Distortion question

[Coytee]

Ok, so I seem to have a (perhaps deserved?) reputation of cranking the bejeezus out of my system and doing my critical listening whilest flailing about with a pneumatic nailer, sawzall and over-ear protection on.

 

I admit at times, that might be more true than not.

 

Here's the point...

 

Since having the system in the basement, I can't get similar volume out of it.

 

I could have it thunderously loud upstairs and it still sounded good.

 

Now, if the volume (original Peach) goes much beyond 50%, not only is it still not loud (as per what I know they're capable of) but, I can hear some distortion, primarily in the lower frequencies.

 

Setup:

 

CD into Peach into Dx38

 

CD player, same as upstairs

Settings on Peach (right/left gains maxed) same as upstairs

Dx38, same again

Crown K2's, same as upstairs

 

So, what is different?

 

Instead of 3' XLR connector between everything, I now have maybe a 2' connector (RCA/XLR (again, same as upstairs)) from Peach to Dx38

The big difference?

I now have about 45' XLR/XLR from the Dx38 to cross the room and the Crown's are on the opposite side of the room.

 

I'm willing to believe that the room itself is causing some issues however, this room is actually more enclosed than the upstairs so I would expect more reinforcement.

 

Part II:  Could the tubes in the Peach be out of spec enough that now I'm finally noticing it?

I usually have system on the LoZ mode to give more drive to the Dx.

 

Oh, and I might add, the input signal LED's on the Dx are NOT clipping at all.  In fact, I'd say they are ...maybe 75% while I'm hearing this bass distortion.

 

The distortion isn't terribly loud, but I can hear it.

 

Has me wondering if I just need a hotter signal up front to push things through the long XLR wires or, maybe need to replace the tubes in the Peach that are now...  I don't know, I'm guessing 8-10 years old.

 

Maybe my speakers suck and I need bigger ones!

 

 

 

[garyrc]

Bigger than Jubilees?

 

Room modes? Sitting in a null? Room proportions?  Although it's not the only way to go, do the proportions fit within the Bolt thing polygon paradigm surface contour (see Dope from Hope).

 

Are speakers in a corner?  I know the Jubilees don't need to be, but as PWK pointed out, moving speakers from out in the room into a corner is like increasing amplifier power by 4 times, at least in the bass.  The increase in headroom might result in less distortion per SPL.

 

Try relocating all of the equipment except for the wires, and put the old, shorter wires back on.  Distortion still there?  Probably.  Everyone from McIntosh to virtually every engineer would say wire length would not make much, if any, difference, providing your basement isn't truly huge.  Is the wire low capacitance, low resistance?   EDIT: Oh, 45 feet is pretty long -- others, more qualified, will address this question.

 

Good luck!

Edited August 2, 2016 by garyrc

[Coytee]

The space here is (guessing) 15x25

 

No, there is no way the system is playing anywhere near what it is/was capable of.

 

The thing is....the sound is perfectly fine up to a certain point then it sounds like I'm overloading the crossover.  I look and it's at 50/75% input strength (based only on the LED's)  Not the first clip light is blinking.

 

I dial the volume back down and that overload cleans up.

 

I also currently (for the last 2-days) have all crowns on 100% gain.

 

So, the gains on each Jubilee are maxed, the gains on the Danley is maxed (all K2's) and when the volume of the Peach gets to "1:00", about 60% of total rotation, I can start to hear this overload type distortion.

 

This is what has me wondering if the tubes in the Peach are doing a slow-die and not putting out the signal they once did.

 

This is however, my first tube preamp so I don't know how they go when they die.

 

(speakers are in corners to answer your question)

[Marvel]

Richard, do you have any spare tubes for the peach? They have probably had enough hours on them and tubes tend to degrade over time, and it can sneak up on you.

 

Bruce

[NOSValves]

Do you have any other way to control the volume on this system? Maybe a different preamp or a CD player with a built in volume control? If so take the Peach out of the chain and see if the problem disappears. 

