EL84 and Subwoofer

[scherffi]

Hi all !

Maybe a stupid question maybe not?

I am considering complementing a
bass-weak electrostatic (Quad ESL 57 type)
with a subwoofer.
Since I'm driving the ESL with an EL84 push
pull power amp of approx. ONLY 12 Watts
(which is absolutely sufficient for the ESL),
is there any chance that I could also use
another EL84 12watts amp for a (small?) subwoofer.
The plan would be to listen mainly to classical
music at moderate loudness, no SUPER-BOOM-BOOM-
BASS for Rock music etc required.

By the way, what would be the best way to divide
the frequency spectrum to the ESL (mids/high) on
the one hand and to the subwoofer (bass) on the other
hand. F.ex. a Behringer Ultracurve ?
Any other suggestions?

Help appreciated !!!

bye all,
Frankie

[mashaffer]

It seems that if you want to use that amp that you would want a rather large (read efficient) subwoofer that doesn't require a lot of damping. Maybe a horn sub. I know they are big and complex to build but I think that a horn would provide the best possible load for that amp.

Qualifier... I am no expert so I could be entirely soaking wet on this. :}

mike

[scherffi]

Thanks anyway ma shaffer!

I will wait what other then have to say...

FrankieS

[mashaffer]

P.S. You might also want to post a link to this thread over on the tube forum as those guys have a lot of experience with the amps that you are wanting to use and can probably give some good insight.

mike

[leadbelly]

Originally posted by scherffi
I will wait what other then have to say...

FrankieS

Could you maybe give some more background into what "turns your crank" in audio? What I mean is, your suggestion sort of baffles me, because, if a person was such a tube purist as to want a tube subwoofer amp, why would you stick a Behringer in your signal path That being said, if that is what you want, mashaffer is right, your application screams "Horn!", or at least a highly efficient PA sub driver.

[scherffi]

Hi Captain Kirk (sorry) !

On 'what turns my crank'.
Yes, true why mix tubes and semiconductors?
I really wouldn't boast that tubes are better
than semis.
But it's all because I completely restored the 60ies
hifi (BRAUN STUDIO2: ECC83phono/preamp and push pull ECC3/EL84 amp)
of my father recently and when I listened to this plus
ESL57 like electrostatics I had an interesting experience:
-how bad the preamp sounds
-how fantastic this vintage EL84 push pull amp sounds

Now the tube thing is more because of this ole
'soldering hobby' and the idea that tube stuff can
be really very good.

Only thing is that the electrostatics are thin
on bass and since I have some more of these EL84
push pulls, why not driving 1 or 2 subwoofers with
them? Maybe possible if music not played to loud ???
Otherwise I also wouldn't like VERY BIG Horn woofers
at my home.
I really thought of the 'normal' average subwoofer and as already
said: NOT playing the music FULL volume.
So I would need a cross over.
Can somebody make recommendations on Behringer or Rane
cross overs or any other?
And some good but small(!) subwoofers that would suffice
for low to average volume classical music?
Thanks for any comment!

yours
FrankieS

[lne937s]

I would run the ESL full range with no crossover and only use a crossover on the sub where the ESL starts to cut out. Electrostatic bass is great, but usually there is just not that much of it. Cutting out the crossover from the signal chain will reduce any coloration those components would empart on the ESL. If you were using a more powerful amp and listening at high SPL, then you may want to limit bass to keep the panel excursion down- but 12w does not warrant this.

In terms of subwoofers- IMHO I don't think most horns will mate well with your panels. Integrating subs with the speed and accuracy of ESL's is very tricky. I also think that going with a modern design of amplifier will provide you with better results, as this will allow you to use a subwoofer that will has good extension and low distortion without having to worry about sensitivity rating or huge cabinets. For design ideas, I would take a look at the Martin Logan Descent- they make subs to mate with ESLs for a living and this unit is highly rated. I am also a fan of any sub that has a balanced driver configuration (with the drivers on opposite sides of the cabinet, pushing in and out of the cabinet at the same time, counteracting the force the opposing driver is imparting on the cabinet). I find that they transmit much less vibration to the floor/walls and usually sound very "tight."

[scherffi]

Thanks Ine !

These are interesting ideas, especially your
suggestion to spare the electrostatics any
cross over.

I will take a look to the Martin Logans.
More suggestions very welcome!

[mashaffer]

Maybe the Augie 15s From Hawthorne (scroll down the page) might integrate well with your current system if you can afford the space to put them on a moderate sized OB out away from the wall a little bit.

I don't know how hard it would be to get the Dayton High Output series where you are but the12" one Should be very nice in a ported box of about 40-45 liters. A pair of those each fed 12 Watts or so should do OK at moderate levels.

One question though is how good (or rather how well designed for bass) is the iron in your amps. If the OTs are not of pretty high inductance (physically big generally speaking) they may not do too well at the really low frequencies.

I wish you luck with this. I also would love to design a tube subwoofer system just for the fun of doing it all tube.

mike

[Calvin]

Hi,

I`d recommend a semi-amp-driven closed box or dipole sub.
Both can be built quite small, but need more wattage than a small EL84 amp can deliver. To cross over You could go several ways.

I: just cross over the subwoofer and have the ESL running full range

II: cross over the sub with the active crossover of its amp-module and cross the ESL with a passive filter (a high quality capacitor) at the Input of the EL84-amp

III: use the crossover of the sub-amp-module for sub and satellites


I: easiest posibility, could give probs with sub and ESL running parallel in the transition band, relatively low dynamic (SPL max)

II: easy to handle, You can use simple sub-amps that have just filters for the sub but not the ESL. ESL and EL-amp are much less stressed with high energy bass which in most cases leads to better sound and much higher dynamics

III: If the sub-amp features active(!) filters for the satellite channels You can use those since theyre filter slope is steeper. Sound can depend on filter quality. Even more headroom for the ESL than version II


Since Your demand for ´loudness´is moderate, I´d suggest solution II for You. To change the low frequency end of the amp simply change the Input cap to a lower value by directly changing the cap or by series connecting a smaller cap (might be done within the cable connector). As a Sub You can use some 8" drivers in Closed box or dipole and a simple and cheap 50-80W amp-module

jauu
Calvin