Monday, 20 February 2012

Advent of the Fried Egg

The Advent Loudspeaker... begins the brochure I have for the, well, Advent Loudspeaker. It also  features The Smaller Advent Loudspeaker. The ones I have are commonly known as Large Advents, and I have both the Original Large Advents (commonly known in short form as OLA) and the New Large Advents (NLA), plus I have a set of the Mini Advents. Enough Advent for you? They made more.

There were Baby Advents and a number of other variants, both before Henry Kloss left the company in 1977 and after when they were owned by Jensen. The Advent company made very few models of speaker at any given time and at least they kept the naming conventione simple. Read more about them here:

My NLA's I bought about a year ago and paid about $150. This was a bit high but they had been kept in very good shape and they recently had their woofers re-foamed. They also were the walnut veneered cabinets with nice bull nose moulding rather then the utility grade vinyl covered ones. These act as my main speakers at home now, and I really like them. Equipped with a 10" woofer they have a nice low low end and a good range overall. I wouldn't call them the highest of high fidelity but they work well for me.

I like them so much that when I saw a pair of OLA's advertised locally for $25 I jumped! I was in the car and heading to North Vancouver within minutes, and soon had them back home. These were also in nice walnut cabinets with moulding of a different design, more of an "innie" than an "outie". They came with the brochure or manual.

Original Large Advent Walnut Veneer

Before I even took them home I saw there was a bit of an issue, though could not tell how significant it was at that moment. The tweeters were mismatched. I had one Fried Egg tweeter and something else. The Fried Egg was an unusual design resembling a sunny side up egg and again was a Kloss innovation. Typically they had the wire cage you see here protecting the yolk...I mean cone.

Original Advent Fried Egg Tweeter

These had also been re-foamed and from what I can tell, they did a good job, but incorrectly. The roll of the foam is the right way as in concave side out, but the outer flange of the foam is supposed to be behind the masonite. I can't say that I could tell the difference if I was able to listen to them side by side with a correct pair so I'm not going to try.

Advent woofer

So this is what the wrong speaker looks like. It is also not painted black on the face, but that is not seen anyway. The tweeter in this one seems to be the same as some later editions of the Advents or at least is considered the replacement for them so is not a bad substitute. See it here at SimplySpeakers.


Tweeter 85C00019

 Knowing some of the people I know, I figured an original Fried Egg should not be hard to find. In fact I didn't even need to ask. I posted a thread about it at Audiokarma and someone sent me a message soon offering any one of 3 he had and he would send the one that had the closest ohm measurement. I paid as much for it as I did for the speakers, but had it sent to me a couple of months ago, and I finally got to install it this weekend.

It took so long as I had since taken the OLA's to the cabin and had not been there too often recently. I also thought I might have to cut out a bit of the cabinet for the large square magnet of the Egg tweeter. Not so however, and it became obvious that the tweeter shown above was a substitute and the speaker originally had matched the other side. That seems like it would make sense but it was possible that the 2 speakers were not together originally. One had a serial #, the other not, and with one face painted black they again did not looked matched.

Anyway the Fried Egg dropped right in and works great. Even the holes for the screws were perfect (but slightly different from the one I took out), so I think the speaker was happy going back to original. Again I'm not sure I can hear a difference though. No pics of it installed though as I did not have the camera with me at the cabin.

And now I have a decent spare tweeter for the 4 nearly identical speakers I have.

Wednesday, 15 February 2012

Paradise...or is that Stereo?...Regained

I managed to find the fault in the wiring that had my Elekit tube amp not performing as it should (see previous post). It took a bunch of steps to find it, though might have been easier if I had just started at the "other end". Or as my dad used to say, "it was in exactly the last place I looked", as if you would continue looking after you found whatever it was.

In looking for the problem, all the obvious steps were at first to check the external wiring. The input cables, output wires for the speakers, and even the speakers themselves were all swapped to no avail. I switched the tubes from one side to the other. Nope.

I then went inside. I poked and prodded at the various wires and examined solder joints and pretty much everything else. I then decided to actually reflow the solder junctions. This essentially means to melt the solder again, and maybe even add a bit, just in case there were any bad or cold joints. Nada.

I suspected also that perhaps the fine shielded wire used to connect the PCB to the speaker terminals might be at fault as I may have shorted something there while stripping the very thin gauge wires. Close but not quite...

I removed some of those wires and added in one to bypass the potential short, and still no dice. Looking more closely I finally figured out that one of those skinny wires was heading to the wrong side of the speaker output. WHITE goes to RED not BLACK dammit!

Once that was redone it plays just great! More listening reports will follow but whew!!

