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Dynaco A-25s and Subs

blau

blau

Member
I just picked up a pair of Dynaco A-25's that I'm driving with a pair of Dynaco MKIV monoblocks. I also have a Polk PSW110 sub-woofer which has a 10" driver. Is there an advantage to running 2.1 when the sub driver is the same size as the woofers on the A-25's?
 
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As said before by Budgetaudio6, a sub and the A25's takes some matching.
I have a Tsunami (Rel) sub that I sometimes use with my A25's and finding the right crossover point, level and phase was a balls ache and to be brutally honest IMHO I think I prefer the A25's without, they just sound more coherent solo despite the lack of really low end grunt.
Then again the room they are in is a pigs ear audio wise, the A25's have the best sound of the many, many speakers I've tried and/or owned.
 
I have two pairs of A25s, one recapped one not, and have been listening/comparing the two with and without a pair of 12" DIY subs (each powered by 250w) and usually prefer them with the subs. I do find that I prefer the crossover point on the subs to be pretty low (around 50-60hz, maybe) as the "little" 10" woofer on the Dynacos can be very musical in the low 100hz range and it sounds like the subs are just muddying things up if I let them crossover much higher than where I have them set. I'm not sure what sort of db the Polk sub generates at frequencies below 60hz, but my 12" DIY subs have very good db down that low and there are still occasions when I prefer not to have the subs at all. If I'm pushin the volume and want slammin bass that's when the subs make the difference as I'll pull some low end out of the eq (generally pretty flat with a little bass boost at low volume) on the Dynacos and let the subs do all the work. Something interesting to add...last night I stacked the Dynacos and actually got some pretty decent volume out of them with very respectable low end db and found they did just fine without the subs. Of course, your room acoustics and sub placement will be a major factor to consider as well.
 
Thanks for the tips guys! When I first plugged them in I had them going through the sub and didn't really notice that much difference. Maybe I need to play around with the crossover more. The speakers are kind of up high so reconfiguring (attaching, detaching, re-attaching, etc.) is a real pain. Plus the kind of music that I listen to doesn't generally emphasize the low end. Mostly indie rock, folk and oldies with a little old school jazz (this being the exception) mixed in for good measure. Maybe I'll spend tomorrow playing with the crossover. I'll post an update.
 
I have a pair of A-25's. I can't imagine running them with a sub. A sub will only smear the beautiful imaging and sound stage for which the A-25s are known. They have plenty of low-end response on there own.
 
That was kind of my initial impression. Assuming that there can be an improvement if I set up the crossover correctly, I guess the question should be "is the time and pain required to tune the sub to the speakers worth the improvement in sound stage or accuracy?"
 
Regardless of the speaker, I say yes it is, if you're using a sub of comparable or better quality.

I see lots of sub disappointment only to ascertain the bottom line is using a sub that is lesser than your speakers or poorly set up typically gives poor results, then you think all subs suck. They don't.
 
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Subwoofers will work with the A25's, if you set them up properly. Running any sub into the 100 plus Hertz range will muddy the sound. It's simply too high a crossover point. There is a proper way to set up a sub, and naturally, an improper method as well. Subs get a bad rap from improper set-up and the desire to turn up the volume higher than it should be. Actually, a "Distributed Bass" system with 3 (or 4) subwoofers is perhaps the ideal for smooth, even and deep bass within an enclosed space.

If you do an AK search for "Distributed Bass" you'll find enough information to help you determine if you might want to try it for yourself.

Best Regards,
TerryO
 
Okay, verdict is partially in. I just ran my A-25's with the sub at about 90Hz and I did notice a pretty substantial difference. I'm getting much more on the low end and the sub is allowing the A-25's to focus more on the mids and highs. Everything sounds bigger, wider and deeper.

I did run into a problem though. It seems that the multi-section caps on my amps need to be replaced. As soon as I brought my system up there was a very noticeable hum coming from the sub. I could even hear it during passages where the low end dropped off. There is a very faint hum without the sub but I can't really hear it when there is music playing. I can only hear it if I put my ear up to the speaker with nothing playing. It looks like I'm going to have to settle for stereo until I can spend the $80 to buy new caps.

