VDS
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On 7/12/2021 at 4:24 AM, Newfangled said:
Yup, I experienced the same exact thing when I tried using a First Watt SIT-3 amplifier.
I ran XLR from Xilica XP4080 to RCA on the First Watt.
Monoprice 104784 3' Premier Series XLR Female to RCA Male 16AWG Cable
https://www.monoprice.com/product?p_id=4785
I confirmed that this is a 3 conductor cable. Signal + goes to center pin on the RCA and the - and shield are soldered together on the RCA outer conductor.
I experimented desoldering the shield and leaving it floating on the RCA end and it didn't make a difference. Whine was still present.
I only heard the whine from the Jubilee HF stock compression driver left and right. Not noticeable form the LF cabinets.
I disconnected everything in my setup and traced the noise to the Xilica.
Unplugged everything.
I didn't plug in any inputs into the Xilica.
I plugged in the First Watt SIT3 and connected the left speaker cable. Turned amp on. Silent.
I plugged in the Xilica and connected the Monoprice XLR to RCA cable. Silent
Turned on the Xilica and when the internal relay turns on after a few seconds I hear the high pitched whine.
Is it possible that this is an issue with the Xilica? Should I contact them? The date code on my Xilica is from December 2020. Curious if the original poster and I have issues with our units. Or is this just an inherent issue with using XLR to RCA with high sensitivity drivers?
I didn't hear the noise when I previously used the Crown D75a or a pair of Amp Camp monoblocks which both had balanced inputs. I'm Debating now if I want to experiment with the Jensen transformers or sell this amp and look into other amps that offer balanced inputs. Also considering other amps with balanced inputs; Cyrus Stereo 200, First Watt J2, Benchmark AHB2.
Exact same situation, Jensen helped a lot, no high pinched sound, but still a hiss.
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Got the Jensen PI-2xx installed. The annoying higher pitched sound went away!
But I have a hiss that remains. I feel like the hiss was there before, but somewhat hidden by the high pitched tone. So it’s definitely an improvement, but I’m not there yet.Hiss is audible from 15’ away.
I’m using Wireworld 3 conductor rca to xlr, 1.5’ cables from Jensen to Pass amp, super cheap amazon xlr to xlr from Xilica to Jensen.
Anybody experience reduction in background hiss by using better cables?@mikebse2a3, you obviously have lots of experience with Jensen isolators, per you setup, do the little slide switches on the bottom offer any possibilities?
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Followed advice of not using Xilica supplied crossover settings, using natural roll off of drivers to set XO point, Flattened FQ response.
Now for the super Phase for Dummies question, What does this phase graph tell me? Shows Phase of 136 degrees, are we theoretically looking for lowest possible (zero degrees)?
What is going on at 4-6khz? I think phase is a combination of speaker and room, but honestly I'm in a fog. Hopefully I'm not the only one struggling to understand the majority of this thread!
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29 minutes ago, Chris A said:
I have said on many occasions on this forum that once you get to Jubilee (or K-402-MEH) performance levels, the amplifiers make a lot less difference.
After using the 402 as the mid horn, with BSM 4592 mid, and now as a 2way, with Axi2050, that the horn creates more “separation”, dynamism and clarity than then Greg’s Fastlane Horn that is in my Cornwalls. (The fastlane horn being a remarkable improvement over the Cornwall 1’s original horn, (k700 or k600?) so kudos to Greg!)
There is a slight edginess that remains, but that could certainly be my room and may not be solved by a different amp.
maybe I should have put these comments in a 402, I’m getting off topic. -
2 hours ago, Chris A said:
There is a long history of those trying to use particular amplifier type nonlinearities to solve all kinds of EQ and other issues in their setups,
I’m starting to feel like “synergy” is basically trying to find the amp with the right non adjustable EQ to pair with non adjustable, passive crossover settings.
If we factor in the adjustability of active crossovers to control the speaker/amp “synergy”, then is the idea of “upgrading” an amplifier still valid?