DSC_0405 crop

Saturday, 11 February 2012

Building a tube amplifier

Over at Audiokarma I was recently the recipient of some karma when one of the good folks there  offered an unbuilt tube amplifier kit for free, "just pay shipping". I was the first to jump in and say "I'll take it!" and picked it up a couple of weeks ago down at Point Roberts. The border guys were skeptical of my free amplifier kit asking what the value was. I said about $100 and after the guy opened the parcel my claim was reinforced by the fact that this kit had been sent from the importer to the guy in Illinois from Canada and the original label was on it, stating a declared value of $100. Ironically the amplifier had been sent from just down the road in Coquitlam in the first place, much closer to me than even Point Roberts. However if I had tried to buy it here at home I would have paid roughly 10 tens as much as the vendor lists it at $335!

The kit is an Elekit from Japan, model TU-870R. It came with 2 6BM8 tubes and a Hammond style black hammertone case. The entire kit was well packaged and parts packed in numerous small bags and other wrapping, and included step by step instructions in English and Japanese. Fortunately the instructions were also well translated with only a few small typos and fractured phrasing.

It's been a LONG time since I built a kit or any electronics from scratch. But late yesterday afternoon I dug in.

I laid out all the parts and went through a checklist to see if it was all there, and thankfully it was complete with perhaps a couple of extra screws and soldering pins. I didn't check the value of the different resistors and capacitors at this point but did do a count of each type. An optional capacitor was included in the kit designed to help the Signal to Noise ratio.

Wile the soldering station was getting hot, I moved to some other prep work. The printed circuit board was in one piece but had to be scored and broken into the main component board and the input connector board. I sanded the burrs from the scored edge just for tidiness.


My soldering technique may be a bit rusty at times, but I pretty soon got it done. Reading some of the resistor values was probably the hardest part as these were tiny 1/4 watt types mostly (and my eyes are also a bit rusty!)  and the colour bands were a bit hard to make out. I got out my meter to check some of them to be sure. As I went along I also was checking off each of the steps I performed as the kit manual suggested.


The tube sockets are installed on the face or foil side of the board and the rest of the doodads from the other side. The non-foil side had pretty clear markings for the placement of the different components and pins.


The outside of the case soon had the power transformer and output transformers installed with the supplied hardware. The main case has been pre-drilled and tapped by the manufacturer. There are 2 switches, one for power and the other to select the source as there are 2 sets of RCA connectors for line level inputs (like CD or MP3 player).


The 2 PCBs are mounted with stand-off posts and with the volume control nut for the main board and some small screws for the speaker and RCA terminals. I realized after I had soldered the connecting pins to the input board that I had done them from the wrong side of the board so I had to unsolder them and do it again. This board goes in foil side exposed so they are supposed to be the opposite of the main board but I initially missed that in the instructions.


Above is before the internal wiring is complete and below is after. I discovered at this point I had made one other slight boo-boo here in that I had not yet installed the cover over the power transformer. I had to unscrew the PCBs to get at the mounting holes under them. It was getting late by now...


The brown wires were also a bit tricky. They are 2 conductor shielded cable and had to be cut to specific lengths and carefully stripped and twisted, and they are very fine gauge. The black and white wires are the AC power and are twisted together to help prevent hum. The same goes for the 2 blue and red wires from the power transformer.

It's getting close now and I am about to close it all up and install the extra cabinet bits.


The face plate is brushed aluminum and has some nice looking allen head screws for attaching it. The volume knob is also alumium and is held on with an allen head set screw and sits recessed into the silver face. The pins on the tubes were all straight and installed nice and firmly.


The feet and bottom are on and look good. The bottom panel is drilled so that you can install 3 feet or four and since I have a nice level surface and don't believe there is any reason not to, I use all 4.


And here is what it looks like, sandwiched in between my turntable and receiver. At this point I have it plugged in the back of the receiver's switched AC jack so the Mitsubishi has to be turned on. I'll rearrange that later, but at 2pm it was bed time!


Build time was probably about 6 hours. I had to stop to make and eat supper (deepfried kalamari with greek salad, homous and pita...yummy!). I probably could have been a bit quicker but I was quite methodical and as mentioned, a bit out of practice.


I hooked it up to my BIC Castle Clyde speakers and had a brief listen last night while I cleaned things up a bit. It sounds great and drives those speakers adequately, but I do have a problem. The left channel is quite a bit louder than the right. It is not a problem with the tubes, cables or the input as I switched everything around and even the speakers. I'll have to break it open again to check and the manual does give me a starting point suggestion in the troubleshooting area. There is a "resistance jumper" at the output terminals which I will check first. I hope it is that simple!

The source is my Rega Planet CD player. In order to attach the turntable I will need a phono preamp which I don't have as a separate unit but I might have to get one.

Monday, 6 February 2012

Realistic Lab-500

My Realistic Lab 500 turntable is a very attractive unit from Radio Shack and was listed in the 1979 catalogue as their top model, selling at that time for $259.95. If you convert 1979 dollars to 2011 ones, you get over $840!!

It is direct drive and fully automatic, quite heavy and solid feeling and a distinctive design. It shared a lot of its design and features with models from Mitsubishi and European brand ITT among others and obviously was made in the same place.

