2-channel preamp with built-in active x-o?

randog · « **on:** 25 Oct 2004, 09:14 pm »

My Marchand will be here soon... however...

I'm curious if anyone knows of a 2-channel audiophile quality preamp with a built-in active crossover for bi-amping and/or implementation of subs.

IRD is planning one (The Audiophile), but the development is on hold.

Randog

R_burke · « **Reply #1 on:** 25 Oct 2004, 10:12 pm »

I asked the same question on another forum and got this:

http://www.clarityeq.com/dsp-product/PDC26P-Preamp.html

It was out of my price range, can't remember what the price was, just that it was more than I want to spend.

EDIT: The price of the above unit is $3,450.00

So I'm impatiently waiting for the audiophile from IRD

jackman · « **Reply #2 on:** 25 Oct 2004, 10:21 pm »

I'd check with BESL (bamberglab.com). Phil is the MAN when it comes to active setups. He's a great guy who will not steer you wrong. Some day, I hope to own some of his speakers in an active setup.

J

JoshK · « **Reply #3 on:** 25 Oct 2004, 11:25 pm »

There is quite a lot of talk on the apogee forum (I frequent for the info) on active amping. Most of them are subscribers to using digital xo's and digital EQ's. Apparently the Behringer digital EQ's and digi xo's can be made to sound nice relatively easily by minor part swapping and dejittering. Also they highly recommend not using the internal vol control but instead using something like Davey's 6ch VCA control.

Davey send me a bunch of info on it and I am going to give it a shot for 2 channel first. Pretty cheap and not terribly difficult looking.

randog · « **Reply #4 on:** 26 Oct 2004, 12:25 am »

Hmmm... I thought as much... the easy solutions are hard to find.

Good ol' Curt's ideas are good, we just gotta get him back in the lab to finish them!

I was also bugging Curt (as were a couple of others) to come out with a 6 channel preamp without processing to support 2-channel as well as multi channel music and HT. I'm completely baffled there's not one on the market (OK, there is, but it's an arm and a leg). He seemed very interested in that as well.

andyr · « **Reply #5 on:** 27 Oct 2004, 03:00 am »

Quote from: randog

My Marchand will be here soon... however...

I'm curious if anyone knows of a 2-channel audiophile quality preamp with a built-in active crossover for bi-amping and/or implementation of subs.

IRD is planning one (The Audiophile), but the development is on hold.

Randog

Randog,

Even tho' that good Aussie company DEQX have one, I don't necessarily think that combining your active crossover with your pre-amp is a good thing.

I run an active setup - I've built 3-way active crossovers for my Maggie IIIas. This means I can have a (mono) xover box and 3 monoblock amps sitting right behind each Maggie - with 3 very short speaker cables.

My stereo pre-amp, though, sits next to my sources - up the other end of the listening room.

Regards,

Andy

vpolineni · « **Reply #6 on:** 27 Oct 2004, 03:12 am »

Quote from: randog

I was also bugging Curt (as were a couple of others) to come out with a 6 channel preamp without processing to support 2-channel as well as multi channel music and HT. I'm completely baffled there's not one on the market.

this is a 5-channel preamp.. closest thing I've seen:
http://www.audiocircle.com/index.php?topic=11999&highlight=margules

randog · « **Reply #7 on:** 27 Oct 2004, 04:22 am »

Quote from: andyr

Randog,

Even tho' that good Aussie company DEQX have one, I don't necessarily think that combining your active crossover with your pre-amp is a good thing.

I run an active setup - I've built 3-way active crossovers for my Maggie IIIas. This means I can have a (mono) xover box and 3 monoblock amps sitting right behind each Maggie - with 3 very short speaker cables.

My stereo pre-amp, though, sits next to my sources - up the other end of the listening room.

Regards,

Andy

Hi Andy,

I'm not sure the difference here. You can still have short speaker cables by making your long run from the crossover to the amp. It's either that or from the preamp to the crossover in your case. So it's basically a wash, right?

Randog

andyr · « **Reply #8 on:** 27 Oct 2004, 05:42 am »

Quote from: randog

Hi Andy,

I'm not sure the difference here. You can still have short speaker cables by making your long run from the crossover to the amp. It's either that or from the preamp to the crossover in your case. So it's basically a wash, right?

Randog

Not quite, randog ... as after each 3-way mono crossover comes 3 ICs - 1 to each amp.

Regards,

Andy

doug s. · « **Reply #9 on:** 27 Oct 2004, 01:25 pm »

Quote from: andyr

Quote from: randog
Hi Andy,

I'm not sure the difference here. You can still have short speaker cables by making your long run from the crossover to the amp. It's either that or from the preamp to the crossover in your case. So it's basically a wash, right?

Randog
Not quite, randog ... as after each 3-way mono crossover comes 3 ICs - 1 to each amp.

Regards,

Andy

i agree - i'd much rather have yust one long pair of ic's from the pre to the x-over, than a separate pair of ac's from the x-over to each amp...

but, randog, i am sure that if ya asked phil marchand, he'd be happy to custom make an x-over for ya w/a separate wolume pot that controls everything, as well as the low-pass/hi-pass controls. likely wouldn't add too much to the cost...

doug s.

