Seduction hum (how much is normal?)

denti alligator · 38341

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Offline denti alligator

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Reply #75 on: September 27, 2012, 10:27:15 AM
Yes, I have the SEX amp. That is indeed what I'm using with the Seduction. On its own the SEX is dead quiet. Dead. Quiet. Hence also my surprise at the levels of hum coming from the Seduction.

Not home yet, but any suggestions for what to try out when I get home would be welcome.

- Sam

Rega P3-24 (w/AT 150MLX) w/Groovetracer upgrades / Eros II / FLAC >J.River >DSD256 >Gustard X20 / Moreplay > Stereomour II / Klipsch Forte II w/Crites upgrades / C4S S.E.X. 2.0 +Nickel MQ Iron / Speedball Crack / Sennheiser HD600 w/Cardas cable


Offline Grainger49

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Reply #76 on: September 27, 2012, 10:43:49 AM
Joshua,

We are 5 pages and 74 posts into this thread.  Sam and I have been talking back and fourth about only the Seduction, starting today in my reply #52.  I don't see my mentioning the SEX amp, since Jan. 9.

In addition I have emailed and PMd him today.  I am sure that Sam and I are on the same page.  I am sorry if we have confused you.  You were not privy to the emails and PMs.

Sam,  I think that Joshua is suggesting to also try a wire from the Seduction to the SEX.  I believe this is redundant with the interconnects, but it never hurts to try.  It is also cheap, quick and might help.
« Last Edit: October 24, 2012, 05:28:00 AM by Grainger49 »



Offline denti alligator

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Reply #77 on: September 27, 2012, 12:44:21 PM
Ground from Seduction touching chasis plate of SEX makes no difference.

I soldered a ground buss on the Seduction to connect the two grounds. No difference.

And I just put on Coltrane's Live at the Village Vanguard Again. The Jimmy Garrison solo at the end of side A is a perfect test. On the speakers I can turn it up and not really hear the hum. With phones I can, though just barely.

EDIT: By contrast, I'm now listening to a great obscure gem, the self-titled album by Lewis Furey. This record doesn't need the volume very high to get it to my preferred volume, so hum isn't an issue at all. So I guess it will depend on what I'm listening to if I choose the 'phones.

What I want to know is: is what I'm hearing normal, but most of you folks just don't turn the volume WAY up? What do you hear (those of you who have my set-up or something close) when you turn the volume to 10 on pre and main amp but don't play a record. Is there hum? a little buzzing? Does holding the Seduction and putting a finger on the ground lug cut out the buzzing and reduce the hum? If yes, then I'm not alone.
« Last Edit: September 27, 2012, 12:51:25 PM by denti alligator »

- Sam

Rega P3-24 (w/AT 150MLX) w/Groovetracer upgrades / Eros II / FLAC >J.River >DSD256 >Gustard X20 / Moreplay > Stereomour II / Klipsch Forte II w/Crites upgrades / C4S S.E.X. 2.0 +Nickel MQ Iron / Speedball Crack / Sennheiser HD600 w/Cardas cable


Offline Grainger49

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Reply #78 on: September 27, 2012, 02:08:24 PM
If, as you describe, the only problem is at the highest end of the volume control and with very quiet music, I would say that is normal.  

The Seduction amplifies the lowest voltage level signal in a stereo.  It is more likely to introduce hum in the system than any other component.  

To me, the problem centers around the low level of the signal (cartridge output), the low signal level (small jazz etc.), low recorded levels (quiet passages or the dead band between cuts) and the amount of gain that is required to make the cartridge's signal usable by the rest of the system.

My comment about equipment reviewers meant to indicate that most of the equipment on the market, except a very few, will have hum when the system is WAO.  Wide Assed Open.
« Last Edit: September 27, 2012, 02:10:23 PM by Grainger49 »



Offline denti alligator

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Reply #79 on: September 28, 2012, 02:05:47 AM
I can accept that. My only question would be: why can I reduce this hum by half just by holding the amp and touching the ground? Shouldn't I be able to do this via some other means?

- Sam

Rega P3-24 (w/AT 150MLX) w/Groovetracer upgrades / Eros II / FLAC >J.River >DSD256 >Gustard X20 / Moreplay > Stereomour II / Klipsch Forte II w/Crites upgrades / C4S S.E.X. 2.0 +Nickel MQ Iron / Speedball Crack / Sennheiser HD600 w/Cardas cable


Offline Grainger49

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Reply #80 on: September 28, 2012, 05:04:09 AM
I believe it is 120 Hz hum as described by Paul Joppa above.  Obviously the Seduction is the source.  

Back at answer $46 Paul Joppa suggested that you try grounding through a resistor.  I am assuming grounding the turntable.  Try a high resistance, 100k to 1M ohms.  But I am just not sure where to add the resistance.

I'm going to have to think on this and get back to you.
« Last Edit: September 28, 2012, 05:09:39 AM by Grainger49 »



Offline Paul Joppa

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Reply #81 on: September 28, 2012, 07:17:38 AM
Hum and buzz is the single most frustrating problem with systems! Patience and persistence seems to be the best answer there is; experience helps (hence the Forum) but not as much as you might hope.

The signal ground starts at the ground plane which is electrically connected to the chassis plate at the ground post. The power line safety ground is connected to the chassis plate near the IEC socket - that's how the two are connected.

