visit HIS HIGHNESS, Steve Wonderboy Rochlin, and listen to his system. Boy, was I envious of all of the equipment he had hanging around there, with names such as VOYD/Audio Note, Clearaudio, Wavelength, etc. I deference to his home insurance company, I wonít divulge the address or the worth of his listening room, but will just say that I feel confident that with his setup he is able to give a true evaluation of any equipment he reviews. That was the first time that I had heard the AvantGarde Uno Hornspeakers sound wonderful. And boy, would I kill for his Clearaudio Insider cartridge. Anyway, thanks Steve for the hospitality, and the great sounds.