JoshK · « **Reply #10 on:** 27 Oct 2004, 02:17 pm »

DEQX is a nice solution but $3500+! ouch! The Behringer XO + EQ + Davey 6ch Vol control plus some parts for minor mods is <$1500. Also, there are some that believe the later is better as well. Of course there is more IC's but also more flexibility.

I have been reading up a lot on active setups lately and there really seems to be two camps; those that don't believe in going active at all and those that believe in going full digital. There is actually far less in the active analog approach. Its seems that the critics of the active analog approach say that no off the shelf active analog xo is very good or flexible enough to get it right. Don't know if that is true or not but certainly you are quite a bit more limited than newer digital xos. However, there is also one more school of thought often overlooked. It is the camp that believes in implementing a passive line level crossover before the amp rather than after the amp. If you split the signal from the preamp into seperate duplicate signals (preferrably seperately driven like the two outputs on the Purist) then you can replicate the passive crossover of your speakers in the line level with correspondingly smaller caps and inductors.

randog · « **Reply #11 on:** 27 Oct 2004, 02:32 pm »

Josh, this is really interesting info.

What's the true definition of passive and active crossovers?

With the implementation of active crossovers for subwoofers you actually put the signal through 2 stages of crossover(ing), first the active, then the passive in your 2-way monitors. I assume this is less than ideal (and far from efficient).

JoshK · « **Reply #12 on:** 27 Oct 2004, 02:36 pm »

AFAIK I believe it means whether it uses passive or active components. I.e. if there is a power cord going to your xo it is active. ACI's line level filter is a passive line level xo, or atleast one side of one.

By the way, I am not suggesting that any of these camps are better than the others as I have no experience with trying any of them. However, I am leaning towards the digital xo or passive line level xo approach ATM for my own experimentation. The later is easier to integrate with analog sources and current analog components but I feel the digital approach has quite a few advantages at least on paper.

randog · « **Reply #13 on:** 27 Oct 2004, 02:38 pm »

That makes sense (doh).

You're too quick for me! You responded while I was adding the last sentence to my previous post.

randog · « **Reply #14 on:** 27 Oct 2004, 02:42 pm »

Quote from: andyr

Not quite, randog ... as after each 3-way mono crossover comes 3 ICs - 1 to each amp.

Regards,

Andy

Right... gotcha.

JoshK · « **Reply #15 on:** 27 Oct 2004, 02:44 pm »

I think if you are tinkering with your own speaker design then what might be useful (by the way this isn't my idea, but csero's) is buying a cheap analog pro xo on ebay and using that to experiment with slopes and points until you feel that you got what you want, then you can implement your passive xo and tweak it to its best potential. In this case you would implement the passive xo in the line level if that is what you wanted to do. Then you can flip the pro xo back on ebay again when your done with it, or keep it for future projects. I plan to pick one up for toying with.

randog · « **Reply #16 on:** 27 Oct 2004, 02:46 pm »

Quote from: JoshK

It is the camp that believes in implementing a passive line level crossover before the amp rather than after the amp. If you split the signal from the preamp into seperate duplicate signals (preferrably seperately driven like the two outputs on the Purist) then you can replicate the passive crossover of your speakers in the line level with correspondingly smaller caps and inductors.

This camp is intriguing... hadn't heard of this before. Are any of the better known crossover guru's working in this arena? Are there any successful products on the market? Does it need to be tailored specifically for the speakers (like typical passives are)? Again, this is pretty interesting...

JoshK · « **Reply #17 on:** 27 Oct 2004, 02:47 pm »

One thing I didn't mention is that I would still probably get a pro xo for experimenting even if I wanted to buy a Marchand xo. With Marchand it seems that either you have to buy their most flexible xo and lots of different cards for points, and sometimes you even have to prespecify the slope. I think it would be better to experiment with a more flexible xo first and when you are satisfied then order the marchand that best suits your needs.

JoshK · « **Reply #18 on:** 27 Oct 2004, 02:54 pm »

Randog,

(I hope I am not derailing this thread too much). Welbourne labs used a variation on a passive line level xo in their Reveille xo. Apparently they had an option for the high pass to be passive (most sensitive part) and then the low pass was an active xo. They must have felt this was the best compromise.

I briefly spoke with Occam about this idea and he was aware of it. I think he mentioned some source that taught how to implement a passive line level xo. Maybe we can get him to tell us what that source was, as I already forgot.

My hunch though is that preamps with seperate line drivers, like as in the Purist, are better suited to drive a passive line level xo. Maybe that is the reason for the hybrid by Welbourne, since most preamps don't do this.

doug s. · « **Reply #19 on:** 27 Oct 2004, 02:56 pm »

Quote from: JoshK

One thing I didn't mention is that I would still probably get a pro xo for experimenting even if I wanted to buy a Marchand xo. With Marchand it seems that either you have to buy their most flexible xo and lots of different cards for points, and sometimes you even have to prespecify the slope. I think it would be better to experiment with a more flexible xo first and when you are satisfied then order the marchand that best suits your needs.

you *can* get a wariable frequency x-over from marchand, but phil sez it's not quite as transparent as his units that require the plug-in modules.
http://marchandelec.com/xm6.html

as the modules for the non-wariable frequency models are only ~$6 each, i think that would still be the way to go. replacing the modules takes only a couple minutes, even less if ya don't have the lid screwed down...

doug s.