AC hum when introducing tube blend in VTB-1

[Tony]

Hello,

FWIW, I know I've well and truly voided any warranty that might still have been valid for this particular unit....

Ok, I recently bought a used VTB-1 from a friend. The unit worked fine and sounded great so I decided to experiment with a different tube - I had a Mullard ECC83 laying around. After inserting the replacement tube and putting it back together I was listening to it, evaluating whether or not I was imagining the marginal difference, when I noticed two black plastic washers on the table. They seemed to have come from the HiZ input, so I took it out of it's case again and put them on the HiZ jack on the inside of the case - I saw nowhere else where they could have gone. After reassembling the unit for a second time I noticed an 'AC type' hum had developed when blending in the tube.

I say "AC hum", although I'm not sure that's what it really is. It's sort of like a rapid throbbing sound.

I thought it might be the Mullard so I put back the original 12AX7 and the hum remained. I'm not generally a TOTAL klutz when it comes to electronics but diagnosing this problem is beyond me.

I would be very grateful for any help or suggestions. By the way, it's a fantastic product and I've already bought a second unit (a new one which I think I'll leave alone!).


Thanks,

Tony

[mentalattica]

I have the same problem, but mine is new out of the box, just came in today. I have previously owned a vtb1 and never had this problem, this will probably be the last SP I purchase. Its a damn good preamp when it is effectively working. I monitored the hum many different ways, my studio monitors, headphones and even ran my headphones directly into the output of the vtb1 just to see if it could have been a cable or interface issue. all checked out well and it was the vtb1 making the horrible noise.

to give sp the benefit of the doubt zzounds did a piss poor job of packaging this thing when they shipped it, the box was atleast 4 times the size of the vtb1's box so maybe something happened in transition.

[Ausrock]

OK, maybe a dumb question, but have either of you contacted PMI/SP direct by email rather than just relying on this forum to offer a solution to the problem.

:cool:

[mentalattica]

OK, maybe a dumb question, but have either of you contacted PMI/SP direct by email rather than just relying on this forum to offer a solution to the problem.

:cool:



For starters I have no reason to contact pmi/sp, as I said in my post I just got this thing last night, so I just sent the unit back to the dealer. The reason I was replying to the original post is because its been a week and no one has yet replied, I wanted Tony to know he wasn't the only one having this problem with this unit.


Are you assuming "either one of us" is relying on this forum?
Or are you stating that as a fact?

[Ausrock]

Sorry, no assumptions, etc., were meant to be made, I was just curious as there was no mention of what action had been taken in view of your problems and no offence meant, but it wouldn't have been the first time I had seen someone post a about an equipment problem on a forum before they thought to contact a supplier or manufacturer.

Also, as the forums are relatively quite, I thought Tony may get an answer sooner by contacting PMI directly rather than waiting for someone to see his post. If I had an answer to the issue I would have answered a few days ago..........unfortunately I don't.

:cool:

[mentalattica]

I understand now, I thought you were being sarcastic with your post. You'd be suprised how many people take a cheap shot at someone on the musician forums that I am an active member of, when in reality the original poster is just looking for some help or advice. That type of behavior gets under my skin because it's pointless. (also didn't see you were a mod until now).
Anyways I hope everything works out for you Tony.

BTW, why are these forums so quiet? I know tons of people with SP products.

[Alan Hyatt]

To let all know, we have been traveling a good deal. We were in the UK for two weeks, came home for five days, tried to catch up and then left for Germany for Musikmesse.

Our sales has increased by a ton, so our service is running behind. We used to have 36 hour turnover, but now we are like the rest of the world and are between 4 to six weeks.

We also get a good deal more SPAM now and had to install a SPAM filter so many e-mails are not answered unledd you address the SPAM filter reply. It is always best to call us on our toll free number.

We want to help everyone with service and are looking for another full time tech for in house. We do not want to anger anyone out there, but our products are very dependable. Unfortunately...Shit Happens, but we stand by our products.

I am sorry no one has been back to you since last week. We continue to have growing pains and deal with everything as best we can. All I can say, is for Tony or anyone else, we are happy to take care of any problem you have, but we need to know about it, and e-mail is just no longer the best way to let us know. We have a Toll Free number 1-877-563-6335 This is a free cal to anyone in the USA. It is listed on all of our manuals, web sites, and advertisments.

Please call us and we will help you out....

[Scott Collins]

BTW, why are these forums so quiet? I know tons of people with SP products.

One possible reason might be that the forum isn't featured on the studio projects website (http://studioprojects.com/). Please enlighten me (seriously - I often miss the obvious), but I don't see why the average customer would think to go to PMI Audio Group to find a Studio Projects forum...?

Gotta let people know about this. I found out about it just searching the web for info on SP... somewhere, I came across a thread that made reference to "the forum Alan Hyatt [is active in]"... And I was like, "You're kidding - the president of the company is active in some forum?"

When I registered here, I thought: Why is this forum so small? Is this just for pro audio folks? It was weird.

Studio Projects might also consider putting the URL to their forum on all their manuals, all their online adverstisements, everywhere.

[Scott Collins]

And, just to elaborate on one point:

The fact that the Pres of the company was/is willing to personally respond in a public forum about the company's products did influence my decision to try SP. I suppose any company could try to mitigate costs without compromising quality - but it could also be marketing fluff. But if I see someone that appears to take the whole matter personally - someone that has a passion about what they are doing - I'm way more likely to give them a chance.

[Brent Casey]

I'll probably need to look at the unit, but is it possible to send over a sound clip. The noise problem sounds a bit unusual...
email: Brent@pmiaudio.com


Brent Casey

[Alan Hyatt]

One possible reason might be that the forum isn't featured on the studio projects website (http://studioprojects.com/) (http://studioprojects.com/%29). Please enlighten me (seriously - I often miss the obvious), but I don't see why the average customer would think to go to PMI Audio Group to find a Studio Projects forum...?

Gotta let people know about this. I found out about it just searching the web for info on SP... somewhere, I came across a thread that made reference to "the forum Alan Hyatt [is active in]"... And I was like, "You're kidding - the president of the company is active in some forum?"

When I registered here, I thought: Why is this forum so small? Is this just for pro audio folks? It was weird.

Studio Projects might also consider putting the URL to their forum on all their manuals, all their online adverstisements, everywhere.


Good point Scott... I will talk with Justin to get some ideas of how to expand it. We may need an outside source to run the site for us. We just have enough time to post on it.

[Tony]

Hello again...

I didn't check this thread for a while as there seemed to be no action, now there's over ten responses! Cool. Thanks very much to everyone for chiming in. I'll try to do the sound clip and send it to you. Just out of curiosity, Brent, are you the designer?

Tony