Success with attenuators between USP-1 and XPA-2

[GEL]

Just wanted to report on my positive experience with RCA line attenuators after purchasing the USP-1 and ERC-2 a month ago.

While I had immediately seen a very significant improvement in soundstage (width/depth) and imaging (voice/instrument placement and separation) when playing my CDs with the USP-1/ERC-2 combo compared to using my PS3 as a source through the UMC-1 in stereo mode, I still had a very limited usable range on the volume knob of the USP-1 (i.e. 3 or 4 clicks maximum on the remote, showing on the knob as between 6:30 and about 8:30 if seen as a clock) before the sound quickly became too loud and distorted for comfort and critical listening, with some bloat/muddiness in the lower bass area and definite harshness in the highs.

I had no clue if the audio signal from the USP-1/ERC-2 to my XPA-2 was too high, if the amplifier gain was too much, and/or if my L/R loudspeakers were too sensitive (90 dB @ 8 Ohms) for what was now being sent upstream. Regardless, I dreaded having (and am not financially ready yet) to spend additional money in order to replace any of those components and was not very happy so far about having bought the USP-1…

After reading many related posts in the Emotiva Lounge, I decided to first try and order three (3) pairs of Harrison Lab 12 dB RCA line attenuators online from Parts Express, to connect all of my 5.1 channels to the binding posts of my XPA-2 and XPA-3, as well as to the RCA line in of my subwoofer, since my stereo/home theatre setup is combined, with the UMC-1 connected through the USP-1 with its very useful HT bypass feature.

I received the attenuators at home yesterday and connected them immediately where my interconnects meet the binding posts of my amplifiers and sub, with no other change or settings adjustment to my system.

Bingo! The bloat/muddiness in the bass and the harshness in the high frequencies I heard before with my USP-1/ERC-2 combo were gone instantly. I have also gained a little more usable volume range on the USP-1 as well, with two more upward clicks available on the remote, which brings the volume up to about 10 o’clock on the knob before it becomes too loud for my (wife’s) taste. Regardless, even at that louder level the sound is not distorting anymore. Great!

One question, for members with technical knowledge of RCA line attenuators, or with direct experience of such devices in their system: is there a break-in period with those? Should I expect some noticeable improvement over time, beyond the immediate benefits I can hear now? Just curious…

It is quite surprising that such a minor addition/tweak could accomplish so much… My peace of mind is back!

I thought I’d let others faced with a similar issue know,

G.

[creimes]

I'm currently waiting for my XDA-1 to arrive to replace the one I never should have sold....heh, I'm wondering if keeping the volume on it at say 65 or 70 instead of 80 will help this instead of using attenuators...?? anyone have this experience with the XDA-1 to USP-1 to amps......??

[roadrunner]

Oct 23, 2012 16:46:06 GMT -5 creimes said:

I'm currently waiting for my XDA-1 to arrive to replace the one I never should have sold....heh, I'm wondering if keeping the volume on it at say 65 or 70 instead of 80 will help this instead of using attenuators...?? anyone have this experience with the XDA-1 to USP-1 to amps......??

Try it and see how it sounds to you. With my combination of equipment running the XDA-1 sounded very good. I would never have guessed there was a problem with digital volume control because at that point I thought it was analog volume control. I typically had the volume set at 70 and it sound superb. It wasn't until months later that it became a problem as nobody reported any loss of performance using lower volume settings on the XDA-1.

Several Lounge members posted running their system with the XDA-1 set between 50 and 60 with excellent results. At some point, different for each system combo, the deterioration will become audible. Let your ears guide you.

[emovac]

Interesting post. I had thought an attenuator was a more restrictive device, not one to provide better soundstage. Glad it is working well for you.

[garbulky]

Ah glad you notice a performance boost. I did too. With attenuators I found no real break-in time. They sort of worked from the get-go. Using them, I noticed a slight sound signature change. A small boost in the low-mids/upperbass and a SLIGHTLY laid back/recessed treble. An analog smoothness if you may. Also dynamics did much better and I found room ambience and depth in general fared better than without. For musics I found this change to be positive and worth the price.

I wonder if this is due to the high gain settings on these amps. If they can be driven to full at 1.4 V and the XDA-1 can likely output more than that on peaks then I suppose this harshness may come from driving the amp past the 1.4V mark on quick peaks. I think it was said that it can push out 12V peaks according to home theater hi fi. The USP-1 can do 9V peaks. Using an attenuator it reduces the voltage and therefore is less likely to overdrive the amp. That's my guestimate as to what's going on. I don't know, I may likely be wrong but so far that's what I think makes sense to me.
Anyway, I'm just glad the fix is so relatively easy!

[Deleted]

This seems strange.

An attenuator reduces the given signal by a given level. How can it improve sound quality.

I see two things improving.

Less noise and a better volume range.

Maybe less noise is making it seem like the signal has improved.

An amplifier is the opposite of an attenuator, with an amp you provide gain and with an attenuator you provide LOSS.

Placebo is a strong effect...........

