[jsalk]

First, before I begin, let me say thanks to all those, especially Marbles, whose efforts retulted in this Circle.  It is extremely gratifying to know one's hard work is being appreciated.  I humbly hope to earn your continued support and encouragement.  Again, thank you all very much.

Now, for those who might be interested, here's an update of what's happening with the HT3a's.

For those not familiar with this project, the HT3a's will be an active crossover version of the HT3's utilizing DEQX.  As such, it will require a DEQX unit (about $3500) and six channels of equal gain amplification.  So it will not be an inexpensive system by any means.

I have done three DEQX "corrections" (active crossovers) to date.  Each has been superior to the previous.  

On August 28th, Dennis Murphy will be flying in to spend a day tweaking this setup.  At the end of the day, we expect to have a speaker "ready for showtime."

The first major showing for this model will be at the Rocky Mountain Audiofest, September 30 - October 2nd in Denver.  A short time later, I will have it set up at the Chicago Audiofest.  Details on this event will be forthcoming as soon as the dates and location are nailed down.

I know many of you are probably wondering how the HT3a's sound.  Well, they are already sounding quite good.  As to how they compare with the HT3 passive crossover version, I have not yet had time to do an A/B comparison.  And the HT3's with that Dennis Murphy crossover will certainly be hard to beat.

But there is one advantage to a DEQX-type set-up, as those of you with TacT units are well aware.  Once the crossover is created, you can measure in-room response and set up an EQ filter to adjust for room modes.  So the in-room response will be flatter than is possible with any passively crossed speaker.

I'll post more as this project progresses.

Thanks again,

- Jim

[zybar]

Jim,

Any idea of pricing on the HT3a's?

In your tests, what have you been using for the 6 channels of amplification?

George

[brj]

Glad to hear the active option is progressing, Jim!

To be clear, your 3 crossover/correction curves have been driver corrections only?  In otherwords, they are based on anechoic chamber measurements and there is no room response factored in at all?

Thanks!

[jsalk]

Jim,

Any idea of pricing on the HT3a's?

Not yet.  I won't really have time to put any packages together until September (building speakers comes first).  But I was thinking of perhaps two or three packages.  One would be with just the speakers and DEQX unit, the others would be complete packages with amplifiers and all required cables included.

I would guess that a pair of HT3a's with a DEQX 2.6P would be somewhere around $7500 and a system with an amp would start at around $9500, but these are just guesses at this point.

I have no idea what kind of demand there might be for this type of product, but I don't really care.  This is just something I thought I would enjoy putting together and, so far at least, it appears as if it was worth the effort.

In your tests, what have you been using for the 6 channels of amplification?

I originally got a couple of 300 watt stereo Tripath modules and was going to build some digital amps for this project.  But I have so many speaker orders to fill, I knew I just wouldn't have time and I wanted to move this project forward.

I wanted to be able to offer a turn-key package or two complete with a 6-channel amp.  And I was looking for something that was fairly good, but reasonably priced for an entry-level package.  

A friend reminded me that SL offers ATI amps with his Orion kits.  He is sold on them, so I became an ATI dealer so I could include their amps in some base backages.  Right now I am using an ATI 2006 rated at 200 watts per channel.  

I would assume that many people will want to use more expensive amps in this type of set-up.  And I really don't want to get into the hardware sales game (I like building speakers and want to concentrate on that).  So I thought that perhaps being able to offer turn-key packages with the ATI 2006's or 3006's (300 watts per channel) would be sufficient for those who don't have the time or patience to assemble a complete system on their own.

- Jim

[jsalk]

Glad to hear the active option is progressing, Jim!

To be clear, your 3 crossover/correction curves have been driver corrections only?  In otherwords, they are based on anechoic chamber measurements and there is no room response factored in at all?

Thanks!

Basically, that is the idea.  I have only done the driver measurements in the room.  They should be fairly close at this point, but obviously not perfect.  

Prior to Dennis Murphy's arrival, I plan on taking them outdoors and doing some additional measurements on a very quiet day.  That should provide very accurate measurements.

But you are right, there should be no room correction until after the active crossovers have been implemented.