When touching things helps, it is quite possible that the interference is radio frequency pickup. For example, perhaps the CD player has a switch-mode power supply which is not well shielded, or which radiates from its power cord (poor line shielding). Or something else - a light dimmer, flourescent lights, battery vibrator in an adjacent apartment (no kidding, it's happened). Another source used to be television signals, with its 59.94Hz vertical refresh rate.  The usual answer is shielding, such as the tube shields and a metal box around the circuitry - the chassis is drilled for it. I can't put my hands on it but there must be a thread or two - can someone find it?

Shielding acts on electric fields by surrounding the circuitry with a metal container which is grounded, draining any induced field to ground. That's one of the reasons I wanted to start the search for causes by making sure all the grounds were in place. Normally I would expect that if the chassis is well grounded, then touching it will just drain whatever your body picks up to ground, and will not have an effect. So I think the jury is still out on what is the real cause of what you are hearing.

Paul Joppa


Offline Laudanum

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Reply #82 on: September 28, 2012, 10:14:38 AM
At this point, I would think the Hammond 1590J be worth a shot ... $12.

Desmond G.


Offline denti alligator

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Reply #83 on: September 28, 2012, 12:16:26 PM
At this point, I would think the Hammond 1590J be worth a shot ... $12.

Does it have the right dimensions? Seems small to me. I have a Hammond that I got for the Quickie but never used. It's surely the right W and D dimensions, but is probably not hight enough...

- Sam

Rega P3-24 (w/AT 150MLX) w/Groovetracer upgrades / Eros II / FLAC >J.River >DSD256 >Gustard X20 / Moreplay > Stereomour II / Klipsch Forte II w/Crites upgrades / C4S S.E.X. 2.0 +Nickel MQ Iron / Speedball Crack / Sennheiser HD600 w/Cardas cable


Offline Laudanum

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Reply #84 on: September 28, 2012, 02:22:47 PM
From the Seduction product description page (and it's also in the manual if memory serves):

"For those who live in RFI rich environments, mounting holes for a die cast Hammond aluminum box (PN 1590J) that you can modify slightly with a file to fit are provided to allow you to shield the entire preamplifier circuit from RF..."

Desmond G.


Offline Paul Joppa

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Reply #85 on: September 28, 2012, 03:57:33 PM
The modification is to make holes for the power STPs.

Paul Joppa


Offline denti alligator

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Reply #86 on: September 28, 2012, 04:11:04 PM

- Sam

Rega P3-24 (w/AT 150MLX) w/Groovetracer upgrades / Eros II / FLAC >J.River >DSD256 >Gustard X20 / Moreplay > Stereomour II / Klipsch Forte II w/Crites upgrades / C4S S.E.X. 2.0 +Nickel MQ Iron / Speedball Crack / Sennheiser HD600 w/Cardas cable


Offline denti alligator

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Reply #87 on: September 28, 2012, 04:48:28 PM
I can definitely say I'm dealing with a low hum. And it isn't THAT bad at the volumes I use my system. BUT, it would be nice to minimize it a la my holding it and touching the ground.... I'm not in a high RF area, I don't think. No dimmers, and really no other electrical things in this side of the house. I'll play around with turning stuff on/off in other rooms to see what difference this makes, and I'll also try completely unplugging the CD player. Turning it from standby to off made a big difference. Maybe unplugging it will do the rest.

If only I could replicate the ground my body serves with something else...

And if someone can tell me which Hammong enclosure to get, I'll try that, too.

- Sam

Rega P3-24 (w/AT 150MLX) w/Groovetracer upgrades / Eros II / FLAC >J.River >DSD256 >Gustard X20 / Moreplay > Stereomour II / Klipsch Forte II w/Crites upgrades / C4S S.E.X. 2.0 +Nickel MQ Iron / Speedball Crack / Sennheiser HD600 w/Cardas cable


Offline Laudanum

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Reply #88 on: September 29, 2012, 12:14:44 AM
http://www.mouser.com/Search/ProductDetail.aspx?qs=lxPAlgZqN%2FwBkmsjCw3f7A%3D%3D
those dimensions wouldn't work.

 I wouldnt think that BH would have named the part and made the holes in the top plate accordingly to line up with those of the Hammond box if it wouldnt work.   It doesnt cover the entire bottom of the top plate, just the preamp section.   The 4 open mounting holes in the top plate measure out pretty close to the listed dimensions of the box.  Granted, I dont have one on hand or installed so I cant guarantee it fits from personal experience.  And I dont know if it will help with your problem.  But Paul mentioned RFI a few posts up and that's what they state the accomodations for the hammond box were made for.  Just thought I'd mention it for what it's worth.

Desmond G.


Offline howardnair

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Reply #89 on: September 29, 2012, 02:57:17 AM
Sam-google- star grounding-read and possibly implement-also go into your seduction and suck or wick  the solder off the grounding points and resolder-ck anything else that gets your attention-ck your turntable ground wire -i have had that as a problem-and this next option always gets me in trouble-get a plug adapter without the ground-if that works -remove the grounding prong with pliers- most houses have the nuetral connected to ground at the panel anyway-now if your listening area has a inch or two of water on the floor -i would not recommend this