| Author | Message | ||
| John Lisenba (johnl)
New Username: johnl Post Number: 1 Registered: 3-2003 |
I am sorry if I posted this in the wrong forum; I didn't see one that seemed to fit equipment questions. This is my first visit. I recently purchased a very lovingly cared for F1X preamp. It was everything I had heard about and more! I love the tone! I was in heaven jamming with it for a few days prior to gigging it yesterday. One problem however: when we hooked up the DI to the PA, there was a very noticeable hiss. The hiss was not present from the F1X through my rig. It's a white noise sort of hiss, not a 60 cycle hum or anything like that. Lifting the ground did nothing. We then unplugged and tried my SansAmp and Stewart DI's, and the noise disappeared in both cases. Plugged the F1X back in, and the hiss was back. I tried both of my basses (Fender Jazz/passive pups, Custom 5 string w/active humbuckers), same story. The eq settings on the preamp are at 3-8-3, with no high or bass boost. I really love the sound I get with it, but the noise through the PA is pretty noticeable. Is this just a tradeoff for using a tube preamp (it's my first tube anything), or is there anything I can do to eliminate the noise? Thank you for your assistance! John Lisenba | ||
| Wayne McLemore (wayne)
Junior Username: wayne Post Number: 45 Registered: 5-2002 |
John- A couple of quick questions (not that I'll have the answer but it might narrow it down for others): Is the hiss there with the DI in "Pre EQ" or "Post EQ" mode or both? Do you have the Bright switch in the down or up position? I've noticed that with the Bright switch up, I get a lot of hiss with my basses - but it's only audible through the horn of my cabinet, so it's way up there in the frequency range. I'll be very interested in the resolution, so I'll know how to handle it if/when I experince the same thing. Good Luck! C-Ya...........wayne | ||
| John Lisenba (johnl)
New Username: johnl Post Number: 2 Registered: 3-2003 |
Thanks for your reply, Wayne. As I mentioned, I am not using the bright switch (PLENTY of highs without it!) The hiss is there pre or post eq, and it's only the DI out, there is no hiss coming from the cabinet at all. | ||
| Mica Wickersham (mica)
Moderator Username: mica Post Number: 743 Registered: 6-2000 |
Since there was at east one other person interested in the response, I've posted what Ron emailed to you here as well: I recently purchased a very lovingly cared for F1X preamp. It was everything I had heard about and more! I absolutely love the tone! I was in heaven jamming with it for a few days prior to gigging it this past Sunday. That's when I discovered a problem: when we ran the DI to the PA, there was a very noticeable hiss. The hiss was not present when playing the F1X through my rig, only after running to the house. the signal path is that the DI buffer is fed from the full-range output so if the signal-to-noise ratio is ok on the full-range output there should be no difference on the DI output. It's a white noise sort of hiss, not a 60 cycle hum or anything like that. Lifting the ground did nothing. We then unplugged the F1X and tried my SansAmp and Stewart DI boxes, and the noise disappeared from the PA in both cases. Plugged the F1X back in, and the hiss was back. the signal level on the F1X DI output is much greater than some other DI boxes. so you'll hear more noise if you just change from one of the boxes you mentioned to the F1X. just checking here, since you mention below that you tried it with different basses, but you need to play the bass and set the levels in the PA based on the output level from the different boxes, and then listen for noise...both the signal and the noise may be considerably greater in the case of the F1X, but the signal-to-noise ratio should be acceptable. that is, you'll be running the PA input at a lower gain with the bigger signal from the F1X and so the noise will also be turned down...the noise level at this lower gain should be satisfactory. I tried both of my basses (Fender Jazz/passive pups, Custom 5 string w/active humbuckers), same story. The eq settings on the preamp are at 3-8-3, with no high or bass boost. I really love the sound I get with it, but the noise through the PA is pretty noticeable. it was reading this that made me think that you had covered the situation properly and that you did have the PA gain adjusted to the proper level for playing the basses and were not comparing the noise without adjusting the gain on the PA input. Is this just a tradeoff for using ! a tube preamp (it's my first tube anything), or is there anything I can do to eliminate the noise? no, the noise can be greater or less with tube gear. some circuits have more noise than others, and sometimes there are circuits that are inherently more noisy when they give a particular tone. but in general, some tube gear and