My AD50VT sounds bad

[tonehungry]

Hi all. New guy here. With the economy not being so great, and because I've returned to school, I don't have much money to play around with for guitar gear. My guitar gear is pretty widdled down at this point, and I decided to pick up an AD50VT for playing and recording at home.

A few years back, I tried out some of the Valvetronix amps in music shops and was impressed with the sound of these amps, for being modelers. I tend to try everything I can get my hands on when I go into a music shop - kid in a candy store. At one point, I did run into an AD30VT that sounded noticeably bad, unlike the other ADXXVT amps that I had tried. I marked it up to my ears being off that day, although they would have to been way off. It seems like whatever was off in that amp is off in my newly acquired AD50VT. The speaker has an unpleasant low resonance to it, and the overdrive sounds cheap and ragged. I remember in particular, the boutique overdrive on the ADXXVT's sounding pretty good (except for that one bad amp), which isn't the case at all with my AD50VT.

Do any of you know if Vox changed up speakers or components in these amps? I feel that something must have changed. I arrived on this forum after googling for speaker swap information for the Valvetronix series. At some point, I found a discussion of Korean vs. Vietnam manufactured Valvetronix amps. Maybe something has changed since manufacturing moved to Vietnam that messed up the sound of these amps. I don't know. I'm fishing for answers. What I'm looking at right now is an AD50VT that is a dog, and I'm wishing for an easy fix. And btw, mine was made in Vietnam.

Any comments and ideas are appreciated.

[tonehungry]

I'm noticing other posts about the AD50VT speaker sounding bad. Maybe it is only the speaker, but I'm also thinking that the unported cab could be undersized for a 12" speaker. What to do here? Sell it off and begin hunting for something else or swap the speaker and see what happens?

[retrobob]

Clean the jacks, especially the headphone jack.
http://www.valvetronix.net/forums/maintenance-tips-on-valvetronix-amps-t141.html

You may have to clean the jacks several times, it really does make a difference.

[tonehungry]

Clean the jacks, especially the headphone jack.
http://www.valvetronix.net/forums/maintenance-tips-on-valvetronix-amps-t141.html

You may have to clean the jacks several times, it really does make a difference.

Hey retrorob, thanks for the suggestion, but I'm positive that dirty jacks isn't the issue here. There is no issue with volume, treble, crackling, scratchiness, or anything like that. I would describe the amp as being too bright, having an unpleasant low resonance, with a ragged, nasty overdrive. And btw, I wouldn't touch an amp headphone jack with a 10' pole, so no worries there.

[retrobob]

The jack's contacts corrode even when not used, the headphone jack deploys the mute and cab sim circuits that can have strange effects on the amp's tone when corrosion is present. Clean the jacks, you may be surprised.

For over treble and harshness, try;
http://www.valvetronix.net/forums/unhappy-with-your-amp-s-sound-read-this-t3774.html

[tonehungry]

The jack's contacts corrode even when not used, the headphone jack deploys the mute and cab sim circuits that can have strange effects on the amp's tone when corrosion is present. Clean the jacks, you may be surprised.

For over treble and harshness, try;
http://www.valvetronix.net/forums/unhappy-with-your-amp-s-sound-read-this-t3774.html

Excellent links retrorob. Thanks. Out of curiosity, I tried the heaphone jack. Everything seems fine there. The cab sims are definitely working, and the headphone jack doesn't sound too dissimilar to what the speaker is putting out, except for the low end resonance, and a bit of typical speaker sound. Maybe my memory of what these amps sound like is distorted. Because I so happen to have some old pillows lying around, I'm going to go ahead and see if some stuffing changes the low end resonance. I'll report back in a bit. Thanks again for the links.

[tonehungry]

The pillow seems to have tightened the amp up a bit - about a medium density, standard, bed pillow. I'll have to A/B more tomorrow after the cordless has a charge, as I'm working with a manual screwdriver and my hand is tired. Also, my manual screwdriving is a bit sloppy to begin with, and I don't want to mess up the screw heads.

I noticed that the tube in this amp is a GT 12AT7. I'm wondering if a 12AT7 is stock for this amp. I was thinking that it would be something a bit mushier, if the tube is in there for response.

The pillow stays in for tonight. I'll report back tomorrow after A/B'ing, and I might as well grab a can of contact cleaner when I'm out tomorrow. It's good stuff to have around any way, and my last can went empty months ago.

