Warwick Hellborg preamp transformer question

[LukeFRC]

My favourite preamp ever is a Warwick Hellborg one - they made it for a short time and a silly price ... then blew them out cheap at Thomann and I hesitated and missed out... the thing is the magic was in the first preamp stage - I could turn the DI off and it would still sound great...

From what I can see... there's a buffer taking instrument input into mic level, a transformer, then the THAT1512 as a the main IC - interestingly the 1512 doesn't need a input transformer so it seems to have been done due to the sound rather than a need... And plugged into an amp it wasn't using the DI output transformer at all!

When I asked Warwick were like "this is legacy we don't have info", and Haufe were like "we can make and sell you 100+ of the transformer but can't tell you anything about it"

What do we think? In my mind the thing I liked was the transformer's tone - but it's probably lost in the midst of time what the transformer is.

Schematics attached!

 

[LukeFRC]

any idea what the Haufe 8161 transformer might be?

 

[LukeFRC]

Anyone?!

 

[Feral Feline]

HEY! Sorry I missed this! I've been half-haphazardly on/off the forum and this slipped under the radar.

Alas, I can't help with the transformer question/answer. Hopefully this will bump it for more people to see and maybe get an answer.


I'm in for a transformer (or two) — we just need 98 more people!

 

[jwin615]

ST = sowter transformer?
Sowter 8161

PRO AUDIO TRANSFORMERS ARCHIVE

Older types not included in our catalog but can be repeated

www.sowter.co.uk

Just a guess

 

[vigilante398]

Anyone?!

Looks like it's essentially a D.I. transformer. THAT1512 is a mic preamp IC so it needs a balanced input, which the 1/4" isn't. The XLR jack is already balanced, but because they wanted the XLR and 1/4" to share the -20dB pad (and as you speculated possibly for some tonal characteristics) they still run it through the transformer so it's kind of like a mic input transformer with the XLR connected.

THAT1512 spits out an unbalanced output, so the "pre out" signal can go into the EQ stages then through to the output.

Does Haufe have a datasheet for the transformer? I refuse to believe they're capable of manufacturing it without knowing any of the specs (impedance, ratio, DCR, etc).

 

[LukeFRC]

Looks like it's essentially a D.I. transformer. THAT1512 is a mic preamp IC so it needs a balanced input, which the 1/4" isn't. The XLR jack is already balanced, but because they wanted the XLR and 1/4" to share the -20dB pad (and as you speculated possibly for some tonal characteristics) they still run it through the transformer so it's kind of like a mic input transformer with the XLR connected.

THAT1512 spits out an unbalanced output, so the "pre out" signal can go into the EQ stages then through to the output.

Does Haufe have a datasheet for the transformer? I refuse to believe they're capable of manufacturing it without knowing any of the specs (impedance, ratio, DCR, etc).

They do but didn’t want to share it with me, the email conversation was typical of a German speaker who deals with B2B getting an email from a non German speaking end user …. A wee bit lost in translation

 

[vigilante398]

They do but didn’t want to share it with me, the email conversation was typical of a German speaker who deals with B2B getting an email from a non German speaking end user …. A wee bit lost in translation

Fair enough, so I guess the next question is how much would they charge for 100 units, and would they then include the datasheet if you were to purchase them?

 

[Feral Feline]

Fair enough, so I guess the next question is how much would they charge for 100 units, and would they then include the datasheet if you were to purchase them?

I bet a legitimate pedal-manufacturer with a line of pedals currently in production would get a better email response from Haufe, when requesting the specs and scale costs of such a transformer...

If only we knew someone with those kinds of credentials.

 

[vigilante398]

I bet a legitimate pedal-manufacturer with a line of pedals currently in production would get a better email response from Haufe, when requesting the specs and scale costs of such a transformer...

If only we knew someone with those kinds of credentials.

Very well could be. Hopefully someone in such a position will come along and pose such a question to Haufe a few minutes ago.

 

[vigilante398]

So apparently Haufe was just waiting for some hack masquerading as a company to shoot them an email. They sent me a datasheet this morning.

My suspicion was correct, the ST-8161 is basically a D.I. transformer, which if you run it "backwards" becomes a mic input transformer. The frequency response isn't completely flat, which may or may not be part of the tone, but it looks pretty similar to what I've measure a Lightning Boy MC15 at. The spec says 30Hz to 15kHz, which is about the useful range of the MC15. Unagi E4305 will give a thicker low end, but that wouldn't be accurate to the original design.

 

[vigilante398]

I'm curious enough to try a couple of the Haufes out, so I asked them if I could make a small batch order for evaluation. I'll let everyone know if it works out and I can make a handful available for those that are also curious.

 

[LukeFRC]

I'm curious enough to try a couple of the Haufes out, so I asked them if I could make a small batch order for evaluation. I'll let everyone know if it works out and I can make a handful available for those that are also curious.

I am very very curious

 

[Feral Feline]

I'm a cat, so curious by nature, naturally.

 

[LukeFRC]

I’m fairly sure it’s their take on the line input transformer on a neve

 

[vigilante398]

I’m fairly sure it’s their take on the line input transformer on a neve

You're probably right. Haufe asked for a bunch of my information so they can set me up as a customer in their system, then they can process a quote for me for a prototype/evaluation run of 10 units.

 

[Feral Feline]

Thank you for going above and beyond.

 

[vigilante398]

Quick update on this, Haufe has been sending me another email every few days asking for more little bits of information about who I am and how I plan to use these. They still haven't sent me a quote for them.

 

[LukeFRC]

Quick update on this, Haufe has been sending me another email every few days asking for more little bits of information about who I am and how I plan to use these. They still haven't sent me a quote for them.

Ah yeah the sushibox man - of course you can have some…

Wait, you run Unagi magnetics too? Wait a moment …

 

[LukeFRC]

Haufe make one of the transformer options for the Bo Hansen Di and silent arts sell them on for €40 plus shipping (plus VAT) - I imagine this will be similar costs … plus whatever tarriffs we are going to see in the next few days…