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Primaluna Evo 300 and Cornwall IVs


T_Evans
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6 minutes ago, T_Evans said:

With regards to speaker wire connection to the Evo, how many are using bare wire wrapped around the post, or using spade connectors? I was recommended Furutech FP-201(G) connectors at about $24 Cdn each. I'm a fan of using bare wire connections, but I find without a hole in the pots, I'm nervous about stray wire strands after wrapping them around the post.  Worth spending the $100 to have piece of mind not having a short, and a secure connection with the spade? Any degrade in the audio?

 

You could  use ferrules to have a good connection prior to installing the Furutech Connectors ,

 

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On 5/11/2021 at 7:56 PM, T_Evans said:

With regards to speaker wire connection to the Evo, how many are using bare wire wrapped around the post, or using spade connectors? I was recommended Furutech FP-201(G) connectors at about $24 Cdn each. I'm a fan of using bare wire connections, but I find without a hole in the pots, I'm nervous about stray wire strands after wrapping them around the post.  Worth spending the $100 to have piece of mind not having a short, and a secure connection with the spade? Any degrade in the audio?

I use Blue Jean Cable locking banana plug wires for all my speaker connections and they work fantastic from my Forte IVs to my Evo Amplifier.

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On 5/12/2021 at 12:11 AM, Fido said:

I use Blue Jean Cable locking banana plug wires for all my speaker connections and they work fantastic from my Forte IVs to my Evo Amplifier.

 

Yup.  Getting ready to pull the trigger on a custom pair of speaker wires for my rig (forks for the Belles, spades for the Quicksilver binding posts) from BJC to never have to worry about it again.  Soldering and crimping your own ends sucks if you're not an EE, and trying to strap your own damn bare wire to the terminal screws is not fun. 

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  • 2 months later...
On 5/17/2021 at 8:46 PM, GriffinFL said:

 

Yup.  Getting ready to pull the trigger on a custom pair of speaker wires for my rig (forks for the Belles, spades for the Quicksilver binding posts) from BJC to never have to worry about it again.  Soldering and crimping your own ends sucks if you're not an EE, and trying to strap your own damn bare wire to the terminal screws is not fun. 

I love all the cables I have purchased from BJC - they are awesome

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  • 1 month later...
  • 1 month later...

Sorry for the late update. Was able to totally illuminate the HT hum with this iso transformer from Amazon:

 

Ancable Ground Loop Isolator,Isolation Transformer,Hum/Buzz/Noise Eliminator for Cable TV Applications https://www.amazon.ca/dp/B074KD8X6S/ref=cm_sw_r_cp_api_glt_i_Q650WMMX4X02AY7EEMP8?_encoding=UTF8&psc=1

 

Thanks @rebuy and everyone for the help!

 

I’ve also pulled the trigger on the KT150s and have ordered a pair of RFT 12AU7s for the gain and two more Mullard 12AU7s for the remaining preamp sections. Excited for those to arrive! Anyone else running the 150s? Did you keep the speakers on the 4 ohm taps? Anything dangerous using those taps with the higher powered tubes? 
 

Was listening to The Wall last night, and it was blowing my mind how good it sounds. Hadn’t spun that album since getting the PL!

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I am curious what you think of the KT150, yes you can get more power with the KT150 vs the KT88, not sure what the increase is with the PL amps but to gain +3db in sound pressure from the speaker you need to double the amplifiers output power. In this case there is no way the power will double so the actual increase in power is negligible to the ear, just a hair more headroom at most but the plate curves for the KT150 is just plain awful, much worse in linearity vs KT88. Luckily this amp uses a fair amount of negative feedback to clean things up but starting with a more linear device is always best.

 

Here are the output plate curves. You can see how wobbly the KT150 is yikes!! Also note that KT stands for kinkless tetrode, the KT150 curves clearly show the negative resistance kink, definitely not good for audio and bias well away from that area.

 

 

kt88.png

kt150.png

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18 hours ago, captainbeefheart said:

I am curious what you think of the KT150, yes you can get more power with the KT150 vs the KT88, not sure what the increase is with the PL amps but to gain +3db in sound pressure from the speaker you need to double the amplifiers output power. In this case there is no way the power will double so the actual increase in power is negligible to the ear, just a hair more headroom at most but the plate curves for the KT150 is just plain awful, much worse in linearity vs KT88. Luckily this amp uses a fair amount of negative feedback to clean things up but starting with a more linear device is always best.