I should try my “bottom of their line” Emotiva amp against my Pass, both properly EQ’ed with Xilica, and answer my own question.
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With active crossovers do we take out the entire notion of amplifier designer “voicing”? I mean boosted bass, rolled off highs, recessed mid, etc, does any of that matter anymore? What amp characteristics are still valid with active xo?
Is amplifier smoothness measurable?
dynamics?Not being sarcastic, I’m really wondering what to look for if I want to change amps someday?
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I have ordered the Jensen PI-2xx. Arrives tomorrow.
@mikebse2a3, I was a little concerned about the 12db loss with the PC-2xr.
I don’t know anything about these isolators, but I did wonder if using the Jensen pc-2xr to do the xlr to rca conversion would be better than the xlr to rca cable. @Chris A said he uses the PI-2xx, so I went with that. We’ll see tomorrow.As for the F3, it’s a Tim Rawson build, I don’t want to bad mouth him at all, but I’ve read many posts on DIY Audio pointing out some questionable build decisions, a safety concern over some lack of grounding being one concern.
Thanks, Ted -
@PrestonTom, xa25 is official Pass Labs, First Watt F3 is clone.
Funny you mentioned grounding to the he chassis, I am just about to send the F3 to someone to fix some decisions made by a he original builder, one of them being the AC mains not grounded to the chassis. I don’t know enough about electronics to fully grasp this, but I’m told it’s a problem and a safety concern.
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On 6/5/2019 at 11:30 AM, Chris A said:
all you have to do is put the HF and LF drivers together without phase shifts:
- Don't use the "crossover filters" that come with DSP crossovers--clear any crossover filters if they're set.
- Set the HF or LF channel delay to get perfect impulse response in the time domain--as seen in the spectrogram view.
- Flatten each driver's SPL response within their pass bands.
- Match the channel gains between flattened phase drivers.
- Use output channel PEQs to trim off response on each end of the bass and high frequency drivers until you've got overall flat SPL across the crossover interference band and smooth handover of SPL vs. frequency. The drivers themselves will tell you where that transition/crossover should occur. [If you're using MEHs, you'll have to use multiple PEQs to attenuate the bass bin peaks in response above the first notch frequency.]
- Use the input channel PEQs to further flatten the overall response within the interference band to correct any dips or peaks in response within that band.
Voila! Flat phase. It's really that easy.
Chris
Chris,
I think I understand 1/2 of this.
instead of using Xilica supplied crossovers, we use natural fall off of drivers, possibly tweaking with PEQ, to create a natural crossover point?
Can you supply more details, dumbed down as much as possible?Ted
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@mikebse2a3 interesting! I’ll try switching outlets. Thanks for your effort in helping.
@PrestonTom, I started with single conductor w/a conductive shield, to a true 3 conductor cable from a respected brand, Wireworld. You always are great at clarification of the issue, I’m confused.
New cables, same noise with Pass, no noise with First Watt clone.
@Edgar, lots of controversy about ferrites. Some say they work best on power cables bringing interference into the amp, or other device.
Thanks for all the help !Ted
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26 minutes ago, babadono said:
ok it sounds like if you want to stay with an unbalanced input amp you will have to use a Jensen ISO MAX or similar. But with the $$ you have already spent I would personally not scrimp on this component. Buy Jensen, they are the BEST.
This is very strange IMHO.
I think I will. I don’t like the idea of having to use only balanced amps.
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Well, hooked up new 3 conductor cables from Wireworld, sound changed slightly, but persisted. Took out Pass Xa25 and put in First Watt F3 clone, sound is gone!
map I guess I’m in the same boat as @Chris A and @Newfangled all of us using rca only First Watt / Pass. I have to decide if I want to just stick with the F3 clone (which sounds pretty damn good) or see if the Jensen isolator may help. -
In general REW seems to give some valuable information to help with “seeing” what your room is adding to the sound. Then REW can help you see what your treatments are doing.
