Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Jennings on December 18, 2011, 12:32:53 pm

Title: 18w output tranny reliability
Post by: Jennings on December 18, 2011, 12:32:53 pm

I've got a couple of 18 watters (one head and one combo) which are my go-to amps for cranked practices and gigging.  Turn them up and off I go...trouble is both have blown output transformers over the last couple of years.  I'm always slightly worried to gig with them now.  Anyone have any opinions on who builds a robust 18w output tranny which can stand being used in a cranked amp as I use them?  Both my amps are kit amps (not Hoffman parts - I'm UK based and have not tried them yet), so I'm not conviced the transformers are the most rugged available.

Title: Re: 18w output tranny reliability
Post by: conger on December 19, 2011, 10:41:29 am

What make OT's are they?

Title: Re: 18w output tranny reliability
Post by: dpm309 on December 19, 2011, 11:03:39 am

I put a Hoffman 18-watt OT in my Lightning 15 Clone (2-EL84s) and have had no problem.  I built this amp back in spring of 2007 and it is my main gigging and practice amp.  This amp sounds great and I would highly recommend putting these in your 18 watter.

Dan

Title: Re: 18w output tranny reliability
Post by: rzenc on December 19, 2011, 11:19:27 am

Make sure your output jacks are tight. Are you using a rotary impedance selector? If so, check if it's making good contact..

Best Regards
Rzenc

Title: Re: 18w output tranny reliability
Post by: Jennings on December 20, 2011, 06:42:08 am

Well the first OT was a Ceriatone.  Sounded ace, but as I'd got the kit amp second hand I can't vouch for how it had been treated up until I got it.  The replacement is a Ceriatone in that amp to I think (was a while ago I replaced it...couple of years).

Second amp was a kit I built last year from a UK supplier.  OT sounded good, but looked physically smaller than the Ceriatone by comparison.  Either way, it lasted as my main amp until this year in a band prac.  I've replaced it with a spare to get me running from the same supplier.  The part's unbranded and comes probably from a UK maker. 

So I'm interested in what folks have to say about some of the global alternatives.  I'd figured the Hoffman must be a reliable and good sounding unit with the reputation here.  Sound like that's the case...how does it compare with Mercury or Heyboer etc?

Good point on the jack connections and selector dial.  Both amps use an impedance rotary, and both have two-jack speaker outs which rely on jacks closing and making contact....I'll check them both out.

Title: Re: 18w output tranny reliability
Post by: mageerc on December 20, 2011, 08:20:03 am

Heyboer makes Hoffman's transformers... probably the best transformers for the 18 watt are from GDS made by Heyboer...

http://gdsamps.com/?page_id=7 (http://gdsamps.com/?page_id=7)