Spring's Coming! Time for the Next B.A.S.S. Meetup! (Connecticut)

[Mark (Basspig) Weiss]

It's coming up on that time again. What time, you ask? Time for the Third Annual Basspig Audiophile Society Social!

The way events are going, I'm likely to settle on April 5, a Saturday, for the meet. Our usual starting time of 2PM is planned.

Dinner and a buffet will be served upstairs, as usual.

The main attraction this year (assuming I can complete it in time!) will be my OTL vacuum tube amplifier. This dual mono amplifier, with separate power supply chassis, is being designed to a conservative 125 WPC rating and uses a dozen large beam tetrodes. The power supply is 1000VA for the high voltage and 40 amperes for the filaments. A veritable contender and should be interesting when the unveiling occurs.

As usual, there will be demonstrations of the world-famous Bass Pig sound system, and probably a shop discussion with demonstration at the shop of Amplifier Experts.

R.S.V.P. to basspig (the "at" symbol) basspig ( dot ) com for address/directions, etc.

The past two years have been great as far as turnout, with attendees from as far as 5 hours driving distance.

I hope to see some of you at this year's meet!

 

[Ethan Winer]

Sounds great Mark, be sure to let me know the final date.

--Ethan

 

[16hz lover]

There is a guy in CT who is installing 8 of the new Stereo Integrity 24" drivers now in his new HT room, maybe next year it can be a "bass crawl" and we can hear both systems

 

[Mark (Basspig) Weiss]

I'm hoping to stick to April 5 as my target date. So much to do in the meantime. The OTL still has a LOT of work to be done to ready it. But I will keep everyone up to date.

 

[cjfrbw]

Another session of flying carpets and blowing out candles from 30 feet away with bass drivers?

 

[Mark (Basspig) Weiss]

It's turning out that this OTL vacuum tube amplifier project demands much larger and more expensive components to make it work satisfactorily.


The initial startup of the system with Totem Pole topology revealed that the power supply capacitance is way under the needed amount for sufficient performance. A change to Wiggins-Circlotron topology may help with this, but it requires that both the power supplies float. Which means I need yet another transformer to furnish the fixed supply for the driver stages.


My research indicates that the minimum supply capacitor size should be 7500uF. Currently, I have 1200uF in series (400 volts total) which means the effective capacitance is only 600uF per rail. There is 10 volts of ripple.


The other problem is these 500VA industrial control transformers only furnish less than 2 amps at 220 VAC per secondary winding. The total draw of the output tubes of one channel wants to exceed 8 amps.


I found some suitable capacitors, 7500uF at 400 volts, but they are 3.5" diameter and 6" tall and won't fit on my existing chassis. I need four of them. And here's the real catch: Mouser Electronics has them, for the princely sum of $400 a piece! Frankly, there is no way I'm going to invest $1600 in capacitors to build an OTL amplifier.


In order to do this right, I would have to scrap the chassis completely and start anew with a much larger chassis, even bigger power transformers and huge filter caps. That's just not possible for me to accomplish in less than two weeks that remain before the next B.A.S.S. meetup, which is tentatively set for April 5.


At this point, I'm wondering if I should even go ahead with the annual meeting this year, since I don't have anything new to demonstrate. We would be relegated to just showing off the Bass Pig's sound system, playing records and maybe a few shop demos, like last year and the year before. I'm not sure that such a presentation would be worth doing. Any opinions?

 

[Ethan Winer]

Mouser Electronics has them, for the princely sum of $400 a piece!

Well that settles that. I know this project was for your personal satisfaction, but for $400 you can get a perfectly good SS amp already built!

I'm not sure that such a presentation would be worth doing. Any opinions?

I'd stop by briefly if only to say Hi and meet folks.

--Ethan

 

[amirm]

Another session of flying carpets and blowing out candles from 30 feet away with bass drivers?

Agreed. And oh, some proof that it is the subs doing that, rather than good helping of beans earlier:

 

[Lee]

Lol!

 

[Mark (Basspig) Weiss]

Well that settles that. I know this project was for your personal satisfaction, but for $400 you can get a perfectly good SS amp already built!



I'd stop by briefly if only to say Hi and meet folks.

--Ethan

And the project requires FOUR of these caps, so we're into $1600. I need to find another way to do this, but it's not going to be in time for April.

 

[mep]

And the project requires FOUR of these caps, so we're into $1600. I need to find another way to do this, but it's not going to be in time for April.

Go to kickstarter and get some seed money to put the amp in production and give the first 1000 people a great deal when they buy your amp.

 

[Lee]

Go to kickstarter and get some seed money to put the amp in production and give the first 1000 people a great deal when they buy your amp.

Now you are catching on!

 

[Mark (Basspig) Weiss]

Go to kickstarter and get some seed money to put the amp in production and give the first 1000 people a great deal when they buy your amp.

