[pardales]

Who's waiting on an Ultravalve amp?  I'll be curious to know what you think...

Me too.

[jtwrace]

Can the U70 be upgraded to the UV specs?  Sonically speaking.

[jtwrace]

Who's waiting on an Ultravalve amp?

nobody?

[Lefty052347]

I don't believe the U70 can be economically upgraded to the Ultravalve.  The board for the Ultra is component side down with a closed chassis.  The layout of all the inputs and outputs have been put on the back the amp.  I will ask Frank to address this issue next week.

I don't know if this counts, but I am waiting for the faceplates to come back from the finisher so I can build my own.

Happy Holidays

Regards,
Dean

[jtwrace]

I don't know if this counts, but I am waiting for the faceplates to come back from the finisher so I can build my own.

Happy Holidays

Regards,
Dean

So this amp can be bought in kit form?

[Lefty052347]

Not yet.  I have recommended that a kit of some type be made available.  The jury is still out.

I am one of Frank's techs, so they are all kits to me.

Regards,
Dean

[Wayner]

Sorry, I don't think a kit is on the table. Dean is an employee of AVA so he gets to do fun stuff that others simply can't.

Wayner 

[jtwrace]

We will be running it (actually a pair most of the time) at our display room #2002 at the Rocky Mountain Audio Fest next weekend, sharing a room with Salk Sound.

Come and listen please.

Best regards,

Frank Van Alstine

Was this being done with an AVA bridge then? 

[Wayner]

Yes it was. So the bridge turned them into mono-blocks with 60 watts a side, or so.

Wayner

[jtwrace]

Yes it was. So the bridge turned them into mono-blocks with 60 watts a side, or so.

Wayner

Nice.  So would that be equivalent to ~200w SS amps?

[jtwrace]

I am one of Frank's techs, so they are all kits to me.
Regards,
Dean

Oh that makes sense...I had no idea that AVA multiple employees. 

[Wayner]

Yes it was. So the bridge turned them into mono-blocks with 60 watts a side, or so.

Wayner

Nice.  So would that be equivalent to ~200w SS amps?

The amplifier in it's normal 2 channel mode is about 35 watts per channel, RMS. When used with the Phase Inverter, it turns the amplifier into a mono amplifier, summing up the 2 channels into 70 watts RMS (mono). So If you have 2 amplifiers, that would be 70 per channel or 140 total, not 200w.

Wayner 

[jtwrace]

that would be 70 per channel or 140 total, not 200w.

Wayner 

Yes, but for the same power output using a SS amp it wouldn't be 200w?  Frank posted above that it's (35w) what you would use where you would use a 100W SS amp.  WIth the bridge you wouldn't double it?

[oneinthepipe]

that would be 70 per channel or 140 total, not 200w.

Wayner 

Yes, but for the same power output using a SS amp it wouldn't be 200w?  Frank posted above that it's (35w) what you would use where you would use a 100W SS amp.  WIth the bridge you wouldn't double it?

Yes, I think that would be the effect.  A pair of UltraValves with a phase inverter bridge in mono will produce 70 watts per side, but the amps will perform, subjectively, much beyond their measured power.   However, I am not certain whether or not the bridged UltraValves should be used to drive 4 ohm loads, if you were thinking about these to drive the HT2-TL. 

Regardless, if you were thinking about the phase inverter bridge, Frank can build the phase inverter into a new Insight preamp as an option for $199.00, IIRC.

[JerryM]

Yes it was. So the bridge turned them into mono-blocks with 60 watts a side, or so.

Wayner

Nice.  So would that be equivalent to ~200w SS amps?

The amplifier in it's normal 2 channel mode is about 35 watts per channel, RMS. When used with the Phase Inverter, it turns the amplifier into a mono amplifier, summing up the 2 channels into 70 watts RMS (mono). So If you have 2 amplifiers, that would be 70 per channel or 140 total, not 200w.

