Guild ThunderStar Bass Reference Post and eBay model

This thread is an effort to catalog information and pictures of the Guild ThunderStar bass. The pics below are of ThunderCat's amp regenerated; links to originals below; remove the [plug], copy, and they will return larger originals:

Front view:


Back view:


Tube deck:


Chassis view:


This amp is 2X12AX7 preamp, 2X6L6 out, and a tube rectifier type ?? but likely 5AR4 / GZ34 for higher voltages. The rectifier is shown back left center in the tube deck view. Since the large-scale pics show no diodes and the tube connected to the T1 secondary, it can't be mistaken for a voltage regulator. The little vertical doo-hickey with the red wire in the middle of the tube deck view (where the 6GF7 lives in later models) is a high-wattage, power-dropping resistor postioned there presumably to dissipate heat. For purposes of comparison, note the relatively small number of punched, but unused, holes in the tube deck view.

eBay ThunderStar : Link to eBay TStar as of this post: Click here

Tube deck view A:


Tube deck view B:


Chassis view:


Notes:
Lots of punched/unused holes; look to be filled with factory plastic plugs,
Rectifier tube gone; big power resistor moved next to chassis hole for rectifier tube,
White wire 'spaghetti' looping around the output tubes :shock: :shock:

This is a project amp, seller sez so, and priced accordingly; shown here for chassis and other points of interest. In the auction Q&A, seller sez he thought someone (not him, of course) had been trying to wire in a solid state rectifier of some kind; original pics not large enough to see details but can't think of a reason for all those jumpers / spaghetti....

cj

Links to ThunderCat's pics;

Based on the fact that the amp has the standard Guild handle mounted on the top of the head instead of the side tell's me this is one of the later models that were produced.

Note: Thunder Star Bass amps have a Line Out/Power Amp In connection on the back panel. On all the amps I have seen the preamp circuit is split providing a line out signal AND direct signal to the power amp. I have considered adding a mod so that the preamp path is a complete break line out so all the output of the preamp is routed through the Line Out/Power Amp In path. The addition of a high power speaker load and this mod would make it easier to use the head as a preamp.

hey capn...Can you keep the outputs of a tube amp open circuited (ie., no speaker attached to terminal) without damaging the transformer if the amp is just biased ON withou a input drive signal? I have been assuming you risk damaging the output transformer of a tube amp in that configuration.

M

matsickma said:

...Can you keep the outputs of a tube amp open circuited (ie., no speaker attached to terminal) without damaging the transformer if the amp is just biased ON withou a input drive signal? I have been assuming you risk damaging the output transformer of a tube amp in that configuration. M

Click to expand...

Well, the general rule is no; can't touch switch w/o load on OT. There's probably a better answer but I'd put a load resistor on the OT. Easy for me to say because my stuff is all low power but with a load, wouldn't have to think about.

Thank you for your comments on the Thunder amp; trying to turn one or two of these threads into a kind of knowledge base for each model that all of us can develop; getting annoyed with bleed-thru on makes and models. Reading some of the old posts, you were kind enough to answer the same questions several times. If the stuff is all in one place, makes finding info and pics much easier and when the same questions come up again, there's a place to go instead of digging every time.

cj