Wednesday, February 8, 2012

October 2010

Five of us met at Fritz's house in Newark, Delaware. We started off listening to Fritz's 6V6 amp from the competition and his Fostex BK16's. Fritz had made some minor changes to his amp's power supply to improve separation and his amp and speakers were a treat to listen to.
A new member, Don, turned up with some beautiful Western Electric push pull 6V6 amps.
Except for the wooden casing, they are apparently pretty much original. I loved these amps and could have listened to them much longer, particularly on band music. Vocals sounded more involving on the single ended amps, but these amps impressed everybody.
After the flop at the competition, my 6V6 entry made a belated appearance and actually worked fine this time. It has settled down a bit and keeps improving with use. I suspect it is the cheap Antek toroid transformers that I use as output transformers which are gradually improving. Inside there are a couple of switches I can flip to switch between using the light bulbs as a parafeed plate load and some 5k Dale wirewound resistors. Everybody could hear the difference between them though preference was mixed. I preferred the lightbulbs at home and the resistors at the meet. To me, the bulbs are more euphonic, if that is the correct word. Most agreed that the bass was more pronounced on this amp than some of the other competition entries. If you want to try the toroids for fun, they are Antek AN0209 ($11 each). Wire the 115 in series and the 9 in parallel and use as parafeed. The amp uses a 12HG7 as input and also has Tubelab's Powerdrive.
We have all been impressed by the quality of sound that the 6V6 amps produce. Try these tubes sometime.
Don also brought along some Altec 755a drivers in these open back cabinets that were originally designed to be suspended on walls. The bass was missing and the treble was subdued, but what a midrange.
Another pair of Altecs, but this time a couple of more modern examples that Tony bought for under $30. He said the tweeter was a piezo unit and it certainly sounded like it. We agreed that replacing it even by a good inexpensive dome would make a huge difference.
David brought these old ElectroVoice 15" SP15B full range speakers in simple baffles. They apparently have a pretty high QTS and are meant for open baffles. They showed a reasonable amount of bass, but initially we were a bit underwhelmed by the midrange. Then we hooked up the SV811-10 amp and they started to strut their stuff. The following CD really worked well with these.
Another CD we used a lot was "Genuine Negro Jig" by the Carolina Chocolate Drops. Tracks 6 and 7 were played quite often.
The SV811-10 amp. I brought it to a meet a year ago but it was yet another of my many failures. This time it worked. Essentially it is a 12HG7 feeding an SV811-10 with Tubelab's Powerdrive in between. The SE output transformers are some Audio Notes that I bought 10 years ago and never really used. It's all very heavy and a bit of a monster, but it certainly was much more powerful than the 6V6 push pull amps and so we used it most of the afternoon to cope with the various speakers we tried. To me at home, the sound of the 12HG7s in this amp of the lightbulb amp dominates the 6V6 or SV811-10. The Audio Note transformers produce more fine detail than the cheap toroids as you would expect. Dollars talk. The 811 amp is just more dynamic which I suspect is due to the power supply.
David's Jordans on top of the modern Altecs. The cabinets are from Parts Express and the tweeters are Aurum Cantus. I've heard them at a few meets now and they continue to impress. The bass is amazing from such small units and the midrange is really good.
Inside my DAC which is the one used in the Lampucera. I've done some of the mods, replacing some of the caps and the output opamp with an LM4562. The replacement caps are very low esr PSA units from United Chemi-con that are avilable fromMouser for 81 cents. I don't know if the caps recommended in the Lampucera article are better, but these certainly made a huge improvement over the stock caps. And yes, the case is from an old PC power supply.
David's AD1865 version of the Lampucera. I didn't hear enough of it to say whether I preferred it to the smaller version. By the way, removing the SMD caps is a pain, but if I can do it, you can.
Finally, David's Lightspeed attenuator. This thing is absolutely brutal in that it lays everything bare. We found that it worked very well with certain combinations but not everything. There is plenty of info on the web about the Lightspeed and I suspect I will be trying it out soon.
So I was really pleased by this meet because I brought my 12B4A line stage along as well and all four of my items worked! Four out of four!

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