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Originally Posted by Quabrumbel
The amp does sound great. I can tell you though that the hum from the FX loop has nothing to do with pedals. As I mentioned earlier, I tried a straight jumper cable from the FX send to the FX return and it still hums. Krueger was able to get his fixed so that tells me there's something wrong.
I just got the amp last week so I'm still within my return period but I'm pretty much determined to get this problem fixed one way or another because I really like the amp and don't want to return it.
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11-23-2013 10:09 AM
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Weird that you get that response from Ampeg. If anyone of you like, you can pm me with your email address and I will forward the relevant response I got from them.
The hum in my fx loop was at a constant volume level, something like 53 dB, and did not increase when amp overall volume was raised. At home it might be a problem, but probably not at gig or band practice levels.
Thomann did fix the problem. The loop is not completely silent and transparent even now, but clearly much better.
I have done all assessment of the loop with a short patch cable connecting send and return, to eliminate other sources of noise. I also use a foot switch to toggle the loop into bypass mode to clearly and quickly hear the differences.
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Originally Posted by krueger
Thanks! PM sent.
That is the exact same issue I'm having. Constant hum, not affected by the amp's volume setting, still hums when using a patch cable connecting fx send/return, not present when I turn off the loop with a footswitch.
If I put it on half power it's not so bad at home but on full power it's very annoying and at a gig with the amp running through the PA, that hum is going to be amplified pretty loud over a 3000 watt PA system. If I played unmic'd it wouldn't be so bad but we mic everything so that hum is going to be loud over the PA. Definitely need to get it fixed.
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If you're having a problem getting the amp fixed. Send them a link to this thread. That should get them off their butts.
At least now they will see that others are having this problem and it's not an anomally.
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OK - in the last half hour I have finally managed to mate my new GVT15 head with my equally new Cannabis Rex (how did DHL get that box through Her Majesty's customs ?). Its way too early to give a review, but firstly I am surprised how quiet the amp is, both in terms of hum and also in terms of guitar volume - although I'm still a long way from combining both gain and volume past 12 o'clock. It's also somewhat brighter than I expected, but that may be due to the speaker not being run-in yet (comments ?).
BUT, yes, as soon as I plug anything into the FX loop, it hums like a bee hive. Just as reported by others above.
The question is now, can I be bothered with the sort of pain that Krueger experienced when returning his combo to Thomann for repair, or, despite hating to pay for a feature that I won't use, shall I just play it without using the FX loop ? As essentially I will be using the amp for its clean sound and deriving any OD from stomp boxes, I can just run my chorus, reverb and delay straight into the front. I have at least 4 weeks to make a decision, given Thomann's 30 day return system. However, if any other Ampeg owners get to know what the official fix for this problem is, I would be happy to hear it, as I am sure it is something I could probably do myself, warranty voiding notwithstanding !
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I sympathize, since I was also toying with the idea of returning my Koch Studiotone for almost a month, finding it a bit too noisy. However, this was presumably more a case of post-GAS depression-induced nitpicking rather than a true problem. I have since come to the conclusion that all it takes is a little care with all those connections and accepting a few basic facts. The Studiotone does hum if I run pedals through the loop with the power supply close to the amp's power supply, and I have found it to be a good idea to move another foot or two away from the amp with my guitar, as this will usually take care of the hum for some reason.
But my Studiotone certainly doesn't hum on bridging the effects loop with a patch cable with no guitar connected, so this does sound like an inherent problem of the GVT15. The fact remains that returning an amp is a hassle. From what I have read about the GVT15, this is supposed to be a clean amp with a very low potential for intrinsic dirt, so if I were in your shoes, I would probably content myself with using any effects in front of the amp. That being said, I would definitely want to make sure that I can use any separate modelers/preamps into the return jack of the amp to take advantage of its 6V6 power stage. Have you checked whether this can be done without alarming the bee hive?
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The bees become active when anything is plugged into the Return jack, so a modeller would also suffer. Having thought some more, I really do want to use the fx loop, as I like to run my looper in the loop, so that any changes made to the EQ for the live track don't influence the current playback track. Originally Posted by palindrome
It may be that I can live with it. The hum isn't anywhere near as loud as that from a VHT 12/20 I tried recently. That hummed even without anything in the loop. Perhaps I was pre-sensitized to the hum in the Ampeg by this thread !
