Question for you sub people

[dtel]

With a plate amp that has the normal line in (which I am using) and also has " high level input " can you use both for two separate sources?

Like a Ht receiver connected normally, "line in" sub cable and another system connected to the "high level input". Two systems connected to the same sub, or do I have to unplug one to use the other ?

What does high level input mean, is it made for full range input or something else, can a full range signal connect to the line in rca connections ?

I just don't know ?

I thought i asked this before but couldn't find it, I doubt you can do this but figured it wouldn't hurt to ask.

[jhoak]

Obviously I can't speak to all plate amps but I did that with my 250W Daton amp and it worked fine.

At the time I had a AVR with bass management and an all tube 2 channel system. I ran line level from the AVR and speaker level from 2 channel amp. The subwoofer was the only thing the 2 systems shared.

On many if not most the high level inputs there is bass management built in to the plate amp. If you set the amp crossover at 80Hz everything above 80Hz will go to the mains and below goes to the sub.

Where I ran in to a little trouble doing this was that my AVR wanted to crossover to the sub at 100Hz but my main 2 channel speakers needed the crossover point to be at 60Hz. Rather than fiddle with it every time I switched between systems I set it at 80Hz. Not "ideal" for either system but it worked out well and they both sounded good. I had to apply a few db of volume boost to the sub in the AVR because the 5.1 speakers were less efficient than the 2 channel speakers. Or was it the other way around? I don't remember exactly. [:$]

[dtel]

Thanks

I don't know what brand it is, I got it from Adaire audio years ago and it does not have a name on it but looks like the Dayton amp.

What you did with the AVR is just what I was looking to do. Right now I use the pre-outs from the AVR for 2 Ch using it as a pre-amp. I was thinking a DAC would sound better than the Yamaha AVR as a pre-amp but the DAC I was looking at only has two set of outputs, RCA and XLR.

I found out people using that DAC have been using both sets for either 4 speakers, bi-amping, but most people were using the other output for subs which is what I wanted to do. I was just trying to avoid having to unplug the sub wires to switch from 2 Ch to Ht.

I may not have a choice, I would use the RCA outputs for the sub so I would need RCA connections on one end and Banana or bare wire on the other end and I can't find that wire. I could always just cut off one end but would not know what is + and -.

These are the problems you get when you try to be cheap, and yes I grew that dust and put the fingerprints. []

[CECAA850]

On many if not most the high level inputs there is bass management built in to the plate amp. If you set the amp crossover at 80Hz everything above 80Hz will go to the mains and below goes to the sub.

I was under the impression that the high level inputs were basically pass throughs and not affected by the crossover. The filter merely works with the signal going to the sub driver.

[jhoak]

Both of the last 2 plate amps I've had specifically mention a "high pass" filter in their instructions. One was the Dayton that I have now and the other was a couple year old GR Research servo model. One of them had a fixed high pass filter at 125Hz and the other eas variable with the crossover setting on the amp. I don't remember off of the top of my head which was which. I'd need to dig out the instructions to confirm

I would think that there would be some manner of high pass filtration on speaker level connection. Otherwise you'd be passing a full range signal to the satellites. Some of the smaller ones can't handle much in the way of bass content.

[dtel]

Good question, it did not come with a book so I can't check.

I was only going to use the inputs anyway.

On the green circuit board on the right are two caps, they are in between the high pass inputs and outputs. Being I don't know what that does I am of no help, again. [:$]

[CECAA850]

Both of the last 2 plate amps I've had specifically mention a "high pass" filter in their instructions. One was the Dayton that I have now and the other was a couple year old GR Research servo model. One of them had a fixed high pass filter at 125Hz and the other eas variable with the crossover setting on the amp. I don't remember off of the top of my head which was which. I'd need to dig out the instructions to confirm

I would think that there would be some manner of high pass filtration on speaker level connection. Otherwise you'd be passing a full range signal to the satellites. Some of the smaller ones can't handle much in the way of bass content.

Sure it wasn't a low pass filter like THIS one? I'm not disputing you (for a couple reasons). As soon as I think I've seen it all, something different pops up and surprises me. Secondly, I've not seen your gear. Thirdly, I'm often wrong!!! I've run bookshelves and sattelites for years with no sub or sub amp and given the little buggers all they could stand. There's low stuff that goes to them but they simply don't play it.

