AD15 Squealing, Please Help!

[Les Paul Lover]

HCW, it's a real shame you didn't post this question earlier today when I took mine apart !!!

I was worried to see i have the plastic lugs too, but they feel really solid so that worry disappeared straight away. You'd have to really hammer the valves in to do any damage to them - and the pcb would be damaged before the plastic lugs I reckon!



I have the 98 design pcb too - and my amp serial is 1053-09-02, so September 2002?



And here you can make out the value of some caps but I wish I had known you wanted them, I could have snapped it then!

The 2 on the right are 100nf k 400v, or .1k 400. And mine are grey. Unfortunately, there's a cable in front of the 2 on the left.....




And seemingly 91k 1w resistors don't exist - we all have 2 resistors in series there!


And i love the labelling for the 8 & 16 ohms taps.....

[steamboat]

HCW, it's a real shame you didn't post this question earlier today when I took mine apart !!!

I was worried to see i have the plastic lugs too, but they feel really solid so that worry disappeared straight away. You'd have to really hammer the valves in to do any damage to them - and the pcb would be damaged before the plastic lugs I reckon!

Good to see you have the 1998 board! I have a feeling if the squealing problem is going to be a common problem that it will be with the 2002 boards. or maybe i'm just hoping that? haha.

Hi Steamboat. Do you have a close-up picture of one of those blue capacitors where you can read the writing on them?

I'll have to take one apart again to get closer pics for you

[HCW]

well, it looks like my friend's Orange was built in 2001. Has the plastic standoffs. Its components look different than mine (It has an actual 91K resistor in R4!), but the board looks the same, as much as I can tell without taking it out. All the traces I can see seem to be the same... and I can make it squeal as well... it's a little disappointing. (Edit: the boards are different versions, but the only differences I can see are with the silk screen, the traces and layouts I can see are all very similar).

There's one other AD15 in the neighborhood I'm trying to get my hands on, but I'm beginning to think these just squeal in the way I'm trying to use them. So if this third one acts the same, I'll just start working around the squeal instead of trying to "fix" it in the hardware. It's not like the AD15 really needs to be dimed to sound good.

[Les Paul Lover]

How do you make yours squeal?

I've had mine dimed before (not many times admittedl), and yes, it was loud and glorious, but squeal free!!!


A 91k resistor... It's a green resistor too....... Mmhh, the secret green resistor society is getting sloppy and letting them out everywhere....!!!

[HCW]

RE: how to make it squeal.

In a band environment where it first occurred I had the master dimed, the gain at noon, not totally sure where the eqs were, but around noon. We were about to play a song and started getting what we all thought was PA feedback. After turning the PA off we realized it was coming out of the AD15, even with the guitar volume down and muted through my tuner pedal. Unplugged the amp from the effects board entirely and squeal was still there. Unplugged cord from amp, it's still squealing... I mucked around with the settings and found usable settings at the volume I needed, but it wasn't as open sounding as I would like. So then I started the quest to fix it that lead me to this thread.

When I've been troubleshooting this, what I do is turn the master volume all the way up, put the gain and all the eqs at noonish, then plug in a guitar cord to the amp. I take the end of the cord that's not plugged in and move it in front of the speaker and I get a squeal. After changing the tubes, cleaning the amp thoroughly, Cleaning all the ground connections I can find, and putting dampening rings on all the tubes, I can now get the gain up to about 3 o'clock with all the eqs at noon. And as I mentioned earlier, cleaning the input jack thoroughly has eliminated the squeal when a guitar cord is not plugged into the amp. I can still get it to squeal turning up the treble, and moving the mid pot can change the pitch of the squeal. I can actually turn my AD15 up to higher setting than I can get out of the AD15 I borrowed to take the most recent pics I posted.

so... I think maybe this is as un-squealy as the/my AD15 gets...? I'll try it out with the band again and see how it does now. It is definitely much better than when I started. And it's not that I don't like the sound of the amp at non-squealy settings, I just thought something was wrong/broken/etc causing this squeal. If it's the design, I don't really want a tech to go in and change the circuit with negative feedback or a notch filter or something... I do still want to try and get my hands on the one more AD15 I know of and see how it does. If it behaves the same, I think I'm done.

