MWM hook up

[colterphoto1]

Heli- if you're usinng DBX 260's for your processing those are dead quiet- so then you're using the XTi's without their processing engaged right? That's why you don't hear the hiss you're not running the converters in the XTi's. They're fine as straight power amps but engage that digtial processsing and sssssssssssssssssssssssssssssssssss

M

[Panacea Engineering]

Michael,

Sorry.....No Soup for You.....! []

I have run the DSP an all of my XTI's, sorry....still NO Hiss.....! The sole reason I bought them was for the DSP. I was driving my Danley's with them in active before I bought larger amps. Maybe I was fortunate and got a "Good: run of these, as I said they were all bought from the same wholesaler and the serial numbers are within a few digits of each other. I've heard all of the stories about the XTI's, I have just not experienced any problems or the dreaded "HISS" from them. For me, they have been solid performers and I don't cut them too much slack when I drive the MCM's and the 362/682's with them at the airfield. They go through about three weeks of solid daily use at the main event in May. I still think the hiss is a source issue, but that is just my opinion.

W. C.

[mark1101]

Crown XTI units send all audio through the DSP section whether it is ON or OFF. You can set it for DSP OFF and it still does A/D & D/A. It just doesn't do any filtering (crossover, EQ, delay, etc). The noise comes through no matter what.

Our church does use a DBX 260 processor..........in fact I programmed the entire system myself. I like the 260. Mike you are correct, it is a quiet unit, and it has a ton of features. We didn't always have XTIs on the high sections of our speakers so I know when the noise starting happening. We use Peavey Sanctuary Series 2-way speakers which sound very good. They have a horn HF section...........and it'll hiss at you.

I suppose if you use an XTI for bass duty and cross it so there cannot be any hiss............that might work. But maybe not. The Peavey Sanctuary Series crosses over at 1.2K................which could allow some of that noise through even the woofer section.

I already know the XTI is unacceptable on the high sections. I have heard these amps in multiple systems in several different environments.........and owned 2 of them and tried them every which way. They all do the same thing.

If they work for you..............then great...........because they sure are cost effective. We are lucky that we all hear differently or there would no choices from the equipment suppliers.

Edit: The hiss happens at idle............when no source is playing. It's actually the source that saves you, and drowns out the hiss. My issue with the XTI has ALWAYS been when the music is NOT playing.

[Panacea Engineering]

Nope....Idle = No Hiss...Sorry to disapoint.

No Hiss...Hum...Spitting...Buzzing...Crackling.....Actually NO Noise at all. Again, maybe I am the lucky one.

W. C.

[BLSamuel]

Nope....Idle = No Hiss...Sorry to disapoint.

No Hiss...Hum...Spitting...Buzzing...Crackling.....Actually NO Noise at all. Again, maybe I am the lucky one.

W. C.

Lucky or deaf. I'll vote for lucky. You certainly don't seem deaf.

I've heard hiss on Michael's Jubilees with XTi's attached and I'm sure I cannot hear problems as well as other postin in this thread but it's not at all subtle, to me even, and it would be hard not to hear even for people who don't care about sound quality. You obvously do care about sound quality and I'm sure would hear obvious problems I'd likely not notice.

So maybe XTi owners should be badgering Crown for the fix to the hiss? Maybe Crown might want to recall your XTi's or at least one of them to find out why it doesn't hiss?

Maybe somebody new put in the wrong part in your run or Crown got a defective batch of something that was used when your XTi's were built and which solves a well known problem.

Very interesting disccusion.

[Panacea Engineering]

I don't know if you can call it a recall, but some time back there was a run of XTI 1000's that had problems with one side dropping out and many were sent back for repair. The ones I have were some of the very first available and I jumped on them for the DSP feature. Looks like the early ones should have exhibited the problem more so than later models. Possibly Crown changed some parts (cheapend) in later manufacturing, who knows. I am certainly not trying to disagree with anyone, just stating MY experience with them. One thing I can tell you is I am a pure NUT when it comes to grounding. Something in my electrical background makes me go overboard on this particular item.

I do have a so called very nice Carver that sounds like a DEN of Rattlers when you first fire it but it quiets down after heating up. The other amps I use are McIntosh and SAE, both brands are rock solid and quite. I have had SAE "02" components for years and really like the quality. They really make up a nice rack system. Shame they are not made any longer in the states.

[colterphoto1]

Mark, i'll stand corrected. Possibly I never even tried using them as straight amps. All I know is that my home has a very low noise floor and I'm very sensitive to extraneous sounds and I can't use the XTi 2000's with Jubilees it's just too noisy. Those old Harmon Kardon 430 receivers are less noisy and they were made in the 70's.

