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Yaqin MC-10T no bass?

Hello all.

I just got myself a Yaqin MC-10T. This is my first venture into better audio stuff and my very first vacuum tube amp. My speakers are a pair of old Wharfendale Emeral 93's that I got on craig's list for real cheap. My music sources so far are either a turntable connected to a Yaqin MS-22b phono stage to the amp or an iphone playing pandora through a usb to a DAC to the amp.

Everything sounds great! I love it more and more every time I listen to it.

Here's the problem. There is almost no bass to this setup. It's like you have a 5.1 setup and someone unplugs the sub woofers. I thought it was the music I was playing but I experimented and its the same thing.

I'm not a bass head and the music I listen to has very little bass anyways, but I just want to know if this is normal or if this is a vacuum amp trait or if there is something wrong with my speakers?

Will the tubes make any difference? I've checked the bias on my current tubes and they are all within range.

Suggestions? Thanks.
tanman2
5 responses Add your response
georgehifi's avatar
georgehifi
10,312 posts
 
http://www.salonav.com/arch/2008/10/028-7raz.shtml

The Warfedale 93 is the same as the 95 but smaller box which will make it even harder to drive.

As you can see (link) fourth graph up from the bottom. In the bass the impedance is not too bad (green trace around 50- 200hz), but the phase angle in that area (blue trace) is bad, at even less than -36 degrees around 100hz, which is the punch/power region for the bass, so it needs an amp with a little current grunt.

Your Yaqin MC-10T needs to be run off the 4ohm speaker taps, which will drop it's 40w 8ohm spec even down to 20w and then at that -36 degree dip it will sag the wattage even more.
Then even this may not be enough to get that bass drive you are seeking.

Have you a 100w solid state amp that is ok with 4ohms handy or a friend has that you can try to see if you can get your bass back you want.

Cheers George
almarg's avatar
Ag insider logo xs@2x
almarg
9,670 posts
 
Even though the speakers are rated as being 8 ohms, if you already haven't it would probably be worthwhile seeing how they sound when connected to the 4 ohm taps on the amplifier. Two-way speakers such as these frequently have considerably lower impedances in the bass region than at higher frequencies. The interaction of that kind of impedance characteristic with the higher output impedance of a tube amp's 8 ohm tap (compared with the output impedance of the 4 ohm tap) will reduce bass response to some degree.

Also, do verify the connection polarities, as Mofi suggested. If the red and black (+ and -) connections are reversed on one but not both channels, that would definitely account for loss of bass. It would also cause imaging that is vague, diffuse, and hard to localize.

Regards,
-- Al
tanman2 OP
1 posts
 
I will check all those when I get back in town. Pretty sure the speaker wires are connected correctly. They are my home built wires but I'll check continuity just to be safe.

I paid $50 for those speakers. Figured whats the worse that could happen. I do have a pair of Acoustic Energy AE1 speakers that I can swap out real quick to see if it makes a difference.

I currently don't have a CD player but I can go get a cheap DVD player to try out.

But like I said, other than the bass, everything else sounds pretty amazing to me.
zd542
5,339 posts
 
Take an actual store bought CD that you know the sound of and play it through an actual CD or DVD player. Using that as a source, is there still a bass problem? The CD/DVD player doesn't have to be anything high end or expensive. Also, your amp may not be fully broken in yet and that may be some of your problem.
mofimadness's avatar
mofimadness
4,982 posts
 
Sounds like maybe the speakers are at fault. Check the
woofers and/or the crossovers.

Also check to make sure you have them phased correctly. Red
to red and black to black for speaker wire. Reversing the
phase will lower the bass output.

Check to make sure the jumper bars are installed and tight
since these speakers do have bi-wire capability.

These are rated from 48 to 20,000, so you should get some
pretty decent bass. Not earth shaking by any means, but
probably a solid response.

There might be a reason why they were so cheap on
Craigslist?
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