Gibson Skylark to drive extension cab?

[GlideOn1]

Hello, I am new here, but the amp that I am looking into to modifying is hardly new at all.

Bear with me now, this might be an earful:

I have a mid 60's Gibson GA-5T Skylark, Class A tube amp rated at about 4.8w, and the features on it are fairly basic:

Two inputs (one is a couple decibels quieter than the main)
One volume knob, dubbed "loudness"
One knob that controls the tremolo, dubbed "frequency"
One knob for on/off
Fuse (not used anymore due to the updated 3-prong power cord).

I had it serviced recently and it works and sounds awesome, save for the tremolo which chooses to work 75% of the time.

Getting to the point, this amp is surprisingly loud enough to keep up with the drummer in my band, but then again, my other bandmates amps' consist of a Marshall JCM2000 , and an Ampeg (most likely 450w+) solid state bass amp with two cabs, one with a 15" and the other with 4x12. The Marshall also has a 1960A 4x12 setup.

Basically, I am sometimes drowned out by the other amps during some songs, especially when it comes to the midrange.

Now, my main guitar has plenty of beef to drive any amp, it is a MIJ (high-quality copy era) Orville Les Paul with a Seymour Duncan SH-14 dropped in the bridge, which produces deep lows, scooped mids, and detailed highs.

Mic-ing the amp worked decently, but it noticeably dampens the other channels used for the mics (4 of them) and the PA is already under strain running the other speakers and mics. Plus, the effect becomes ultra-sensitive to feedback (and we use Shure SM57's)

So, to take the burden off my bandmates, I have decided to take it upon myself to upgrade my setup (since I am also a bit of the sound guy) and make upgrades while still keeping my setup and sound beautiful and unique.


bla bla bla bla...(when is he going to end?!)


If any of you have tried and recommend adding a line-out to a vintage class A amp, and if it would be enough to drive at least a 1x12 cab i am looking into purchasing, I would be grateful!!!

I have a basic knowledge of electronics; I have soldered and installed pickups in my guitars many times with no problem, and I understand some of the basic principles involved.

[Enzo]

When did a three wire power cord remove the need for a fuse?

One simple trick would be to mount a voltage divider across the speaker wires, and sample that as a lineout. Try a, oh 10k pot for starters and see how it works. Once you get the overall right, then make the pot into a resistor and pot, since ther is a point you will never want to turn it up past. The resistor would be the upper part of the divider, adn the pot part would be limited to the useful range of the divider.

[olddawg]

That might also be a useful mod for a VJ, but in my experience that old trick brings the noise floor up to an intolerable level. Hissssssssssss!

[Enzo]

Hence the suggestion try it and see how it works. If it meets his needs... if not, ther are other options

[GlideOn1]

Whew...okay, I'm gonna have to whip open my old electronics' basics book again and get a couple of parts in order to do this...

When I said that I had a basic knowledge of electronics, I meant pretty darn basic, as in "I'm not an idiot, but I can figure it out" kinda thing.

But if i got you right, are you saying that its a matter of inserting the jack off of the speaker wire?

Not to mention that I still am not sure if i will have enough power to drive 1 or 2 other speakers?

[Rob Mercure]

Glide, unfortunately you've mixed up terms which has resulted in off target advice. You referred to a "line-out" which is a "line level" signal - usually under a volt used to drive another power amp. But then you refer to driving a speaker and I believe you're referring to driving the speaker directly off the Skylark's output tranny in parallel with the internal speaker - correct? This isn't a "line out" but an "external speaker" jack. So you simply solder a jack in parallel with the existing speaker wire making sure not to use the shorting terminals if your jack has them. Now in theory you want to keep the same load impedance for the output tube (6V6 I assume - many different Skylarks) and paralleling a speaker with the same impedance as the internal one will provide only 1/2 the load the amp was designed for. But in general most older USA amps can tolerate a mismatch but don't use a speaker of any lower impedance than the internal one. In fact you might consider just replacing the internal speaker with a more efficient one or using only an external speaker of the original impedance that's more efficient. Hope I've understood you correctly.

Rob

[drlowlow]

Enzo isn't talking about driving more speakers from the line out, he is talking about an attenuater to bring the speaker output signal to a line level to be re-amplified.

If you want to drive other speakers from your current amplifier (might be louder if the the sensitivity is better) you could just put a jack on your speaker wire, but then you have to check the impedence issue. its not really a matter of having enough power (people often run 4-12 cabinets with fractions of a watt). The problem comes from the fact that the amp is designed for a certain load and tube amps are more sensitive to impedence mismatches then solid state technology and if you run the wrong impedence you could fry your output transformer (some manufactures are more prone to this problem then others). If it was me I would ohm out the current speaker and disconect it while I try it with another cabinet (mayber your bandmates 1960A) and see what difference you get.

