Just landed my dream amplifier....

[flez007]

Looks like a great buy Keith!, I have always lusted for VAC gear and the Phi series are definitely SOTA, I am sure you will get lots of pleasant listening hours on it.

 

[microstrip]

How is this amp getting 110 watts out of a pair of KT-88 tubes? My ARC VS115 uses four KT-120s per channel and it has roughly the same output. 60-75 watts is more the norm with a pair of KT-88s.

Modern KT88's used in class AB1 can supply more than 100W - see the KT88 Shuguang claims:

The KT88-Shuguang has an absolute maximum anode dissipation rating of 50W and is designed
for use in the output stage of an a.f. amplifier. Two tubes in Class AB1 give a continuous output of up
to 120W.

 

[mep]

Modern KT88's used in class AB1 can supply more than 100W - see the KT88 Shuguang claims:

The KT88-Shuguang has an absolute maximum anode dissipation rating of 50W and is designed
for use in the output stage of an a.f. amplifier. Two tubes in Class AB1 give a continuous output of up
to 120W.

In order to do that, they would have to run a very high plate voltage. And, tubes should never be run at their maximum design values if you expect long life out of them. The only way that I can see that VAC is getting anything close to the power output they are claiming is that they are running these tubes flat out to their maximum ratings.

 

[microstrip]

In order to do that, they would have to run a very high plate voltage. And, tubes should never be run at their maximum design values if you expect long life out of them. The only way that I can see that VAC is getting anything close to the power output they are claiming is that they are running these tubes flat out to their maximum ratings.

VAC amplifiers are known to be very reliable - at less my old PA80/80 could operate for several years with the same power tubes. It was a great amplifier and last time I heard about it it was driving a pair of Sonus Faber Amati homage with success. You would love the PA80/80 - it had four slots in the front panel for easy biasing with two color LEDs for each tube - no need to perform brain surgeries on them!

 

[c1ferrari]

Cool, Keith

Happy Listening

 

[MylesBAstor]

In order to do that, they would have to run a very high plate voltage. And, tubes should never be run at their maximum design values if you expect long life out of them. The only way that I can see that VAC is getting anything close to the power output they are claiming is that they are running these tubes flat out to their maximum ratings.

How does Luke Manley get the 450 watts from the same number of tubes as my cj that puts out 275 watts? Yet, my friends VTL MB450 Mk. II has been utterly reliable since the day he bought it.

 

[MylesBAstor]

VAC amplifiers are known to be very reliable - at less my old PA80/80 could operate for several years with the same power tubes. It was a great amplifier and last time I heard about it it was driving a pair of Sonus Faber Amati homage with success. You would love the PA80/80 - it had four slots in the front panel for easy biasing with two color LEDs for each tube - no need to perform brain surgeries on them!

I've had two VAC amps in over the years for review and both performed flawlessly. In fact, the old Rennaissance series was one of the best sounding tube amps of its day.

 

[JackD201]

VAC Phi Beta = Keeper

 

[KeithR]

In order to do that, they would have to run a very high plate voltage. And, tubes should never be run at their maximum design values if you expect long life out of them. The only way that I can see that VAC is getting anything close to the power output they are claiming is that they are running these tubes flat out to their maximum ratings.

My current Quad II 40s are rated at, well, 40 watts.

I don't need more than 20, so it's not terribly important to me - but I've never heard of Vacs burning through lots of tubes like Jadis or some other brands. In fact, doesn't VTL run tubes hard?

 

[microstrip]

(...)

I don't need more than 20, so it's not terribly important to me - but I've never heard of Vacs burning through lots of tubes like Jadis or some other brands. In fact, doesn't VTL run tubes hard?

Keith,
It is not easy to say what means harder. Tube loading will depend a lot on the characteristics of the output transformer, that are usually unknown. I can only refer to idle conditions : VTL operates their tubes at 575V 27mA, ARC at 420V 65 mA, I do not remember the VAC PA80/80 anymore. I only assume that the ARC runs harder because the power tubes of my VTL 750 are known to last longer (> 3500 hours) than those of the ARC equivalents (> 2000 hours) .

 

[A.wayne]

I'm not sure Kevin is a proponent of the KT120?

Not surprised , Luke Manley told me the same thing , surprisingly Bob Carver loves them ....