[Coytee]

Well, a couple answers:

 

Bruce:  I do have some spare tubes.  I am not 100% sure they were for the Peach or a prior preamp...  I'd have to look.

 

Craig:  Actually, I hadn't thought of swapping.  I happen to have an extra SS preamp.  It's a Lexicon.  I think it's a DC1 if I recall correctly.

 

I've had it in the system before, it sounded nice.  I pulled it out because its output voltage is simply lower than the Peach so when it comes to needing to drive the input of the Dx38, the Peach has always had more capability.

 

I guess it won't hurt to give it a whirl.  (other than the pain to fight the nest of wires back there!!)

 

 

[Coytee]

I didn't think of this...

 

If in fact it's the tubes getting old (the Peach if I recall, was one of the first version so it's been around for a while)

 

Anyway, if it's the tubes going south, which ones would be the ones to look at?

 

As I recall, it has three smaller tubes and two taller tubes (not looked inside of it for probably 5 years so it's based on poor memory)

 

I hesitate to call the tall tubes "power" tubes as I know power tubes go on power amps....  I don't know what their respective jobs are.

 

I DO have some smaller tubes laying around, I don't want to say they are something like a 12ax7 (I'm not even sure if that is a correct number) but it's the little 1 1/2" tall signal tubes)

 

Guess I need to find the manual too.

 

[Chris A]

Try moving your preamp and amplifiers out of the closet and into the room near the loudspeakers, using much shorter XLR (balanced), RCA (unbalanced) and loudspeaker wires...without changing the settings of the preamp and amplifiers.  Then run your loudness test again.  If distortion is still there, swap out the preamp (the item with the lowest reliability) with something that you know works.  THen change the gain settings.

 

The above suggestion will probably save you a fair amount of dollars on tubes and wires if the problem is merely gain-staging. 

 

My recollection is that Mark Deneen mentioned that his preamps have trouble driving regular SS amplifiers,especially professional amps, like the K2, etc.  We witnessed some of that once when JC was testing his Peach II.  I'd check with Mark first about tests to run, and/or mods to the Peach to handle the driven and driving impedance on your preamp.

 

Chris

[NOSValves]

If the Peach is an early original not upgraded then it utilizes 3- 6DJ8's and 1- 12X4 recitifier. Its pretty hard to say which tube is causing the weakness/distortion (if it is the Peach causing the problem). If you have had the Peach for a long time and used it allot you should probably re-tube regardless. Probably cost less than $100 for all of them unless you want some hard to find expensive vintage 6DJ8's. 

[mark1101]

I had the same issue years ago.  Talked to Mark D. and he said he never took pro audio gear into account when designing Juicy music products.  He admitted they did not interface properly and would not work well with pro audio gear.

 

It's simple, use a different preamp if you are using pro audio gear down stream.

 

You can use an art clean box.  I tried that and it worked to some extent.  I was not happy with the sound however.   It was just a poor sounding band aid.  Not audiophile.

 

The Loz mode did not work any better than teh HiZ mode when connected to pro audio equipment.

 

By the way I am using Craig's NBS driving a pro amp directly to power subs on the loZ output, while simultaneously driving VRDs on the hiZ output.........and it works just fine.  I also have a pro audio EQ on the tape monitor loop of the NBS (which Craig custom built for me) and that works fine as well.  In fact it is a lot better than just fine.  It's the best I have now.  

 

You need to upgrade Richard..........

[babadono]

Sounds like the signal is already distorted before it gets to the DX 38. The DX 38 balanced outputs SHOULD have no problem driving 45' balanced cables into a balanced input.

[WMcD]

I would not jump to the conclusion that the electronics are distorting.  Try listening to the output on headphones.  Wasn't okay in the old installation? Buying new equipment is an expensive way of troubleshooting.  You should determine what, if anything, is at fault, first.

 

I suspect that something(s) in the new room are rattling  I have some experience.