Also rewire your fuse. a three prong wire wont protect the amp and if you have something short out it could damage alot more components.

Really I think the 2 best solutions are either upgrade your PA and possibly use an issolation technique to get rid of the feedback or upgrade your guitar amp to something with more power. If you like your current tone I would recomend option one though it might be more expensive.

[GlideOn1]

Thank you guys for correcting me again. If i'm not too careful, i would go and shoot my mouth off like i know what's what.

But no, I'm not trying to do anything but run an extention cab to go with it (check this thread's title again).

But DRLowLow is right, the most practical solution would to get a new PA, but it would also be the costly solution ($500+ for a decent PA nowadays).

I'm not sure what impedance the amp should run at (correct me if i'm on the right track here), but I can tell you (and i forgot to mention in the first place) that i have an Eminence Ragin' Cajun' installed that is rated @ 8ohm and it has given me no trouble so far, in fact, it has allowed the amp to be 25% louder than it was stock with the crappy Jenson speaker that came with it.

The Eminence is also partly responsible for the scooped mids i get out of my sound.

Which is why I thought it would be indeed a semi-practical solution to run a cab out, rated at the same specs of course.

I even found the perfect place to get a cab; custom made and pre-loaded with a Celestion Vintage 30. It even matches my amp perfectly, for far less than getting a new PA here:
http://www.lopoline.com/catalog/item...23/4833827.htm

The speaker in this one is also rated @ 8ohms and would compensate my need for mids due to the nature of the speaker installed.

Again correct me if I'm wrong and if there is more to it than this, but this almost seems exactly like the solution i was looking for in the first place.

Again, sorry for the misconceptions. I am learn more about these things everyday.

[TD_Madden]

You might also consider a replacement for that pickup with the scooped-mids....mids are what you need to "cut through".

[Enzo]

I am sorry, somehow I got the idea you wanted to run a second amplified speaker across the stage, but I see you said nothing of the sort other than to misuse the term line out.

[GlideOn1]

Funny how the terminology can easily confuse - Technically, I would be running/sending a line, or the load to another set of speakers or amplifier.

But whatever, you get the idea, I want to run another set of speaker(s) in a specially made cabinet I am interested in (or I would have built) in the previous link that I gave you guys.

But that's just one solution i guess.

I am also contemplating other options; getting a better PA system (most effective and costly), trading for a better amp (was thinking about the Orange Tiny Terror, another Class A amp, but I would still have to get a cab), or simply (or difficultly) modifying my amp to drive another cab that I would have built.

As for the trading my amp option, I would trade my amp in -

I just had it serviced, everything works great, plus I got a new speaker with a higher impedance and louder volume, and including the appreciated value since I got it, i could probably get $400 for it.

Then I have my Visual Sound Jekyll and Hyde Pedal (brand new version) that is extremely hard to get, and i have had it only for a short while and it is in mint condition, with the extended 1 year warranty from guitar center, making it about $150.

So total, I would sell for a reasonable $550, which the same price as the Tiny Terror

The Orange Tiny Terror is also one channel, but it has a speaker out (x2 8ohm and x1 16ohm respectively) and a gain control knob, plus a tone control knob.
So, the benefits here are obvious...

...I already have that Class A tone that I love, but again, the Tiny Terror will sound a little different, and I will still need a cab, but I guess I will still use the same site to get the cab, as the matching cabs form Orange a a little pricey.

And I would be without an amp for some time...probably 2-3 weeks if i time the sell/buy right.

I don't have to do this immediately, but either way, i will probably have to spend money soon on 'more sound.'



...and i replaced my pickup because it would squeal with too much gain, but that was probably the pedal's fault, so if i get this new amp, i might put my old one back in and sell the SD. I had no complaints with my old one otherwise



Whadya guys think?

[drlowlow]

I think the prices your talking about fetching for some of that gear is a bit optimistic, at least if you wish to move it quickly. You said the speaker you installed was of higher impedence but you said before it was 8ohms and the schematic I saw for your amp has the stock speaker being 8ohms. I do think the tiny terror is a more suitible amplifier for your application but be sure to try other amps on the market that fit your criteria. Blackheart has a switchable 15/7 watt class A push pull amplifier for considerable bit less than the Orange. I would find a shop that has both of them (if you can) and A B them and any other amps that might meet your needs. Check the user reviews for any possible amps on www.harmonycentral.com (though make sure you have a salt shaker nearby because you will need a grain or two). I would steer away from trying to drive another cabinet with your current amplifier as a solution, it wont give you anymore power and if it is used with your current internal speaker will change the load impedence and could negatively effect the frequency responce of the rig. Good luck