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Different Tubes and general purpose?

I’m trying to get a better midrange push or clarity out of my Line Magnetic 501ia tube amp.   Can someone help me understand what the specific function each type of tube performs in a power amp?  

I would like to upgrade several or all of my “stock” tubes but would like to understand where to start to beat enhance each aspect of the sound spectrum.   On my 501ia i have 4x KT120 and i believe those are power tubes, but please help clarify if wrong.  There are 2x 6SN7EH 1x 12AU7 and 2x 12AX7 (but the AU7 and AX7 look interchangeable to me).   As i look to upgrade where to i look to start, and why?  
Thanks in advance for help. 
gunners01
ggc
178 posts
 
Hi gunners01

I have an amp that uses a similar tube compliment. This is what I have done. And it made a Significant Difference! 
Perhaps it can help you in your search towards refining your sound.
 
On the Line Magnetic Website:
https://www.line-magnetic.eu/en/products-line-magnetic-en/integrated-tube-amplifier-line-magnetic-en/lm-501ia-amplificateur-int%C3%A9gr%C3%A9-push-pull-kt120-2x100w-detail

They include this helpful  info:

Tubes Basics              Common Replacements

12AX7                         12AX7EH, ECC83, E83CC, CV4004, ECC803,                                          5751
12AU7                         ECC82, 12AU7EH, 5814, 6189, CV4003

6SN7                           6NP8, 6H8C, 6H8M, 6F8G, CV181, QB65,                                                  ECC32

As others have mentioned, I too have used Brent Jessee as a resource to educate myself on the differences - 

https://www.audiotubes.com/

For the 12AX7/AU7 - I have tried Telefunken, Mullards, Heath, Mazda and Siemens.

Currently I have been very pleased with.. 

2EA. 13D5 /12AU7 Brimar longplates and 1EA. E83CC Siemens 

This combination has the right amount of detail and musicality for me. Increased the depth of the soundstage, fleshed out details in midrange.

Although I find that the Telefunkens are the most detailed, they seem too focused on the upper end, and conversely the Mullards can be too sweet sounding and not capturing the same details in the midrange.

I do not use the 6SN7 Tube, but If I did, I would be inclined to look towards RCA, Westinghouse or GE.

On the Line Magnetic Website they state:

Tubes we choose are.... and Tung-sol KT150

The KT 150s are expensive so perhaps start off rolling the signal and driver tubes, and then move to the KT150s or see if LM would give you a break on a set of replacement KT150s.


Every bit counts, so replacing stock fuses and power chords do help.

I have been happy with Isoclean Audio Grade Fuses

https://www.vhaudio.com/isoclean-fuses.html

Power chords is subjective - cable company has a lending library

https://www.thecableco.com/lending-library


Best of Luck


lowrider57's avatar
lowrider57
5,393 posts
 
Good find on the tube info.
TUBES
Input stage: 2x 12AX7
Rectifier: 1x 12AU7
Drivers: 2x 6SN7 (Electro Harmonix)
Power stage: 4x KT150 (Tung-sol)

The tubes that influence the sonics the most are the 12AX7 inputs. They are the preamp and the input gain to the amplifier. This gain stage has a high amount of voltage, thus the sonic signature of different tube brands will be most audible.  
The drivers will have a lesser effect on sound. Their job is to
take the input signal and split it into two identical signals, each 180 degrees out of phase with each other. These signals drive the output tubes. IMO, you can live with the stock 6SN7s for now.
Rolling rectifier tubes most definitely influences the sound.


lowrider57's avatar
lowrider57
5,393 posts
 
You have very low hours on your amp. To increase the burnin process you can leave the amp powered up while you are home. Never leave a tube amp unattended.
You only need to have the amp turned on, no components, no music, but the amp must be connected to the speakers.


oddiofyl's avatar
oddiofyl
3,450 posts
 
My amps can take many different output tubes....  that said , it sounds completely different based on the output tube.   The input tube also changes the character of the amps.    It was voiced using EL34 and even the different brands have their own sonic signature ...    currently using JJ EL34 and it is the best sounding of its type I've used.
papafrgog
101 posts
 

I run all Aesthetix Eclipse gear: Atlas monos, Janus pre and Romulus DAC/transport. Fully upgraded LP12 with Lyra Kleos (please don't bash the Linn) and Raidho TD2.2's.   My system is pretty much where I want to be.  I rolled tubes in my Aestheix gear for about 18 months before I got what I wanted.  Major impact will come from the transformers and caps (mention above). I noticed this when I upgraded my DAC to the eclipse model.   

The more resolving your system, (obviously) the more dramatic the effect of different tubes. My experience (guided by the fine people at Aesthetix - Jim and Glenn) was the biggest jump in SQ was in the phono preamp. V1 will have the most impact. I tried PSvane, Treasure, Gold Lions, Tele NOS, and finally found it in Amperex ultra low noise12AX7.  Moved the Tele's to V2 and V3 and changed from (6DJ8)6922s to 7308s. For me it was all about low noise floor - which opens up every other sound spectrum IMO.

Changed to Tele 12AX7 NOS and Mullard 7308s in my DAC/CD - which for me really gave it the analog sound I wanted. Based on my experience. I prefer NOS versus new tubes. 

Takeaway:  get everything else where you want it to be first. including your room acoustics!  Identify what you want to improve and check out what Brent Jesse has to offer.  His descriptions are good and will help you identify a possible solution at a given price point. Be careful, with NOS tubes, there are a lot of imposters out there. 

Make it fun.  Enjoy the process.  Good luck

 




 

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