[jhoak]

Take a look at the manual for the Dayton model you referenced. It says " The signal to the L/R speakers will be shaped by an internal 6 dB/octave 125 Hz high pass filter.

Here's another current Dayton model that has the speaker level high pass filter set at 90Hz @ 4 ohms or 180Hz @ 8 ohm.

http://www.parts-express.com/pe/showdetl.cfm?partnumber=300-803

Sunfire did it a bit differently on this model with the high pass filter at 70Hz but this time at line levels

http://www.sunfire.com/manuals/True%20Subwoofer%20Signature%20Manual.pdf

I had a generation or two earlier version of the Sunfire sub referenced above. KICK @$$ subwoofer in a teeny tiny little box.

I haven't been able to locate any documentation for the GR Research amp that I had but I'm pretty sure that it had high pass filtering on the speaker level connections. The current model does not speaker level pass through. (I.E. only speaker input connections).

It's been a lot of years since I've been subwoofer or plate amp shopping. What I'm seeing in current products is either no speaker level connections at all or input connections only. That's not how it used to be. I suspect that's because 99% of all AVRs and preamps didn't have sub-out connections. In the days when subwoofers first became popular most buyers had to rely on speaker level connections.

For most of the time I've had subwoofers here they've been IB constructs. I usually ran one of the Behringer crossovers with a sub-out connection driving some manner of pro amp. I never did worry about passing bass frequencies to the mains that they couldn't play. I just always set the crossover point to the sub at a little above the -3dB frequency of the mains. That always worked well for me.

I guess I'm living in the past. [:$] That's nothing new. []

[CECAA850]

Aaah, never looked at the manual, just the product info on the main page where they mentioned the low pass filter.

[jhoak]

I don't recall seeing (at the time) any production subwoofer or plate amp that had speaker level inputs AND outputs that didn't have some manner of high pass filtering. Many were at a fixed frequency but a few of the better ones (read more expensive) the frequency was variable along with the low pass adjustment to the sub. It's pretty easy to apply fixed high pass filtering. Variable? Well... Not so much.

I installed a nice little Polk 2.1 system for a client. Somehow I managed to either hook it up wrong or had the subwoofer set wrong. I don't remember now. A few nights later he was entertaining a dozen or so guests. After more than a few cocktails sombody decided to crank up the tunes and the little Polk satellites puked their woofers on to his living room floor. Those early sub/sat speaker systems absolutely relied on the high pass filters to ensure the survival of the woofers in the sats.

Let's just say that I didn't end up making much money on that install. [:$]

[dtel]

I guess I'm living in the past. That's nothing new.

But I like it there. [:$]

[CECAA850]

I don't recall seeing (at the time) any production subwoofer or plate amp that had speaker level inputs AND outputs that didn't have some manner of high pass filtering. Many were at a fixed frequency but a few of the better ones (read more expensive) the frequency was variable along with the low pass adjustment to the sub. It's pretty easy to apply fixed high pass filtering. Variable? Well... Not so much.

If you don't plan on usung the high pass output on the plate amp, would it hurt to wire your sub amp high level input and your mains parallel? I can't imagine it would change the impedance that much.

[jhoak]

I don't know for sure. It only makes sense that doing so wouldn't change the load on the amp.

On the few systems that I've helped set up with high level inputs only I always put the mains on the "A" speaker outs and the sub on the "B" speaker outs.

I have a friend with a Mirage sub that he's not using right now. On the high level side there's only inputs. I may borrow it from him and and see if it changes the load presented to the amp.

HMMM... Now I'm curious.

[CECAA850]

Please report back or PM if necessary. It would save me a ton of wire and work if I could. Thanks! I can't imagine that the amp draws much current from the receiver that way.

Yes dtel, this is a threadjack.

[jhoak]

Yes dtel, this is a threadjack.

It ain't like he's never done it... []

It'll be Tuesday at the earliest before I can get my hands on the Mirage subwoofer. My friend is out of town for the long weekend.

The Dayton plate amp in my subwoofer has both high level inputs and outputs. Just for grins a giggles I'm going to dig out some speaker wire and try it parallel and pass-through and measure the resistance at the receiver. I'm currently hooked up using the low level sub-out connection from my Onkyo receiver.

Were I a betting man I'd wager the farm that there will be very little if any difference between the varients. Either in resistance at the amp or sound quality.

