Preamp Deal of the Century

Thanks for the thoughts and observations on the hum issue. I will check the voltage at my panel to see if it really is 120v. I have also tried unplugging all components except the pre with all other breakers off to see if it was interference from another component but there was no change. It's not a major issue because it is only noticeable from a few feet away. I will also check the bolt tightness. I had not considered that because it's a new unit. Thanks again.

Here is a link with some more info on transformer hum induced by DC on your AC line.
http://www.diyaudio.com/forums/showthread/t-83784.html

Another point I want to bring up regarding a.c. coming into your home.Residential and commercial construction through out North America in the past few years has been incredible. This has put a strain on the grid in some areas resulting in poor supply, inconsistent supply of a.c. to your home. Where we use to live tens of thousands of new homes have been built along with many commercial factorys and business.Moving to another area, far less population, I have noticed consistent performance with my system . Like your vehcile,if its getting proper air density /fuel mixture it will perform at its peak....

I once had a louder then normal hum coming from the power supply of my Chenin.I was letting things warm up ,came back into the room. The hum was loud enough that it caught my attention from across the room.First thing I checked was the power and umbilical cords,they were fine.I went about listening to music. I marked it up to fluxuating a.c., a dip in current coming into my house.We have moved since then and I have not experienced this loud hum again.

Halogen lights[or their transformers?] in my house can cause hums.
Fortunately I only have them in an adjoining room and can turn them off.

Any number of experts wil tell you this should not happen but it does.

If it was me having a hum issue, I will find out first if it is electrical or mechanical. Electrical, well, try simple process of elimination. Mechanical, make sure the bolt that hold the toroid in the PSU is tight (can easily seen from the top of hte PSU).

Pardon me but I have a question to ask to those who understand the subject matter well than I can. Bear with me and I dont intend to insult anyone. How can the umbilical cord produce a hum? I thought it carries DC voltages only. Hum if electrical, is AC isn't it? Its an oscillation ain't it? On this regard, another question if you guys do not mind. Why would an umbilical cord make a difference with regards to shielding if it only carries DC? Not to mention that the first stage that the power after rectification (PSU unit) will encouner is the regulator (there is an specific tolerance range where the regulator if working properly will regulate the voltage +/- a certain criterion)on the main preamp box itself so that the length of the cord, if not excessively long, will not degrade/decrease the DC voltages to a significant amount for the application as it encounters environmental interferrence when travelling from the PSU to the main preamp box.

Using a decent power cord from wall to the PSU, I understand that there can be improvements because I am experiencing it. Vibration points, I understand as well and agree that it makes a difference. But a shielded umbilical cord that carries DC improves the preamp performance? In what way and how?

Please, forgive me, but I am not looking for an argument but an explanation only. I want to learn what I am not familiar with (no sarcasm whatsoever!).

Mgv,

Thanks I will try that. I did try turning off all breakers except audio and still had the hum so what you are saying seems logical.

Bryan

Bopo,

I had a similar issue, try moving the umbilical cord around as it is not shielded.

Dave,

Thanks for the info. I will try unpluging my other components and see what happens. I am running my audio on a dedicated circuit but it's worth a try. I also didn't notice it when I first recieved it. If I need to I will get some sort of line conditioner. Thanks again.

Bryan

Bopo,
I'm not sure if this is similar to your situation but I had a problem with transformer hum coming from both my SS amp and Chardonnay power supply. The hum/buzz came from the power supply and not from the speakers and was audible from several feet away. Through some experimentation.. unpluging various AC sources, I discovered that when my plasma TV was on the same AC circuit the hum/buzz appeared. Now with the plasma TV is on a separate circuit and a PS-Audio Hum Buster in line, everything is nice and quiet. Apparently rogue DC current on your AC line can 'rattle' transformers.

Dave

I have recently purchased a Chenin and have a question regarding noise. I have not read all the posts so I appologize if I missed previous information. I am hearing a destinct hum out of my power supply even though it is away from my amp and not very close to my source. Is this normal? It isn't super noisy but it's definately there.

NP and good luck I still think you should give the Umbilical cord a try....hopefully Brad will work out what ever issues he is having right now servicing everyone. If and when you decide to upgrade from the Cortese let me know as I am running the Chardonnay right now but love Vinyl. I run the Phonomena for the phono section.

Thanks very much Ooslik...I just received some of the earliest RCA 6SN7GTs, and will try them in my system. I am also waiting to receive a few nice sets of early Ken Rads as well as single set of the Tungsol Rounds. Like you, I have on hand an early Mullard GZ34, but also a Mullard GZ33 and an Amperex 5AR4. The thuds and microphonics vary, of course, depending on what tubes are being used. In most instances, I can live with those issues. I just want to scotch the glare bugaboo. Beyond that, the Cortese is a wonderful unit. I have my slightly modified Air Tight ATM-3 monoblocks, and an extremely fine ribbon/driver hybrid pair of speakers built by the brilliant friend I alluded to in my previous comments. Then there's my Dunlavy SC-IVs, which are sitting in taped boxes in another room. As much as I enjoyed them, I have enjoyed the hybrids even more. Okay, enough for now. thanks again for the [hopefully] reassuring words.

