Our Ultravalve Tube Amp is Ready!

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trebejo

Re: Our Ultravalve Tube Amp is Ready!
« Reply #80 on: 23 Feb 2010, 04:12 am »
I like the screws in the faceplate. That tells you it's a real Van Alstine.  :eyebrows:

Listens2tubes

Re: Our Ultravalve Tube Amp is Ready!
« Reply #81 on: 24 Feb 2010, 01:55 am »
Now you guys have me looking at the screws on the T8 faceplate...Hmmm :eyebrows:

Wayne I like the bias meters idea. Will these be left on or switched on only when checking the bias with no signal present?

Wayner

Re: Our Ultravalve Tube Amp is Ready!
« Reply #82 on: 24 Feb 2010, 12:40 pm »
Quote

Wayne I like the bias meters idea. Will these be left on or switched on only when checking the bias with no signal present?

I had planned on leaving them on all the time, maybe I should ask Frank if that's OK.

Wayner  :D

avahifi

Re: Our Ultravalve Tube Amp is Ready!
« Reply #83 on: 24 Feb 2010, 04:44 pm »
Assuming that the input to your meters is high impedance, leaving them connected should not harm anything.

However, note that the bias voltage reading will go much higher as the amp is driven harder, more than doubling.  So make sure the working range of the meter circuit can accommodate this.

Regards,

Frank Van Alstine

Wayner

Re: Our Ultravalve Tube Amp is Ready!
« Reply #84 on: 24 Feb 2010, 07:16 pm »
100M ohm input impedance.

Wayner

martyo

Re: Our Ultravalve Tube Amp is Ready!
« Reply #85 on: 28 Feb 2010, 01:49 pm »
Very nice update Brian.
Quote
It really is the kind of amp you buy and then find good speakers for

I read a comment such as that and want to start building a second system.  8)

jtwrace

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Re: Our Ultravalve Tube Amp is Ready!
« Reply #86 on: 28 Feb 2010, 01:50 pm »
the kind of amp you buy and then find good speakers for

such as?

simon wagstaff

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Re: Our Ultravalve Tube Amp is Ready!
« Reply #87 on: 28 Feb 2010, 02:42 pm »
To me the best match is something pretty efficient. Even better would be one of those speakers that incorporate a powered subwoofer. I have a pair of Infinity IM4.1.  this is my match made in heaven. I have no issues with volume, they play louder in my room than I can stand. the u70 sounds absolutely fantastic with them. You can find them sometimes at a very good price. These are the last of the big time Infinities in my mind and they really sound fantastic. I have seen them used for as little as $1500 a pair and the matching center and im2.6 for rears can be picked up at a bargain price as well for a home theater set up that can't be beat. I guess they never got the reviews to make them really popular on the used market but I love my pair and an excellent match with the u70.  Probably the Mythos would be a good match as well.

Another good match would probably be a sat sub set up where you would be able to cross over the u70 at 80 hz. In my case I run the IM4.1 full range and also have a pair of VMPS subs. I get great pleasure in thinking that I have 35 watt a channel for the fronts and  2200 watts for the subs. 850 per speaker and another 500 for the subs.

"Insert evil laugh here"

I have true "bass lock" in my room but Phil Lesh deserves the best, don't you think?

nature boy

Re: Our Ultravalve Tube Amp is Ready!
« Reply #88 on: 28 Feb 2010, 02:48 pm »
Can you run KT-77's in place of EL34's in Ultravalve amp? I assume the bias would have to be set slightly higher.

NB

avahifi

Re: Our Ultravalve Tube Amp is Ready!
« Reply #89 on: 28 Feb 2010, 03:30 pm »
Yes, you can use KT77 tubes in the Ultravalve amplifier.  I tried a set here, same bias setting as normal.  One problem was the JJs I got had smaller pin diameters than normal so they were an "iffy" loose fit into the tube sockets which I did not like so they came back out pretty quickly even though they sounded just fine, but no better than our normal tubes here.

