Bottlehead Forum
General Category => General Discussion => Topic started by: RayP on January 03, 2010, 05:29:52 AM
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Steve and I have set the date of the competition for Sunday, April 11. The cutoff date for entries will be February 1. Please visit http://829b.com/6V6.aspx (http://829b.com/6V6.aspx) for the updates and rules.
Towards the end of the document under the judging process, I have a link to a proposed scoring system at http://829b.com/6V6competitionscoringsystem.aspx (http://829b.com/6V6competitionscoringsystem.aspx). Please feel free to suggest improvements. Again thanks to all who have suggested improvements.
ray
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What a great contest! I hope you will post a full report here, including whatever pictures you can. I happen to like this little tube quite a bit from work on guitar amps, so I love to hear about people using it for DIY HiFi.
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Certainly, there will be a report with pictures. You can see some from of our other more recent meets at http://829b.com/bottleheads.aspx (http://829b.com/bottleheads.aspx)
I am at the breadboard stage now and I have my Ikea container ready so I will start putting it all together soon.
ray
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Man, I sure wish you guys would take shipped submissions, but I can totally understand why you wouldn't. Be sure to post pictures when you can!
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I sympathize with you.
So far, I only know of three entries. The Dowdy Lama is bringing his entry, Steve has a design and partial build and mine will hopefully play some music tomorrow for the first time. If we don't get a few more entries by the end of the month, we may have to reconsider the rule limiting to 'carry in'. Ideally I would like to have about 10 entries so if you are in the Mid Atlantic / DC area or somehow could make the trip to DC, please think about submitting an entry.
ray
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I'm in, I got to tell you the V-caps are killing my budget..John
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We still need a few more entries so if you are thinking of entering, please let me know asap.
After a few iterations, I've got my breadboard mostly done except for deciding on the coupling caps. There is a picture of it posted all the way down at the bottom of the '6V6 Rules' website. I've also included a couple of details about it.
http://www.829b.com/6V6.aspx (http://www.829b.com/6V6.aspx)
By the way, other entrants are not required to post details of their design at this stage. I've opened the kimono to generate some interest.
One more point, I've been contacted by a Gary Gill of Capital Audio Fest which will be held in June in the Rockville, MD area. He is interested in letting us have a table to show our amps if we wish to do so.
http://www.capitalaudiofest.com/ (http://www.capitalaudiofest.com/)
ray
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That's pretty cool. How did Gary hear about the competition?
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I think you have me beat for clip leeds...John
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I don't know how Gary found out but he mentions that he will try to attend our April event. It will be interesting to see how his big event in June goes.
ray
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Count me in!
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It looks like we will have 5 or 6 entries. So far, all are single ended. To add a bit of interest, I will bring the Poinz Music Machine PP 6V6 amp that my daughter built and have it as the ringer though it won't be eligible for the prize. It will be interesting to find out if we can consistently pick it out from the SE amps. It has Edcore transformers so should be competitive. I will change the coupling caps to something cheaper, probably whatever I end up with in my amp.
ray
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It looks like we will have 5 or 6 entries. So far, all are single ended. To add a bit of interest, I will bring the Poinz Music Machine PP 6V6 amp that my daughter built and have it as the ringer though it won't be eligible for the prize. It will be interesting to find out if we can consistently pick it out from the SE amps. It has Edcore transformers so should be competitive. I will change the coupling caps to something cheaper, probably whatever I end up with in my amp.
ray
That`s great. I was looking at Poinz`s amp for my next project. I am looking forward to doing a push pull next.
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I was just thinking about the coupling caps and how it plays such a large part of the 'flavouring' process. I was trying a 716P orange drop and just for fun, bypassed it with a russian silver mica SSG-2. What a difference but then again, not allowed under the 'no Ebay' rules.
Perhaps if we do another competition we can specify what the coupling cap should be. Actually, in the back of your minds, think about what the next competition could be. Perhaps a 'salvage' amp? In many ways, the constraints are what makes this interesting.
ray
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David and I went to Steve's place for a mini meet last Sunday to talk a bit more about the competition and see how an actual entry would work with the JBL / waveguide speakers. I brought along my breadboard version and fortunately it worked and seemed to handle the proposed music.