- Jim

[Marbles]

I know many of you are probably wondering how the HT3a's sound. Well, they are already sounding quite good. As to how they compare with the HT3 passive crossover version, I have not yet had time to do an A/B comparison. And the HT3's with that Dennis Murphy crossover will certainly be hard to beat.  ...

Jim,

At this point, since you are used to the sound of your speakers, without A/Bing them, have you approached, been even with, or surpassed the passive XO's?

Thanks for your thoughts...

[jsalk]

At this point, since you are used to the sound of your speakers, without A/Bing them, have you approached, been even with, or surpassed the passive XO's?

Thanks for your thoughts...

Marbles,

Tough question.  I am not trying to evade it, but it is really too early to draw any conclusions.  Some aspects are better and some not at this point.  

The DEQX corrections I have applied so far have been, for the most part, very good.  But I think it would be prudent to let Dennis Murphy have a hand at it before reaching any difinitive conclusions.  He has about the most well-developed sense of hearing I have ever come across, especially when it comes to voicing speakers.  

With DEQX's steeper slopes, the G2 can be crossed lower, taking advantage of great horizontal dispersion.   And being able to correct for room responses is a huge advantage just as Zybar has noted with his TacT unit.

I will certainly be able to give you an honest appraisal, based on A/B listening tests, at the end of the month.  

- Jim

[jermmd]

I'm sorry if this is a stupid question, but can't the active x-over be set up to be exactly the same as the passive x-over? I mean, at the same frequencies and with the same slopes? Then the sound would be at least as good as the standard HT3 but with tri-amping/room correction/phase correction as well.

Also, if you believe DM's passive x-overs can't be beat, what advantage does the DEQX offer over the Tact used on the standard model with a single high quality amp (such as George's system)?

And finally, I can't wait for my new speakers!

Joe M.

[ctviggen]

One benefit would be speaker correction of all three drivers.  The TACT only does room correction.  Correction of phase relationships between two drivers could be corrected.  In other words, both the low and mid frequency drivers will be playing overlapping frequencies at around the crossover point between the two drivers.  With DEQX, one could adjust the phase of the drivers at those frequencies to be the same; with the TACT, this is not possible.  The TACT can adjust the phase at any one frequency, but if there's a phase difference between two drivers, both of which are playing the same frequency, then the DEQX should correct for this better than the TACT.

Can the DEQX correct for (I assume linear) distortion of a driver?  That would be a benefit.

Also, the DEQX gives you more options.  You could, for instance, have a steeper slope on the low frequency driver than on the mid frequency driver.  This might not be a bad thing if the low frequency driver (for example) tends to distort at the crossover frequencies (i.e., the frequencies on the slope).  Because the frequencies are adjustable, then you also can play around with that, too.

[ekovalsky]

One benefit would be speaker correction of all three drivers.  The TACT only does room correction.  Correction of phase relationships between two drivers could be corrected.  In other words, both the low and mid frequency drivers will be playing overlapping frequencies at around the crossover point between the two drivers.  With DEQX, one could adjust the phase of the drivers at those frequencies to be the same; with the TACT, this is not possible.  The TACT can adjust the phase at any one frequency, but if there's a phase difference between two drivers, both of which are playing the same frequency, then the DEQX should correct for this better than the TACT.

You can do this with the TacT too, but it does require multi-amping with the TacT digital amps.  This basically requires the RCS plus multiple S2150 amps, and also the TACS software which is a free download.  

Since the DEQX comes with three internal stereo DACs, the user has complete amp freedom which is certainly a plus.  The drawback is the quality of the internal DACs which are not state of the art.  External DACs can be utilized, but with significant added expense -- $500 digital output option for the DEQX plus the cost of the extra digital cables and of course the DACs themselves.  The Benchmark DAC-1 would probably be the least expensive upgrade DAC, and three of them will cost nearly $3000.  

Separating speaker and room correction functions was a good idea by the DEQX design team.  The TacT can do both by user manipulation of the target curve, but it is more cumbersome.  Speakers of proper design shouldn't need driver correction, but with some drivers it can obviate the need for a notch filter.  And it is perfect for dialing in EQ.

