[macdane]

I posted about this earlier on a relevant but old thread. It may be better to start a new topic and keep it simple so I'll stick to the salient details.

My main speakers are Omega Super 3S (8 ohms, 94.5dB) driven by a 75wpc Hegel H80 integrated. Subs are an old pair of Fried D/2 (8 ohms, 88-89dB?) driven by a pair of bridged mono 150wpc Dayton APA-150 amps fed by the variable line out of the Hegel. With the Daytons' volume controls at max, I'm getting no bottom end ... have to touch the sub drivers to tell if they're doing anything.

Given that my main speakers are ~6dB more sensitive than the subs — and assuming the Hegel is feeding the same signal to the line out as to its internal amp — is it oversimplifying things to say I need to have roughly 4x as much power driving the subs as I do the Omegas? Because I only have 2x ... could that explain the lack of bass? And would replacing the Daytons with a 400wpc Crown amp likely remedy the mismatch?

Thanks,
Dane

[YoungDave]

Do

I need to have roughly 4x as much power driving the subs as I do the Omegas?

I would not jump directly to that conclusion.  If the sensitivities you specify are accurate, it might indeed be necessary to have 4 times as much power to maintain equivalent high sound pressure levels at a given frequency.  But you are not matching levels at a given frequency - the subs get a completely different signal, i.e., the low frequency component of the music, and therefore power matching is not nearly as simple a matter as that.  Furthermore, you do not state the sensitivities of your amplifiers - if the variable out of your main amp is not large enough to drive the sub amp to maximum, it doesn't matter what that maximum power is - you won't get it. Also, you may be laboring under a misapprehension - if your crossover frequency is sufficiently low, as is often recommended (say, 70 Hz or lower), there really is not much music down there and it would not be surprising to not feel the woofers move, except for rock music.

Bottom line, there are a lot of variables beyond just power requirements to match SPL's.  I'm sorry to say the sub integration will take a good deal more figuring, in my opinion.

[Early B.]

You probably have it wired wrong. 

[macdane]

You probably have it wired wrong.

I wish it was that simple, Early! I've triple and quadruple checked every connection, switch button and knob ... it's all correct. Even without all the checking, I knew it was correct because it was working like a charm prior to inserting the Hegel into the system.

Dane

[macdane]

I would not jump directly to that conclusion.  If the sensitivities you specify are accurate, it might indeed be necessary to have 4 times as much power to maintain equivalent high sound pressure levels at a given frequency.  But you are not matching levels at a given frequency - the subs get a completely different signal, i.e., the low frequency component of the music, and therefore power matching is not nearly as simple a matter as that.

That makes sense.

Furthermore, you do not state the sensitivities of your amplifiers - if the variable out of your main amp is not large enough to drive the sub amp to maximum, it doesn't matter what that maximum power is - you won't get it. Also, you may be laboring under a misapprehension - if your crossover frequency is sufficiently low, as is often recommended (say, 70 Hz or lower), there really is not much music down there and it would not be surprising to not feel the woofers move, except for rock music.

The sensitivity of the Dayton sub amps is 1V. The Hegel manual doesn't specify that sort of thing but I have an email in to them about this issue. As for crossover frequency, I've normally cross over to the subs around 70Hz, but I've tried the whole range available from 50Hz-150Hz ... there's virtually no output from the subs at any setting with any music including really crazy organ stuff.

Bottom line, there are a lot of variables beyond just power requirements to match SPL's.  I'm sorry to say the sub integration will take a good deal more figuring, in my opinion.

I think "a good deal more figuring" sums it all up. Worst case, I can always revert to my old setup using my Meier Prehead and Wright 2A3 amps in place of the Hegel, but I'd like to give this a shot. Best option I've come up with so far — with the help of Louis at Omega — is that the Crown amps provide a means of selecting a higher input sensitivity (0.775V) for cases of low level sources, which I just posted about on the other thread.

Thanks,
Dane

[Early B.]

Hmmmm.... woofers are getting a signal, volume turned up really high, but you're hearing very little bass -- this is precisely what will occur when the subs are wired out of phase. I know you said you checked your connections several times, but check them again. The difference in sensitivity between your subs and your speakers would not cause this issue.

[JLM]

Steps I'd try (in order):

1.)  Get a good night's sleep and with a fresh start double check all your connections.

2.)  If all is good look for some sort of bass filter feature on the Hegel (perhaps buried in a menu accessed only via remote control and called something else).

3.)  If no hidden bass filter check all external/internal fuses and circuit breakers (if on a different wall receptacle?  Might have blown a fuse or tripped a breaker hooking everything up.

4.)  If no blown fuses/tripped breakers next carefully (with a low volume signal) try the fixed output from the Hegel (if it has one).  This would check the Hegel's variable output. 

5.)  If still no signal connect the subs to the Hegel speaker outputs directly.  (Some prefer this approach if they want to hear the Hegel's power amp.  You're right the efficiency mismatch requires the use of the Daytons.)  The Fried D/2's have got to be old (not familiar with them, but was a Fried cult member back in the day), maybe they just died (but both at once?) or you blew them up (hard to do without knowing it).  You should get bass if they haven't died/been blown.

