Recommendation to lower noise floor with tubes and horns

SteveRB · « **on:** 14 Jan 2015, 08:49 pm »

Hello,

I am running a Leben phono-stage (RS30 EQ) and Leben integrated amp (CS-600) into custom Belle Klipsch horns. The overall noise floor of the system seems pretty high. I was hoping there may be some advice for power management that can reduce the noise floor somewhat.

My hifi is in a non dedicated room in a 40 yearly condo in Vancouver BC. The power circuit is shared with a couple wall plugs (tv, internet, lamps...). I have around $500 budgeted for this, but could raise more money if the solution proved to be a big upgrade.

Thanks for any advice.

Wayner · « **Reply #1 on:** 14 Jan 2015, 08:55 pm »

I'm assuming the speakers are really efficient,....no? If so, that is the nature of beast to some degree. I do suspect your phono stage, and the set-up between it and your cartridge. Do you have the ability to adjust gain? Are you running MC? We need to know more info I guess.....

Wayner

SteveRB · « **Reply #2 on:** 14 Jan 2015, 09:04 pm »

The speakers are very efficient. I understand that a little noise within my system components is going to happen. That's the trade off I get for the dynamics of the horns.

I cannot adjust gain on my phono stage (23.5 dB). I am running an older Grace F9 MM cart with a new Soundsmith cantelever on a stock VPI Classic 1. Blue Jean RCA interconnects. The listening level is consistent with other sources. All components are plugged into an off the shelf power strip. I do not have any upper end AC cables, just generic, grounded plugs.

There is no specific buzz or ground loop hum. Just a reasonably high noise floor apparent from the listening position.

paul79 · « **Reply #3 on:** 15 Jan 2015, 12:06 am »

Is it the phono stage causing the hiss, or the integrated? Or both perhaps?

A line conditioner or cables likely won't help this much. May be a noisy tube somewhere.

BobM · « **Reply #4 on:** 15 Jan 2015, 02:27 pm »

I'm not familiar with your source electronics. Are they tubed? if yes, could be tube rush, or in general better transformers usually have lower noise floors.

As for your analogue, do you have to trun the gain up pretty high to get the sound level you want? If yes, then perhaps you need a step up.

vortrex · « **Reply #5 on:** 15 Jan 2015, 03:14 pm »

I've had that phono stage and it is dead silent, that is not the issue.

vortrex · « **Reply #6 on:** 15 Jan 2015, 03:27 pm »

Seems like you have a bad match between your cart and phono stage. Your cart is 6.5mv output? The recommended gain is 34db. I would put your money towards a SUT and better (MC) cart. You have such high end electronics, can't imagine you are getting anywhere near the performance you should out of them.

Wayner · « **Reply #7 on:** 15 Jan 2015, 04:02 pm »

You do not have enough gain for your MM cartridge. Most MMs require about 40db of gain. If your cartridge does in fact put out 6.5mv, you should have plenty of volume and lower noise floor with a proper gain phono stage. I suggest getting a new phono stage (I have the iPhono, XPS-1 from Emotiva), and a $500 dollar budget should get you right into the ballpark.

Wayner

vortrex · « **Reply #8 on:** 15 Jan 2015, 04:50 pm »

You have awesome Leben gear. For the love of God don't take that advice and throw in a junk $500 phono stage.

SteveRB · « **Reply #9 on:** 15 Jan 2015, 05:28 pm »

HA!
You guys are all over the place. But I do appreciate the effort and comments. There is noise when not using the phono pre, but obviously more with the phono pre...

I am willing to roll a few tubes and carts to see what matches work a little better. Perhaps I will borrow a decent step up transformer to see the results.

But all I am hearing from you guys is that power conditioning is probably not an issue...?

jimdgoulding · « **Reply #10 on:** 15 Jan 2015, 05:38 pm »

Well. for under $500 phono preamps from Vista Audio and Hagerman are well advised. I've used both very successfully. Don't remember how much gain is offered. The Vista is under 200 bucks if memory serves and it currently resides in a friend's system that sounds stupid good.

JoshK · « **Reply #11 on:** 15 Jan 2015, 05:57 pm »

I think your problem has to do more with the self-noise of tubes then any other suggestion, although higher gain in the phono would help with that specific source. As you say, you have a high noise level with other sources, so that leads me to believe I am correct. The noise level rises and falls with volume? That would suggest self-noise. In these cases power conditioning isn't going to help all that much, but could help a tiny bit (not enough to justify the cost IMO).