The summary of all the things I did:
Sprayed out the input and speaker jacks with contact cleaner with a cable inserted, and brushed the contacts with a wire brush/steel wool.
Sprayed out all the pots.
Cleaned and polished up the chassis ground and speaker wire and other easily accessible crimp tab connections.
Replaced all the tubes.
Put silicone dampening rings on each of the preamp and power tubes (didn't have one that fit the rectifier tube).
Put kapton tape on the connection leads near where the bolt comes down close to the transformer lug connections.

[Les Paul Lover]

Here's a picture of the caps around V2, I quickly opened it up yesterday when making a coffee:



And i tried to recreate that squeal..... And succeeded i think.
I thought you were talking about almighty proper feedback squealing type noise, but it actually is a very low volume whining, isn't it?

I managed to get it with the volume maxed and it appeared when the gain was pushed beyond noon. It's barely noticeable at noon, which is why I never noticed it before. It becomes a bit more prominent as you push the gain further.

But it doesn't take over the amp, it's still a low volume high pitch noise. I would probably never have noticed it if it wasn't for you! It's not gonna bother me either as I never have the gain beyond 12 or 1 o'clock, and usually have it set between 10 and 11 o'clock.

I'm not sure I'd be bothered much either if I set my gain higher, as the squeal is very low volume and just part of the background humming the amp produces.

I assume we are talking about the same noise there?


Steamboat, could you try your various AD15 to see if you notice anything similar?

[tspaceman3]

Hello All

To alleviate any confusion, the squealing exhibited by my AD15 was a very loud and clear oscillation. From the sound of it this is quite different to the squealing that other people are hearing. I think mine was clearly a fault whereas the more minor squeal is probably an inherent quirk of the amp.

[Les Paul Lover]

Hello All

To alleviate any confusion, the squealing exhibited by my AD15 was a very loud and clear oscillation. From the sound of it this is quite different to the squealing that other people are hearing. I think mine was clearly a fault whereas the more minor squeal is probably an inherent quirk of the amp.

Thanks for clearing that up, it's nice to know we are talking about different things.


I now want to try an AD30 again.... And an AD140. Their preampreamps are meant to be the same, and they are, I believe, the same now as when they came out (I believe channel 1 on the Ad30htc is the same as the old 1 channel AD30.

If it is, then they should exhibit the same problem, however minor it is - and it is totally minor/anecdotic in my amp at least.

[HCW]

The issue/squeal I'm getting, once it starts, is definitely not something you could just ignore and keep playing. The steps I described before are just what I've been doing to test it out. If I keep the gain cranked with the master dimed, I can get some really gnarly sounds. The amp will go into oscillation and eventually make crazy old-school-dial-up-modem like sounds if I don't do something to stop the squeal once it starts. That being said, I can als get very awesome and usable sounds out of the Ad15 as well, just not with the master past 3 o'clock.

I have three EL84 amps. The AD15, a Vox AC15HW, and a Blues Jr. Typically in a band setting, with a 15ish watt amp, I'll start with the master all the way up, and work from there to find the sound I want. I think I just need to approach the AD15 differently. It is probably the only amp I've played that doesn't have any negative feedback in the circuit.

[Les Paul Lover]

Ade Emsley was saying in an interview recently that eliminating all negative feedback was a major part of the Orange sound - and very difficult to do.

Now, if only I could remember where I read/heard that......

So my AD15 doesn't behave like yours either then....
I couldnt hear a high-pitched noise, but it was at hum level, and barely noticeable.
Certainly not an issue to me, not at that barely noticeable level.

I hope you can fix yours somehow. You should be able to find schematics for the AD15, perhaps some capacitors have gone off value?