6.)  If that worked check the Daytons.  Do they have high level inputs?  If so try connecting them to the Hegel's speaker output to the Daytons via speaker cables/zip cord to check to see if the Dayton's output amps are working.  If still no signal, the Daytons have somehow been damaged.

7.)  If still no signal next try hooking up the Daytons to the Omegas (via line and speaker outputs), this would double check Daytons. 

If none of this works seems to me the line outputs from the Hegel is the only variable left.  Is the amp new?  If so, can it be returned/exchanged?  If not find out it's output voltage/impedance.

[macdane]

1.)  Get a good night's sleep and with a fresh start double check all your connections.

Already too late for that!  But I hope you're right, Early B and JLM, and I somehow managed to wire something out of phase and haven't caught it yet.

2.)  If all is good look for some sort of bass filter feature on the Hegel (perhaps buried in a menu accessed only via remote control and called something else).
3.)  If no hidden bass filter check all external/internal fuses and circuit breakers (if on a different wall receptacle?  Might have blown a fuse or tripped a breaker hooking everything up.

I've looked but haven't found anything useful in the Hegel in this regard. And already confirmed all fuses/breakers involved.

4.)  If no blown fuses/tripped breakers next carefully (with a low volume signal) try the fixed output from the Hegel (if it has one).  This would check the Hegel's variable output. 
5.)  If still no signal connect the subs to the Hegel speaker outputs directly.  (Some prefer this approach if they want to hear the Hegel's power amp.  You're right the efficiency mismatch requires the use of the Daytons.)  The Fried D/2's have got to be old (not familiar with them, but was a Fried cult member back in the day), maybe they just died (but both at once?) or you blew them up (hard to do without knowing it).  You should get bass if they haven't died/been blown.

Hegel doesn't have a fixed line out, but I've confirmed it works by dragging an old set of Fried Studio IVs (I really like Frieds) in from the next room. Sounds wonderful with the Hegel. Next, after a meeting this morning, I'll keep everything as-is (with the Hegel wired to the Studio IVs) and just add the Daytons and subs back into the mix.

6.)  If that worked check the Daytons.  Do they have high level inputs?  If so try connecting them to the Hegel's speaker output to the Daytons via speaker cables/zip cord to check to see if the Dayton's output amps are working.  If still no signal, the Daytons have somehow been damaged.

Daytons do not have high level inputs. Line level only.

7.)  If still no signal next try hooking up the Daytons to the Omegas (via line and speaker outputs), this would double check Daytons.

I intend to try using the Daytons full-range driving the Omegas and also (because I'm curious) driving the Studio IVs.

If none of this works seems to me the line outputs from the Hegel is the only variable left.  Is the amp new?  If so, can it be returned/exchanged?  If not find out it's output voltage/impedance.

The Hegel was used so cannot be returned. But I strongly suspect it's not the problem.

Thanks guys ... stay tuned.

Dane

[JLM]

Go back to step 5, connect the subs to the Hegel to see if the subs are working.

If the subs work, next try feeding the Daytons a source signal (starting with the volume turned way down) while connected to the subs.  If that works the problem must lay with the Hegel line level outputs.

[macdane]

Go back to step 5, connect the subs to the Hegel to see if the subs are working.

If the subs work, next try feeding the Daytons a source signal (starting with the volume turned way down) while connected to the subs.  If that works the problem must lay with the Hegel line level outputs.

I see what you're saying, but my speaker cables are inflexible, of weird lengths, and hard to get to ... that's why I'm planning to first try the Hegel/Studio IV and Dayton/Subs combo. If the subs work in that scenario (as they did two days ago) then I've verified operation of both the subs and the Daytons in one step, right? If they don't, I'll hunt down some additional speaker cables and break it down into two separate steps as you've described.

[Tyson]

Try reversing the phase on the subs.  Even though you think they are wired correctly, sometimes it helps to experiment.

[macdane]

Try reversing the phase on the subs.  Even though you think they are wired correctly, sometimes it helps to experiment.

It's easy enough that I'll try it when I get home. Like I said, I hope it's something this simple ... but I haven't changed the wiring on the subs since they were working great a couple days ago.

[Tyson]

The other thing to try - unplug everything except the subs.  Turn off all filters and undo any/all settings.  Send the subs a full range music signal - you should be able to get a good amount of volume and be able to hear the music fairly clearly (although no high frequencies, obviously). 

Once you've verified basic functionality above, add back in 1 filter at a time (or change one setting at a time).  After each change, verify you're still getting good output, BEFORE moving on to fiddle with the next setting. 

Once you have the subs all dialed in and playing fine by themselves, THEN it's time to add in your main speakers. 

If there's a problem, these steps will show you where exactly it is. 

[macdane]

My starting point for today was that the Hegel driving the Omegas combined with the Daytons driving the subs yielded virtually no bass. JLM laid out a series of investigative steps that made a lot of sense to me, but I'm very reluctant to try using the Dayton amps to drive anything other than the subs right now.