[JoshK]

Just curious, not for myself really, but more of a general question; what about those who already own a DEQX, are they precluded from the HT3a?

[JoshK]

The drawback is the quality of the internal DACs which are not state of the art. ...

From what I have read this isn't true, although the analog output stage may not be current SOTA the DACs are way up there and hard to dispute.  I'd be interested in info otherwise.

[JoshK]

Speakers of proper design shouldn't need driver correction, but with some drivers it can obviate the need for a notch filter. ...

Again I am not so sure about this.  Not to pick on you Eric, you are indeed a smart man, but in principal the speaker correction should flatten a driver's response, which even the uber flat excel's aren't perfectly flat, not that that matters.  However, I think the real key of SC comes in phase response correction which even the best tend to deviate from linearity.

[Bingenito]

Josh,

It appears that DEQX causes one to change their avatar on a daily basis. Why is this?  

Is it related to DACs?

[JoshK]

I have been going through an Avatar identity crisis.  I think hitting 4000 posts might have been the equivalent to mid-life crisis for audiocircle.

[Gordy]

It's an DEQX option, Bryan.  The Auto Adaptive Avatar...

[Bingenito]

Try this one

[jsalk]

I'm sorry if this is a stupid question, but can't the active x-over be set up to be exactly the same as the passive x-over? I mean, at the same frequencies and with the same slopes? Then the sound would be at least as good as the standard HT3 but with tri-amping/room correction/phase correction as well.

Yes, and no.  The W18, like any metal cone driver is prone to cone resonances.  Dennis Murphy designed a trap circuit in the passive crossover to address this situation.  So it is not an issue.

DEQX offers the capability of using very steep slopes that can accomplish the same thing.  Another benefit of these steep slopes is being able to cross the G2 tweeter lower than in the passive crossover.  Since the tweeter has better dispersion than the W18, this can also improve things.  But, as you can see, the crossover is now not the same.

The bottom line is that to take advantage of what the DEQX offers, you will most likely not use the same frequencies and slopes as you would in a passive crossover.

Also, if you believe DM's passive x-overs can't be beat, what advantage does the DEQX offer over the Tact used on the standard model with a single high quality amp (such as George's system)?

I didn't say DM's crossover can't be beat.  But they certainly set the bar very high.

In a passive crossover, you set the frequency, the slope and the relative level of the drivers.  Everything else is essentially left to the natural performance of the drivers.

DEQX correction, on the other hand, can address time and phase relationships between the drivers as well.  So, in theory, you should be able to create a better crossover.  With lesser drivers, the results can be rather dramatic.  In fact, DEQX can made some very mediocre drivers sound very good as it can correct for their deficiencies.  With the drivers in the HT3's, less "correction" is required to begin with.

As for George's approach, you have a good point.  The most glaring problems using any speaker in any room are going to be in the area of mid-bass and bass response.  Both DEQX and TacT, used on conjunction with the passive crossovers and a 2-channel amp, can address these issues.

But there are gains to be had by having separate amps for each of the drivers as well - lower distortion among them.

As I indicated above, time will tell as to whether or not the DEQX version of the HT3's offers a compelling justification for the increased cost and complexity of the system.

There are obviously a number of alternatives to either DEQX or TacT that cost considerably less.  But the major benefit of DEQX is that a single unit is capable of doing the entire job.  Behringer, for example, makes some very inexpensive and fairly capable electronic crossovers.  But you need to set up a computer-driven measurement system in order to dial them in properly.  With DEQX, everything is contained in a single unit that is much "friendlier" for the average consumer.

And finally, I can't wait for my new speakers!

Likewise.  It should be a very fun project.

- Jim

[jsalk]

Just curious, not for myself really, but more of a general question; what about those who already own a DEQX, are they precluded from the HT3a?

Not at all.  I would simply build an HT3 without the passive crossover and with appropriate termination to the drivers.

- Jim

[Marbles]

So how is the testing going?  Was Dennis able to better his passive XO with "The Future"?

Thanks for your thoughts on the DEQX and HT3a's.