 

[A.wayne]

How does Luke Manley get the 450 watts from the same number of tubes as my cj that puts out 275 watts? Yet, my friends VTL MB450 Mk. II has been utterly reliable since the day he bought it.

Agree VAC and VTL Are very reliable amplifiers ......

 

[MylesBAstor]

Not surprised , Luke Manley told me the same thing , surprisingly Bob Carver loves them ....

And ARC, cj and Carver swear by them Typical audio story. Put 50 audiophiles in a room and you'll get 50 different opinions! Only one that counts is how it sounds in your system.

 

[kach22i]

Congrats on the purchase, it's a real beauty.

Turn up the A/C it looks like you could use it at a cook-out.

 

[KeithR]

Finally arrives tomorrow...seems like I have waited forever!

 

[KeithR]

Here are a few iPhone shots in the house- the unit is quite large, but exudes so much eye candy it's a welcome addition to my room. Sound is very, very good. Bass is tremendous. Will tube roll a bit as I move along, but what a sensational piece. It sounds better than the Vac Phi 200 I had in my system (with a diff preamp of course). Could be synergy, could be BT KT88s, no idea.

 

[Bill Hart]

Here are a few iPhone shots in the house- the unit is quite large, but exudes so much eye candy it's a welcome addition to my room. Sound is very, very good. Bass is tremendous. Will tube roll a bit as I move along, but what a sensational piece. It sounds better than the Vac Phi 200 I had in my system (with a diff preamp of course). Could be synergy, could be BT KT88s, no idea.

View attachment 6640 View attachment 6641

Great looking piece, enjoy~

 

[John Brooks]

Phi Beta 110i - tube rolling?

Keith, your post is a couple years old, but I just acquired the last 110i to roll out the door. It was held back for Kevin's personal use, then sold through their website 2 years ago. I saw it then, paused to reflect too long, and it went to someone else. He listed it on Audiogon earlier this month and I didn't hesitate this time! Took possession last week.

Curious what tubes you have (1) tried and (2) settled upon.

I've tried some NOS Sylvania 6SN&-GTA's with some success and Telefunken 12AX7's also with good success. Am waiting for a pair of 12AX Bugle Boys to arrive. Thinking about a pair of Tung Sol balck glass 6NS7's.

Don't want to wait for the long burn-in of the Treasure tube 88's, so will stick with Kevin's specially spec'd Shuguang SC's.

My previous amp was the VAC Sigma 160i integrated which sounded great and with which I was very happy. But the Phi Beta is several notches better. Soundstaging is immense, dynamics are like nothing I've ever heard before, imaging is focused and palpable, noise floor is oh-so low that I can hear low level information that was inaudible before.

Will be my amp for life for sure.

Feel free to post or PM me with your thoughts.

Thanks, John

Here are a few iPhone shots in the house- the unit is quite large, but exudes so much eye candy it's a welcome addition to my room. Sound is very, very good. Bass is tremendous. Will tube roll a bit as I move along, but what a sensational piece. It sounds better than the Vac Phi 200 I had in my system (with a diff preamp of course). Could be synergy, could be BT KT88s, no idea.

View attachment 6640 View attachment 6641

 

[Holli82]

I want to play too!

I've tried Red Lions, Shuguang Treasures, now back to VAC spec Shuguang 88's.

 

[Shadowfax]

Hi all, new guy on the block.

I see this thread is a bit old, but wanted to chime in with feedback on VAC longevity. I am the second owner of a VAC CLA1 MKII Pre-Amp from the 90s. When I got it, it was tubed incorrectly, which I rectified with some tubes I had in stock. Knowing it could do better, I reached out to VAC for advise. Kevin Hayes spent a good deal of time on the phone with me explaining lots about his gear and how/why he chooses the tubes for each pc.

I ended up ordering both 12AU7s and 12AX7s from Kevin, which are what he uses in new gear and what he recommended for my older Pre. I love VAC gear and have it coupled with a Counterpoint NPS-400 driving Clearfield Continentals with all Synergistic cabling. I purchased this complete setup from a neighbor who was the original owner.

The only downside to this Pre is no Remote and 2 separate Volume Knobs to adjust, with click stops. I like to use the Buffered Passive at night and the Normal Gain during daytime sessions.

I would live to be able to afford some newer VAC gear.

Cheers,

Brian