Opus88 the glare issue seems to have been worked out for me by doing several things.....

1. I tube rolled and bought several sets of 6sn7 tubes here is what I bought
RCA's black base with grey glass
Sylvania's GTW ( I am at work so I can't rememeber axactly but it was the set that were for military use)
2 set's of Tung Sol's all black base
Ken Rads
I also replaced the rectifier tube with a Mullard. so far I have tried and burned in the RCA's and TungSol's. I did not like the RCA's but really like the TungSol's. With the RCA's the high's seemed a bit bright and the mids on some musical passages were harsh. I burned in all of the tunbes for about 100 hrs prior to listening. Did the same for the umbilical cord as well. Have not tried the Ken Rads or the Sylvania's hopefully I get to before my second child arrives. The other improvement I got from Tube rolling was that my loud thud through the speakers when you tap on the pre-amp is now completely gone....Everytime I went to mute or just tap the unit I would get this stinkin loud thud through the speakers...only when you tapped the unit or hit the mute a small thing but it did bother me. With the NOS tubes gone problem solved. It's been great. As for system cohesion I run an Accuphase A50A amp to B&W 802N speakers.

Sorlowski, I understand how you feel. If Brad really has a problem fulfilling the orders, just say so. I don't mind waiting so long as the reasons are valid and he keeps me updated on the progress but nothing from him so far...
If anyone reading this knows Brad personally, perhaps you could let us know what's happening. Appreciate that.

I have ordered umbilical cord from Brad on 02/01/2007, every week he is promising to ship it next week. I really hope that this is not a scam. After one month he stopped answering my emails. I called him, he is just about to send it (for the forth time). What would not just he say that there is a 2 month backorder ? Why do some people do not have any regards to what they are saying? No self respect whatsoever....

Opus88,
I think I've experienced similar midrange problem with my Chenin as well. My experience with tube rolling is very limited, but I feel NOS RCA Grey Glass helped in this regard.
I feel that most of the Supratek owners are kind of hush regarding this very issue and reading this thread very carefully, I've come across very few owners posting similar impressions as well.
I'm sure system synergy is very important, and one has to be very careful pairing Supratek preamps with the "right" amp and speakers.
I decided to give it another chance and oredered Cortese and Mondeuse, hoping that synergy will be "right".
Please, do share your further impressions.

Ooslik...I find it interesting that you mention the following: "...the impression I am getting is that the transients are a bit faster with less glare throughout the musical range." I have burned in for 200 hours both the line and phono stages of my Cortese. I am still getting what I hear as some glare or harshness in the upper midrange, especially with instruments like trumpets. I did not have this before purchasing the Cortese, which was the only component that changed in my system. Let's just say that my previous preamp, built by an extremely brilliant friend I had known, no longer became serviceable. It too was an extremely fine unit with fairly high gain. Anyhow, I've tried some tube rolling ( replacing Sovteks will Mullard, Amperex, Siemens, etc.) but still haven't scotched the problem. I have yet to try the likes of 6SN7s by Ken Rad, RCA or Tungsol. I otherwise like the Cortese very, very much. It is a superb component. But there is that somewhat "glaring" issue that you've experienced too. I'm wondering what needs to be done to neutralize it. I still do have other options beyond tubes that I've yet to try, but do you, or any others having faced the same issue, have any suggestions---or---have any of you found as solution for it ? Thanks very much.

I received an email from Brad Sunday 3/11 stating that the umbilical "will be on it's way shortly", apologizing for the "unforeseen delay"..... I will post once it arrives.

On another subject: I just finished replacing the stock feet on both the PS and the head unit with Walker Audio Valid Points and Resonance Discs. Noise floor seems to have dropped another 10-20% over the rubber stock feet.

did a lot of listening this past weekend and I have to say that it's suttle. again the impression I am getting is that the transients are a bit faster with less glare throughout the musical range. Bass seemed to have a bit more slam and kick as well with the overall soundstage being wide and deep. Now it's been about 10 years since i have had a Tube pre...used to own CJ and ARC and listen to a bunch of Macs when I was a Rep working for high end shop in the DC area called Myer Emco. So some of this could be the pre itself coming into it's own......Apparently I was one of the last to get the 1 meter at a decent price I only paid $219 with shipping so I am not disappointed in the purchase. I also did not have any problems with Brad. So I am sorry to hear that others here are having some issues.

Slipnot1 and Ooslik : Any word yet on what you're hearing with the Revelation Audio Labs umbilical for the Suprateks ?

Yep. The plastic fuse holder pops out with a screwdriver. Very simple. The gold fuses from The Cable Company (www.fatwyre.com) are a very worthwhile tweak for $35.

richmon:

i believe you can just insert a flat blad screw driver into the gap at the bottom and pry the fuse holder open. you might wanna double check with mick first. obviously, make sure it's unplugged before probing around with a screw driver.

