Too much gain?

vortrex · « **Reply #80 on:** 16 Jan 2013, 06:12 am »

with the Zesto at 55db I need to raise the volume more on the amp, to the point where I can hear the hum even with music playing.

tomorrow I will reinsert a CD player to double check what I heard before.

neobop · « **Reply #81 on:** 16 Jan 2013, 01:49 pm »

Quote from: vortrex on 16 Jan 2013, 05:58 am

new update here, as I am losing my mind...

I added yet another phono stage into the mix and still have the same issues! The new (Zesto Andros) phono stage is well known to be dead quiet. I'm now running at 65db with no SUT. The KAB calculator recommends 62db so this should be spot on. I still have horrible hum and white noise. Since this has been 3 high quality phono stages, various output levels, and the same results, I say this cannot be a phono stage issue. BUT, since my amp works with a CD player just fine that kind of throws me for a loop as far as blaming the amp.

I've disconnected the cable TV line as it comes off the street, shut off every breaker in the house but the circuit I am on, removed anything else from the wall on that circuit, and none of that made a difference. I've replaced all the tubes in the amp and the three phono stages, no change. Below you can see all the setups I have tried, all sound roughly the same. The LM amp does have the high input sensitivity of 250mv, is that being overdriven by the output of the phono stage?

The fault is with the integrated - 3 high quality phonos with same results, but no problem before you got the new integrated.

Why don't you borrow a nice, quiet integrated and substitute that?

I forgot, did you run an additional ground wire from your phono stage to an unpainted chassis screw of your integrated? Sometimes this eliminates hum. That would be normal tonearm ground + phono to integrated from same ground terminal, with no additional ground wires. Obviously input sensitivity has nothing to do with it. It's a grounding problem with the integrated.
neo

vortrex · « **Reply #82 on:** 16 Jan 2013, 04:05 pm »

if I knew someone local with an integrated to borrow I would surely do that. my dealer is out of town now, so I will have to wait a couple of weeks. there are no exposed screws on the integrated to use for an additional ground. does grounding have anything to do with white noise though? it's confusing why both devices work fine, just not together.

orientalexpress · « **Reply #83 on:** 16 Jan 2013, 04:55 pm »

i got an old yamaha reciever u could borrow if u want.I'm in san francisco/city college.

lapsan

vortrex · « **Reply #84 on:** 16 Jan 2013, 05:01 pm »

Quote from: orientalexpress on 16 Jan 2013, 04:55 pm

i got an old yamaha reciever u could borrow if u want.I'm in san francisco/city college.

lapsan

thanks, I actually have a solid state receiver in my video gear that I could use. I was trying to at least keep it apples to apples with comparing a similar tube amp. to confirm I am not crazy, I just put a CDP into the system and it is dead quiet. with no music playing I can peg the volume at max and there is no noise or hum. to give you an idea, I would be scared to do what with the phono connected, it's that much noise/hum.

orientalexpress · « **Reply #85 on:** 16 Jan 2013, 05:11 pm »

Have u try difference SUT ?

lapsan

vortrex · « **Reply #86 on:** 16 Jan 2013, 05:21 pm »

I've tried two phono stages with no SUT, two phono stages with the same SUT, one phono stage with a different SUT.

just did an unscientific measurement. with the CDP connected or no input connected to the amp I get a reading of 28-30db on my phone by sitting directly in front of the rack. when I switch to the phono stage input (with table connected to phono or not) the constant noise/hum reads 68-70db, and can peg up to 75db, from the same sitting position.

watercourse · « **Reply #87 on:** 16 Jan 2013, 05:45 pm »

It's an interaction with your integrated - just run a wire from the phono ground and touch it to the metal part of the chassis. The noise may go away and then you know that you'll need to have a permanent ground wire connection.

vortrex · « **Reply #88 on:** 16 Jan 2013, 05:46 pm »

Quote from: watercourse on 16 Jan 2013, 05:45 pm

It's an interaction with your integrated - just run a wire from the phono ground and touch it to the metal part of the chassis. The noise may go away and then you know that you'll need to have a permanent ground wire connection.

