Turtlerock Forum

Hi All,

So awhile back I secured a small quantity of Trimax A55 line amps. They sold like hot cakes and Rob at Proharmonic has racked at least three (check his website). I've now managed to secure another slightly larger quantity but let me tell you de-installing these is a real hassle and there's nothing like forty years of dust to bring on the allergies! Built here in coburg melbourne around 1962-65, these are a really interesting 4 valve design and feature high quality input and output transformers, high grade wirewound resistors, stepped gain controls in 1db and 10db steps, and outstanding build quality. I have included the schematics as well. The input transformers are the hermetically sealed case for use even in the tropics and areas of high humidity and can also be used for class A single ended output stages if that takes your fancy! There are 8 for sale at $250 each. 6 sold and 2 still available.

Seriously this is real quality gear and the users who have them are loving them...






I also have another set of transformers. The ones on the left are trimax 1:2 or 1:1 transformers type TA 605 rated to +18dbm these are excellent transformers and are easily mounted. They can be used as line isolators, splitters, line output etc. I have 4 more to sell $50 each. They retailed at 6 pounds, 7 shillings and sixpence in 1965! The ones on the right are all sold.

There will be a few more pieces to add in the next few days but this should get the ball rolling...

If you have any questions don't hesitate to PM.

Thanks Angus!

I've added the price now too, 250 each. Bit of a bargain really.

Cheers
Myles

hmmm...

I have a UA LA-610 already that I like to drive with drum machines and synths, and it drives nicely to give a nice thickening of the sound, up to a bit of a crunchyness when I push it harder...

I was thinking of going for another pre for running synth gear through... to be honest I was pretty set on some kind of neve alike as a 2nd option. probably one of the JLM kits, or maybe the great river pre....

But see, I like gear with stories, and that is different from what anyone else can just get.... and this has a much cooler story and is way more unique than a great river preamp or a straightforward kit, but will this preamp give me a different enough sound to the LA-610's pre? or should I stick with the neve plan for something more different to what I already have?

Well I'm pretty certain that these sound nothing like UA gear. Completely different topology, completely different purpose. These were made to be incredibly hifi with as low distortion as possible to the standards of the day. The schematic says something like +/- .5db betwenn 100 and 10k frequency response. But of course being valve they can be overdriven, being transformer i/o they can be overdriven. They will also sound and respond very different to neve gear. Angus has a list of sound examples comparing his v72, neve and trimax preamps. maybe have a listen and see what you think there...
There are of course all kinds of options too, add an eq in the feedback path, switch the input transformer in and out of circuit for different colours, it might be possible to add a voltage reduction circuit to starve the valves of current and create distortion that way kind of like gtr amps.

I definitely like gear with history and I prefer the lesser known gear. I don't want to sound like everyone else and in these days of ubiquitous protools setups things like these set your sound apart. I also have a stash of beautiful blueprint schematics that I'm going to frame and put on my wall just cause they look awesome!

And also check out this thread for a discussion of Rob's racking of the A55.

http://www.turtlerockmastering.com/foru ... ght=trimax

well its been a busy day! Lots of interest and 4 already sold...

Hi Myles
I'm up for a pair
Just exactly what do I need to add to them to get them working
Thanks

mylesgm wrote:something like +/- .5db betwenn 100 and 10k frequency response

Myles is this the possible freq response?

No no the frequency response is much greater. There's a frequency plot from robs racking here.

http://www.turtlerockmastering.com/foru ... ght=trimax

What the stated frequency response of +/- 0.5db at 100 -10khz merely shows is the incredible accuracy of the units. How many valve amps with transformer i/o will show that smooth a response? and on checking the specifications its actually 30hz to 10khz at +/- .5db.

oh i see on the specs it goes down to 30hz. :)

The Tasmanian wrote:Hi Myles
I'm up for a pair
Just exactly what do I need to add to them to get them working
Thanks

Hi Chris,

Well obviously they need to be racked and a power supply needs to be added as these were powered by a central source in a large facility. Power requirement is +130v HT and +24v heater rail. Also the usual things need to be added like pad, phantom etc. You could add a VU meter etc but these are of course not necessary. I think you might be able to get two in the one case depending on the layout or put them in two cases with a shared power supply. I'm sure there are lots of options and Rob could answer you better.

Shall I put two aside for you?

M

mylesgm wrote: +/- 0.5db at 100 -10khz merely shows is the incredible accuracy of the units.

Yeah good point Myles. Thanks. I'm interested but it seems your ads are everywhere and you must be getting these sales sown up.

:)

Ben Moore wrote:oh i see on the specs it goes down to 30hz. :)

The full frequency is much greater than 30-10k. Have a look at the diagram below.

http://www.gearslutz.com/board/attachme ... -sweep.jpg

Hi Ben,

If Chris takes two I'll still have two left if you want them...

Myles

damnit, OK I'm interested.
:-)

If there's 2 left, consider them sold. (if not, well I do have plenty of other projects to work on anyway...)

I'd like a play with some tubes and old transformers, and from the schematic it all looks pretty straightforward to DIY for different stuff.

Hey Myles,
I have PM'ed you about some transformers.

Mac

Hi Mac,

I didn't receive your pm?

M

got it

So there are now 2 left.

Did you say it has a max of 50db gain?

In its current state it has a max gain of 50db. I don't know if that can be changed. %0db though is lenty of gain for most situations with condenser mics and plenty of situations with dynamics. Most of the time you follow with a comp anyway so a little bit more gain can be added there if necessary. V72's usually only have 50db of gain I think.

The usual sources for this kind of mic pre, Vocal, drum spot or room, electric gtr, etc 50 db would be more than enough. Probably wouldn't use it on a string quartet though....

M

So thanks for all the interest, I'm packing and posting today. There is still 1 remaining unit if there are any last stragglers...

Cheers
Myles

woo! my 2 showed up today....
thanks Myles!

now to find the time to do something with them!!
;-)

Don't they look military grade old school? I want all my gear to look like it was built into a 50's nuclear reactor monitoring station. With those enormous meters and switches....

That'd make the coolest looking control room ever. and we know that its all about looks...

mylesgm wrote:Don't they look military grade old school? I want all my gear to look like it was built into a 50's nuclear reactor monitoring station. With those enormous meters and switches....

That'd make the coolest looking control room ever. and we know that its all about looks...

Totally agree here
(:

ever been into the snowy mountains power stations ...?
it doesnt matter if you havent anyway because when australia finally goes 100 % solar /wind /waves whatever

i have first dibs on the future abandoned snowy power sites and i am moving the turtlerock empire into all of those power stations !
then i can play with all the old really heavy stuff and big knobs you could ever imagine and stop for a fish out the back window during a break
and still have enough room for anything i ever want to construct or deconstruct

seriously they are worth a look in if you have never seen them- they are amazing - and thats what i call engineering
not this knob twiddling stuff we all do .

err.... note to self and anybody listening
" the day you decide to stop and have a tour leave your other half behind somewhere warm ( not in the car ) -
its only an interesting tour for the types that like old heavy stuff
its just cold and boring to anybody else "

ha!

I've been for a tour of those facilities...

*
Shit!
Perhaps that was the time when, as an innocent young(er) child, the pervading spirit of the big heavy stuff also entered my impressionable psyche and now can never be removed!?

Hmmmm... something to think on there.