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Getting back to frequency response. In very general terms, and disregarding a house curve, when people try for a flat curve what are reasonable goals for maximum dB variation? I seem to get to 6dB max peak to valley. at this point is it just about “voicing” or personal preference? Generally is worth while to strive for 4db spread?
Obviously what sounds best is best, just wondering if there much anecdotal agreement that the flatter the better? -
Yes! Now I get to ask, why? And explore some more
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I thought might measure a lot more than DSP can effect.Im working on seeing the effects of PEQ by taking a lot of sweeps to start to get a feel for what the changes in settings actually do. Lots of “unintended consequences” that surprise me when I take measurements!
Now I’m trying to see how the room is effecting the sound. I’m starting to look at Spectagram (kind of starting to understand). Wondering how to interpret Impulse and Decay, RTA(?). Thinking a fast drop off in first 10ms is desirable for sound clarity.
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So I’m starting to get a feel for using Xilica to flatten frequency response. I’m trying to listen and see if I hear any unpleasant frequencies and trying to adjust. Early days though!
im trying to read spectagrams and see how room treatments affect the 4-6ms reverberation.
wonder what else I can measure with REW and possible correct with Xilica? Using 402 MEH, so time alignment seems good.thanks, Ted
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5 hours ago, babadono said:
@babadono what do the dummy plugs do?
ordered some low end cables from wire world. I’m going to start there, before ordering the Jensen isolator, I can use the cables with the Jensen anyway
thanks everybody!
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“Of course the sky is the limit as far as cables go.“
That’s the problem with this crazy audio stuff, the sky is always the limit!
I’ll check out Monoprice. I’m also talking to a guy at Blue Jeans Cable, they seem like a high value brand. I use their rca interconnects.
and I’ll try lifting the ground
thanks.
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This is the cable I’m currently using.
i mean it says “superior construction” ! Maybe not so superior?
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Any opinions on 3 conductor shielded xlr cables? Good brands to look for?
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3 minutes ago, babadono said:
Both the Pass Amp and Xilica have 3 prong AC plugs...Just as a short term test put a cheater on one of them.
@babadono dummy plugs?
cheater, you mean those adapters for ungrounded outlets? Is that what people call “lifting” the ground to test for ground loop problems?
is there a simple way for me to buy the right cables? Until now I’ve never bought a xlr cable. “Need “xlr cables for dummies” explanation.
thanks, Ted
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this is somewhat noticeable at listening position, and the frequency is so annoying, like a super high speed dentist’s drill in your ear!
I have 2 experienced people, at least, suggesting the Jensen isolator. Unless anybody can think of anything else I think I’ll try that.
once again I’m so thankful for all the help and knowledge I’ve received from this forum! Really you guys are great! Thanks, Ted
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7 minutes ago, Chris A said:
This looks very similar to my "hiss" noise issue before installing the ISO-MAX (i.e., same frequencies at ~1500, 3000, 4500 and 6000 Hz), however, I don't remember seeing such large SPL spikes.
Chris
If you solved similar problem with the Jensen isolator I’m seeing that as the most likely solution at the moment.
its not loud, but audible during slow passages of solo piano music, between song, etc. And it’s a very annoying frequency for my ears!
High pinched whistling
in Technical/Restorations
Posted
Update, I forgot to order another pair of cables for Xilica to Jensen, ordered Monoprice, hopefully here tomorrow. I stole the cables from Xilica to bass amp to test the Jensen on the high frequency drivers. Like I said much improved, hiss still there. Reinstalled F3 to listen to music and let go of some frustration.
i need to reread some of the more technical suggestions tonight, get Pass fully installed with Jensen as soon as cables arrive.
I thing I never thought of, now that I’m dealing with only hiss, is gain. Some of you have mentioned this. My preamp has adjustable gain up to 30db, which is where I always set it. The Pass has 20 dB gain, so I was running it with 50db gain. Maybe too much? I will try to turn down gain to 10 or 20, to get total gain of 30 or 40db instead of 50.
Like I said I’m rereading everyone’s suggestions more throughly tonight.