M

[djk]

Signal to Noise Ratio (below rated 1 kHz

power at 8 ohms): XTi 1K, 2K, 4K: 100 dB (A weighted).

The XTi 2000 is rated at +27dBW into 8Ω.

The Jubilee HF section is 110dB/W, 110+27=137. 137-100=37dB

A weighting rolls off the highs and lows, so the residual noise is 37dB plus the amount rolled off in the weighting filter (say 10dB).

That might be audible, kind of dependent on the room ambient noise, your hearing, etc.

[ClaudeJ1]

Signal to Noise Ratio (below rated 1 kHz

power at 8 ohms): XTi 1K, 2K, 4K: 100 dB (A weighted).

The XTi 2000 is rated at +27dBW into 8Ω.

The Jubilee HF section is 110dB/W, 110+27=137. 137-100=37dB

A weighting rolls off the highs and lows, so the residual noise is 37dB plus the amount rolled off in the weighting filter (say 10dB).

That might be audible, kind of dependent on the room ambient noise, your hearing, etc.

Agreed on the base specs............... It's possible for mass produced units NOT to meet specification. Also big horns with big compression drivers that reach 110 db/watt makes high power amps the worst choice for music, even with an ultra conservative "crest factor" 23 db, it still makes a 20 Watt amplifier for a mid-tweeter seem very powerful lindeed, which is where you look at S/N ratio referenced to full output, which you NEVER reach in a mid tweeter situation except for PA stacks for live music. For home stereo, even the most dynamic of recordings don't require that kind of voltage swing. All other things being equal, the smaller power amps win the audible noise detection game every time...............oh, yeah, judicious SYSTEMS approach to GROUNDING too.....................I used to designe PC boards and that applie to audio as well as digital circuits.

PS: I typically use only MILLIWATTS for normal listening from my not-so-conservative 90W/ch. power rating of my Onkyo receiver. I have to put my ear up to the horns to hear hiss..........dead quiet by way of short connections/integration good ground in a single box.

[BLSamuel]

Mark, i'll stand corrected. Possibly I never even tried using them as straight amps. All I know is that my home has a very low noise floor and I'm very sensitive to extraneous sounds and I can't use the XTi 2000's with Jubilees it's just too noisy. Those old Harmon Kardon 430 receivers are less noisy and they were made in the 70's.

M

I can vouch for Michael's claims that his home is very quiet - almost eerily so late at night - in the city of Indianapolis.

And that his Jubilees are noisy with his Crowns. I've only heard them a couple of times both with the XTi's. The first time x/o but no PEQ or not the current desired PEQ with another forum member when we had some down time so while Michael was showering or something and told us how to fire up his Jubilee rig or did so for us and left us with his Music Hall TT, Discwasher brush and a stack of all kinds of cool LP's. I think aforementioned forum member picked a great jazz LP but then wanted to talk about how he couldn't hear a difference in his Klipschorns with Trachorns installed as opposed to stock - when we had the keys to Klipsch Holy Grail he wanted to talk about Trachorns vs stock horns?!?.

2nd time after tagging along to a bar band gig we put on my virgin pressing of Steely Dan's Aja - the 180 gram Cisco one everyone was talking about the next morning when I probably should've been hitting the road..... so only made it through the 1st 3 tracks I think.

Left channel fully PEQ'd, right channel only x/o as Michael hadn't yet loaded the PEQ (with his other rigs, the Jubiless are kind of easy to overlook - but probably not if he now has them dialed in with an amp that isn't so hissy. [8][8][8][H][8][8][8]. The lack of PEQ in the right channel kind of "shouty" as Michael put it by comparison to the uber smooth left channel. He asked me how it sounded and I was like naturally floored but the right channel seemed louder and not quite right.

Both instances. Hiss at very low levels and maybe masked by the music once it kicked in but maybe audible in very low level passages.

Ironically I think Michael said he moved from his Grandparents farm, I think near Rushville, to Indianapolis to get away from the noise (and smells?).... as the Amish built a buggy factory accross the road.

[BLSamuel]

One last comment that I'm pretty sure is something Mr Paint told me at a Pilgrimage. His theory as to while Klipschantics love the sound of tubes and t-amps, especially for the higher frequencies is that tube amps and t-amps are extremely linear and easily exceed their noise and distortion ratings in the first wat to first few watts while solid start aren't so linear in the extremely critical 1st watt and don't really get in their zone until closer to rated power.

I think it was ClaudeJ1 who was carrying around one of those cheap little funky looking t-amps at the first Pilgrimage I attended in 2007 though I'm not sure if he hooked it up to anything and tried it out (I miss the Klipsch Chips!). But somebody had the Klipsch engineers measure a t-amp, maybe Claude's (forgive me if that's not your real name but I forget) and said it was VERY quiet in the 1st watt or two.