some solid-state gear is quiet and some is more noisy. to understand the set up you were using, did you have the direct boxes you were comparing with patched in between the F1X and the power amplifier? this is the place that you should have them if you want to have the effect of the tone controls included (and the F1X of course in the 'POST' position) if the F1X is working properly you should not have a poorer signal-to-noise ratio at the DI ouput than at the full-range output. there is a dual op-amp in the F1X where one of the op-amps amplifies the signal after the front-panel volume control and feeds the direct output. the other op-amp in the package is a buffer amp with only a gain of 2 that feeds the transformer that is connected to the XLR connector on the front panel. usually if there is a problem with the op-amp, it will just be dead, but it could be defective and cause noise. if it needs replacing, it is fairly easy, since it is socketed, so you don't have to do any soldering to replace it. let us know if you feel the signal-to-noise ratio is worse on the XLR output compared to the full-range output, and then we can either supply you with a replacement op-amp or if you'd rather, you could send the unit back in and we could replace it for you. | ||
| John Lisenba (johnl)
New Username: johnl Post Number: 3 Registered: 3-2003 |
Thanks Mica. Since Ron was so kind to reply, I will include my remarks back to him if it helps anyone else. Reply to Alembic help desk: Thank you for your reply, it was very helpful. Below are a couple of responses based on things you brought up. "the signal level on the F1X DI output is much greater than some other DI boxes." --this explanation was probably the key, I'll have the soundman reduce the gain at the board next time, and boost the gain at the preamp, and see if that cures it. "to understand the set up you were using, did you have the direct boxes you were comparing with patched in between the F1X and the power amplifier?" --No, I unplugged the XLR from the F1X and into the two different boxes, so the signal chain was Bass>DI>House, bypassing the rig entirely. | ||
| jimbobv
New Username: jimbobv Post Number: 1 Registered: 4-2003 |
F1X tube replacement time? I am also hearing F1X preamp noise, however there are a couple specifics: 1. It just started recently, after a rack tumble. 2. It is very frequency specific - C# in particular. 3. When I disconnect the effects loop RETURN plug (effects loop), the noise goes away - not so with unplugging SEND. (I've isolated the noise to the pre-amp via isolating effects 1 x 1). I'll try replacing the tube next... Jimbo | ||
| cntrabssn
Junior Username: cntrabssn Post Number: 13 Registered: 6-2002 |
Jimbo, When you remove a plug from the effects return jack, the return connects to the send jack internally. So the signal from your bass effectively bypasses the loop, and both stages of the tube are used. It sounds to me like your F1X tube may be OK. Could you give a bit more info on how you isolated the effects? Thanks, nate. | ||
| mica
Moderator Username: mica Post Number: 871 Registered: 6-2000 |
Check the nuts holding the jack on the F-1X to make sure that during the tumble they didn't come loose. I'd also make sure that the external cabling wasn't damaged in the fall - have you tried a different cable in the effects return connection? I asked my dad and he said it doesn't sound like a tube related problem. | ||
| jimbobv
New Username: jimbobv Post Number: 3 Registered: 4-2003 |
Mica, thanks for the help - I'll try your suggestions. Other effect isolation: I've isolated the processors (SF2, Tuner, Comp, EQ) in the effects loop one by one (there's 4 in the chain), taking each effect out at a time (now 3 in the chain) and I processed thru each combination. The noise is there no matter the effect combination. I need to try the patch cables next. I was thinking the effect loop was driven off one of the triodes. More to follow. | ||
| jimbobv
New Username: jimbobv Post Number: 6 Registered: 4-2003 |
Tube not seated securely? The noise got terrible this week with nothing in the effects loop. All jacks checked and are tight; all internal connectors are seated. Replaced tube, powered up, and no sound (bad replacement tube). Put original tube in, and noticed that it seated much more securely than when I removed it 5 minutes prior. Powerup - no problem. New spare tube in hand. Is there a spring-clip retainer sort of thing to make sure tube remains seated? Thanks, Jimbo | ||
| jimbobv
New Username: jimbobv Post Number: 7 Registered: 4-2003 |