I was never planning to market the amplifier. I've been down that route before and it's a big boy's corporate world. Deep pockets and powerful corporate lawyers required to play in that field. I'd need to raise a half a million dollars just to get started, not $1600. And I doubt there are enough audiophiles in the world where the percentage into OTL would be large enough to buy 1000 units.

I'll just have to patiently watch eBay auctions and snag a capacitor or two whenever something close to my requirements goes on the auction block.

 

[Lee]

I was never planning to market the amplifier. I've been down that route before and it's a big boy's corporate world. Deep pockets and powerful corporate lawyers required to play in that field. I'd need to raise a half a million dollars just to get started, not $1600. And I doubt there are enough audiophiles in the world where the percentage into OTL would be large enough to buy 1000 units.

I'll just have to patiently watch eBay auctions and snag a capacitor or two whenever something close to my requirements goes on the auction block.

Hmm, that seems like the perfect scenario to do a kickstarter...

1. You are not sure of demand. The success of the kickstarter campaign will provide you the exact number of units. (You can sell more if you like).

2. If you don't raise enough money from interest in buying the units, kickstarter does a refund and you don't move forward.

 

[Ethan Winer]

Deep pockets and powerful corporate lawyers required to play in that field.

Yes, at least if you plan to do it right. As we discussed the other day, just getting UL approval is extremely expensive!

--Ethan

 

[mep]

I was never planning to market the amplifier. I've been down that route before and it's a big boy's corporate world. Deep pockets and powerful corporate lawyers required to play in that field. I'd need to raise a half a million dollars just to get started, not $1600. And I doubt there are enough audiophiles in the world where the percentage into OTL would be large enough to buy 1000 units.

I'll just have to patiently watch eBay auctions and snag a capacitor or two whenever something close to my requirements goes on the auction block.

Think big Mark. You are thinking like someone who is beaten before they start. You just need to write up a nice marketing plan that shows you are an amp designing and building genius and people are going to receive an OTL amp like none other ever conceived and it will provide them with magical sound at a price that can't be found in the commercial market place. You just need to figure out what your final design really is and how much it's going to cost you to actually build them and what you will need to charge to cover all of your costs. People will either buy-in or they won't.

 

[Lee]

Mark is about to drop the bass.

 

[Mark (Basspig) Weiss]

Ambition like that is for younger people. My last round with the "bull" was in 1985, when I presented a noise reduction and dynamic expansion system, designed for the FM broadcasting system. FMX was my closest competitor, from CBS Labs in Stamford, and all it was supposed to do was reduce some hiss and it didn't work very well. I took my idea to patent lawyers and was told that it's a very nice concept (and I even had a working prototype) but that by the time any of this would make it through regulatory hurdles, they'd all be dead and buried. Back in the late 1970s, I tried to market a superior, yet economical stereo generator (FM multiplex), but got shot down by the costs and regulations. I'm done doing that sort of battle.

Actually, when I first heard of Kickstarter, I thought "I can't think of anything I would be able to use that for". Then last year, it hit me: I got this crazy idea of inviting a Japanese movie soundtrack composer to the US, to give a concert, which my company would make the best audiophile recording of, as well as a multicamera video shoot. We'd also have an audience and sell tickets to the concert. I was thinking, start smaller, with a less known composer and do the concert with a regional orchestra. Then, if that was successful, invite Joe Hisaishi to conduct and perform his pieces with the New York Philharmonic. I would again do the recording and add my special magic to the process, and make a high level Blu-ray and audio discs of the concert. Now for something like that, a Kickstarter program makes sense.

 

[Mark (Basspig) Weiss]

EVENT CANCELLATION NOTICE:
The 3rd Annual B.A.S.S. Meeting, tentatively scheduled for Saturday, April 5th, 2014 at 2PM is cancelled.
It was a difficult decision to make, but I felt that, without having the OTL amplifier project ready to show, there would not be much content of high value to show. I don't want these meetings to be just sessions where people spin records--I wanted to add some science and demonstrate unique amplifier designs. The technical hurdles to accomplishing this will require me to invest far more cash into the project than I had anticipated. Therefore, it's been postponed another year.

 

[Mark (Basspig) Weiss]

I got lucky on the capacitors and scored four 6800uF/450V capacitors on eBay for $20 each. They're 3" in diameter and 7.5" tall. A larger power supply chassis will be necessary to fit these.

The last 'hard to find' item will be power transformers. The cheap industrial control transformers have too high a voltage and far too little current capability. 240 volt at 1 amp produces a 340 volt DC rail, where I need 180-200 VDC and 5-6 amps minimum.

The ideal transformer would have two independent secondary windings of 130-140 VAC each. I also need another transformer with more traditional voltage for the preamp/housekeeping power. I probably have a few of those kicking around the shop.

So when I find the appropriate transformer, I can resume construction and testing of my OTL amplifier.