No idea if Mr Paint (Michael Hurd) is onto something but it makes sense and I'm not sure anybody's ever really measured different amps in only the 1st watt or 1st few watts.

Just my 0.02 db from the thoughts of another far more knowledgeable about such things, as are the main posters in this thread.

[kg4guy]

Well I called Crown Tech support today and the tech did confirm that cheaper parts used in one section of the xti is the cause of the hiss on HF he did say that the new XLS series , not the XLS 1000, but the rest have better and has half as much hiss as the xti's.

[Guest " "]

shame on them for posting signal to noise ratio of 100db weighted and 95db unweighted. If you can hear his...then we are talking SN rations in the low 80's. Did some googleing....the hiss is a very popular pain point in the crown xls line.

[kg4guy]

I guess I'll look into a QSC amp for my HF.[8o|]

[mark1101]

I have been using Terry DeWick rebuilt Macs (MC2100 on my HF horns, and MC-250s bridged on mid-bass modules)........QSC PLX2 1104 on MWMs, and QSC PLX2 1804 on subs. I wil probably get another MC2100 and replace the bridged MC-250s to simplify things. Same result, 100wpc.

The old mac rebuilds are a friggin' bargain...........and sound like tubes. Old s/s designs from the 70s. They have been very reliable and look great too. I highly recommend for the HF and MF.

Honestly, when I used the QSC PLX2 1104 on the K402 HF horns.............I didn't like them. They lacked detail. They are clean and quiet but just didn't quite do it for me. They are a world of improvement over a Crown XTI for sure. You will surely notice an immediate difference. I'm just letting you know what I tried and found.

On the HF horns I would recommend against a pro amp in a home system. Or I would just say this. That a home audio amp can give you finer detail in that HF and MF horns where you need it. Even on my big MCM-Grand 3 the Macs sound far more detailed than the pro amps I've tried. 100 watts per horn, which is what I'm using has been plenty for me.

Everyone think you need to win the lottery to afford Macs. Not so. An MC 250 goes for around $500 on ebay or audiogon and Dewick charges around $250 to replace the entire audio path and update the power supply, new RCAs, power cord, thorough cleaning.....and measured performance documentation. It took me a couple of years to accumulate them, but they all look brand new and sound wonderful.......just like tubes with no maintenance.

Forum member and resident uraologist JWC turned me on to how good these particular vintage Mac models sound with Klipsch horn speakers, and I just jumped on it and starting buying them up and getting them rebuilt. DeWick sends thme back looking like a shiney new car inside and out. Like brand new. Totally worth it to me.

If I can score another 2100 I'll have a beautiful pair of MC250 monoblocks for a second system.

[kg4guy]

Thanks for the info I think I will get both the QSC and look around for that Mac to use when I'm not using them for commercial use.

[ClaudeJ1]

One last comment that I'm pretty sure is something Mr Paint told me at a Pilgrimage. His theory as to while Klipschantics love the sound of tubes and t-amps, especially for the higher frequencies is that tube amps and t-amps are extremely linear and easily exceed their noise and distortion ratings in the first wat to first few watts while solid start aren't so linear in the extremely critical 1st watt and don't really get in their zone until closer to rated power.

I think it was ClaudeJ1 who was carrying around one of those cheap little funky looking t-amps at the first Pilgrimage I attended in 2007 though I'm not sure if he hooked it up to anything and tried it out (I miss the Klipsch Chips!). But somebody had the Klipsch engineers measure a t-amp, maybe Claude's (forgive me if that's not your real name but I forget) and said it was VERY quiet in the 1st watt or two.

No idea if Mr Paint (Michael Hurd) is onto something but it makes sense and I'm not sure anybody's ever really measured different amps in only the 1st watt or 1st few watts.

Just my 0.02 db from the thoughts of another far more knowledgeable about such things, as are the main posters in this thread.

Yep, that's my name, and it was me with the Sonic Impact T amp. It teste out at 6 Watts per channel simultaneously into 8 ohms (or maybe 6 ohms, I can't recall which). If you want more watts you need a 4 ohm load, but nonetheless, the engineer who tested it at Klipsch/Indy said it was almost perfect for PWK's original quote "What the world needs is a good 5 Watt amplifier." I'm sure if PWK had lived to see it, he would have been impressed. Just keep in mind that beyond the 6 Watts, the THD rose dramatically, so it's NOT for Decibel freaks, even on Khorns. Hey what do you want for a 12 Volt, single ended power supply. A portable CD or MP3 player, this amp with 8 AA batteries, and a pair of LaScalas at the beach would cause all the members of the Swedish Bikini Team to start dancing for sure.