On to more debug - after a month of clean sound, I got more static this past weekend in the studio. Again, severe scratchy sound was coming through both the speaker and the DI out. I disconnected the entire EFX loop (S & R cords pulled from F1X), and the CAB sound cleared up, but still had static on DI. Engr used another DI, but CAB volume was noticeably lower. In spite of this, we were able to dial up good sound. Next day, however, same setup, and volume level came up HUGE! Had to tweak it back down to find prior day's level. I'll be home doing some debug this weekend - new patch cables, check tube seating, check all jacks. Any other ideas? Static seems to really resonate on F, F#. Jimbo | ||
| mattheus
Junior Username: mattheus Post Number: 46 Registered: 5-2003 |
I've had the same problem a short while ago. And I've been through my whole set-up. I even did a complete re-wiring. Still there were these problems. Later on I found it, it wasn't in my set-up. A simple cable, connecting the patchpanel to the monitor-mixer was in a bad condition. So, perhaps you should look somewhere else to find the solution. Mostly earthing is very critical. Have fun, running through the wires. I hope you can solve your problem. Mattheus tDo | ||
| jimbobv
New Username: jimbobv Post Number: 8 Registered: 4-2003 |
Woo hoo! Another earthing problem! I think I've got it! I disconnected the F1-X power cord from the power conditioner, plugged straight into a wall outlet, and she cleared right up! The light switch on the F*rm*n seems to be the culprit. How'd I find it? Checked tube - ok; replaced the 8-pin op-amp. Put F-1X back into the rack, plugged in the full range cable and power cable (via conditioner), no FX loop, turned her on, and had noise within minutes. Then I noticed the LED's on the other rack gear (still plugged into conditioner and on), were flickering with the noise...bad system ground in the conditioner...unplugged F-1X from cond, into wall outlet, and voila! No more noise! | ||
| shakeyeraz
Junior Username: shakeyeraz Post Number: 16 Registered: 11-2002 |
OK - I've got the same problem in my F1X (I think). A noise that sounds like an old-style Geiger counter (crackle) is intermittent. I replaced the tube but there was no change. I'll look at the cables to see if there is a 'bad' connection somewhere. I know (but I’ll check again) that the power grounding is OK. Any other thoughts are welcome and greatly appreciated. | ||
| cntrabssn
Junior Username: cntrabssn Post Number: 17 Registered: 6-2002 |
Hello shakeyeraz, You may want to check your effects return jack as well. The jack has a connection that shorts "send" to "receive" when you're not using the loop. If that shorting connection doesn't make good contact, you can run into intermittent issues that seem like a bad tube. If you're not using the loop, you can try plugging a short cable between the send and receive jacks to see if it makes things better for you. If you still have problems with a cable installed, there is still a possibility that your jack is defective. I'd suggest taking a look at your cable connection at the receive jack. Sometimes a 1/4 inch plug can be a little fatter than expected and deform the jack's tip connection. You know, you should probably check the send jack too, but I've had more trouble with the return. The send jack is essentially bypassed when you don't use the loop. I hope this helps, - nate. | ||
| shakeyeraz
Junior Username: shakeyeraz Post Number: 18 Registered: 11-2002 |
Thanks - I'll check each. Is the fix to replace them and, if so, where can I obtain replacements? | ||
| cntrabssn
Junior Username: cntrabssn Post Number: 18 Registered: 6-2002 |
shakeyeraz, If connecting a cable between the send and return jacks fixes your problem, you can continue to run with the cable, or replace the return jack. If you find that the send jack tip connection is deformed and causes problems when you use the loop, you can gently bend the jack back into place if it's an open frame type of jack. You can find jacks at any decent electronics parts outlet. I'd recommend using Switchcraft brand parts. - nate. | ||
| mica
Moderator Username: mica Post Number: 1270 Registered: 6-2000 |
Before you try anything drastic, so the excecise routine - simply plug and unplug a cable in the jack 20-30 times. This is especially needed if you never use the effects loop or always leave something plugged in. This action cleans any corrosion off the contacts and solves 90% of F-1X woes. Sound funny, but it really does work. If you need to replace a jack, we've got some really nice Switchcraft jacks custom made for us that are superior to the Switchcraft standard ones we wre buying before. | ||
| shakeyeraz
Junior Username: shakeyeraz Post Number: 20 Registered: 11-2002 |
I poked around with this today and I believe that it is the switching jacks. I was able to scrape them a bit to clean them and, once I did, the noise went away. I'd like to replace each jack that has the built-in "switch" - I think that these are the Effects Return and the two input jacks. Please advise on how to order. I can replace them myself. Thanks and thank you to everyone on this thread for the assitance. |