 

Here are the output plate curves. You can see how wobbly the KT150 is yikes!! Also note that KT stands for kinkless tetrode, the KT150 curves clearly show the negative resistance kink, definitely not good for audio and bias well away from that area.

 

 

kt88.png

kt150.png

The KT88 looks smoother, better. Sometimes I really don‘t know how much marketing bla bla is the trigger to make alleged improvements. But I don't want to spoil anyone's fun in experimenting and trying things out. It is part of the hobby to collect different sound experiences.

 

I would always use the good standard type for which an amp was originally designed. 

I admit that I also hear differences, e.g. a 6550 on my MC275 sounds different than a KT88. And I seem to remember that Mcintosh used to ship both types in the 60's using the same circuit. Most likely, the KT88 and 6550 will be much closer together in terms of electrical values and energy consumption compared to the KT150.

 

Back to the KT150 why should I choose a tube that tortures the current and voltage supply of my amp more?

 

The rest of this post I have ported to a new thread regarding the benefits of parallel power tubes.

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20 hours ago, captainbeefheart said:

I am curious what you think of the KT150, yes you can get more power with the KT150 vs the KT88, not sure what the increase is with the PL amps but to gain +3db in sound pressure from the speaker you need to double the amplifiers output power. In this case there is no way the power will double so the actual increase in power is negligible to the ear, just a hair more headroom at most but the plate curves for the KT150 is just plain awful, much worse in linearity vs KT88. Luckily this amp uses a fair amount of negative feedback to clean things up but starting with a more linear device is always best.

 

Here are the output plate curves. You can see how wobbly the KT150 is yikes!! Also note that KT stands for kinkless tetrode, the KT150 curves clearly show the negative resistance kink, definitely not good for audio and bias well away from that area.

 

 

kt88.png

kt150.png

I didn’t look for charts or graphs for the 150, just went by what others have stated with their experience with them with the same amp and similar speakers.  I’m no expert with this, but if PrimaLuna states in their material that the amp is fully capable of running the 150, I’m inclined to believe them. I installed them last night, and I can unequivocally concur with every else’s experience that they have a far more powerful low end, and they make the Cornwalls sound absolutely amazing, and that’s right out of the box! I’m looking forward to them being burned in after a few more days to see how they really open up! Maybe I’ll try the KT88s next once the 150s have served their time. 

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25 minutes ago, T_Evans said:

I didn’t look for charts or graphs for the 150, just went by what others have stated with their experience with them with the same amp and similar speakers.  I’m no expert with this, but if PrimaLuna states in their material that the amp is fully capable of running the 150, I’m inclined to believe them. I installed them last night, and I can unequivocally concur with every else’s experience that they have a far more powerful low end, and they make the Cornwalls sound absolutely amazing, and that’s right out of the box! I’m looking forward to them being burned in after a few more days to see how they really open up! Maybe I’ll try the KT88s next once the 150s have served their time. 

 

I did not mean to say the amp cannot run those tubes, everything has trade offs so I was more interested in what is gained and what is lost changing power tubes. My guess the better bass is from the lower output impedance but since the KT150 is much less linear I am curious to see a distortion vs frequency plot between the two tube types because often higher even harmonic distortion at low frequencies can be confused with more bass. I presume it is the lower impedance and increased current that with the KT150 that is giving you the better bass performance. BUT, is the midrange and top end as nice compared to the KT88? Has anything else changed besides the better low end? I am in the camp where I feel one tube is optimized for an amp and whichever gives the better overall performance is what should be in there.

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Ah, understood. So far as my ears can tell, zero loss in mids at all, and the highs seem just as nice also. I find the sound stage width expanded as well. So for me it sounds more like a solid state in terms of the bass, but the mids and highs have the beauty tube sound! It would be interesting to see it plotted, but to my hearing, I’m loving the power and the detail with the 150s. 👍

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On 11/13/2021 at 6:58 PM, T_Evans said:

Ah, understood. So far as my ears can tell, zero loss in mids at all, and the highs seem just as nice also. I find the sound stage width expanded as well. So for me it sounds more like a solid state in terms of the bass, but the mids and highs have the beauty tube sound! It would be interesting to see it plotted, but to my hearing, I’m loving the power and the detail with the 150s. 👍

Thanks for sharing... your speaker/amp combo is high on my list of my next 2 channel system, I haven't had one in over 10 years now. I've been using my HT system since then which is surprisingly good, but I would still like to also have a good 2 channel system for my music listening.

 

Being a fellow Canadian I'm curious as to where you are getting your tubes from? I've never owned a tube rig yet but it does sound like a lot of fun.

 

 

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