Regards,

Frank Van Alstine

nature boy

Re: Our Ultravalve Tube Amp is Ready!
« Reply #90 on: 28 Feb 2010, 03:55 pm »
Frank, thank you for the quick reply.  I have been very pleased with Genalex Gold Lion (New Sensor) reissued EL84 tubes in my current amplifier and wanted to see if KT77's were a viable option. Now I just have to figure a way to convince my wife I need an UltraValve amp  :lol: :lol: :lol: :lol:

I am working on it.

NB


Yes, you can use KT77 tubes in the Ultravalve amplifier.  I tried a set here, same bias setting as normal.  One problem was the JJs I got had smaller pin diameters than normal so they were an "iffy" loose fit into the tube sockets which I did not like so they came back out pretty quickly even though they sounded just fine, but no better than our normal tubes here.

Regards,

Frank Van Alstine

Wayner

Re: Our Ultravalve Tube Amp is Ready!
« Reply #91 on: 28 Feb 2010, 05:57 pm »
Ah, that is where the saying came from "I asked God for a new bicycle and it never came, so I stole one and asked for forgiveness."

Wayner  :eyebrows:

simon wagstaff

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Re: Our Ultravalve Tube Amp is Ready!
« Reply #92 on: 1 Mar 2010, 12:56 pm »
I have to disagree about efficiency a little bit. I mean, really, the strength of the U70 is not "the vise like grip on the bottom end" like you would get with a big Krell or something like that. I admit to having some youthful tendencies when it comes to the bottom end. If you can take 80hz on down and take it away from the U70 you get the best of all worlds.  But I do agree, the U70 has plenty of power for most applications, just ease up the requirements for current.  A sub/sat system or a speaker system with a powered bass system will do that just fine.

Wayner

Re: Our Ultravalve Tube Amp is Ready!
« Reply #93 on: 1 Mar 2010, 09:50 pm »
My project for the Ultravalve is almost complete, needing a missing add-on (resistors) that will change the reading level from <200mv to 20 volts. They are metal film resistors that are 1/2 watt, .1% tolerance, and not available at Rat Shack. The good news is that AVA is a Velleman dealer and could get the kits thru Frank (Dean was the help on this one, thanks!). Anyway, apart from that, all has gone fairly well and it will free up my 2 other VOMs. I decided to put into service a 9 volt wall wart, and have that power supply switchable, and I also decided to switch out the bias test points from the Ultravalve, so that they are not connected all of the time. When the project is complete (and successful), I will publish a bill of materials and some drawings if anyone is interested in this kind of a DIY project. Total cost is about $50, so you might be better off buying 2 VOMs, but this is more compact and not battery operated.

 

 

Wish me luck!

Wayner  :D

rlee8394

Re: Our Ultravalve Tube Amp is Ready!
« Reply #94 on: 1 Mar 2010, 09:57 pm »
Wayner,

I'm definitely interested!! :drool:

Looks very nice.

Ron

simon wagstaff

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Re: Our Ultravalve Tube Amp is Ready!
« Reply #95 on: 1 Mar 2010, 11:48 pm »
In another thread somebody talks about how big a difference the rectifier tube makes in the sound of the U70.  Any thoughts on this?

Listens2tubes

Re: Our Ultravalve Tube Amp is Ready!
« Reply #96 on: 2 Mar 2010, 01:25 pm »
Lookin' good so far. :thumb:

rlee8394

Re: Our Ultravalve Tube Amp is Ready!
« Reply #97 on: 3 Mar 2010, 01:19 am »
Wayner,

Would those two meters be the PMLCDL model?

Thanks,
Ron

rlee8394

Re: Our Ultravalve Tube Amp is Ready!
« Reply #98 on: 3 Mar 2010, 01:27 am »
wayner,

Quote
needing a missing add-on (resistors) that will change the reading level from <200mv to 20 volts.

Of course you could change the bias set resistor on the UltraValve to precision 1.0 ohm units and use the meter as is with the 200mv full scale range. You would then set the bias to 100.0mv on the meter.

Wayner

Re: Our Ultravalve Tube Amp is Ready!
« Reply #99 on: 3 Mar 2010, 01:45 pm »
Wayner,

Would those two meters be the PMLCDL model?

Thanks,
Ron

Yep. Frank is helping out. The one thing I will not do is alter the Ultravalve. It stays original.

Wayner  :D