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Prima Luna Prologue 2 tubes due for change?


exSG

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Hi All,

 

Can anyone kindly tell me if my tubes are due for a change?

Can the tubes be rolled to kt150? If so what brand best suits and where to buy please?

My listening room is 3.5 m wide and 5 m long. Mainly vocals and instruments.

Speakers are 805s. Would it be too boomy?

 

Thanks.

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It's my impression that the KT150 is better in every setup, provided the amplifier is designed to take it, though others would disagree. While the KT150s are better in every measurable way, you may prefer the sonic signature of your existing valves, and an amp may not be designed to really make the most of them even if it's compatible. They are also a LOT more expensive than the KT88s you currently have. There is ONLY one brand of KT150s on the market so you have no choice there, but there is the matter of matching which varies according to the seller - upscaleaudio probably have the best matching around if you wish to go that route.

 

Valves don't usually "need" a change unless they start misbehaving - no sound, popping, crackling, noisy whooses in response to microphonic sounds etc. Try tapping the top surface of the amp to listen for microphics (don't tap the tubes.) It's hard to know if you'll benefit from changing them due to age alone without actually trying a new set of valves. Over thousands of hours of playing the sound will change so subtly that it'll never be obvious that the sound has deteriorated, however there is one simple rule - if it still sounds good to your ear absolutely, then there really is no need to change them (even if relatively the sound has deteriorated and you haven't noticed.)

 

If you're planning on keeping the amp for quite a while longer, the easiest thing to do is buy a new set of valves and try them - if it doesn't sound any better, take them out and store them, and keep using your existing ones.

Edited by Ittaku
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I thought the earlier Prologues were rated to take up to KT120's?

 

Might be best to call the PrimaLuna distributor in Australia which I think is Magenta and ask the question.

I also really enjoy KT150's and wouldn't be without them, however even if your amp is restricted to KT120's I would still try them, most reviews I have read from PL owners is the KT120 are a very decent improvement over KT88's. Regarding boominess, the KT88's are the most bass driven tube I have heard so far, I believe with KT120's you may find you lose some of that and gain every where else.

 

 I know plenty of people really enjoy their KT88's but out of all of the main tubes I have had in my PL amp to me anyway they are the least desirable, but that's my preference only.

 

Good luck with what ever you decide to do with power tubes.

 

Just noticed these for sale it might be an idea to check these 12ax7's out as well.

 

 

cheers Terry

Edited by TerryO
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1 hour ago, Janjuc said:

Hi @exSG ,

 

From the Prima Luna website:

 

"In addition to KT88s, you can use 6550, KT90, EL-34, KT77, 6CA7, 6L6GC, KT66, 7581, EL37, and any of their equivalents."

 

JJ

I would still ask Magenta, most of the info pages for the various PrimaLuna amps look like they have not been updated since the amps release which can be quite a few years ago, often before either KT120 or KT150's were even available.

 

cheers Terry

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Thank you all for sharing the info.

 

The tubes are not making any of the crackling noises.

 

I kinda like the bassy kt88. I feel it has more than sufficient power to drive the 805s but was wondering how much more power the kt150 will give it in terms of control.

 

Cheers.

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  • 3 months later...

Hi All,

 

I bought a quad of second hand kt88 prima luna recently and could hear an improvement over my old tubes. Unfortunately one blew up into the second week.

Have now bought a quad of Tung Sol KT120 and a pair each of 12AX7 and 12AU7 Gold Lion gold tips from Evatco. Kevin was nice to deal with. Looking forward to receiving the new tubes now.

Intend to leave the preamp tubes and change the power tubes first to hear the difference. Then change out the preamp tubes. 

Just to confirm - I can change the tubes without needing any biasing or added work right? After seeing one KT88 blow, I am a little nervous. Would changing all eight tubes at the same time have any issues?

Will need to sell the remaining KT88s now.

Thanks.

 

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3 minutes ago, BATMAQN said:

Shouldn't be a problem

 

 

This may be of interest

https://forum.audiogon.com/discussions/rolling-kt150s-in-primaluna-hp-integrated

Thanks for your reply Batmaqn.

