I need help before I kill again!!!!

LordCloud · « **on:** 10 Apr 2004, 12:46 am »

I have a tube preamp (Music Angel from Shengyi Audio) and solid state monoblocks (Ird Audio MB-100). The problem seems to be with the preamp, my center image is off to the right. I know, I've switched everything, the center image shifts from right to left depending on what cables I swap. I've taken it to a repair shop but they can't find the problem since they've never heard of the preamp (neither has anyone else). I know it's a shot in the dark but does anyone have any suggestions as to what the problem may be? Even if you guys can't help, thanks anyway.

_scotty_ · « **Reply #1 on:** 10 Apr 2004, 12:51 am »

Try swaping tubes in each channel and see if the problem follows a tube from left to right, you may have a failing tube.

LordCloud · « **Reply #2 on:** 10 Apr 2004, 01:11 am »

I've swapped every tube and the problem still persists, but the image shift does not change sides with the swap.

markC · « **Reply #3 on:** 10 Apr 2004, 02:48 am »

Could be a problem with the volume pot? Does the left/right dominance alter as you turn the volume up/down?

LordCloud · « **Reply #4 on:** 10 Apr 2004, 03:45 am »

Nope, it's constant no matter what the volume.

Pez · « **Reply #5 on:** 10 Apr 2004, 04:00 am »

Time to shift your speakers around. Even a slight difference in toe-in between the two could throw the image way off.

LordCloud · « **Reply #6 on:** 10 Apr 2004, 04:25 am »

I've tried that my friend, the first thing I thought was that it was a room speaker interface issue but that urned out not to be the problem. I may kill soon, I can feel it.

Sonny · « **Reply #7 on:** 10 Apr 2004, 04:55 am »

Take your speaker cables and do a continuity test...
make sure that the positive on one end of the cable is the positive on the other end...
I know...seems like a dumb thing to get wrong, but I had a pair of cables, I won't mention who or what, but it was terminated with a positive marker on one and the other was marked negative...
so, Check the speaker cables...
let me know what happens.
Sonny

Pez · « **Reply #8 on:** 10 Apr 2004, 05:10 am »

Clean out your right ear.

Mike B. · « **Reply #9 on:** 10 Apr 2004, 04:40 pm »

It is so hard to diagnose via internet. Can you determine the tubes that are the signal output tubes? There usually will be coupling caps between them and the pre outputs. Anything from .22 to 10 uf. They block dc voltage. check the input side toward the tube and see if the voltages are the same or within a couple of volts. You can also check channel voltages at the power supply end if that is easier. What I am suggesting will help you define the pre as the problem. Good luck and be careful. Audio hell is no place to be.

joeling39 · « **Reply #10 on:** 13 Apr 2004, 05:03 am »

aaron

,

I had the exact same problem as you. The center image seems shifted to the right. very frustrating. I tried a multitude of things. not sure which ones were more effective but the problem seems to be solved now :

1) Phase of the audio system. I seem to be sensitive to this. Most easy to check is to swap the +wire of speaker to negative terminal of speaker & vice versa. Of course, this has to be done to both speakers. I find that sometimes, the image can shift after this. The bad news is that some tracks as +phase while others are -phase sometimes even on the same album. Some pre-amp have a switch to toggle phase on them.

2) Symmetery of the room. Try to make the room as symmetrical as possible. I put some egg crates (made into a panel about 4ft X 3ft) on the 1st reflection at the side walls. I find that if I shift the panels either closer to the speakers or closer to me, it also makes a difference.

3) I had a audiometric (? not sure if it is the right word) test done to check if one ear is more sensitive than the other. I use the mobile phone a lot & was afraid this affected my hearing. Lucky me, no problem

4) Room correction system - I bought myself a second hand TACT RCS room correction unit. This helped a lot to focus the image in the middle.

5) Seating position - need to make sure that you are sitting exactly alongthe centerline of the 2 speakers. Some songs are particular about this - Rebecca Pidgeon - the raven.

Hope this helpful.

Regards,
Joe Ling
Malaysia

joeling39 · « **Reply #11 on:** 13 Apr 2004, 05:05 am »

oops, I seem to have misread your question. You are talking about your preamp, not the whole setup. My apologies.

Regards,
Joe Ling

WerTicus · « **Reply #12 on:** 14 Apr 2004, 06:44 am »

dont pre amps have balance controls?

there was a discussion on audio circle somewhere about how they are so important in getting things 'right' and im inclinded to agree... after all it would be impossible to have two channels that are exactly the same...

maybe one of your posts or cables has slightly more oxidisation on it and its not letting as many watts through.. maybe some capacitor somewhere is slightly off value affecting x over frequency....maybe its a resistor resisting too much....who knows!

LordCloud · « **Reply #13 on:** 28 Apr 2004, 12:57 am »

Thanks you guys for all of your suggestions. As it turns out it is a synergy problem with my amps. I have borrowed a couple of preamps from some fellow members of the Utah Audiophile Society and my center image problem is gone! I also took my preamp to a member's home and there was no problem. So now I have to decide whether to keep the amps or the preamp. I am leaning towards keeping the preamp since I haven't gotten that third dimension and palpability with the other preamps. Thinking about trying a pair of the ASL 25 watt monoblocks. Thanks again to you all.