[retrobob]

12AX7 is stock, the AT7 will have less gain, try a AX7.

[tonehungry]

Not wanting to wait around on shipping, I went ahead and bought a can of contact cleaner and a 12AX7 locally. The tube was $20 and the contact cleaner was $30. Not exactly cheap, but it was either that or wait around a week or so for an order to arrive. I probably should have waited.

Contact cleaner in the jacks and switches - No change. I already knew that it wouldn't change anything, but it is good stuff to have around any way.

Tube change - Big change in output, but no real change in tonal quality. This one surprised me after reading a few threads here about how different tubes change the sound of these amps. My tube change was pretty extreme, from a Groove Tubes 12AT7 to a Mesa 12AX7A, with nearly no change in tonal quality, but a big change in output. The amp is much louder with the 12AT7. For example, with the 12AT7 in and master at 9 o'clock, the amp puts out about the same volume as with the 12AX7 in and the master at 10-11 o'clock. That's a pretty major difference in output. As far as the ragged overdrive qualities that I'm hearing, there was no change. The funny thing is that ragged overdrive reminds me of the sound of the popular single ended, low wattage, tube amps being sold today, and I never heard one of those that I like the sound of.

Stuffing a.k.a. pillow polyfill - No major change. The cab seemed to tighten up slightly, but nothing to brag about. It didn't kill that low mid resonance.

Back off of amp - This one was very surprising. No major change in tonal quality, at low to moderate volumes. It seems that the cabinet isn't to blame here for that low mid resonance. I'm willing to bet that the cabinet simulations are to blame, not so much the speaker, but the cabinet simulations are adding to the speaker's natural resonance, resulting in what I'm hearing. If I were in a big room, playing with a drummer, I might notice some difference in how the amp cuts with the back off, but at reasonable living room volume, there is no major change in tonal quality with the back of the amp removed. There is less bass with the back removed, but the bass quality (not volume) isn't good to begin with.

To anyone reading this thread, my words of advice here are that if you aren't content with the sound of your AD50VT, move on. Don't waste your time and money adding poly, changing tubes, or swapping speakers. It is what it is. I could confirm my hunch about the speaker, but I trust my ears enough that I don't see the point in doing so. I've owned and played quite a few tube amps, solid state amps, and modelers, with various cabinets and speakers, and I feel that I'm at least somewhat educated on the sound of amps. There are good and bad amps no matter if it is tube, solid state, or a modeler, but I don't think that I would ever be happy with anything other than a good tube amp. If you're looking for a mild to mid gain overdrive, I would suggest to you to try some real tube amps made by Vox, Marshall, Fender, Orange, or any of the boutique makers, depending on your playing style, while avoiding the low budget models. Low cost means compromise in sound to meet a price point. Good tube amps cost more, and they don't do low volumes well, but there isn't a substitute for a nice sounding amp that does something for you. Opinions vary, and this is only mine.

[cosmicrepairdude]

A few issues:
1. I'm surprised you bought it, given how much you dislike its sound and the fact that you likened it to an AD30VT that you disliked the first time you heard it.
2. The cabinet doesn't seem small to me for a 12" speaker, I've seen smaller ones that were sealed.
3. You haven't mentioned what speaker is in it. The tube was obviously changed by a previous owner, maybe the speaker was, too? Is it the original, a Celestion 70/80?
4. Some people, as you say, don't like that speaker, but the majority of reviews I've seen of this amp, both expert and consumer, liked its sound. A friend of mine has one and it sounds fine to me.
5. The settings of both the Master Volume and Power Level affect the tone. MV is best left at 1:30 to 3:00 for tube saturation and PL as high as possible without the hiss intruding. Then use the Volume to adjust the loudness. You didn't mention your eq settings but a very good case has been made that none of them should be turned past around 12:00.
6. Given that so many people like this amp and that speaker choice has a huge influence on the kind of tone issue you're talking about, I can't see why you'd suggest that changing the speaker is a waste of time. There are certainly enough posts from people who have done exactly that. Other than the Peavey ValveKing 112, which I own, I'm not aware of any all-tube amps of that power in that price range and certainly none with modeling and effects options. The brands you're talking about are all way more expensive for that size and power.
7. And as you may have noticed on the stuffing thread, some people have used a beam blocker or a layer or 2 of black t-shirt material to tame piercing highs, although turning down the treble could have the same effect.