[garbulky]

My best guess-planation to why would be what I posted just above (#4) which is the signal required to drive the amp to full (1.4V) is being exceeded by the xda-1 making dynamics harsh or less natural sounding, or the input of the amp itself is overloaded on peaks causing the same effect on dynamics.
An alternative guess-planation is that the attenuator isn't attenuating all frequencies equally and/or at all volume levels. Thereby producing an alternative sound signature. This alternative sound signature is more pleasing to the ear.
^^ I don't have any measurements or proper experience to back this up.

[carlp336]

i added them to two of my systems..

in my HT the emo amps were to hot for audyessy calibration
and in my main viewing area with fairly efficient speakers (usp and xpa2) i added for volume range..

they did both systems a great service.

[RichGuy]

I have been using attenuators on my system for about 2 years.

I love what attenuators do for my system, really a nice improvement for music quality.

I use -15db XLR attenuators at all of my amps inputs then my volume is increased 15db at the volume control so there is not a loss of volume. However there is a very nice difference to overall sound quality. It tames harshness, giving a very natural warmth and an improved detail.

I have been very happy with the results and love the sound quality my system has.

Here are a few links on using attenuators.

www.enjoythemusic.com/magazine/equipment/0803/rothwell.htm


www.rothwellelectronics.co.uk/html/attenuators.html


www.rothwellelectronics.co.uk/html/hi-fi_plus_review.html


www.rothwellelectronics.co.uk/html/customer_feedback.html

Here is a pic of the back of my amps where you can see the attenuators at my XLR inputs.

[paradigmE]

So I just wanted to add my intial thoughts with USP-1 Plus XPA-200 combo. I was prepared to buy the harrison labs -6 or -12's but just got my USP-1 and can report the following. I think when running into the new Emotiva 29db Gain amps that these will not be required. At least I dont see a reason yet after my first few hours of audio bliss with my new combo.

[garbulky]

Most likely they will not be required for the lower gain 29db amplifier.

[creimes]

Exactly, I noticed a difference between my UPA-1 mono's and my UPA-500, the UPA-500 actually sounding better with more volume control, I've heard from some that have purchased the XSP-1 pre find it not to be an issue with the 32db gain amps....

[garbulky]

Creimes: you've used attenuators on both and you don't find it to make a benefit on the upa-500 vs the upa-1 on which it did?

[creimes]

Dec 21, 2012 5:26:47 GMT -5 garbulky said:

Creimes: you've used attenuators on both and you don't find it to make a benefit on the upa-500 vs the upa-1 on which it did?

I never have used attenuators, I'm just saying I noticed a difference between the UPA-1 and UPA-500 with the USP-1, the UPA-500 allowing more volume useability with the USP-1, also seemed to sound more open, I was thinking it was due to the UPA-1's 32db gain.

I did a comparison one night changing back and forth from the UPA-1's to the UPA-500 powering my RX6's and I actually like the sound better with the lower gain amp(UPA-500), not that there is an issue with my UPA-1's but didn't seem like the best match to the USP-1, that's why I sold it and was gonna go to the XSP-1 but my budget is pushing me towards the XMC-1 w/40% card and the XPS-1 phono pre when they are released.

[RichGuy]

I have only used attenuators with my current system so I cannot say if
the 32db gain amps are why they make things sound better or not.

However from what I have read about using attenuators it has more to do with digital music sources as to why attenuators can be beneficial.

I can say that from my own experience the attenuators make music on my system sound much better than without them but I don't see any benefit using them for home theater only for music.

Also I was very happy with my system before using attenuators however I really love the change they made.

[mathwizard]

I have the same question as in post #2 above. Does operating the the XDA-1 at a lower volume function the same as using attentuators? When I used attenuators between the XDA-1 and the USP-1, I heard an echoing effect from the speakers. I suspect that the attenuator are introducing a timing difference into the chain.

[RichGuy]

Dec 23, 2012 9:14:24 GMT -5 mathwizard said:

I have the same question as in post #2 above. Does operating the the XDA-1 at a lower volume function the same as using attentuators? When I used attenuators between the XDA-1 and the USP-1, I heard an echoing effect from the speakers. I suspect that the attenuator are introducing a timing difference into the chain.

To answer the first question, no lowering the volume is not the same as using the attenuators.

When using attenuators you want to turn your volume up higher to make up for the volume lost to the attenuators. One reason for using attenuators is for systems where the actual volume is already fairly high when the volume level is not turned up all that much.

You are not listening to your music at a lower volume, the volume you want to listen to your music will stay the same. Think of it as adding more levels of detail.

There is an added dynamic range to lower volume listening and less harshness to higher volume listening, an overall more musical effect.

As far as your echoing I do not know what would be causing that. Unless something is faulty I do not think it would be caused by the attenuators.

[brubacca]

Oct 23, 2012 16:46:06 GMT -5 creimes said:

I'm currently waiting for my XDA-1 to arrive to replace the one I never should have sold....heh, I'm wondering if keeping the volume on it at say 65 or 70 instead of 80 will help this instead of using attenuators...?? anyone have this experience with the XDA-1 to USP-1 to amps......??

Not exactly the same. Theoretically you lose resolution below 80, but to be quite honest I have best result with my Xda-1 in the 65 to 70 range. I continually creep back up over time to 80 because that is the way it should be, but it never sounds as good above 70.

Merry Christmas everyone.