That'll have to wait until tomorrow though. I just finished mowing the sub-tropical jungle otherwise known as my overgrown lawn in the 90+ degree Florida heat. There's a beer (or 2...or...7) in the fridge with my name written ALL over it.

I'll be back to you soon.

[dtel]

Yes dtel, this is a threadjack.

It ain't like he's never done it...

Good, it got me thinking and yes it did hurt a little.

I went off into google land and found what I was looking for which was I was completely screwed up in my thinking, again.

I realized I can't use the high level inputs, I am coming from a DAC which is a line output, not a amp output which uses the high level input.

So I will just have to unplug the RCA's from the AVR to plug in from the DAC, it's no wonder no one makes a RCA to banana wire.............. Feeling dumber by the day[:S]

At the same time I was looking for how high level inputs handle the signal, one plate amp said it does use "a" filter, it was like 110hz and everything went on out on the high level output, most said nothing, but none said it was connected to the adjustable lo pass filter. It looks like they may all be different ?

[CECAA850]

It looks like they may all be different ?

That's a safe bet.

[CECAA850]

Were I a betting man I'd wager the farm that there will be very little if any difference between the varients. Either in resistance at the amp or sound quality.

I'd bet the same. It will sure make my life easier.

That'll have to wait until tomorrow though. I just finished mowing the sub-tropical jungle otherwise known as my overgrown lawn in the 90+ degree Florida heat.

It hit 100 here today. I was out in the (un-air conditioned) garage all day working on my next sub. I decided enough was enough. I'll do one panel tomorrow and kick back by the grill the rest of the day. Thanks for your help.

[jhoak]

Well I certainly never intended to "hurt" you at all. I hope you know that.

What is it you're wanting to do with the XDA-1 DAC?

I've had a couple of them which have come and gone. In my case had they handled the USB connection better I'd still have at least one here. At it's price point nothing else comes even close performance wise for everything but USB.

I never tried to use my XDA-1 as a "preamp". I always kept the volume level on at 100% and fed its output in to whatever I was using as a preamp at the time.

As a DAC and ONLY a DAC sitting between a decent CD or other "digital" transport you simply won't find a piece of kit that sounds any better. If you're wanting to stream from a computer by USB look elswhere. I like the HRT Music Streamer devices for USB to analog conversion of high quality FLACs.

If you're looking for a "full featured" preamp that just happens to be a good DAC... Well... Again... Look elsewhere. The Peachtree stuff looks nice. I've never owned or heard any of it but from what I read it's a great value

The XDA-1 is what it is. A good DAC and nothing more. Is it worth the $200 cost of admission? Oh HELL yea. So long is that's all you're asking from it.

Now all of that said I have a friend who has an XDA-1, an ERC-1 and a pair of Emotiva's TOTL self powered speakers... What are they called? Airmotiva or Airmotive or something like that and he swears that it's the best sounding system he's ever owned. I haven't heard it yet but I know that he has the XLR outs (I built the cables for him) from the XDA-1 going to the speakers and the RCA outs going to a pair of HSU subs

I was hoping to get up to his place today or tomorrow but with my Dad being laid up I doubt it'll happen.

[dtel]

Well the only thing that hurt was trying to figure the best connections for what I want avoiding USB and still connect everything like I wanted to make everything usable.

What I wanted first was to eliminate the AVR as the pre-amp for 2 Ch which will make it easier for others to use and I would hope also improve the sound.

The way the XDA would be connected would be Optical input from the BR player and satellite box. The BR player does steaming internet radio and BR, DVD's and CD's, those 4 are 99% of what I listen to.

So it would be optical inputs to XDA-1 and 2 XLR's out into the DX 38 (active crossover) which has 4 XLR's out to 2 amps which actively bi-amp the mains. Also I would use the RCA outputs from the DAC to go into the sub. Emotiva says you can use both sets of outputs at the same time, I did check, I would hate to let the magic smoke out. [:|]

The other thing I read is the XDA-1 does not have the best volume control, it has the best sound when turned up past 50% and around 80%. What I think will help me is the DX-38 has gain controls for the incoming L & R signal, right now they are turned up all the way, I could always back them down some to make the DAC volume knob stay on the higher side.

The reason the DX-38 volume knob are now left at 100% is because DrWho hot rodded this DX so the voltages closely match non pro equipment, he has it where I leave it all the way up and it runs perfectly at any volume and never flickers a red light.

I'm thinking it would work fine.