Wayner 

Is that correct? Frank's website description states: This sums the voltage swing of the two channels, at least triples the power, and eliminates common mode distortion. Separation, imaging, and dynamics are improved. There is no better way to get such extraordinarily high power. I seem to recall past discussions of bridged Ultra 550s being 1 kW systems, too. That wouldn't be possible if the wattage only doubled.

Am I missing something? 

[oneinthepipe]

Yes it was. So the bridge turned them into mono-blocks with 60 watts a side, or so.

Wayner

Nice.  So would that be equivalent to ~200w SS amps?

The amplifier in it's normal 2 channel mode is about 35 watts per channel, RMS. When used with the Phase Inverter, it turns the amplifier into a mono amplifier, summing up the 2 channels into 70 watts RMS (mono). So If you have 2 amplifiers, that would be 70 per channel or 140 total, not 200w.

Wayner 

Is that correct? Frank's website description states: This sums the voltage swing of the two channels, at least triples the power, and eliminates common mode distortion. Separation, imaging, and dynamics are improved. There is no better way to get such extraordinarily high power. I seem to recall past discussions of bridged Ultra 550s being 1 kW systems, too. That wouldn't be possible if the wattage only doubled.

Am I missing something? 

If I understood earlier discussions correctly, the tripling of output power is with the AVA solid state amps.  The U70 and UltraValve output power is doubled when bridged with the phase inverter bridge.

[Wayner]

Yes, OITP is correct.

Wayner 

[jtwrace]

If I understood earlier discussions correctly, the tripling of output power is with the AVA solid state amps.  The U70 and UltraValve output power is doubled when bridged with the phase inverter bridge.

So I was correct then...

[Wayner]

Yep.

Wayner 

[JerryM]

Is that correct? Frank's website description states: This sums the voltage swing of the two channels, at least triples the power, and eliminates common mode distortion. Separation, imaging, and dynamics are improved. There is no better way to get such extraordinarily high power. I seem to recall past discussions of bridged Ultra 550s being 1 kW systems, too. That wouldn't be possible if the wattage only doubled.

Am I missing something? 

If I understood earlier discussions correctly, the tripling of output power is with the AVA solid state amps.  The U70 and UltraValve output power is doubled when bridged with the phase inverter bridge.

Yes, OITP is correct.

Wayner 

I'm confused. Here is an old post regarding the Ultra Bridge, and U70 amplifiers:

We have brought back our hybrid phase inverter bridge completely modernized to Ultra standards with a new multi-stage regulated power supply, new audio circuits, and an astonishing level of performance -- it simply is so transparent it is not there at all.

We did it because the Ultimate 70 vacuum tube amplifier is soooo good, only lacking in absolute power, and we wanted to see just how useful it would be to run two Ultimate 70 amplifiers bridged, with an absolutely pure bridge - phase inverter circuit.

We did it.  It works.  The results are pretty magnificant.  A dual mono reasonably high powered vacuum tube power set that sounds nothing at all like a big vacuum tube amplifier.  Attacks and dynamics and range are oh wow startling, but no rough edges, no grain, no glare at all, just all of music, all of the emotions but no mud!

The connection is from your preamp to the left and right inputs of the Ultra Inverter, and from the left and right inverting and non-inverting outputs of the Ultra Inverter to the inputs of two stereo power amplifiers.  Then the speaker wires are connect from the hot terminals of each channels (ground side terminals not used) and on to your speakers.  The inverter sums the voltage swing of both channels, and since power is essentially voltage squared, the result is close to four times normal single channel power, subject to real world inefficiences of course.

Disadvantages, none except that you need two stereo power amplifiers and the Ultra bridge to make it work.  The configuration is not advised for low impedance speakers as the bridge connection causes your amplifier to look at a speaker load as being one half of normal, so this is not useful with 4 ohm speakers or less.

Thanks for listening.

Frank Van Alstine

Has this changed? How does the inverter know if it's being fed tube watts or SS watts?

Sorry to go OT, but I am curious about the true output of bridged Ultravalves.

Jerry