Tube Amps, Magnapans and Impedance


I have tubed monoblocks running in class A with the output transformers rated at 8 ohms. They are driving Magnapan 3.7s which are rated at 4 ohms. Before I bought them I called Magnapan to get the frequency curve for their speakers. The engineer advised me that they are nominally rated at 4 ohms, the lowest load they present at their lowest frequency, but the frequency curve was essentially flat at 6-8 ohms throughout the audible range. The curve he faxed was satisfactory and I have been running them this way since new.

The reason for this thread is: A friend brought over his friend for a visit and listen. When the subject of tubes and planars arose and the impedance ’mismatch’ was discussed, he stated I was missing out by not having a 4 ohm amp. I tried to alleviate his concern with the above to no avail. I stipulated that it is good electrical practice to match the load to the amp but in my case a 6-8 ohm load across the band with tubed monoblock running in class A at 8 ohms was not significantly audible if at all to justify altering the transformers. I just didn’t bother after listening.

My question to my fellow audiophiles, particularly those who have tubed amps running at 8 ohms into loads between 6-8 ohms - Magnapans being the best - what are your thoughts on the subject?

In my experience it would take a speaker with a 4 ohm rating in the midrange where the music lives to really affect the performance with an anemic amp. Anemic bass and washed out mids are sure signs of an amp struggling with its load - which I do not have. My Magnapans sing from the very bottom of their range to the top. The human voice is especially seductive.

I think he had a case of ’wish I had a system like this’ blues. I think there is a term for that. Thoughts are appreciated.
128x128keesue
@frogman 

Thanks for that 8 ohm comment! 

My memory of what I heard from Magnapan may be faulty.  It was in 1992-ish if I recall correctly. I got the tubes and speakers within months of each other. The file with my notes is long archived.  I just have the manuals on file but Dennis modified everything so it may have been he who said it wouldn't be a problem. At any rate, they sure sound good.  Thanks again!  

Contention, as the OP in that thread postulated, is counter-argument with little value except to personalize and incite discord.  This is counter productive and what has chased so many away.  Just look at the demographics of the forum and the sparsity of new posters. I've been around here and watched the decline.  No new blood, so-to-speak.

In the headphone forum, Head-Fi, Jude set up a separate place for objectivists to share their views, and several other forums followed.  The arguments were ruining the enjoyment with dogma and the overwhelming messianic compulsion to demean another's experience.  What one person hears isn't necessarily what another hears and no amount of recitation of theory will ever change that.  It is the passion of the hobby.

I am all about measurements, hence my stipulation.  My post was genuine.  I wanted to get my fellow audiophiles' experiences with tubes and Magnapans.  Doubt was sown and I needed a lifeline!  Frogman to the rescue!

As I compose listening to an acoustic jazz track, that double bass player owns that fret.  The drummer owns the high hat and cymbals and the piano has that wooden quality that one would hear sitting down front listening.  It was that which drew me to Magnapans.  

Best to all!
@OP,
Doubt was sown
Considering that you enjoy your system as it is, I would discount any  inference to the contrary.
But.
we are all subject to the opinions of others.
That being said(written), I would contact Magnepan directly with your concerns.
Another good person to contact is John Rutan (Audioconnection). He sells Maggies and knows just about every company out there. He can give you free, unbiased information that will help guide you.
bob 
Excellent, thank you very much!  I'll do so indeed. 

I was considering, at one point, Autoformers, to adjust the output impedance down to 4 ohms.  Apparently, they really help with Magnapans and are a good way to match amp to speaker load. I'll run that by your contact.  If anyone has any experience with them, I'd welcome the input.

Now, I'm off on a toot to get Walsh Ohms for my home office.  I heard a pair once and the way they hung an image in the middle of the room was breathtaking.  I'm not moving the Magnapans out of my study.  That's where they live.  I'm too spoiled by the intimacy of sitting in front of them in the sweet spot and getting lost in the music..

Lastly, I wanted to share another tid-bit.  I received some solid silver interconnects from a fledgling company as part of a transaction - source to pre and pre to amp(s).  I was told they would be good with tubes with their reputation for being detailed.  Well, I lived with them for many months and I did enjoy them.  After a while, I started thinking they were a bit too strident.  I replaced them with my original interconnects, Mogami studio wire, and voila!  

Damned if this isn't a OCD hobby!  


I just may have a set of Autoformers coming to passively step the impedance down to 4 ohms.  I'll give them a listen.  Could very well marry 'good practice' with 'good listening'!  👍

I'll post my findings to close this out and return back to anonymity.