Rocket/ac30/dc30 like build. OT?

[arjepsen]

Hey.
I'm planning on doing an amp, pretty close to an ac30/dc30 amp.
And so, for inspiration, I've been studying the Rocket.
What I'm curious about, are the differences in the output section.

It seems, that both the Vox and Matchless are using an OT with 4k primary impedance, but the ac30 is using 50R cathode resistor, while the dc30 is using a 62R.
The Rocket seems to be using 50R like the ac30, but according to the BOM, it's using an OT with 5,2k impedance.

I wonder what differences in tone I would get, by using the Rocket OT instead of a regular ac30/dc30 OT?

[rawnster]

no, should be something like the Heyboer HTS-8093-1 Dynaco 470 Variant 4.3k. That's what I used on my Rocket build, and comes recommended by most Rocket addicts. However, also used a 6.6k Pacific on another Rocket-type build, which sounds killer.

[arjepsen]

Odd..... The BOM says:

Use 5.2K Ohm primary , unit labeled as "Dynaco A-470 MOD, 9950843". RJ Guitars also stocks the appropriate Heyboer and Pacific trannys.

[Clyde]

I used the 5.2K Toneslut in my EF86 Rocket, very nice.

[M Fowler]

Your going to see variations of OT used here. I used the A470s with very good result but doesn't mean I couldn't have used the 5.2k or gone with Edcor or even Magnetic Components tranny. What ever you wish to use.

Mark

[RJ Guitars]

Arpjensen,

There is not going to be just one right answer... but there is a bit of a consensus that the Heyboer HTS-8093 is closest to the original. This is a somewhat modifed version of the Dynaco 470 transformer. I have never heard of it having a 5.2K tap. That is something that is common in other Trainwreck models but not for the Rocket. Everything I know about these transformers has always indicated that the primary had a 4.3K impedance (just like Rawnster mentioned).

Ultimately, the best sounding tranny for the output of a Rocket is the one that makes your ears happy. I have several Rocket builds and no two of them have the same output tranny. My favorite sounding one uses a Heyboer 5.2K vintage tranny like I sell for the Liverpool amps.

I have built a Rocket with all VOX trannies if you want to go that route... there are really so many choices that you'll have to pick one and see if you get what you are after. Then build another one, then build another one, then build just one more... etc..

If you want a true clone, the only acceptable answer around this place is going to be the HTS-8093... although I have also heard a lot of votes for the pure Dynaco 470 as well...

rj

[arjepsen]

Thanks for the input.

Oh, I know about the addiction to amp-building.... Somehow I always get a zillion ideas for another amp, when one is done.
However, this is an extremely costly hobby...
And so, since I don't have (right now) the money to buy 3-4 different OT's for this project, the next best thing I can do, (imho) is to ask for peoples opinions.
I presume there are differences in the tone, whether I get a heyboer, edcor, mercury magnetics, hammond, etc...
But I'm a little inexperienced in how big a difference there is in tone.

I heard a sound clip comarison between an ac30 and a rocket, and I personally like the rocket best. However, I also understand that there are other things than just the trannies, that color the sound.

I guess what I'm trying to get at, is a dc30 clone, where the "top boost" channel sounds as close to a rocket.

btw. I came across this website:
http://transformerdesignandsupply.com/
and they advertise as being the original matchless trafo supplier.
However, with such a simple website, and such a yahoo address, I get a bit cautious....
has anyone had any experience with them?

Regards.
Anders

[RJ Guitars]

Anders,

Transformers are just part of the magic in any amp, but a critical part in all cases. It is all about taste and nobody can tell you what tastes good to your senses. You can always follow the well worn path that has been proven and if that is your thing, go for it. For Wreck transformers and especially a Rocket, go with the the Dynaco 470 output and you're likely to succeed. If you don't find the info you need on the forum, send me a PM if you'd like a list of transformer options and a few builders to talk with that have explored a lot of successful ways to build a Rocket.

I am an experimenter myself and I have found that to be very rewarding. However, it is probably worth noting that when I build a good sounding amp I talk it up and share it with the forum. Meanwhile I have built several that just didn't work out and I've not shared all the failures with that same enthusiasm. Failure is a critical element of success in my philosophy.

Ken Fischer was famous for using whatever he had available and in one case I learned of a story where he built a great sounding amp using a transformer he took out of a television set. I think part of following in the direction Ken was leading us is to take what you have and work with it until you have made something great or exhausted all the possibilities. Then, move on to some other idea.

rj

[FYL]

has anyone had any experience with them?

TDS is a very small manufacturer. They designed and supplied on an OEM basis the original Matchless (Sampson period), beginning in '91 or so, with - if I understand correctly - their designs rapidly subcontracted to Mercury Magnetics as TDS didn't have the resources needed in order to manufacture them in relatively high volumes.

Matchless switched to TMI (Transformer Manufacturers Inc.) for PT's / OT's and to Heyboer for the chokes sometime in the mid '90s, then folded in '98. Remaining stocks of iron were purchased by Dave West (West Labs) who resold them to the general public at a discount - and now seemingly has them built again TMI-style.

I've never heard or read bad things about TDS, they're a quality-oriented pop'n son operation.

[breakfastbuddy]

in general how will a transformer with lower impedanse sound compare to one with higer impedanse . i know a lot of you like the fender thing , sweet clean sound , but what if you like a bit of edge ? more like a marshall. is a lower impedanse the way to go ?

[arjepsen]

It is all about taste and nobody can tell you what tastes good to your senses.

I know. The best thing would be to just experiment a lot, till I got an amp to sound the way I want it to.
But as stated I lack the funds to gain experience by experimenting to such a degree, and so I have to draw on the experience of others.

I think I'll try to go with the heyboer/dynaco OT mentioned.

Thanks for the GREAT info so far

[arjepsen]

Oh by the way.
Anyone know what the specs on the choke used in a DC30 is?

I "think" the AC30 used a 10H, 100ma one, but I'm not entirely sure about the DC30. Only place I can find that seems to sell replacements are Mercury Magnetics, and they are usually both a little too expensive, and also quite tight about specs on their trafos.

[M Fowler]

The DC30 uses a 150mA, 10H choke, not sure what the resistance is.

Mark

[JamesHealey]

trust your ears, the OPT is the heart of the amp and has it's limitations but if you understand how to voice an amplifier you can work around an average sounding OT.

I've used what ever I can get my hands on at times using cheap horrible rubbish, but after a few hundred hours on each amplifier it's left my workshop sounding awesome, that particular OT might require more treble, more bass, obviously it has limitations and some OT's sound a bit gritty especially the cheaper ones, but exploit this and make it part of the tone.

Following a schematic to the tea and not trusting your ears and sticking to something for the sake of being "original" isn't very clever if you think about it tbh..

Have the target tone in your head, learn frequency ranges understand what the circuits are doing and tweak, tweak and tweak more.

[breakfastbuddy]

not more than 100 ohm