Musicians Roadhouse

Hi All,
I understand that a popular OT upgrade for the Class5 is the ClassicTone 40-18031, which has both 5K & 8K primary taps. I'm not certain which tap would be most appropriate. This brings up a related question. I have a rather substantial Heyboer (I think) made OT that has 2.5K & 5K primary taps and 4, 8 & 16 ohm output taps. Could I use this transformer appropriately in my Class5, utilizing the 5K primary? I guess the simpler question (if known) would be "what is the primary impedance of the stock Output Transformer?"
Thanks,
Gene

Ah, well, that is the crux of the biscuit isn't it?

A few weeks ago Marshall requested removal of all schematics.

Up until then we could venture a guess from the information we had.

Your only hope now is the black market where you might be able to obtain a preblackout copy of the information.

Unless you are still under warranty

I happen to have a schematic, however it does not list the specs of the OT, only the part number. I could supply the values of components related to the output tube and transformer, or possibly share more via PM or email. From all other research, it appears that a 5K ohm primary tap would be most closely suited to my application. FWIW, the Heyboer unit that I have is indeed designed for single ended use.
Thank You Sir,
Gene

Primary coils impedance should be close to the impedance of the tubes anode. This will give it the most efficient operation.

Gene, just curious as to why you are changing the OT.
Has the original died, or does it improve the amps tone?

shaun wrote:Gene, just curious as to why you are changing the OT.
Has the original died, or does it improve the amps tone?

Shaun,
Original transformer is still Ok, I was simply hoping to improve the clarity a tiny bit. I realize that you can only get "so much" of a shine on a turd, no matter how much you polish it, but besides adding 4 ohm capability to the existing 8 & 16 ohm taps, it did improve the clarity (not clean-ness) a little as wel as slightly improving headroom. FWIW, I run this amp through a 4x12 greenback cab. In stock form the distortion (amp mostly cranked) was a tad muffled, fuzzy and muted. With the new transformer, the distortion is a tad clearer and especially the bottom end has changed from being simply a muffled "woofiness" when the bass is turned up too far and now you can clearly hear the bottom end distort if the bass is turned up too far. Overall, better definition and this transformer runs considerably cooler. I'm not sure that there is enough improvement to warrant the big $$$ of a Mercury upgrade and am not certain that a Classictone would give the same improvement, but I just happened to have this fairly massive custom Heyboer on hand, with the right specs, so it was worth a try. I will likely try adding a choke as an experiment, once I determine the correct values for it. FYI, I have been pounding the crap out of this amp, on a daily basis for a year and a half and it's like a TIMEX, "takes a lickin' & keeps on tickin'!" In answer to your last question, it did not truly "change" the tone, per se, but improved the clarity of the tone, if that makes any sense!
Thanx 4 Your Interest,
Gene

Hey Gene, how did you go with you low wattage kunumdrum. The C5 vs DSL5 vs SL5.

I am actually after less headroom with this amp, so i have a JJ EL844 in it. So far so good, but it does not get used for hours on end, on a daily basis.
Upon further reading, my 4 12 cab does turn out to be a mid/late 70's Hiwatt cab, with 2 greenbacks, and 2 blackbacks (25 wt 75 hz). The speakers are not original to the cab, but if you ever come across one, get it.