 

A very good buddy cranked SK's in a new room and thought a woofer was rattling, and bought replacements from Crites. I took a close listen before we did the installation work agreed something was wrong.  Playing some music loud I noticed that a door to the new HT cabinet was rattling and not something in the speaker unit.  Finger pressure on the door switched the distortion on and off.  My good buddy agreed, though he might be annoyed with me pointing out his misperception.  We're gonna have to put in the Crites units someday because the parameters on the SK woofer are all wrong.

 

In another case.  I bought a piano for my wife.  She walked out anyway (sob). But later I was selling the piano to a talented lass who tested it with great bravado.  Wait, what is that distortion?  It was a window nearby which was rattling.  A matchbook between the frame and molding solved it, like a switch, on and off.

 

Let me suggest you get software or a CD to sweep tones. I think you'll find the problem. It is a fun experiment.

 

WMcD

[Coytee]

Can't do anything for a while as I'm having my arm operated on in about 2-hours.  (rotator cuff)

 

I can however, state that it is in fact, something from the system, not the room.  This isn't happening at room shaking levels.

 

To best describe it, I would say it sounds like the Dx is clipping on the input side, which it is not according to the input LED's.

 

Something else...

 

I've noticed recently, a strange sound effect.  I don't have any clue how to describe it....but it seems to only be noticeable when the tv (DTV) is playing through the system and does NOT seem to happen when I have a CD or DVD playing.

 

Hard spoken sounds, like the letter K, have a distinct and unpleasant grain to them.  This is 'new' (couple months, not days)  I've noticed it and been wondering in the back of my head if these hard sounds were because of the satellite feed (and they may be for all I know).

 

With this 'blubbering' that is happening, I now wonder about the Peach.  Specifically, I'm wondering what to preamp tubes sound like as they begin to go out of spec.

 

Probably won't be able to fool with this for a couple days at least, some tell me a couple weeks as I wait to get my rotator cuff back.

 

 

[DrWho]

Distortion at lower frequencies tends to be related to power supply issues with the circuits I'm familiar with. None of my experience includes tubes though. Bias would be another place to look. Have you checked that nothing got jostled around during the move? Perhaps reseating everything and cleaning contacts might be an easy first try? 

 

I hope the shoulder feels better! I've been through that twice, so I know what it can be like. Is there at least an epic story behind the injury? 

[pauln]

A possibility...?

 

Some poorly designed power amps "hang" at their rail voltage when they clip, so the amp's voltage level does not instantly and gracefully recover from a clip as the signal voltage drops below the rail voltage, but instead by power supply hysteresis hangs at the clip voltage until a certain drop in the signal voltage occurs. This is a distorted sound.

 

When a pre-amp clips, a perfect power amp even though running well below its own clipping level can sound just like the poor rail hanging amp mentioned above, because it is trying to play the pre-amp clips with fidelity.  This is not the power stage clipping - the power amp is trying to amplify the pre-amp signal's flat spots of DC.

 

This is rare in integrated amps because the designers know the pre-amp and the input sensitivity of the power amp stage. It is something to be aware of when matching consumer level audio components, but rarely a problem; happy variations in the right direction are just called "synergy". Pro gear power amps often have diminished input sensitivities (requiring more voltage for rated output), so consumer audio pre-amps may lose headroom with respect to a pro-amp.

 

For example, a very common input sensitivity for consumer audio power amps has been 0.775V for rated output. A common value for pro gear is 2V. That would be a loss of almost 9dB of the pre-amp headroom, which might be a source of clipping in front of the pro amp.

 

Just something to check...

 

edit> just took a quick look and found this...

 

Per the K2:

"K2: 32.88 dB gain at 1.4 volt sensitivity; 25 dB gain at 3.0 volt sensitivity"

 

Per the Peach:

" There are 2 listening modes, Hi and Lo, and 1 bypass mode. The Hi mode is for amps with a high input impedance and uses only 1 tube in it's gain stage. The Lo mode is for, you guessed it, amps with a low input impedance. This mode includes the other 2 tubes for the gain."

 

If you know what these settings were before the move, check and see if they were changed during the move.

