2018 Carverfest Tube Power Amplifier Build

12th Annual CARVERFEST 2018 September 5th - 19th
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Magnaryder
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Re: 2018 Carverfest Tube Power Amplifier Build

Post by Magnaryder » Mon Feb 05, 2018 12:18 am

Bob did mention in a conversation with Harry, Mark and Shortcake the magic number would be 105. I'm glad it's spot on.


ray
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Its going to be used equipment when I sell it, so it may as well be used equipment when I buy it.

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Robert R
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Re: 2018 Carverfest Tube Power Amplifier Build

Post by Robert R » Mon Feb 05, 2018 3:36 pm

Talking with Bob today about tube prices. As to brand, he appears to be sticking with Tung-sols. The price with KT-120's is almost fixed, in the neighborhood of 50 bucks extra. He also wants to come up with a lower number, for those who would buy their kit/s with no tubes at all. But he's very distracted - he's in Hawaii at the moment (good thing I didn't call early!), so it might be a couple of days before we have final numbers. After that, we'll be asking everyone to choose their tube complement; that will dictate the bottom line. Then we can finalize the list of purchasers and Ed can start gathering in the first payments. Then Bob will know how many and what types of tubes to order. A lot of that front money will be used to pay for the tube order. Our tube costs will basically be his his cost, and that's a fair bit less than the rest of us can buy them for.

Personally, I recommend getting the KT-120s. For less than 10% extra you get around half-again the power and headroom.

RR
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BrianT
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Re: 2018 Carverfest Tube Power Amplifier Build

Post by BrianT » Mon Feb 05, 2018 4:07 pm

Robert

Thats for the update, yes I will be going with KT120's I really like that tube.

Do you know if there is still going to be an option for a gain control in the amp.

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Re: 2018 Carverfest Tube Power Amplifier Build

Post by Robert R » Mon Feb 05, 2018 5:20 pm

Got it, Brian - all 120's. Haven't heard mention of the volume control lately - not sure that means anything one way or the other, though.

Personally I'm ambivalent about a gain control. If you are moving these amps from one system to another frequently, it can be very handy. But it's often hard to get things adjusted so that the gains are equal between channels - even the dual-concentric types have some 'slop' in their tracking. If I'm not changing systems around, I prefer using an equal pair of fixed resistors in each channel to lock-in the sensitivity where I want it.

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Magnaryder
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Re: 2018 Carverfest Tube Power Amplifier Build

Post by Magnaryder » Tue Feb 06, 2018 11:10 am

Robert R wrote:
Mon Feb 05, 2018 5:20 pm
Got it, Brian - all 120's. Haven't heard mention of the volume control lately - not sure that means anything one way or the other, though.

Personally I'm ambivalent about a gain control. If you are moving these amps from one system to another frequently, it can be very handy. But it's often hard to get things adjusted so that the gains are equal between channels - even the dual-concentric types have some 'slop' in their tracking. If I'm not changing systems around, I prefer using an equal pair of fixed resistors in each channel to lock-in the sensitivity where I want it.

RobertR
Then might I suggest a precision stepped-attenuator. Insanely accurate, and can be insanely expensive just ask Miko. Schiit builds one just for this purpose, but theirs is priced by Ferenghi Grand Nagas Zek.

ray
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Its going to be used equipment when I sell it, so it may as well be used equipment when I buy it.

"Racing is life, the rest of the time you're just sitting around."-Steve McQueen

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Robert R
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Re: 2018 Carverfest Tube Power Amplifier Build

Post by Robert R » Tue Feb 06, 2018 11:21 am

Yeah,, Ray - I know there are controls that are very good. But this project is on a budget that can;t go there.
My usual answer is to use no control at all - just two pairs resistors - as voltage dividers of a fixed value. You can go through a bunch of resistors with your ohmmeter to get precise matches. Waste of time, of course, unless your master volume control is high quality.
May these days use electronic gain controls, of course, in their playback source. But I still use a preamp myself.

