M-125 First Build!

Hi guys,
This is my first post here.  However, I am a member in other forums and enjoy this hobby as much as the majority of you folks out there.  I just want to share some impressions I shared with another member in another forum follow by some pics! I also want to mentioned my speakers are Magnepan mg12s with outboard crossover.  The preamp is a BAT vk-30  and a Yulong D-100 DAC.  Moreover, currently I am using only two output tubes per amp and a Weber wz68 rectifier.
    I've done just a little bit of listening. So far I noticed when listening in triode the amp is not as loud but it sounds more natural and real.  To me, the difference in both male and female voices are just a bit clearer in triode but it also has less bass with pentode being more punchier. I will report back when I get to do more listening.
    So far everything is excellent! I don't listen loud so I might leave it in triode. I use two subwoofers so if there is some bass lacking the subwoofers will take care of that. The bias is spot on!  
    After some more listening I found the speakers sound more dynamic in pentode mode and preferred them that way. However, after few more days of listening the high frequencies were starting to sound unpleasant and all over the place. Nevertheless, I know how placement picky magnepan speakers are. I recognized the issue and attributed the unpleasant high frequencies to the placement of the speakers. I guess the frequency response from a solid state amp and tube amp are not the same? But anyway, I started playing with the placement and after some toe in adjustment everything is now just beautiful!!!! I listen at around 70 to 74 dbs and I don't feel the need to crank it anymore as I feel and hear what I like at those levels. In addition, I haven't try to play music extremely loud. In another note, these amps are super quiet!
    This was my first amp build ever and I would like to suggest that you take your time and follow the instructions Step By Step!
  These past couple of day I have found  myself switching back and  forth from pentode to triode and I think is fantastic to have this option.  I listen to all music genres but particularly Classic Rock, Vocal Jazz and Spanish Salsa as well as Latin Jazz.

Lookin' good, and many years of listening pleasure!

The PT switches CAN help some for compensating for the room and speakers, but that's a bit of a bandaid approach, as there's no substitute for proper placement and tuning the room. You did discover the real advantage of the PT switches ... different types of music just sound better depending on how you set the amps. Triode is mostly jazz and laid back orchestra. You do lose power, but that doesn't sound like it's a problem for you. I like prog rock and I like it LOUD with a side of PUNCH, so I spend most of my time in pentode. Same holds true for orchestral in most cases as I use a dbx expander and that can really suck up amps in the crescendos ...

And ya ... every amp sounds different and will require some tweaks to the listening environment. Keep at it, and you may be amazed at the results compared to what you're getting now. Took me 30 years to get it right ... almost ... just ... one ... more ... tweak ...

** Not to forget, you can make some MAJOR changes in what you hear experimenting with tubes. The drivers especially can make it sound like an entirely different system.

Precisely!  I definitely want to try different driver tubes when funds start to recover....

Nice work, Pedro!!!

Thank you Bill!

Congrats on the new build.  Any reason why you are just running 2 tubes with Maggies?

I have been eying them for a while, but would like a little more juice to drive larger Maggie panels.

I didn't have enough cash for four tubes at the time but I am now running four tubes per amp!

pedrocols wrote:I didn't have enough cash for four tubes at the time but I am now running four tubes per amp!

How did your Maggies respond with 4 tubes versus 2 tubes?

I found the triode mode exceptionally better with four tubes.  The pentode mode is about the same.  Mind you, I don't listen very loud.

pedrocols,
Nice-looking build, sir.
What output tubes are you using? From the camera angle they look like new 6550s. Quite a variety of options there (KT-88s, -120s, etc.) but I would concur with sKiZo that you'll get more bang for the buck upgrading your driver tubes. GE made some very nice 12BH7A novals that fit nicely into those driver holes; they're not too expensive and IMHO will give you a huge improvement over the EH's you're using.
Be sure when you're tube-rolling to give the sockets a cleaning with DeOxit and a bit of re-tensioning to ensure good pin contact.
There are far more exotic tubes than the NOS GEs but they work for me on the driver boards. I prefer RCAs in my preamps but the GEs worked better in my M-125s.
Enjoy.
dave
P.S., welcome to the booby hatch!

deepee99 wrote:pedrocols,
Nice-looking build, sir.
What output tubes are you using? From the camera angle they look like new 6550s. Quite a variety of options there (KT-88s, -120s, etc.) but I would concur with sKiZo that you'll get more bang for the buck upgrading your driver tubes. GE made some very nice 12BH7A novals that fit nicely into those driver holes; they're not too expensive and IMHO will give you a huge improvement over the EH's you're using.
Be sure when you're tube-rolling to give the sockets a cleaning with DeOxit and a bit of re-tensioning to ensure good pin contact.
There are far more exotic tubes than the NOS GEs but they work for me on the driver boards. I prefer RCAs in my preamps but the GEs worked better in my M-125s.
Enjoy.
dave
P.S., welcome to the booby hatch!