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I don't trust this fx loop. If I bypass the preamp and put the guitar directly into the fx return, I get the same high volume as by using the front input with gain at maximum and volume at about noon. That is unusual isn't it? Going directly in the fx return of a Hot Rod Deluxe was much less volume. Originally Posted by newsense
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Perhaps it would be fair to just take the loop for what it is. I have just noticed that the manual of the GVT15 specifically points out (1) that the send jack provides a "line-level" signal and that (2) any signal fed into the return jack should come from the send jack. Originally Posted by Quabrumbel
This would suggest to me that the loop is designed (1) NOT for pedals but for rack-type effect units and (2) NOT for just plugging into the return jack.
The effects loop in my Studiotone is different, which is also clear from the manual.
One way to address the problem might be to use some box that allows you to adjust the send and return levels ad lib. I am currently interested in a solution of this type (http://lehle.com/EN/Lehle-Parallel-L) for a different reason, i.e. I would like to parallelize the serial loop in my amp to use some digital pedals that clearly affect the signal if used in a serial configuration. So if this consideration makes sense to you also, a box of this type might actually allow you to kill two birds with one stone.
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On second thoughts, perhaps my latest post doesn't make a lot of sense, considering that a "line-level" loop would involve a higher volume level coming from the send jack. So the return level should actually be lower for compensation, which is in contrast to what has been said here about the GTV.
Not sure.
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Sorry to hear you are all having such trouble. My fx loop works fine but i only use a BBE Tremolo pedal in front of the amp anyway. I am still in honeymoon mode over this amp. It just makes my Gretsch sing, ahh I get butterflies just talking about it. ��. Brrgh, Hrumph, "football", "muscle cars", how bout them Bears?
After two weeks I can happily say this is a great amp for me and my multiple needs. Big Band capable, check. Surf trio gig, check. play quietly at home at 0530 while family is still asleep, check.
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Another 24 hours on: No, I definitely can't live with the hum. So, its either not use the FX loop or return it. I'll give it another week. Originally Posted by newsense
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I called Ampeg and the phone support rep told me yet again that they had never heard of this problem. I insisted that it was in fact a known issue and asked him to please ask around until he found someone in the company who knew about it. He put me on hold and finally came back and said that yes, he found someone who knew about it and that they do have a fix for it. I asked him to please send me the instructions but he said he couldn't because it is information that is proprietary and only authorized service centers are allowed to have it. Originally Posted by newsense
I asked to speak to a supervisor and the supervisor also refused to send it to me. He was actually somewhat snarky at first and really put me off a bit but as we talked, he became a little less snarky and more helpful. He still didn't send me the info but he did contact my nearest authorized service center and preemptively sent them the info so they would already have it when I drop off my amp there next week.
So, that's where it stands now. Ampeg does have a confirmed fix for it but they refuse to tell anyone what it is. I wonder what would happen to someone whose amp is out of warranty and they need to fix it themselves. I guess they're screwed? I guess I'm more or less relieved that I'll be able to get it fixed under warranty but overall, Ampeg's support has left me a little disappointed.
Maybe you'd have better luck contacting them than I did? Is there a different Ampeg support department in the UK? If there is, maybe they would be of more help in getting you the info directly?
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There isn't a support department in the UK. Andertons in Surrey did have the GVT for a while (have you checked out their arsed up GVT You Tube clip??) but they only carry the Bass amps now. They may do a warranty fix for you via Ampeg HQ?!? Originally Posted by guitarman3001
The main importer was/is Thomann.de in Germany. My GVT 15 doesn't hum in the FX loop but as it's a valve amp I would expect some sort of hum and buzz.
The following is from http://www.ratvalveamps.com/ ebay site http://www.ebay.co.uk/itm/RAT-HOTROD...e=STRK:MESE:IT which has a GVT5 combo that they have modded...
New on the Market, the 'GVT5-110' Combo. The Concept behind most 5w Valve Amps is that they Get 'Dirty' very Quickly, with almost NO Clean Headroom. The Ampeg does not do that, it stays 'Clean' almost up to Full Power. Very 'Fender' Sounding. If you are looking for a 'Clean' 5w Combo, this is it.