I have updated the website http://829b.com/6V6.aspx (http://829b.com/6V6.aspx)with a bit more about what will happen on the day. Please note the timing, we can't run late because I am flying off to London later that evening.
Entrants, also note that you need to think of a name for your amp.
So how did my amp sound? Well we also played David's fully tricked out Sex amp and his sounded better, particularly in the midrange, but I was still pleased with mine considering the $200 limit. We tried bypassing with the SSG-2 silver mica caps later in the day and that really helped my amp.
My breadboard has now been dismantled and it is being reassembled in its container. If you are entering and haven't got too far with your building, you need to get cracking.
ray
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With less than four weeks to the competition, I figured it was time to open the kimono and show my entry, the Lumiere. It really has been a fun project.
I have done a write up showing the schematic and parts cost along with a page with a bunch of photos.
http://829b.com/6V6Lumiere.aspx (http://829b.com/6V6Lumiere.aspx)
Other entrants do not have to reveal their entries at this stage, just bring your schematic and parts list along with your amplifier. Of course, you can release details if you wish.
ray
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Very cool, Ray!
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Looks good Ray, I need to get things finished up!!!
:)
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Well it
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Here is my entry.
Rudolf, he should have antlers that double as heatsinks for the CCS,
unfortunately that would put them at 150V
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I think we are going to have some very fun entries (as well as good sounding). So what is that thing, I can't recognize it.
ray
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I think its this:
http://cgi.ebay.com.my/Horse-Shape-Cake-Pan-Ikea-Teflon-Retro-Red-/350310923200
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Yep, that
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I think we are going to have some very fun entries (as well as good sounding). So what is that thing, I can't recognize it.
ray
Friday afternoon. getting ready for Sunday. Can someone bring a preamp also as i seem to have an intermittent fault in mine that i haven`t pinned down yet. I`m looking forward to this although i won`t be presenting an entry due to work constraints etc. See you all Sunday, Steve.
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Fritz is going to bring his Foreplay 2. I can also bring my new 12B4A linestage as a back up, but with new capacitors, it is still a bit bright.
How about everybody with a linestage with a continously variable pot bring what they have and then we can select one.
ray
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This is starting to sound like a real fun event - wish I could be there. Please post when it's over!
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My entry is nothing special with regard to the circuit. Even though it is remarkably similar to the design found on the Boozhound Laboratories (http://boozhoundlabs.com/howto/), I came up with the circuit myself after reading many books and websites throughout the year. I understand the purpose of each resistor and capacitor in the circuit and why I chose the value. Even though I have built several Bottlehead kits and other projects, I never understood anything about what I was putting together. Now I can look at another circuit and actually decipher what is there. This is a big step for me!
I was beginning to think that I would not have an entry either, but have managed to pull it together at the last minute. Then there was a horrible hum that would not have prevented my participating, but certainly would not have allowed me any chance of scoring well. Once I got that worked out, I was disappointed with the sound. Of course, I was playing it with my bench system - an old NEC external CD drive meant for a computer, into a Adcom solid state preamp from the early 90's with Spica TC-50 speakers. I turned the Adcom all the way up (literally) to get a decent level to listen. Problem was, there was huge amounts of audible distortion. In addition, the sound was dull and lifeless.
So, I swapped out the NEC with my ARCAM CD73 (which we will be using for the competition). Big difference! The level put out by the ARCAM was higher than the NEC, so I had to turn down the Adcom but there was still a lot of distortion.
Finally, I decided to bring the system into the home theater room where I have my ART Arrays and my Foreplay III. HUGE DIFFERENCE! I'm sure the Foreplay has more gain than the Adcom, but its only on the third click. The ART arrays are around 92dB while the Spica's are 84dB efficient (just looked that up didn't realize they were that inefficient). Now, the room is filled with sound (as arrays will do) without any distortion. No buzz, no distortion! I'm VERY surprised by the bass. I have yet to run it through some torture tests to see how much there really is, but on regular music tracks it is very pleasing.
Finally, after reading about Steve's linestage not working and our needing a continuously variable volume control I tried something I never tried before. I read somewhere that Lightspeeds should not be used to drive tube amps (not sure why, something about impedance mismatching or something). So, I'm using the Foreplay simply as sort of a tube buffer. I ran from the CD player to my Lightspeed Attenuator to the Foreplay III then to my amp. WOW! I'm really amazed how good this system sounds. I have the parts for another Lightspeed on the way for a different project - now I'm thinking I might want to follow it with a tube buffer.