I'm going to work on that, this is the last thing to do I think. there are no exposed screws or bare metal on this amp. the only good place to ground it might be under the chassis, and this beast is 75lbs, so it's not easy to work with.

vortrex · « **Reply #89 on:** 16 Jan 2013, 06:33 pm »

ran a ground from the phono pre to the amp, as best I could, no change in anything.

watercourse · « **Reply #90 on:** 16 Jan 2013, 08:06 pm »

I had a problem between my phono stage and the later amp stages, would intermittently crackle loudly in a worrisome way. I ran a ground wire from the phono to the amp, and haven't heard a peep since. Pass Labs helped me figure out what to do, confirmed that it was electrically safe to do what I proposed.
Hope you figure it out, because you have a nice front end that you can't use. Manley should be bending over backwards to help you use their integrated, IMHO.

vortrex · « **Reply #91 on:** 16 Jan 2013, 08:11 pm »

I can still use it, it's mostly an annoyance. I am sure once this background noise is all gone I will notice a big difference though. I gave up on the Manley and got a Zesto the other night, same problem as the Manley.

neobop · « **Reply #92 on:** 16 Jan 2013, 08:37 pm »

Either you didn't make a good connection or the integrated chassis isn't connected to the ground plane?

Either way, your old set up was balanced from phono pre to amp. Balanced has a ground in each channel.

The extra gain on your phono doesn't explain the hum/noise which you don't get on the CD. The difference is the ground. If you were overloading your input, you'd get distortion not hum/noise that varies with your position on the volume control. The evidence is overwhelming.

I don't know what SQ is like on your 218a, is it better than the old balanced amp? You mentioned something on page 1 about not being able to find a stepped attenuator. The best are right there in Calif. balanced or single ended, your choice of impedance. Given your gain situation, you could ditch the line stage altogether. That's the best of all possibilities. The best line stage is no line stage. They all suck, it's just a matter of degree. Most people aren't in the enviable position of being able to do without one.

http://www.goldpt.com/index.html

neo

vortrex · « **Reply #93 on:** 16 Jan 2013, 08:46 pm »

the integrated sounds phenomenal, I'm keeping it. surely there must be a solution here. there's at least one other person on this forum who has the same amp, but I forgot his username. one other has just ordered this amp, so it will be interesting to see his results.

rollo · « **Reply #94 on:** 16 Jan 2013, 08:51 pm »

Agree it is a grounding issue. Do you ground your arm as well as motor ? try removing one. Try a cheater plug on intergrated . try same for TT. Report back.
I have tried every passive pre out there. LDRs, Trannie based, resistor based attenuators, CDP with digital volume control. While there was more info and a lower noise floor the body or gestalt was MIA. weight as well was MIA. There are trade offs with either active or passive. No one is better than the other. Lately going over to a battery powered Pre the quest has been put on hold. time will tell.
Try both and hear for yourself. Goldpoints are very good as well as Komenko.

charles

vortrex · « **Reply #95 on:** 16 Jan 2013, 08:54 pm »

I used a passive on the K&K, and I agree, the weight is somewhat MIA.

The issue is there with the table not even in the picture, so it has nothing to do with that. No input to the phono stage yields the same result of high noise.

Quiet Earth · « **Reply #96 on:** 16 Jan 2013, 09:43 pm »

Do all three phono stages have 3 prong AC plugs?
Does the CD player have a 2 prong plug?
Does the new integrated have two or three?

If the CD player only has two and there is a fault with the new integrated, maybe that is why you aren't getting the hum with the CD player..... (Maybe)

If the integrated amp has 3 pin on the AC plug, can you get an ohm meter and see if the ground pin is wired to the the case?

You mentioned a dealer wayyyyy back in the beginning of the thread. Did you buy the new integrated from your dealer?

vortrex · « **Reply #97 on:** 16 Jan 2013, 10:05 pm »

interesting! everyone is a 3 prong except the CDP. I never noticed that because the CDP is really just the Oppo from my video system and is never used for audio.

I have a meter here, how do I check for ground safely? do I just set the meter to ohms and touch the ground prong and one of the other prongs?

yes, bought from a dealer. he is out of town now but will work on this when he's back in a couple of weeks.

Quiet Earth · « **Reply #98 on:** 16 Jan 2013, 10:27 pm »

First of all, unplug your integrated from the wall and from all other components.

Take the ohmmeter, set it to read 2k ohms, and check continuity between the earth prong on the AC plug and a bare metal part of the integrated chassis.

vortrex · « **Reply #99 on:** 16 Jan 2013, 10:41 pm »

Quote from: Quiet Earth on 16 Jan 2013, 10:27 pm

First of all, unplug your integrated from the wall and from all other components.

Take the ohmmeter, set it to read 2k ohms, and check continuity between the earth prong on the AC plug and a bare metal part of the integrated chassis.

with it on the 2k setting it reads 007.