Substituting first the Fried Studio IVs, and then Fried C/3Ls, in place of the much more sensitive Omegas gave me some bass … approximately what I'd expect from each of those speakers on their own but nowhere near what I'd expect when they're augmented by the subs. So that didn't do much more than confirm that I have a problem.

Next I tried only the Hegel driving only the subs — full range — which provided still more bass but not anything that struck me as "normal." As an interesting aside, my Fried subs don't have the 99Hz internal crossovers they're supposed to have, so they played a reasonable facsimile of real music. It left me wondering if this is how my dad hears things with his high frequency hearing loss.

At this point I stopped to verify, again, that the subs were wired in phase. They are, so I switched +/- on one of the subs anyway which really, really verified they were in phase to begin with … I then switched the +/- back.

I had been taking breaks at each step to compose a private message but by now I was so frustrated I felt like my head was going to explode. I grabbed a bottle of bourbon from the other room but resisted pulling the cork. More and more, I was convinced JLM was correct in suspecting the variable output of the Hegel. The Hegel's manual refers to "extra features" that become available when using the fancy metal remote, which I have, including the ability to perform a factory reset. But it doesn't say how, and neither does the manual for the remote … so I shot an email off to Hegel and am awaiting a reply.

This is where I did my best impression of an audiophile fetal position. I figured the only hope of keeping my sanity was to go back to my original setup (using the Meier Prehead and Wright 2A3 amps instead of the Hegel) and confirm that it's in fact possible to go back to the glorious sound I had just two days prior. It was, and I was content to leave it playing beautiful music for the remainder of the day.

I don't anticipate hearing back from Hegel until next week, but over the weekend I may take a stab at running the Dayton amps full-range into various other speakers.

Dane

[opnly bafld]

With just the subs hooked up to the  Hegel preout and the volume all the way up, you only had a little bass?

[JLM]

With just the subs hooked up to the  Hegel preout and the volume all the way up, you only had a little bass?

Where is the v/c set when driving the Omegas?

The subs being used are passive (originally part of a two piece, 3-way speaker system), so would be very under powered trying to use preamp outputs on them.

[macdane]

With just the subs hooked up to the  Hegel preout and the volume all the way up, you only had a little bass?

Where is the v/c set when driving the Omegas?

No pre-out involved in that setup; the only elements were source > Hegel > subwoofers and the volume control on the Hegel was set around 40-50 (on a scale of 0-99). And I wouldn't characterize it as "only a little bass," just that I don't get the bass I expect ... or the bass I get with my standard setup using the Wright 2A3 amps to drive the Omegas and the Daytons to drive the subs.

What seems weird to me (as if literally *everything* happening isn't plenty weird) is that 40-50 on the Hegel volume control seems to produce the maximum comfortable volume regardless of speakers used and regardless of whether the pre-outs and Daytons are also driving the subs. I understand that volume controls are rarely linear and that talking about a range of 40-50 can cover a lot of ground, but it seems odd that I'd be comfortable in the same volume setting range when driving speakers that are 88-89dB sensitivity as with the 94.5dB Omegas.

Again, the Fried subs do NOT have internal crossovers as they normally would. Is it possible that the raw crossoverless driver in the Fried TL cabinet has a higher sensitivity than it would with the xover in place? Seems like it might be, but then it also seems like that would make them easier to mate with the Omegas.

The Hegel keeps appearing to be the odd part of the mix.

Dane

[opnly bafld]

Hegel - Dayton - subs 

 

[macdane]

Hegel - Dayton - subs 

I can't believe you knew to ask about overloading the Dayton input, but can't figure out what the problem is.
How hard is it to insert your other pre and raise the volume like recommended. 

It didn't occur to me to stick the Meier between the Hegel and the Daytons until you mentioned it yesterday, but I think it's a great idea. And it's certainly not hard to do. I'll try to be more clear about what I'm asking.

Starting with the Meier's volume at zero and raising it slowly, there should be a point at which the Daytons receive a high enough level of input to give me the subwoofer output I need. Let's call that point A. Presumably, there's also a point B at which the inputs of the Dayton are being overdriven, right? Until I try it, I don't think there's a way to know whether point A or point B will be reached first. If it's point B, and I overload the Daytons' inputs before getting the sub output I want, what audible signs should I be alert to, and what risks of damage exist?

There are plenty of people that could tell you what you need to know in 30 min if they were at your house.
Internet problem solving is a pain.

I completely agree! I'm in Lansing, Michigan ... if anyone is relatively nearby and wants to take a listen, I'll buy lunch!

Dane

[opnly bafld]

If the problem is the Hegel's preout is too low, adding gain (preamp) to bring it up to the level needed is no different than having enough gain in the preouts in the first place.

I do the opposite, I have a preamp that I really like, but with most amps I can hardy use the v/c.
I put a unity gain tube buffer between my 2v CD player and the pre to reduce the output to @1v, more complicated but sounds better to me than just the tube buffer alone and it allows me to turn the preamp v/c up to 40~50 %.

Sorry my reply was a bit harsh, I edited it, but it was too late.