RR
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Re: 2018 Carverfest Tube Power Amplifier Build

Post by Shortcake » Tue Feb 06, 2018 11:55 am

just because I have no idea what the heck you are speaking here - Harry will let you know what I decide on lol, since he will be 'helping' me build mine and then explaining it all to me later. I already have this decision / discussion built into his usual and customary fee for the entire project lol.
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Re: 2018 Carverfest Tube Power Amplifier Build

Post by Toy Maker » Tue Feb 06, 2018 5:22 pm

Shortcake wrote:
Tue Feb 06, 2018 11:55 am
just because I have no idea what the heck you are speaking here - Harry will let you know what I decide on lol, since he will be 'helping' me build mine and then explaining it all to me later. I already have this decision / discussion built into his usual and customary fee for the entire project lol.
If you don't take the time understand, you don't get a say in the matter.

Jezz... sounds like a US election up in here or something

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Magnaryder
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Re: 2018 Carverfest Tube Power Amplifier Build

Post by Magnaryder » Tue Feb 06, 2018 5:58 pm

Bwaaahahaha, sounds like some of the conversations I heard at the polls.

....poor fucking Harry :rolleyes: You need to jump in the pool CarolLee and get yer feet wet.

ray
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Its going to be used equipment when I sell it, so it may as well be used equipment when I buy it.

"Racing is life, the rest of the time you're just sitting around."-Steve McQueen

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Re: 2018 Carverfest Tube Power Amplifier Build

Post by Shortcake » Sat Feb 17, 2018 5:17 pm

in order to make the decision, I will rely on Harry. Trust me, by the time he goes over it again and again with me after selecting - I will know and understand. My brain is a bit slow when NOT on vacation for anything other than work...when on vacation, I have more space in there to figure it all out lol.
“Music gives a soul to the universe, wings to the mind, flight to the imagination and life to everything.” ― Plato

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Robert R
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Re: 2018 Carverfest Tube Power Amplifier Build

Post by Robert R » Wed Feb 21, 2018 6:20 pm

Bob is finally back from his Hawaiian vacation, and we talked a little today. On the subject of the amplifier kits, he plans to get the circuit board designed soon. He's decided that the board will contain the tube sockets. The downside is at least a theoretical increase in fragility. but the build will be a lot easier, with around three dozen fewer connections for the builders to solder.

Also, he's decided to make the KT-120's the tube of choice. This will add around fifty bucks to the price, but everybody who already specified a choice has opted for that tube anyway. If you want to buy them with KT-88's or anything else (including tubeless), Bob says he will have some available at the Fest, and do a cost adjustment there.

Also, the final decision on first payments is now official: $350 by April 1st. Ed Atkins (sea) will provide payment details any time now.
Second payments will be due in mid-July; the final amount will be known soon: it figures to be less than the first payment – I'm guessing in the neighborhood of $300. Bob is doing these at his cost, but he hasn't figured his tube costs exactly yet.

As more details trickle in I will post...

RobertR
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oldtexasdog
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Re: 2018 Carverfest Tube Power Amplifier Build

Post by oldtexasdog » Wed Feb 21, 2018 6:43 pm

Looking forward. It might be easier for Ed (sea) to post a separate sticky post site? Just a thought.
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Re: 2018 Carverfest Tube Power Amplifier Build

Post by Robert R » Wed Feb 21, 2018 7:04 pm

OTD - I'm sure Ed has something effective in mind. But first I have to provide him with a final list of buyers. Working on that right now.
Actually the list won't be absolutely final for a while, but it'll be close. Anybody on it will stay there, unless they want out.
RR
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Re: 2018 Carverfest Tube Power Amplifier Build

Post by kve777 » Wed Feb 21, 2018 7:20 pm

I still don't see our, Val and Kevin's, names on the amp build list.??
Kevin

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Robert R
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Re: 2018 Carverfest Tube Power Amplifier Build

Post by Robert R » Wed Feb 21, 2018 11:41 pm

Updated buyers list coming very soon. It will include kve777 and everybody else I know of who is supposed to get a kit, or two if they wish.
There will be some kits left over, and most of those will go to new attendees who have already spoken of their plans to attend.
Then, as they last, any further remaining kits will be offered to long-time forum people who expressed an interest but probably thought they were not going to have a chance get one, as they could not attend. There will be a sort of waiting list, though we're already at Bob's limit. But a few kits might pop up if people for whom they were reserved decide they don't want them; if some drop out, those kits will be offered to others. Those on this contingency list who wanted two kits will probably have to be happy with one; time will tell.
But not too much time, I hope - this should all get settled right after April first, when the first payments are due. That's when we'll know who's in or out.

RobertR
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