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Anyone running KT120 & KT150 together in PrimaLuna?


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Just wondering if anyone else is running KT120 & KT150 at same time in their PrimaLuna amplifier?

 

I have a PrimaLuna Dialogue Premium HP and have been running it for 3 years since new with eight KT120s.
Just for the heck of it I purchased a Quad matched set of KT 150s from Evatco and plonked them in the front row while keeping the KT120s in the back row.

 

image.png.2b2ce06b5a9869b57b63948e4d3925e8.png

 

Wasn't going to lay down $1,380AUD for four Tung Sol KT150s branded PrimaLuna, when I could get four Tung Sol for $550AUD just for a bit of fun.

 

image.png.972ab71f46afab51f4871fb874d0fc84.png

 

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3 hours ago, rockpig said:

Just wondering if anyone else is running KT120 & KT150 at same time in their PrimaLuna amplifier?

 

I have a PrimaLuna Dialogue Premium HP and have been running it for 3 years since new with eight KT120s.
Just for the heck of it I purchased a Quad matched set of KT 150s from Evatco and plonked them in the front row while keeping the KT120s in the back row.

 

image.png.2b2ce06b5a9869b57b63948e4d3925e8.png

 

Wasn't going to lay down $1,380AUD for four Tung Sol KT150s branded PrimaLuna, when I could get four Tung Sol for $550AUD just for a bit of fun.

 

image.png.972ab71f46afab51f4871fb874d0fc84.png

 

Did that mix work? I've used kt80, kt120, kt150 and el34 with them. But never mixed them before. Is it safe? Have you tried it? 

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1 hour ago, DMax said:

Did that mix work? I've used kt80, kt120, kt150 and el34 with them. But never mixed them before. Is it safe? Have you tried it? 

 

Yep, have been running them together for a bit over a week now. not a problem.

I believe the auto biasing is taking care of the difference in valves.
Obviously you cannot mix EL34 with KT120/KT150

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Just now, rockpig said:

And the reason being?

They are different tubes.

 

Was the circuit designed with this in mind to do?

 

How often do you see this kind of thing being done? never! apart from the odd guitar guy with his guitar amp.

 

Why? It's bad practice.

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Just because something can be done and works without smoke and tears, does not mean It should be done.

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16 minutes ago, muon* said:

Just because something can be done and works without smoke and tears, does not mean It should be done.

From memory, PL have an Auto bias that caters for this.

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No need to buy the overpriced PL branded Tung Sol KT150.

Banzai Music will do a matched octet for $830aud incl. postage. https://www.banzaimusic.com/cart.php

I'd be confirming your mix 'n' match manoeuvre with PL.

Is the setting on the amp for KT120/150 one and the same?

 

 

Edited by deanB
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46 minutes ago, Wimbo said:

From memory, PL have an Auto bias that caters for this.

So they advise customers to mix different power tubes?

 

If they have done it for this reason I better make sure I never own one.

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40 minutes ago, muon* said:

So they advise customers to mix different power tubes?

 

If they have done it for this reason I better make sure I never own one.

Suggest you read up on the following articles which discusses how Primaluna are doing things differently.

https://www.primaluna-usa.com/adaptive-autobias

https://www.primaluna-usa.com/tube-rolling

 

Kevin Deal (Primaluna USA) says the stock tubes are excellent, but recognises that some people like tube rolling.  The adaptive autobias allows people to experiment without doing any harm. Whether it sounds better is another thing...

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14 minutes ago, Snoopy8 said:

Suggest you read up on the following articles which discusses how Primaluna are doing things differently.

https://www.primaluna-usa.com/adaptive-autobias

https://www.primaluna-usa.com/tube-rolling

 

Kevin Deal (Primaluna USA) says the stock tubes are excellent, but recognises that some people like tube rolling.  The adaptive autobias allows people to experiment without doing any harm. Whether it sounds better is another thing...

Don't need to read it.

 

Sounds messy mixing two different tubes at the same time, different operating capacitance and maybe impedance (New Sensor doesn't disclose all the specs).......and different curves..............Yuck!

 

Edit: I guess Primaluna are not for me.

Edited by muon*
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I have seen a video where Primaluna ran four different power tubes in one amp. They did this demonstrate the adaptaive bias but did not recommend mixing the tubes for actually listening.

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Is there a switch on the PL amps that allows mixing KT120's with KT150's in PP arrangement? Or is the adaptive auto bias set always to a default current draw regardless of tube type inserted?

 

I have played around with this concept for many years.

 

My suggestion is two-fold: 1) get yourself a quad set of tube socket adapters from flea Bay that allow you to measure plate current through a cathode resistor and plate voltage with a DVM: 2) use the FTBC lite mobile app and enter in these 2 values and work out if these are in the cold (blue), proper (green) or hot biased (red) range for the given tube type. You are then in control of flying that A380 for safe touch down.

Edited by xlr8or
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At the 4 minute mark of this video he details the HP amp running 8 different output tubes. Again this is just to demonstrate the adaptive biasing. Running a mixed bag of tubes would, in my opinion (and Primaluna's), compromise the sound.

 

https://www.primaluna-usa.com/adaptive-autobias

Edited by kelossus
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The switch allows changing between EL34's and KT88's. I suspect plate voltages are fixed for these 2 tube types with the adaptive autobias circuit changing and maintaining plate current to suit each tube type. I also gather that when using anything more than a KT88 it will run cold bias.

 

DSC_0853.thumb.JPG.9edb8d6437065d943456e9508cf84743.JPG.jpg

Edited by xlr8or
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Lots of experts. Some of whom don't even own PL gear. If what you have done is working, sounds good. Then enjoy 😎.

Edited by cafe67
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PL does not change the two different types of valves inserted so no reason owning one makes a shred of difference when looking at this type of tube use.

 

Edit: sure it can be done, and some may even like the results, I once had three different caps paralleled to make up a value in a XO and I liked the sound at the time, caused an echo effect.....but did I keep it like that or would I do it again, nup.

 

So yeah, lots of things 'can' be done.

Edited by muon*
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  • 6 months later...

6 month update
I have been running KT120 and KT150 in my PrimaLuna Dialogue Premium HP since August 2020.
I like it and have not had any issues.

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