Thank you Sir. I am currently using KT88s.

pedrocols wrote:I found the triode mode exceptionally better with four tubes.  The pentode mode is about the same.  Mind you, I don't listen very loud.

Is this the kind of tubes you recommending?
http://www.ebay.com/itm/Vacuum-Tubes-RADIO-TUBES-GE-12BH7A-2-NOS-NIB-/321612019164?pt=Vintage_Electronics_R2&hash=item4ae191f5dc

deepee99 wrote:pedrocols,
Nice-looking build, sir.
What output tubes are you using? From the camera angle they look like new 6550s. Quite a variety of options there (KT-88s, -120s, etc.) but I would concur with sKiZo that you'll get more bang for the buck upgrading your driver tubes. GE made some very nice 12BH7A novals that fit nicely into those driver holes; they're not too expensive and IMHO will give you a huge improvement over the EH's you're using.
Be sure when you're tube-rolling to give the sockets a cleaning with DeOxit and a bit of re-tensioning to ensure good pin contact.
There are far more exotic tubes than the NOS GEs but they work for me on the driver boards. I prefer RCAs in my preamps but the GEs worked better in my M-125s.
Enjoy.
dave
P.S., welcome to the booby hatch!

Is this the kind of tubes you recommending?
http://www.ebay.com/itm/Vacuum-Tubes-RADIO-TUBES-GE-12BH7A-2-NOS-NIB-/321612019164?pt=Vintage_Electronics_R2&hash=item4ae191f5dc

pedrocols wrote:

pedrocols wrote:I found the triode mode exceptionally better with four tubes.  The pentode mode is about the same.  Mind you, I don't listen very loud.

Is this the kind of tubes you recommending?
http://www.ebay.com/itm/Vacuum-Tubes-RADIO-TUBES-GE-12BH7A-2-NOS-NIB-/321612019164?pt=Vintage_Electronics_R2&hash=item4ae191f5dc

Those are the ones. Not a bad price, either.

deepee99 wrote:

pedrocols wrote:

pedrocols wrote:I found the triode mode exceptionally better with four tubes.  The pentode mode is about the same.  Mind you, I don't listen very loud.

Is this the kind of tubes you recommending?
http://www.ebay.com/itm/Vacuum-Tubes-RADIO-TUBES-GE-12BH7A-2-NOS-NIB-/321612019164?pt=Vintage_Electronics_R2&hash=item4ae191f5dc

Those are the ones. Not a bad price, either.

Thank you! I will give them a try. So should I get four or only the two for the front?

pedrocols wrote:

deepee99 wrote:

pedrocols wrote:

pedrocols wrote:I found the triode mode exceptionally better with four tubes.  The pentode mode is about the same.  Mind you, I don't listen very loud.

Is this the kind of tubes you recommending?
http://www.ebay.com/itm/Vacuum-Tubes-RADIO-TUBES-GE-12BH7A-2-NOS-NIB-/321612019164?pt=Vintage_Electronics_R2&hash=item4ae191f5dc

Those are the ones. Not a bad price, either.

Thank you! I will give them a try. So should I get four or only the two for the front?

I use two in each amp. The front holes are the more important for good tubes, but if you get four use them, and if one of the back tubes goes south you've got those EH's for backups.

deepee99 wrote:

pedrocols wrote:

deepee99 wrote:

pedrocols wrote:

pedrocols wrote:I found the triode mode exceptionally better with four tubes.  The pentode mode is about the same.  Mind you, I don't listen very loud.

Is this the kind of tubes you recommending?
http://www.ebay.com/itm/Vacuum-Tubes-RADIO-TUBES-GE-12BH7A-2-NOS-NIB-/321612019164?pt=Vintage_Electronics_R2&hash=item4ae191f5dc

Those are the ones. Not a bad price, either.

Thank you! I will give them a try. So should I get four or only the two for the front?

I use two in each amp. The front holes are the more important for good tubes, but if you get four use them, and if one of the back tubes goes south you've got those EH's for backups.

Thank you!!

Well I got the GE tubes and they do bring some nice balance in my system!!!

Still going strong after 8 months....