Classic Design, All Valve, Class A, Single Ended, Cathode Bias.
It's a 'REAL' Valve Amp - NO Transistors, Chips, Digital Processing or SMT (Surface-Mount Technology).
The Amp is Superb Build Quality - Thick Steel Chassis, Decent Transformers, Nice Double Sided PCB with Thick Copper Tracks and Correctly Rated Components. There is NO Background Noise (Hum or Buzz). It's so Quiet that it is difficult to hear if the Amp is ON. There is a nice little Feature with the Pilot Light - It's RED in 'Standby' Mode and GREEN in 'ON' Mode. The Combo Cabinet is very well built from Void-Free Ply with a Celestion 'Tube 10' Speaker (G10E-30, 16 Ohm, 10", 30 Watt). There are a few Minor Issues - The 'Toggle' Type Power Switches are Very difficult to Operate - The Internal Mains (Blue and Brown) wire connections are 'Back to Front' - Somebody in the Amp Factory has got carried away with the use of 'White Silicon' to hold Components in place - If you want some 'Crunch', you are out of Luck unless you use a Pedal in front of the Amp. Other Than that it's a Fantastic Sounding Little Amp.
I guess this guy could sort out your problems but obviously invalidate the manufacturers guarantee.
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I notice the price of this amp has shot up to $429 on Musicians Friend today. The power of this forum!
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I guess there's a need for tube amp makers to cover their backsides. Giving end users instructions on how to fix bugs inside a tube amp wouldn't strike me as a particularly wise business policy. As a case in point, the manual of the Palmer Drei states repeatedly that tubes should not be exchanged just to experiment with different sounds, even though the whole design of that amp is obviously centered on allowing end users to do exactly that. Originally Posted by guitarman3001
But Ampeg could do something about their perceived customer friendliness by publicly offering to fix the problem even out of warranty.
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Hi Guys,
I just ordered the ampeg gvt15h amp. Because I love the EQ, and the "low" wattage (it isn't low... its logarithmic, so 100W>10W= half as loud)
I read about the problems...
About the fx loop:
When a guitar is plugged in at the return it is loud,
have you tried it with a patch cable inserted at the fx send? It could work as a switch...
Ive had a repair/mod shop for a while, so I'll probably end up modding this amp.
Replacing the caps etc... and reworking the solderworks. (maybe put some el84's in)
Ill post some tips if I've got them
About the long reverb. put in a anothertank , or be creative, and put some cotton wool loosely inside the reverb pan. it could fix it (and it could suck bigtime)
I think this amp could be great with a bass guitar aswell. Any one tried it. If i change the caps, ill put in some larger values to pass the sub freqs.
Cant wait till it arrives. (ordered a b-stock from thomann)Last edited by EVOSTARS; 11-27-2013 at 07:42 PM.
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Yep, I cut the Bass control back as it was making things vibrate in the room. Sounded nice, but I wouldn't play too loud as I didn't want the speaker to pop, I'd rather it break in gradually. Originally Posted by EVOSTARS
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Good to hear it works with bass. I got 2 2x12 cabs , cant wait to hook them up..
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In the block diagram it says, true bypass. But it needs the switch jack to operate in true bypass. This is interesting, because it bypasses the fx and reverb opamps, and turns it into a true tube amp without opamps in the signal path.
You could use a single jack, and solder it in the right position, if you never use the reverb or fx loop.
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guitarman3001: If you do take your GVT into the service center, I would be really interested to hear what they have to say about the repair. Meanwhile, I plan to contact Ampeg, both Head Office and UK importer, next week before I decide whether or not to send it back to Thomann for the repair. I'm not keen to do so based on Krueger's experiences. Originally Posted by guitarman3001
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just got a reply from the tech about the fx/reverb bug:
The fix is only applicable to boards built before Rev D00, and involves removing C36 and C37, then soldering 2x 2200uF caps in parallel with D16 and D17
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What is Rev D00? Originally Posted by EVOSTARS
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Its on the print board. They give updates to the board. Starting with revision a, rev a Originally Posted by jazzbow
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My GVT15 head is now on its way back to Thomann for, I hope, a swift repair. I suggested they read this thread for guidance
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