Golden Age Project Pre73

[joni0001984]

Originally Posted by Hotstuff

Hi joni0001984,

Do you own a GAP PRE-73?

I did not understand your post, did you like it or not?

The pre in my opinion at least needs the output transformer upgrade to get rid of the distortion that stars appearing when it is set to 50 or so, but this is also source dependent. I have 2 and they both started to distort and they both benefited from the upgrade, I have made great recordings with this pre and the best way to try a pre is to test it yourself.

The test just proves that it works and is right up there with the "best". Don´t forget this is a +/- €265 pre compared with a €3000 pre.

Hi,
No, I only had the samples to go on. You are the expert.

Well I liked different things about the guitar samples. The Neve had hi treble in my speakers, which made everything sounding very clear, perhaps too clear, i.e. the treble may be too loud. The mids was also high but that was kind of disturbing and I understand what someone on the thread said about a wobly bass.

The GA Pre73 was best modified as in Guitar_2, because then it sounded more flat, though the treble was a bit low, which I liked in this case with acoustic guitar. I don't know if a low treble is useful all the time. This may all be adjusted in a proper EQ. That is why a too high treble with a clear tone may be better, as in the original Neve, because then you know what you want to edit out and what to keep.

It could be that my experience of a low treble is due to the lower volume on all the GA samples, or more interestingly if the components are of low quality or the GA is a worse design than the Neve. Four guitar samples is little to go on. API, why didn't you have four $4000 Nuemann microphones to test everything at once!

I would never buy the Neve, and I think I will look around a bit before I settle on the GA Pre73. A preamp that is emulating a sound I did not really like the original of is perhaps the wrong pre for me.

But I could be wrong all together. The changes in sound are minute and I may be exgagerating.

[Hotstuff]

Hi,

I´m by no means an expert, I´m just a hobby recordist.

I have never really worried to much about preamps and don´t think there is a holy grail of preamps and I think that a lot of novice recordists, like myself, think that buying a preamp will all of a sudden make there recordings better.

For me once I have decided that a preamp is good I don´t worry about it anymore and just concentrate on making good recordings through good and creative mike placement, correct tuning (guitar, bass, drums), getting the best performance out of musicians etc...

The samples for me just prove that the preamp works and sounds good and for the price is a good buy.

By the way the output transformer upgrade is very easy to do, I am no technician, my experience in soldering is making my own cables and multicores and I was able to perform this upgrade easily, soon I will order the Input transformers and do the upgrade also.
Coin at Audio Maintenance provides a great service and is the man to get the transformers from

[whitedwarf]

This goes to API. I got a LL1538 and wondered how to connect it. Can you help?
Also what's the value of the output cap? 2A103J is what the original says..?
Thanky you for sharing..

-WD

[Matti]

A Lundahl transformer is a totally different thing than Carnhill or the Chinese one, if you mean by output cap the cap on the transformer, it´s there for adjusting that transformers ringing and would be different for a Lundahl if needed at all. Consult Lundahls site for the value they suggest -and the connections for that matter

Matti

[whitedwarf]

Ok that's too bad. What is the Carnhill input tranny part number? I have to order one then.
Thanks for your reply.
-WD

[Matti]

Audio Maintenance Limited Transformers and Inductors
Lundahls are exelent transformers but for that N...ish vibe Carnhill might be closer

Matti

[whitedwarf]

Alrigt, I will go for that.
Thanks a lot MATTI.
-WD

[API]

Yes, It is not even sure that you could use the Lundahl on the input, I do not know that model but it might be something completely different but it could also work, I do not know.

Regards,
API

[whitedwarf]

Can anyone give me a hint on wiring up the Carhill tranny and the value of the output cap?
That would be nice.
-WD

[API]

Hi.

Just wire it the same way as the original transformer in there, you need to hardwire it though since there is no pcb on the carnhill version.
It uses the same pinout though, see my pic above for reference.
Outout cap is 10nF.

API

[Matti]

"Outout cap is 10nF" -for the original chinese or for the Carnhill or for the
original st.Ives ? Really those will need different values.

Matti

[synthetik42]

@ joni0001984

Dude, you're crazy!!!

[Matti]

Me, what!?
You,yes!!

Matti

[Hotstuff]

Hi Matti,

The output cap is the same value as used in original neve preamps, its a 10nf cap and a 1500 ohm resistor in series across pins 5 and 8 on the output transformer.
Just look for Neve 1073 schematics and it is there on the output.