I will be at Steve's early tomorrow to get things set up. This should be fun!
P.S. The chassis is a cutlery tray (http://www.ikea.com/us/en/catalog/products/50021095) and the transformer covers are cutlery caddies (http://www.ikea.com/us/en/catalog/products/30011832) from Ikea
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That tray looks familiar
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John,
Is that a prototype Stereomour?
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I've got a great sounding 76 linestage that I'll bring.
Also my amp is finally done. It sounds better than my reference amp, so I'm eagerly awaiting tomorrow.
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... Even though I have built several Bottlehead kits and other projects, I never understood anything about what I was putting together. Now I can look at another circuit and actually decipher what is there. This is a big step for me!
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- now I'm thinking I might want to follow it with a tube buffer.
Dude, that's what it's all about. Congratulations!
There's a buffer in the works - preliminary design but not prototyped yet. Doc B. has the cathode follower buffer we were working on a while back but we think we can do better sonically. :^)
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The competition was a blast, too bad Jim's amp didn't survive the trip. Johns little cake pan amp really sounded great!
Pics and other info to come!
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Here are a couple of quick cell phone shots of some of the contestants.
Hats off to Ray, Steve and the rest of the organizing committee for proposing this, it was a lot of fun
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One more
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Another great event hosted by Steve. As always, thank you.
I think everyone was very happy with all the entries and disappointed for those amps that didn't survive the trip. It goes to show you can make a more than decent sounding amp for less than $200. John's amp that won (the one in the horse-shaped cake pan) was also the least expensive - $143 including tubes!!! I want to review his schematic some more and see what changes I can make to improve my amp.
The bad luck award goes to Ray. What are the odds of having TWO amps work during setup, then having both amps lose a channel during the actual competition? Maybe Ray's amps have performance anxiety.
I'm looking forward to the next competition. While we haven't decided what it will be, I like the idea of making a budget line-stage. We should not allow anyone to submit a Foreplay I or Quickie. Although, it might be fun to include them in the judging - I have a stock Foreplay I that we can use.
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Some comments and lessons learned from last Sunday's event which I really enjoyed.
The scoring was incredibly close in the first round. A change of a single vote would have changed the order completely. I found that some amps suited certain music better than others.
Oddly enough, after the closeness of the 1st round, there was no doubt in the final round that John's amp was the winner and also the cheapest at under $150.
We definitely had problems getting the sound level correct for each entry and we need to re-think how we do this for next year's competition. Since it was a nice day and the world outside was quite active, there may have been noises other than the test tone affecting the db reading. Let's play with this aspect during our future meets to develop a better method.
I appreciate our team of judges being so quiet during the music and taking this event seriously.
Although I was not judging, I found it very difficult to pick an order during the first round and perhaps at future meets, we can talk more about scoring techniques. For myself, I think in future I would do a preliminary score just after the first piece based on first impressions and then adjust as I heard further music.
Finally, could those who submitted entries and would like their schematics posted, please email them to me. Now I have arrived at a house with a fast internet connection, I can work on getting them posted. And no, I can not see any volcanic ash in the beautiful blue sky near Whitby.
ray
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I guess I should have brought a camera, I'm not seeing many pics.
Ray, I've made some changes to my amp since the meet, should I incorporate those in the schematic or send it to you as it was?
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I'll post some pictures in the next couple of days.
Perhaps you could send both schematics with an explanation of why you have made the changes.
ray
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I have uploaded some photos which you can see at http://829b.com/6v6entries.aspx (http://829b.com/6v6entries.aspx) and I will post the remaining schematics as they arrive.
This was such a fun competition and I would urge all of you to try something similar in your geographic location or perhaps just build one for yourself if you are experienced in building amps. These amps sounded really great and it was amazing what could be achieved for $200. It was particularly interesting to have the cost of parts restriction and it really makes you ponder when you have to make tradeoffs; do I spend $$ here or there.
Many thanks to all of those who took part and to Steve for hosting.
ray
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Looking at the photos, I think the real winner was Edcor
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It's very hard to beat the price/performance value of Edcor.
I was very happy to hear Fritz's amp with the Hammonds and how good it sounded.