If you don't recall the original settings, maybe time to do some careful testing...

 

[Schu]

Anyone here have a cure for Sibilance?

I mean besides turning down the volume

[Chris A]

5 hours ago, Schu said:

Anyone here have a cure for Sibilance?...I mean besides turning down the volume

Yes.  Fire up Audacity on your laptop or computer holding the source music files, and look at the area of 5-10 kHz on the Spectrogram log(f) view across the entire duration of the track. Sibilance events will show up those frequencies shown as "loud" in terms of their spectrogram colors.  Simply highlight the brief time slices where this occurs, and then run Equalization with an EQ curve that attenuates those frequencies by about 3-6 dB at those brief points in time only. 

 

Voila! Sibilance is fixed forever for the offending music track.

 

(Note: the mastering engineer should have done this before releasing the track...or the mixing engineer before adding the vocal track to the mix down track...so you can consider residual sibilance in recordings as a failure of the person mastering the recording.)

[twk123]

On 8/4/2016 at 7:15 PM, WMcD said:

I would not jump to the conclusion that the electronics are distorting.  Try listening to the output on headphones.  Wasn't okay in the old installation? Buying new equipment is an expensive way of troubleshooting.  You should determine what, if anything, is at fault, first.

 

I suspect that something(s) in the new room are rattling  I have some experience.

 

A very good buddy cranked SK's in a new room and thought a woofer was rattling, and bought replacements from Crites. I took a close listen before we did the installation work agreed something was wrong.  Playing some music loud I noticed that a door to the new HT cabinet was rattling and not something in the speaker unit.  Finger pressure on the door switched the distortion on and off.  My good buddy agreed, though he might be annoyed with me pointing out his misperception.  We're gonna have to put in the Crites units someday because the parameters on the SK woofer are all wrong.

 

In another case.  I bought a piano for my wife.  She walked out anyway (sob). But later I was selling the piano to a talented lass who tested it with great bravado.  Wait, what is that distortion?  It was a window nearby which was rattling.  A matchbook between the frame and molding solved it, like a switch, on and off.

 

Let me suggest you get software or a CD to sweep tones. I think you'll find the problem. It is a fun experiment.

 

WMcD

This has happened to me before. I also thought I blew I brand new 15'' Dayton Audio subwoofer when in reality I didnt install it with a good gasket and it was vibrating against the box. My wife gets mad now though because she will come into our music room and I will have socks and t-shirts jammed into our sliding closet doors etc.

[Marvel]

1 hour ago, twk123 said:

My wife gets mad now though because she will come into our music room and I will have socks and t-shirts jammed into our sliding closet doors etc.

 

I don't have that many socks...

[pauln]

On 8/11/2016 at 10:35 AM, twk123 said:

This has happened to me before. I also thought I blew I brand new 15'' Dayton Audio subwoofer when in reality I didnt install it with a good gasket and it was vibrating against the box. My wife gets mad now though because she will come into our music room and I will have socks and t-shirts jammed into our sliding closet doors etc.

 

Reminds me of a story...

 

I got one of those "come see the property and get a free gift" things in the mail, had free time so went to check it out. The guy showing the place was driving a very old but nice car from the 60's all over the rough still unpaved roads of the development... the car was dead silent, not a squeak was heard. I have been in old cars before that even just rolling down a nice paved road the noise from the interior and dash sounded like the bridge of the Enterprise from the original Star Trek... all chirps, beeps, squeaks, boings, etc. I finally asked him how his car was so quiet...

 

He opened the glove box and inside was a butter knife and a dozen packs of paper matches. He said in the months that he had been doing this he had heard lots of squeaks, but for each one he folded a match over the end of the knife tip and pushed the match into the crack, seam, crevasse, or whatever place was the source of the sound... as many as it took to tighten up the offending parts. Over that time he had stuffed hundreds of matches into the dash and interior until it rode quiet.

 

.......

 

I'm still curious to know if the selections on the K2 and/or Peach for input sensitivity and/or target input impedance got changed during the move.