Thanks for the input guys!
 
Blau,

Sorry to hear you've got a problem with your system. When you get everything back online, try running the sub to as low a frequency as you can and then raise it up a notch if it isn't satisfactory. I'm a little foggy on the A-25's frequency response, but I would think that around 50 or so Hertz would be in the ball park, where you'll not only get get good bass, but more importantly good, seamless bass integration. It shouldn't take more than an a couple of hours to really dial it in and then you can enjoy it forever!
:thmbsp:

Best Regards,
TerryO
 
blau said:
Okay, verdict is partially in. I just ran my A-25's with the sub at about 90Hz and I did notice a pretty substantial difference. I'm getting much more on the low end and the sub is allowing the A-25's to focus more on the mids and highs. Everything sounds bigger, wider and deeper.

I did run into a problem though. It seems that the multi-section caps on my amps need to be replaced. As soon as I brought my system up there was a very noticeable hum coming from the sub. I could even hear it during passages where the low end dropped off. There is a very faint hum without the sub but I can't really hear it when there is music playing. I can only hear it if I put my ear up to the speaker with nothing playing. It looks like I'm going to have to settle for stereo until I can spend the $80 to buy new caps.

Thanks for the input guys!
Click to expand...

Could it be a ground loop?
 
@TerryO - I'll give that method a go.

@FloridaSam - I was actually talking to a friend of mine who's an electrical engineer who suggested the same thing. I'm planning on getting a ground lifter as soon as I can and test it out again. I have high hopes because it'll be way cheaper than new can caps!
 
Bad news! I went out and bought a pair of ground lifters, opened the package and went to plug one in only to find that my sub isn't grounded. Five bucks down the drain and my can caps still need replacing. Crap!
 
I tried the ground lifters on my amps this weekend. No luck. I narrowed it down to the amp running my left channel. It looks like I'm going to have to do a can cap swap to see it that's the issue. Thanks for the help guys!
 
clydeselsor said:
I have a pair of A-25's. I can't imagine running them with a sub. A sub will only smear the beautiful imaging and sound stage for which the A-25s are known. They have plenty of low-end response on there own.
Click to expand...

I totally agree. I have the latest version A25XL version and the imaging and midrange beauty is just superb. They do have good tight bass when positioned correctly and driven w/ good amplification, whether vintage or modern electronics. :thmbsp:

Mine have sounded so seductive w/ a vintage Sansui A717 integrated as well as a modern Denon DRA395 stereo receiver, and like I said plenty of tuneful bass when positioned correctly. I wouldn't want to gum up the sound w/ a subwoofer. :no:
 
mjcmt said:
I totally agree. I have the latest version A25XL version and the imaging and midrange beauty is just superb. They do have good tight bass when positioned correctly and driven w/ good amplification, whether vintage or modern electronics. :thmbsp:

Mine have sounded so seductive w/ a vintage Sansui A717 integrated as well as a modern Denon DRA395 stereo receiver, and like I said plenty of tuneful bass when positioned correctly. I wouldn't want to gum up the sound w/ a subwoofer. :no:
Click to expand...

Properly integrated into a system, a decent subwoofer will cetainly improve the sound and a proper "Distributed Bass" set-up will vastly improve it.
You're certainly entitled to an opinion, although the facts relating to Bass are based on rock-solid Physic's.

Rather than going over all this once again, do an AK search for "Distributed Bass" for a fairly comprehensive coverage of the whole thing.

Best Regards,
TerryO
 
Terry,
I'm not denying 'rock-solid Physic's' as you claim, but it is much harder to implement and integrate a sub into an existing system to give it that holistic sound, plus more expensive to do it correctly. I'm just saying the vintage A25's sound fine 'n dandy as they are. Just my 2¢ as an owner of them in a minimalist tube system.
 
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