The one that comes with the pre is not bad and can be reused, if not just get a new polypropylene or polyester cap with the same value, a polystyrene cap is also a good choice.

[Matti]

Originally Posted by whitedwarf

Can anyone give me a hint on wiring up the Carhill tranny and the value of the output cap?
That would be nice.
-WD

Sure I didn´t even think I could help with the values or so

Thank you for this!

Matti

[Matti]

Originally Posted by Hotstuff

Hi Matti,

The output cap is the same value as used in original neve preamps, its a 10nf cap and a 1500 ohm resistor in series across pins 5 and 8 on the output transformer.
Just look for Neve 1073 schematics and it is there on the output.

The one that comes with the pre is not bad and can be reused, if not just get a new polypropylene or polyester cap with the same value, a polystyrene cap is also a good choice.

Thank You

Matti

[whitedwarf]

Is the IC: TL072CN in the signal chain or just used for the led meter?

[Matti]

So I would say NO or Bo is a lier, wich I know he is not.

Matti

[whitedwarf]

Hi,
So I wired it up just like orig. one. All I get is noise and at -80 it gives a little output.
So pin 11 is ground? and pin 7, 8, 9 and 10 goes in on the line transformer side? Pin 2 and 5 on the other side where 3 and 4 is wired on the board?
Please help.

-WD

[API]

Originally Posted by whitedwarf

Hi,
So I wired it up just like orig. one. All I get is noise and at -80 it gives a little output.
So pin 11 is ground? and pin 7, 8, 9 and 10 goes in on the line transformer side? Pin 2 and 5 on the other side where 3 and 4 is wired on the board?
Please help.

-WD

What did you change?
I guess that you are talking about the input transformer.
Pin 11 and pin 6 are ground, on the china transformer those are the two lone pins at either short end of the transformer.

API

[whitedwarf]

Please se next post

[whitedwarf]

I did just as you told and used your picture as guidence.
Maybe something else went wrong

[API]

I am not sure I told you anything, I said regarding the output transformer that "you" should wire the pins as the chinese transformer.
The input is a different thing and the pics i posted could be wrong, please do not take those as a manual to do something yourself, I only posted them to show my work and what I do, not as a "manual" for someone else.

What you need to do is trace the mic transformer input and output on the board and wire the new transformer in the same way.
You will need a copy of the original schematic, also it is recomended to wire all the pins to the board if you are not sure what you are doing.
The pics i posted show a custom configuration.

API

[whitedwarf]

Well since i have the same mic input transformer I hoped that your wirering would do the same trick for me. If you don't want to share that is fine by me but if you don't mind I would like a bit of advise on how to connect it. I am not a tec and can not read schematics that well - and don't have it.
If you can help me it would me much appreciated.
Thanks
-WD

[whitedwarf]

If you have the schematics I could try to figure it out if you would mail them to me?

[whitedwarf]

I got the Carnhill VTB9045 mic input transformer to mod the GA PRE73. But it was not as simple as I thought. Can anyone give me a hint on how to connect it to the board. All i get is noise and no gain.
It will be much appreciated.

-WD

[API]

The pins on the Carnhill transformer does not correspond directlyt to the pins on the board.
If you could read the schematic to see what pins are used where in teh circuit and trace the input and output on the PCB you should be able to connect the right numbers to the right places on the board.

API

[whitedwarf]

YES! Got it working. This is kinda big for me since I have generally no idea what I'm doing. But I have a nice multimeter, and a little measuring on the transformer compared to the original, and then it was no prob. It was actually very easy
Sounds very nice and open.
Thanks for all you help on pushing me in the right direction API.
Could you replace some other components to make it even more audiophile?

-WD

[Branislav]

Originally Posted by API

I guess that you are talking about the input transformer

And I guess that you are talking about the microphone input transformer, but this thing has two input transformers, as the line input has it's own transformer, which nobody mentions. As I might be interested in getting some color for my keyboards, my primary concern is the line input. Have you (or anyone else) done any tests using the line input? Should the line input transformer be changed and if yes, what would be the best substitute?

Branislav

[API]

I have not tried to change the input transformer just for the reason that it would be to expensive to change both mic and line transformers.
It is quite labor intense to change just one of them and takes alot of time.
But I am sure that there would be a good benefit to be had with a Carnhill replacement

By the way, I just finished modding three PRE73´s today but only two are spoken for.
So I am selling the third, brand new and modded with Carnhill (mic) inut and output iron.
PM me for price and info.

API