Thanks for the cautionary tales, my enthusiasm for replacing the umblical is now low, given the troubles versus the marginal improvement. Guess I'll put a gold fuse in the Chenin for my latest upgrade fix.

Anybody know how to get the fuse out of the Chenin? It's supposed to be inside the iec, (on the PSupply side or preamp side?), do you have to take the base apart to get at it?

gotta be something cause he was great with me prior to the sale as well as after the sale. The transaction only took about a week and a half for me. i would give it a bit more time.

Hi Guys, It could be that Brad is ill or has had a tragedy in his family. Hang in there ,Im shure you will find out soon...

I have not received mine either - ordered about a 4-5 weeks ago. He answers his emails but in an elusive sort of way...can't seem to get a straight answer. Not sure what to make of it. I'll give it a bit more time.

Interesting. Not less than 2 hours ago, I sent Brad an email to inquire about my order for same. I ordered and paid about six weeks ago too....

His last communique to me said he would notify me when it ships. Maybe the wait for the upgraded umbilical is like the wait for the preamp ;)

Has anyone heard from Brad of Revelation Audio Labs recently?
It's been 6 weeks since my friend and I placed an order and paid for 2 umbilical cables for the Supratek preamp but we have not received the cables nor heard from Brad. Brad was prompt and polite when replying our queries before the sales. We are not too happy with his current level of service.

Thanks Kg, much appreciated.
I'm dying to get my mitts on this pre and if it betters
my Syrah I'll be very happy
Simon

simon:

i think mick uses dhl now, but the 25kg fedex box that my chardonnay arrived in measures roughly 17" x 22" x 14".

Dum I know - but- can anyone tell me the dimensions of the 25Kg box Mick ships in.
Bought another used Supratek pre and can't get an answer re dimensions of the box which is holding up shipping.
Tried Fedex website but no joy, maybe since I'm in the UK.
thanks Si

yep hear you on that but I couldn't resist and got back into vinyl about 3 years ago. It's been a challenge with the wife as I have gone through a bunch of equipment and now the Suprtek. Wanted to get the chenin but couldn't swing the change in order and also the cost at this time.

just cd. no vinyl as i can't justify the added expense of the equipment as well as having to purchase all the "necessity" albums. couple this with the fact that most of the music/bands i listen to rarely, if ever, release on vinyl.

cool good to see and know that there is another 2 channel guy in town. I work on Dauphin st. for Xante corp...are you listening to vinyl at all or just cd's

i live in west mobile, around schillinger and airport.

Hello Kgturner where in mobile are you? I live in Daphne and work in Mobile.

Hi Kevin,

Glad to you that you and your family are ok. I feel sorry for thoses that were affected by the tornado's.

tom:

thanks for the kind words. i live in mobile, alabama. enterprise is about 180 miles northeast of here. the weather was definitely bad and we were under a tornado watch for most of the day, but i don't think a tornado was ever spotted around here. typically, the biggest worry around here is hurricanes. only three more months until the start of the 2007 atlantic hurricane season!

Hello Kgturner,

Hi Kevin, I hope you were not affected by the tornado's that hit the south last week. I could not remember if you lived in Alabama or Florida. Let us know if you are alright.

Thank you very much for the rapid answer. Pablo.

pablo:

the buzz is still present, but it may have more to do with the booster amp in the dB99's than the actual malbec amplifiers.

Kgturner:

I am glad you are enjoying the Malbecs. I am still waiting for mines. I have a question for you: what happened with the buzzing you were experiencing when you got the Malbecs? Thanks, Pablo.

powers:

the malbecs sound very open and dynamic. the best way i can describe them is they are a bridge between tubes and solid state. taking all the positives of each and very little (if any) of the negatives.

Kgturner,
How are your Malbecs sounding? Over time, has their sound changed during break-in?

i'm not real familiar with the tubes in the phono section of supratek's so take all this with a grain of salt. from what i can gather, the M8081 is the same as a CV4031. i tried searching a few sites for both and came up with nil. however, there is a person in switzerland selling 31 CV4031's for $60 on eBay right now. it's not my auction. it was all i could find on short notice. good luck in your hunt.

I have Chenin. My came with Mullard M8081 tube. I cannot get this tube anywhere. I have asked Mike, he told me to use 6J6. I have tried CBS 6J6 (1959). What a difference, unfortunately for worse. So went back to M8081. So what are valid; possibly better-equal replacement for Mullard M8081 (6J6).
When one buys tubes for Supratek (except 6L6) all are double triodes, and Mike said that Supratek uses both sections.
Is it possible to buy matched pair with all four section matched ?

Agreed my schedule has been really out of wack and I have not devoted the needed time to listen and let it break in. It's realy been a couple of Saturday afternoons for a couple of hours at a time.....but I should be able to post something a bit later.