When I got mine it was pretty sad looking. Dirt and duct tape residue covered the lid and other surfaces, and the cueing arm was stuck in a down position. With that in mind I was able to talk the owner down from $60 to $40. When I brought it home I was fairly easily able to get the cuing lever working again with some lubrication and persuasion. The lid was more trouble, and cleaning and polishing it revealed some significant cracking that is unfortunately not going to be fixable. However it works great!

The headshell and cartridge were not stock, but were certainly not a bad alternative. The original headshell, the R9000E LWS, is a plastic one and integrated (i.e. glued) into it is a Shure M95 cartridge. The combination is very lightweight and the tonearm counterweight is correspondingly low mass. Mine however came with a headshell from what might be Nagaoka and a Mission 773 MM cartridge. I can`t fine many references to the Mission cartridge, or at least very little on their Moving Magnet versions.

I like to bring my vintage gear back to original specifications if I can within reason. With that in mind I managed to find someone who would sell me the original Radio Shack headshell & cartridge. It came without a stylus, but I was able to find a cheap aftermarket replacement on ebay. That has not worked out so well though...

If you look at the picture above, you will see what looks like a healthy stylus cantilever, at least as far as the record to cartridge distance goes. Have a look at the picture below for a somewhat different look. 

In the pic above you can see the stylus holder (the yellow part) is VERY close to touching the record. In fact on a very slightly warped record or maybe even with a bit more stylus pressure it would touch, which is not good. And this is actually AFTER I did some work on the headshell to improve the angle. If you look at the next pic (sorry it`s a bit dark, but you can see some of the same features in the pic above, or the one at the bottom of this post) you can see I have pointed out some key areas. 

Arrow 1 points to the actual stylus, 2 points to a gap between the stylus holder and the headshell. 3 marks a difference between the fact that the bottom of the headshell and the sides of it which are no longer parallel. When I started the gap at 2 did not exist, the difference at 3 was essentially non existent, and 1 was in a much worse position as the yellow part was scraping along the record with the stylus cantilever basically buried in the yellow part that was rubbing directly on the record. Not Good!

My ``fix`` which was not really a fix, was to pry the cartridge from the shell (it was glued in) and put a wedge of poster putty behind the cartridge which changed the angle so that the stylus sort of works. It is still too close for comfort though. In order to be confident enough to use the cartridge I have I will have to source another stylus to test with it. This one either is not well made, or is not designed for this cartridge.  So for now, I have the Nagaoka and Mission installed and that`s not all that bad as they are quite capable and sound good. 

Update: I have another stylus for the above headshell now and it does work better, but comparing the design of this headshell/cartridge with comparable Shure cartridges does show that the angle of the lower body relative to the record does dictate the stylus required. Another thing I am going to try to fix is that the collet end of this headshell I have has some play in it where the plastic surround of the headshell attaches to it. I may need to use some epoxy to make that less flimsy feeling.

Thursday, 2 February 2012

I unloaded some gear this week.

Tomorrow I ship off my Advent 300 receiver to Newfoundland for a new life as a preamplifier for some nice tube amplifiers.

The purchaser helped design some of the equipment for a high end audio company based in Newfoundland called Aurum Acoustics. Unfortunately it looks like the company did not last long. It's too bad because the equipment looks and probably sounds very nice. Now apparently the guy helps design UAVs (Unmanned Aerial Vehicles). Now I am not quite sure why an unmanned aerial vehicle would need a killer audio system, but you never know. It might pick up a really small hitchhiker sometime who needed some entertainment I guess.

As well as selling the Advent I unloaded the Sony PS-1350 turntable last night. I think it's going to a good home, a masters student in architecture who came to get it by bus. I felt sorry for him as he was going to have to take it home the same way, so I drove him home across town with it. I would hate to think of the turntable falling as he ran for the bus in the rain, so I think I did the right thing.

A few other things are moving on, or have already. The Harman Kardon receiver I acquired and fixed up last month, the RFT BR26 speakers I have had kicking around for years, plus the (who knows what model, but it was free) Sony DVD player have gone to Linda's living room for her mom to give her something to listen to downstairs as he she naps on the couch. The entire system's most expensive part was the B&W speaker stands I bought at Value Village for $10.

Enzo (the Jack Russell) is not quite sure he approves, especially of the volume control rotating on its own, but actually by remote control. Please pardon the cel phone picture...

For the last item, next week I will meet with my AudioKarma friend Mike, to swap a large pair of Optimus 5b speakers for a pair of Realistic Pro-10 headphones of similar vintage.

He and both appear to like the old Radio Shack gear. However he seems to have a better shop than I do and will probably be better able to refurbish these speakers which do need some work. I also just don't have the room for them, so Karma rules and I offered them to him the other day. Me getting the headphones from Craigslist but picked up by him was just a favour I could ask of him. They are a lot more portable for my small space!