[ClaudeJ1]

I think the best approach is to split Home vs. PA applications into 2 separate "Amp Camps."

The dynamics of live instruments not matched in recorded music, So for PA you need big power amps that use all the watts (with intelligent limiters on speaker controllers) for full S/N ratios in that application that has a VERY ambient noisy environment (large venues, lots of people).

In the home, the quiet ambient noise level, small environmnet, low noise, few people, and compressed dynamics of recorded music (even the best ones) vs. live musicians has a completely different requirment for S/N ratio. So you NEED lower power amplifiers to get the required S/N ratios for that.

My vote would be for a SYSTEM (music source/DSP/amplifiers) that can be dead quiet with big horns and 113 db/w drivers in either place. That logially means, for example, 1,000 Watts (30 dbWatts) for Live Music, and only 10 Watts (10 dbWatts) for home use.

That 20 db diffential in the inherent signal to noise aspect of both systems would then have similar ear detection characteristics, matched to the application on a SYSTEMS level.

Let's hear kvells and kvetches.

[BLSamuel]

Yep, that's my name, and it was me with the Sonic Impact T amp. It teste out at 6 Watts per channel simultaneously into 8 ohms (or maybe 6 ohms, I can't recall which). If you want more watts you need a 4 ohm load, but nonetheless, the engineer who tested it at Klipsch/Indy said it was almost perfect for PWK's original quote "What the world needs is a good 5 Watt amplifier." I'm sure if PWK had lived to see it, he would have been impressed. Just keep in mind that beyond the 6 Watts, the THD rose dramatically, so it's NOT for Decibel freaks, even on Khorns. Hey what do you want for a 12 Volt, single ended power supply. A portable CD or MP3 player, this amp with 8 AA batteries, and a pair of LaScalas at the beach would cause all the members of the Swedish Bikini Team to start dancing for sure.

I thought it was. I don't think I got around to introducing myself to hadly anyone. I think you also pointed out the Klkipsch Chips (Tex Joy steak seasoning. I asked the chef) mmmmm some of the best chips I've ever had. Mmmmmm.

A little t amp might work pretty good for a second system in our home as I think 80 db in our living room is too loud but typical for TV as my wife and daughter both have hearing issues. .

[RRFL]

I have been using Terry DeWick rebuilt Macs (MC2100 on my HF horns, and MC-250s bridged on mid-bass modules)........QSC PLX2 1104 on MWMs, and QSC PLX2 1804 on subs. I wil probably get another MC2100 and replace the bridged MC-250s to simplify things. Same result, 100wpc.

The old mac rebuilds are a friggin' bargain...........and sound like tubes. Old s/s designs from the 70s. They have been very reliable and look great too. I highly recommend for the HF and MF.

Honestly, when I used the QSC PLX2 1104 on the K402 HF horns.............I didn't like them. They lacked detail. They are clean and quiet but just didn't quite do it for me. They are a world of improvement over a Crown XTI for sure. You will surely notice an immediate difference. I'm just letting you know what I tried and found.

On the HF horns I would recommend against a pro amp in a home system. Or I would just say this. That a home audio amp can give you finer detail in that HF and MF horns where you need it. Even on my big MCM-Grand 3 the Macs sound far more detailed than the pro amps I've tried. 100 watts per horn, which is what I'm using has been plenty for me.

Everyone think you need to win the lottery to afford Macs. Not so. An MC 250 goes for around $500 on ebay or audiogon and Dewick charges around $250 to replace the entire audio path and update the power supply, new RCAs, power cord, thorough cleaning.....and measured performance documentation. It took me a couple of years to accumulate them, but they all look brand new and sound wonderful.......just like tubes with no maintenance.

Forum member and resident uraologist JWC turned me on to how good these particular vintage Mac models sound with Klipsch horn speakers, and I just jumped on it and starting buying them up and getting them rebuilt. DeWick sends thme back looking like a shiney new car inside and out. Like brand new. Totally worth it to me.

If I can score another 2100 I'll have a beautiful pair of MC250 monoblocks for a second system.

A friend of mine is a GSC dealer and he has done some comparisons with Home systems. He was not impressed with the QSC for home systems compared to amps specifically designed for this purpose. He considered the QSC ideal for PA use. So I would expect it was the midrange and up where this was an issue.

Considering the noise issues from DSP's and the gain on the amps and speaker sensitivity and what experiences are being shared. I have been pondering small amps verses large amps.

The amps I have for my Jubs develop 350watts from 26dB gain with an input 2.65volt

An alternate smaller amp develops 30watts from 26dB gain with an input 0.77volt

In both examples I suspect the noise present at the speakers would be the same. Does anyone have and comments on this?