DR103 Output Transformer opinions?

[Yukon Cornelius]

I just picked up a 1974 Hiwatt DR103 that needs a bit of work, including an output transformer. Anyone have recommendations for modern production transformers that are most similar to the original Partridge iron that was in these amps?

I usually go with Heyboer iron on fresh builds, but I saw someone else mention Merren Audio, and am tempted (although just barely) to hold out for a used Partridge transformer to pop up somewhere. I got this thing for a pretty decent deal, so don't mind spending a little extra to get something that will sound more authentic and maintain resell value. Anyone have much experience with different transformers on this circuit?

Thanks!

[Tony Bones]

Have you reviewed the various forums? The general consensus is that the Heyboer HTS-5912 is the preferred replacement. Supposedly it's not just a generic 1750 ohm, 100W OT, but a reproduction of the Partridge TG5479 as used in Hiwatt DR103's.

But, that's just what I've read on the internets. No personal experience. It's possible that Chris Merren is also making a TG5479 reproduction...

[Yukon Cornelius]

Thanks for the response!

I did see a lot of people mention that the Heyboer transformer is generally accepted as a good replacement. I'm leaning towards that, since I've used Heyboer in the past with excellent results, but was hoping someone had direct experience with the DR103 OT from Merren that is found here: http://www.merrenaudio.com/marshall_output_transformers.

Merren claims the following:

"This output is wound in the same winding geometry and tradition Partidge made famous.

This is the only reproduction of this transfomer to be using the more costly correct grain oriented core material, responsible for the strong, explosive low frequency response expected from a Hiwatt amp."

This will be my first experience with a Hiwatt amplifier, so I'm trying to do some due diligence research, but if people are generally happy with the Heyboer iron it sounds like I've got a couple of good options at least.

[dcribbs1412]

No experience with Merren iron, but I've built a few Hiwatt style amps using the Mojotone Hiwatt iron which I believe Heyboer makes. They are big,built solid, and priced competitively.
My 2 cents

D

[Stevem]

The original non Bell type OTs ( 1980s models) where a far and away a over rated ( in over rated I mean in a good way ) Hi Fi OT, and other then the interleaving on them such a OT and it's quality level is just not needed for 6 string non dropped tuning guitar usage!

Since these amps can muster well over 100 watts RMS I would concider a Hammond 1650T a great sub!
I don't however know about its mounting size though!

[Yukon Cornelius]

Thanks for the input everyone!

If I end up going with the Merren, I'll report back to let you know how it sounds. I've got a buddy with a 1973 DR103 that is all stock, so we're gonna do some A/B testing once I get mine up and running.

[gldtp99]

I've built many, many Hiwatt DR103 and DR504 clones.

I'm a believer in the Heyboer Partridge clone transformers----- I usually buy them from Mojotone.

I've A/B'd Hiwatt clone amps using these transformers against many real Hylight Hiwatts and the Heyboer iron performs wonderfully.

I built one DR103 clone with Edcor 100 watt PT/OT and the three owners the amp had (over a 10 year period) loved the amp.

But I felt that the big 100 watt Edcor OT was too "Hi Fi" sounding----- I adjusted the NFB circuit to let more poweramp character shine through and it was better (but still not all the way there, to my ear).

My doubts about this DR103 clone's tone didn't seem to bother the eventual owners who used the amp heavily over the next 10 years and got great tone/service from it.

Eventually I bought the amp back (from the third owner)----- It hadn't been serviced or had any tubes changed in the 10 years since I'd built it------ one EH 12ax7 had failed and the amp was beat up and filthy.

I cleaned it up and retubed/serviced it and now it runs the Bass Guitar stack in my shop jam area.

And I still think that the DR103 clones I've built with the Heyboer Partridge clone iron sounded a little better. But every time I heard any of the three owners playing the amp in the past it sounded wonderful------ Headroom, Note Clarity, Rich Tone----- everything a big Hiwatt is known for-------one owner played loud/clean R&B type music and used only a Boss reverb pedal----- he made that amp sound great.

But every Hiwatt clone I've built since then has been with Heyboer Partridge clone iron. It's a no-brainer.