There are ways to address this issue in your leben gear but unfortunately it means modifying your gear by adding heater regulation and/or under-volting just a hair. That typically cuts the noise (raises the SNR) quite a bit. I would consider that a serious upgrade, so the effect on your resale value wouldn't necessarily be bad. Does your integrated have hum pots? There are a number of other well known tricks you can do to quiet a tube amp, but I'll leave that for later.

If you wanted to go this route, I would suggest talking with your Leben dealer and then finding a good tech to do the work for you, unless you are able.

macrojack · « **Reply #12 on:** 15 Jan 2015, 07:20 pm »

Your speakers are 103 db efficient. If your Leben has an S/N of 100 or less, there will be noise, with or without sources and whether solid state or tube. I had a similar issue with my horns. Perhaps there is a way to pad down the speaker efficiency by modifying your crossovers. Consult Klipsch for advice. They must hear this complaint daily.

SteveRB · « **Reply #13 on:** 15 Jan 2015, 07:24 pm »

Quote from: macrojack on 15 Jan 2015, 07:20 pm

Your speakers are 103 db efficient. If your Leben has an S/N of 100 or less, there will be noise, with or without sources and whether solid state or tube. I had a similar issue with my horns. Perhaps there is a way to pad down the speaker efficiency by modifying your crossovers. Consult Klipsch for advice. They must hear this complaint daily.

Thanks interesting. How is signal to noise measured?
I wouldn't be surprised if my horns were closer to 105 dB...

macrojack · « **Reply #14 on:** 15 Jan 2015, 08:32 pm »

Quote from: SteveRB on 15 Jan 2015, 07:24 pm

Thanks interesting. How is signal to noise measured?
I wouldn't be surprised if my horns were closer to 105 dB...

Sorry - I'm not qualified to answer that question. Consult Google for an explanation.
I got the 103 db figure from the Klipsch page.

BobRex · « **Reply #15 on:** 15 Jan 2015, 08:39 pm »

Quote from: macrojack on 15 Jan 2015, 07:20 pm

Your speakers are 103 db efficient. If your Leben has an S/N of 100 or less, there will be noise, with or without sources and whether solid state or tube. I had a similar issue with my horns. Perhaps there is a way to pad down the speaker efficiency by modifying your crossovers. Consult Klipsch for advice. They must hear this complaint daily.

Are you sure about that? Signal to Noise is a ratio such that S/N=100 means that with a signal of 100db, noise is 1dB. With a 100dB sensitivity speaker, you would be using 1 watt, the noise should be inconsequential. Now if there is noise with no signal, that's not S/N, that's tube rush or broken.

macrojack · « **Reply #16 on:** 15 Jan 2015, 09:18 pm »

I'm not sure of anything. I'm really just relaying an explanation I was given. My horns, when I was using an active crossover, were about 107 db efficient. I had a persistent hiss sound coming through at all times. I tried isolating components, questioned the amp and preamp, and talked to many people. Ultimately it was pointed out to me that the dbx Drive Rack PA that I was using had a S/N of only 100 db and was therefore the cause of my noise. I replaced the dbx with an XTA DP 224 and never heard any noise again. For that reason I offered my belief in how to fix the OP problem. Am I wrong?

BTW - the above example was without tubes. I was using a Jeff Rowland Capri preamp and my NCore amps. Before the NCores I had Parasound Halo.

BobRex · « **Reply #17 on:** 15 Jan 2015, 09:38 pm »

An S/N of 100 is actually pretty good. And since noise rides on the signal, assuming the pre was off or fully attenuated, something was creating the noise. I'm thinking rf might have been the culprit. Or, the DBX was misbehaving.

SteveRB · « **Reply #18 on:** 20 Jan 2015, 04:38 pm »

Well, I picked up a couple used shielded power cables (Crump Cable) that were for sale locally -- but got no results.

I then re arranged and tidied all cables. I also moved all other devices off the circuit that my amps are connected to. This resulted in a 5% reduction of noise which was noticeable from my listening position. Next up is a MM cart with a slightly higher output. Then maybe try rolling tubes in the phono stage.

On a separate note: anyone want to buy some AC Cables... they are 4' each.

vortrex · « **Reply #19 on:** 20 Jan 2015, 05:33 pm »

A little more output of your MM cart is not going to do anything for you, your matching is so far off. It seems like you already have one of the highest output MM carts made. KAB says you would need +20mv to match well with your phono stage. Can't recommend a decent MC with a good SUT enough. You would be amazed on how much performance you are missing from that expensive Leben gear. I would at least get everything else in order first before chasing noise issues.