I read this thread as well before making the purchase. Probably read all the threads available on tubes and prima lunas. 

Unfortunately my prologue 2 cannot take KT150 otherwise I would have taken the plunge.

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I reckon you will be very happy with the KT120's they are in my opinion a nice step up over the KT88's and will change the sound of your amp considerably. Looking forward to reading your feedback, if you are buying new you need to give them a good twenty plus hours of burn in for them to start sounding near their best, they could sound a bit bright and brittle when new.

 

cheers Terry

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Hi Terry,

 

Thanks for your reply. Your posts in this forum provided me invaluable insight to make an informed decision on which tube to buy; especially when I haven't got a chance to hear any of these tubes. I nearly bought the EL34 seeing that it is the stock tube for Dialogues but changed my mind after I reread the posts and also saw that KT120 are the second best selling tube on upscale audio, after Gold Lion KT88. Recalled I tested the Prologue 1 before buying the 2 and preferred the 2 as it had more power over the EL34s.

Look forward to hearing the difference.

Thanks again. ?

 

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  • 2 weeks later...

Hi All, 

I received the new tubes yesterday and so far the kt120 have clocked over an hour. I can already hear the family sound of kt88 but it is better in all areas bass treble airy top end micro details depth. Strong powerful well controlled sound. Very happy with the purchase. ?

 

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Good to hear that you are happy with the KT120's exSG, even with only one hour up on them. I'm looking forward to hearing what you think when they have more then twenty plus hours or so up on them. Now for a couple of NOS gain tubes and your PL will sound like a new amp.

 

cheers Terry

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My grouch is it does not glow like kt88.

 

With kt88, my volume knob is normally around one quarter. Now it is half of that. Spent another hour listening just now. The vocals are very forward, detailed and real. Very live. Nils Lofgren guitar was crisp and shimmered. Felt like i was in the studio with Jeff Buckley singjng hallelujah. 

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Slotted in the gold lions tubes this evening. I must say this probably is the best i have heard this system sound from memory. 

Deep bass, airy extended highs, big and deep soundstage, natural clear vocals, crisp with great transient norah track 13. Can hear clearly the light tapping of cymbals. Very musical with good pace.

I would think kt88s would be similar to primare i30 but this combi makes music so much more enjoyable esp if vocals and instruments.

The prologue 2 is a great value for money amp.

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I must add there is a much bigger sound difference between kt88 and kt120 than prima luna to gold tip gold lions pre amp tubes.

And it can play loud, very loud. If your ears and neighbours can handle it. ?

Edited by exSG
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  • 2 weeks later...

I have a Dialogue Premium and have Kt 88, 120and 150 tubes.  There is a dramatic and satisfy difference between the 88s and the 120s which are my favourites.  I find the 150s just intrude a little bit too much into the music for my tastes.  They are a bit in your face and I lose the subtle and quiet.  Fabulous power and projection however

 

What truly fabulous amp these are

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Hi Jamesrc,

 

I noticed that the KT120 is more forward sounding than KT88; so I am not surprised if KT150 is even more forward and powerful sounding.

I feel the system has become very transparent in that I can easily hear bad recordings compared to before. It is like the extra power has magnified any imperfections or subtleties.

Perhaps KT88 is more suited to easy listening and KT120 is a good blend between KT88 and KT150?

 

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It is a pity you are not Sydney based as I could loan you the 150s. 

 

I do forget to flip between Ultralinear and triode as often as I should, but the triode helps deal with the excessive enthusiasm you get with some recordings and the 120s

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10 hours ago, jamesrc said:

It is a pity you are not Sydney based as I could loan you the 150s. 

 

I do forget to flip between Ultralinear and triode as often as I should, but the triode helps deal with the excessive enthusiasm you get with some recordings and the 120s

Thanks for your kind offer.

From what i read, the prologue 2 cannot take KT150. It also does not have switchable ultralinear or triode modes.

In its current form, it really reveals what the 805s max performance capability is especially in terms of high frequency...there is enough juice to push the drivers.

I think 805d3s and dialogue premium HP would be perfect.

Edited by exSG
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