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  3. 153593-7535

Level mismatch in speakers when using tube amp

I’m having a strange speaker level issue in my system and wanted to see if anyone had some suggestions. I recently purchased a pair of Polk Lsim 703 monitor speakers for a great price and wanted to hear what they could do after reading comments and reviews about how nicely they scale up with decent electronics. I hooked the Polks up to my Primaluna Dialogue HP amp and noticed the level of one speaker was much lower than the other. I then switched sides by moving the left speaker to the right channel and vis versa. The level mismatch followed the speaker. I tried both the 4 ohm and 8 ohm taps of the PL but same results. I even tried replacing my 7581 power tubes back to the stock EL 34’s, same results.

Great, I thought, something wrong with a driver, crossover, something in the one speaker. I can correct the issue by adjusting the preamp balance but I have to adjust it pretty significantly to get the image centered. When I do that they sound really nice albeit at a lower level than normal based on preamp volume setting.

Then I decided to place the Polks in my other system which is a solid state Yamaha AS3000 integrated amp. Both Polks work perfectly when connected to the Yamaha and actually sound great. Full sounding, a little warm with good but not great detail, a bit of a surprise none the less. What’s strange is I have three other pairs of speakers of various brands that all work perfectly with both the tube system and solid state system. What could be going on with the one Polk speaker that isn’t playing nice with tubes? I was going to send an email to Polk tomorrow and see what they recommend but would like to hear your opinions.
Thanks everyone.

System:
PS Audio Directstream jr D/A (Streaming Tidal)
PS Audio BHK preamp
Primaluna Dialogue Premium HP amp
Yamaha AS3000 integrated amp
Acoustic Zen Absolute and Analysis Plus cabling
arch2
13 responses Add your response
luisma31
516 posts
 
This is an interesting topic and I had an answer from the beginning on a possible issue.

I owned the as2100 always wanted the as3000, excellent SS amp, beautiful looking, anyway I think the root of your issue could have been an impedance mismatch, which is more difficult to handle by the primaluna than the SS amp.

Polk's answer about the crossover issue and sending a replacement was great

arvincastro's avatar
arvincastro
121 posts
 
Growing up here in Baltimore, Polk was always viewed very fondly as a small, hometown company that really made a name for themselves.  Glad to hear that even though they've changed ownership a few times since Mathew Polk passed, their customer service continues to do things the right way...

Arvin
arch2 OP
308 posts
 
Well I procrastinated but I did end up getting in touch with Polk last week about the level imbalance. After some back and forth and a little further testing it was determined the crossover was not functioning probably. Keep in mind I’m not the original owner nor do know their age but after talking with Polk this past Friday they sent me a new crossover and I received it this morning (Tuesday), for free. Took me about 1 1/2 hours to replace and all is right with the world. Well, all is right with the speaker anyway. Kudos to Polk for standing behind their products.  FWIW I’m now using KT150s and love them.
arch2 OP
308 posts
 
testpilot, in regards to the tubes I tried both the 7581’s and the EL34’s and in each instance I switched speakers, right to left and left to right. The lower level always followed the speaker. I’m convinced it’s something about the one Polk speaker that is causing the issue, just seams really strange. Busy day today and I didn’t have a a chance to get in touch with Polk but I plan on following up with them.
testpilot
949 posts
 
I know that you tried different tubes, but did you try using the same tubes and then swapping the Left to Right channels? 
arch2 OP
308 posts
 
Yep, both jumpers are tight on both speakers. I’m sitting here listening to them with the Yamaha and all’s well. Sounds great even. With the tube amp one speaker is lower level. Again, all drivers are playing, just at a lower level than the other speaker. 
donvito
400 posts
 
Are you sure the bi-wire jumpers have a real tight connection?
arch2 OP
308 posts
 
Well, I’m certainly not intentionally mean but after a long day maybe I’m just not giving enough attention. Wait, what are we talking about?
millercarbon's avatar
millercarbon
12,531 posts
 
Its a fault with the speakers. Could be a bad connection or crossover part, whatever, its clearly the speakers. Either that or your Prima Luna is clairvoyant and knows which speakers and which channel to decrease just to make you upset. Have you been mean to it lately? Called it any names? I mean before this started happening....


rocray's avatar
rocray
1,448 posts
 
 I'm sure someone here will respond that has way more knowledge than myself. I will be following this thread,as this seems to be a very odd problem. I hope it's something simple. 
    
      Ray
arch2 OP
308 posts
 
Physically switched the speakers. Right one moved to the left stand and left one moved to the right stand.
rocray's avatar
rocray
1,448 posts
 
Did you physically switch speakers,or just swap cables at the amp?
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