LB head failure

so here i was doin a gig last sat..when 3rd song into the set the amp just stops working..i had power and everything..but no sound whatsoever..so at first i thought it might be a tube problem and it just didnt show it..as i always carry a spare set with me.. i changed the tubes and still nothing..by this point i was soo pissed off i kicked my gibson halfway across the stage and busted one of the tubes....so monday i take the amp back to the shop i got it....turns out that the transformer blew on the amp.. granted..this amp is only a cpl months old..and by no means should anything like this be happening..i mean its been across the country with me already and not one problem till now.. dont get me wrong.. i love this amp..i just think its kinda shitty that a problem like this would happen this early into the amps life.. kinda makes me worried bout whats gonna happen down the road..and now since its gotta be fixed..im without a head for at least the next 2 weeks while randall sends them the parts n all that crap..thank god we got some time off and no shows comin up..anyways..just figured id share my story with all you guys..

I symphathize with you totally. I had a very similar experience with my RM100 gone down during a gig. I'm happy to say that since the repair, i had no problem with it so far (knock on wood). :x
Nothing more frustrating than being all psyched to play and you gear f##$ up! But you actually kicked your Gibson? :lol:

How long did you have the amp before that happened? Was the service center able to tell you what caused the problem? Usually when this happens it?s because the impedance switch wasn't set to match the cab. The amp will work for a little while but eventually the power transformer will blow. This can also happen if you are using instrument cable instead of a speaker cable between the head and cab.

I got a silly little question... or two... or three

Here is an explanation c/w scenario.

On the back of the Lynch Box it has two speaker outputs and one is designated as the main... USE FIRST and the other as an extension. There is a impedance slider switch that is 4, 8, and 16 ohm selectable.
If I'm using a 8 ohm cab such as I am with the Lynch Box cab then I simply plug into the USE FIRST output and set the impedance to 8 ohm... done... rokk out!

What if in the above scenario I plug into the "extension" speaker outlet... what will be the outcome? will it have a negative effect?

On many other amps there are two speaker outputs but no designation ie; the user can choose either one being there is no difference.
And in many cases these two speaker output jacks have an internal wiring relationship that is parrallel. This means that when two 8 ohm cabs are utilized one must select 4 ohms of impedance as two 8 ohm loads in parrallel equal 4 ohms.

Does the above apply to the Lynch Box? Are both speaker outputs wired parrallel to each other internally? If so then why the USE FIRST and EXTENSION designations?

I underdtand that loading a head is very important in that if you select the wrong head impedance for the speaker LOAD being utilized then the results can be very negative on the tranny... to the point of burn out.

Transformers are techinically defined as reactors and reactors by nature will react infinetly to a load. I also understand that tranformers are rated on counter EMF tough we commonly see watts used in ratings the watts = power which is a product of CEMF, impedance, Power Factor and Effeciency.

I see this as being a potentially bad thing... if the Lynch Box speaker outputs are wired series then two 8 ohm cabs need to be impedance matched by the head at 16 ohms and not the usually seen 4 ohm.

Unless I've missed it there is no explanation for speaker cab connections in the manual. Since it is such a critical issue this is something we could all benifit from learning more about.

So what up?

Craig

If you plug into the extension jack you won?t hear any sound. Because of the way the way the ?use first? jack is wired, the ?extension? jack isn?t activated unless the other jack is also plugged in. Bruce is really the best guy to explain the WHY. He was the guy (read ?incredible freakin? genius?) who designed the amp and I?m sure he has his reasons for not wiring the jacks in parallel.

If I'm getting this right the jacks are not parallel then. So for guys like myself and others who are not sure this is good info.
If they are not in parallel then they should be in series.

That makes a huge difference in the head impedance thats selected...

Thanks Rich I will ask Bruce the why question.

Craig

I passed on a copy of my above post to bruce and here is his reply...

Dear Craig,
Actually there are quite a few amps with "Use First" or "Main/Extension" speaker outputs. Most Fender amps have Main and Extension jacks for speaker outputs. VHT, Egnater, Rocktron have the terminology "Use First". You are correct, the speaker jacks are wired in parallel. Two 16 ohm cabs (one per jack) set the switch to 8 ohms. Two 8 ohm cabs (one per jack) set to 4 ohms. Internally, the Main or Use First jack has a normalling contact so that when no speaker is plugged in, the output is shorted. This helps prevent damage to the poweramp in case the user forgets to connect the speaker and tries to play. It will not harm a tube amp (over a short period of time) to run it into a short, which is what occurs when no speaker is in the Use First jack. It is harmful to play your amp into no load (no speakers connected) for the reasons you stated below. Shorted output transformers and power tubes are the usual fatalities. So, the reason for the Use First jcks is to protect the amp from user error. Some amps that do not have the normalling jacks have a resistor (usually around 250 ohms)connected across the speaker output jacks to help protect the amp in case of an open load. At least the amp still sees some load. These are only short term protection methods. The idea is that if the amp does not make sound, one would stop playing and find out what the problem is. FYI, if you plug into the "extension" speaker jack first nothing bad will happen. You will probably hear a little bit of very distorted sound because the Main speaker output is still shorted. Hope this answers the questions.

Thanks
Best Regards,
Bruce Egnater

Thanks Bruce for getting back to me so quickly I'm sure this info will be of significant value to those using Egnater and Randall amps and to anyone seeking out knowladge of amps in general.
Personally I've seen the main/extension designations before but the USE FIRST was new to me... knowing the reasoning behind it is very good iformation indeed.

Craig

Hey Craig,thanks for posting that cool info!

your welcome

sorry for the delay gettin back to ya....ive had the amp for about 3 months
now...luckily the shop that i bought it from has a tech there thats
great he didnt say what caused it but im sure ill ask him what it could be that way i can avoid that happening in the future..otherwise i was just gonna drive up to the factory or distribution center or whatever it is since its not really too far away from me.. and i had the impedance switch set at 8ohms cuz thats what i was told to run it at?? and im running all the correct cables for it..is it supposed to be run at 8ohm or 4ohm??....oh..and Tung... yes.. i actually kicked my gibson haha i was that pissed lol..