Hard to say. Something is open in the signal path first guess, try the line in (effects return) and see if it’s louder, at least you can isolate the stages. Check the discussions at aztechmusic.com

I doubt if you blew all 4 speakers but it wouldn’t hurt to run the speaker out to another box for a sec to check it. At this point if it’s in the output a component could of worked itself loose from heat or a cold solder joint, still a guess.

Gary

46 seconds ago I have a Fender Deville 410 and after one jam session it all but stopped working.. The sound coming out of all speakers is quiet and muddled.. almost with a phase variance as if someone was constantly moving every dial back and forth.. I confirmed its not blown speakers by connecting it to another speaker cabinet separately and the same sound. All tubes appear to be fine and glowing normal. No capacitors appear to be blown or extended on top.? What is the likely cause?

I tried playing through the effects input but same result. Even on clean channel it has a strange mildly-moderate overdrive tone. and also low volume even when turned way up. The night it stopped working I was playing it louder than I ever have before turned it up past 6 (normally 4 is more than enough)

Is it possible a capacitor(s) is blown/broken without showing tell tale signs ?

You didn’t hurt your amp by having it turned on before it was plugged in, not a good habit but one chance in a hundred it would do something to harm your amp

If the amp is completely dead, I would check the fuse or the ac cord or something simple if it’s been sitting awhile. Probably not that bad of a repair.

Cheers,
Gary

I live in Spain and have a fender concert valve amp 60watts. I think its the 1983 model. I haven’t used it for 3 or 4 years and it used to be fine. But I switched it on today and the red light never came on so it’s not working. I left the standby on for sometime before switching it on and still no signals. However, the first time i switched it on I forgot to plug it in – could that have damaged it?

Hope this helps…
Gary

When plugged in, the amp powers up just fine. Unfortunately, when you plug a guitar in to the input jack, you get almost no sound what-so-ever. Only when everything is cranked, and i mean on 11, do you hear a faint sound of the guitar playing. I used to get around this by plugging in through the return jack in the rear, but this no longer works.

Any suggestions?

Thanks,

Andy

Don’t take this wrong because I’m only speaking from experience…I wouldn’t experiment or learn your chops on a Marshall 800 that is working…one little mistake and it won’t be working…..now since it’s in the preamp section you probably won’t do much harm, like take out a transformer but you possibly could….

What you’re talking about is the input grid, plate and cathode…look at tube theory more in your book. You’re getting there but I would find another old tube amp or something on eBay and build a prototype of what you want to do…you will learn tons of stuff by doing this.

You know how to twist the wire and hook up your heater. Now you have to decide phase on the tube, this will determine how you hook up the input to the tube, and how you hook up the plate and cathode…the components around the tube will determine what it does and how..(also a tip) I’m not sure if the tube is already in place that you’re going to use but anytime you modify you can induce noise so beware. …there will be test equipment also that you probably don’t have…like a variac to slowly bring up your voltage so you don’t blow something….

since you’re theory may have a ways to go, you might be the type of tech that experiments by replacing one component at a time..take careful notes…see what each one does…for example with the book you’re reading…build a circuit that he talks about and change values of resistors and see how it effects the sound….

Again I admire you enthusiasm, but I wouldn’t hack on your marshall till you know what you’re doing…

my 2 cents worth…

Gary

I know the transformer can take it I just need to know where to attach the connections to I already know to tie the heaters together to the closest pre amp tube the other connections are where I am lacking the knowledge I have a general idea but am still not positively sure and do not want to cause any damage any tips would help Thanks Dan still tubing in Indy!!! Ps.

I also know that I will be using only one side of the new pre amp tube the plate pin1 the grid pin2 the cathode pin3 and the heaters pins 4-5-9.

Thanks,
Dan

Thanks for commenting on my site. Feel free to use the blog to leave a post or I can always paste this email there if you don’t mind, I won’t use your real name..it helps build traffic…

I assume your extra tube is for more gain? Let me know what you want it to do…are you adding it to an existing amp or building it from scratch? Probably the reason you’re not getting many answers at this point it the question is too vague. I have friends that would use the older fenders with the 2 channels and gut the bass channel. Keep in mind when you add a tube you’re gong to tax the power supply so if you get an amp with it already in place like an old fender you’re doing well. If you add a tube to an existing amp, you have to make sure the supply has enough gas and regulation to take it on, especially in the high gain area…if you build from scratch you can figure all this in.

I’ve been reading the book that is in my resource area…The guitar amp handbook..a guy over at groove tubes turned me on to it after I did a review of their mod output tube plugins…it won’t tell you how to do a mod but when you get through with it, you will know what the ciurcuits are doing in an amp (except for the power supply, he doesn’t go into that,,people can hurt themselves if they don’t know what they’re doing)

Another thing is to study schematics of amps that you like after you read the book above and compare circuits and tinker…
And then you will get into the black art of components which this book does also…and then you can sit online and argue with people LOL

Hope this helps,
Gary

I also wanted to ask you about adding an extra tube to the pre amp circuit do you have any info on this subject or know of any sites or books or any where to find out about this their is no info that I can find and have emailed several people about it with no response and I will add that I do not mind paying for any kind of knowledge about this subject and anything involving tube amps and the expansion of my knowledge of them I have been tinkering with tube amps for the last five years and I know alot about them but still have a long way to go any info on this would be very helpful in my quest for my ultimate tone

PLEASE RESPOND and Thanks
Dan still tubing in Indy!!!