A 1272 type preamp on my bench [NEW! pics posted]

These days I had a Brent Averil N_E_V_E 1272 type preamp on my bench.
Unbelivable what a piece of crap. Two boxes atached to a front panel and tons of wires hanging from the whole thing.
How can they sell something like that? What a shame. Our DIY jobs look much, much better.
Will post pictures.

chrissugar

most of thier stuff is put together like that. not top notch construction, but the customer service is great. they also package the stuff with power one supplies which are really terrible for neve's IMO, I changed those out in a pair of 33114's I had and it made a tremendous difference in depth with the eq's.

dave

:green:

... just had to step in with a comment and yes this comment is inspired and reflective of certain events here in the past few weeks.

Here we have a commercial product, built from a previous commercial product, re-built, re-packaged and re-badged ... all for profit.

The original posted suggests it is a load of crap.
CRAP could be relative but relative to what.
:grin:
bare with me here ... I'm going somewhere with this.

It could be crap relative to other products of similar price or status ... or more importantly it could be crap compared to the posters own DIY projects.
:green:
This brings joy to my heart. Knowledge is shared and spread. The possibilities of DIY are now seen as on the same footing as anything commercial, past or present. The second posted suggests a retrofit to a product already repackaged and give some reasoning to the choice. The changes involve a product that is solved for profit I might add and the results are improved. The opinion of improved may be different for all people but the posted bases judgement on experience obtained through DIY and the use of both DIY and commercial product.

Even though everyone is on a different path and their relative positions on those paths are forever diverse we can find common ground in our discussions. Newbies or old hacks like me can share experiences and present judgments based on those experiences.

In order to do this we might have to consider explaining ourselves better. Present a case as to why something is crap. Give a little detail. The benefits of presently crap here may at first seem spiteful BUT there is method in my madness. Only by discussing these topics, with both good and bad can we truly begin to present the good.

"This project or method is better because .... " :roll:

Communicate new knowledge by bringing some facts and reasoning so all people can make an informed opinion. This presentation can help to continue to inform people and so continue to spread knowledge and this is ultimately the best part of the journey.

Of course there is a chance that bringing a point of view may cause some people pain and the forum will have to deal with the consequences. Brent may feel a little upset at the above and it would be excellent if he could comer and give some discussion and reasons to his methods. He should be welcomed and respected. Healthy and vigorous discussion can bring new possibilities and this was proven more than once back at Tech Talk were products got renamed and errors corrected.

Chris, please do post some pictures so we can all see and have a think.
:thumb:

you might also consider removing the DI completely, all that does is load the whole circuit down, its completely unbuffered and just a bad idea they way they have it implemented. Between the $22 power supply they use and the really poorly conceived DI you can argue that those things arent the greatest deal in the world. Considering that a 1272 is in a metal cassette, you can argue (and Im sure they do) that you dont NEED a chasis since the transformers are already shielded. It looks sloppy, but once in a rack you never notice.

So far as Im concerned, there isnt much difference between what BAE does and what we do except for the fact that they are trying to run a business, and Im sure if I was faced with all the things that go with that, my racking jobs wouldnt be nearly what they are right now, probably both negatively and positively. Considering how long they've been around and the reputation they have, it seems someone overthere has figured out some balance of compromise between ultimate quality and keeping their customers happy. I'll admit though, the 33114's I bought from them I wound up ripping out of thier rack, returning to stock and moving along on my own with them, they just didnt sound good as supplied. The racks with chasis are really pretty though, which sadly, has to count for more than it should in a large percentage of the people that buy that stuff.

dave

[quote author="Kev"]The opinion of improved may be different for all people but the posted bases judgement on experience obtained through DIY and the use of both DIY and commercial product. [/quote]And I'll try harder to abstain from my self-elected role of "R.E.S.P.E.C.T. Police"... :green:

Peace!

I'm really very interested to see those pictures! Originally I had the notion that all 1272's were a darker, and less exciting preamps than the pre section on say a 1073 or 1081. After building my SCA N72 it dawned on me that comparing it to a 1272 might be misleading. The 1272's I have heard did not sound as open in the highs, or as sparkly as the N72. The N72 sounds more like what I'd expect the 1073 to sound like without the EQ. Still, there is no third gain stage, but even up to 60db gain I still think the N72 sounds much more open than the 1272 replicas I have heard before.

So is there an issue with other's power supply? Is it how they are racked? Are they using cheaper caps or connectors? What is it? Obviously the circuit must be pretty much the same.

I know the SCA power supply is pretty robust, so maybe that's the beginning of it. I will say this, the Averill 1073 sounds mighty fine. I wonder what (aside from the lack of the third gain stage) is going on different in their 1272 circuit.

Shane

there's nothing different going on in a 1272 than a 1073 below about 40 something dB. With the averill, the di ran a piece of coax to a switched DI jack and then back to the board, so there's that added capacitence from the cable which when removed, makes a difference. The main thing, tim's kits spec regular electrolytics where a real neve used tantalums, so the N72 sounds a bit more open and its because of that. He used to package the kits with panasonic FC caps which would produce an even more open and hifi sound than if you used tantalums like neve did.

dave

I know Mark at Brents, he's a real nice guy. Brent has let me talk his ear off many times. A cool dude. I was going to have a client pick up a pair of his 1272's based on a recent conversation I had with those guys. I was told their clones are acurate down to the imported engligh wire. I have an api rack made by BAE that is very good, with a very good power supply. If there's a better finished clone (true reproductionish) out there let me know, and I'll tip off my client. I know Chandler had power supply issues at first, but Wade got it fixed, Maybe you got a turkey that slipped through.
Peter

[quote author="soundguy"]there's nothing different going on in a 1272 than a 1073 below about 40 something dB. With the averill, the di ran a piece of coax to a switched DI jack and then back to the board, so there's that added capacitence from the cable which when removed, makes a difference. The main thing, tim's kits spec regular electrolytics where a real neve used tantalums, so the N72 sounds a bit more open and its because of that. He used to package the kits with panasonic FC caps which would produce an even more open and hifi sound than if you used tantalums like neve did.

dave[/quote]

Thanks Dave,

That's just what I was curious about. I am thoroughly enjoying both the A12s and the N72s alike, despite them being two different animals. I'd love to take on the 1081 project, but my confidence isn't up to it just yet. With the SCA pres sitting in my rack though, my recordings certainly won't suffer for it.

On the SCA site Tim has a fft graph comparing the N72 to a vintage 1272 converted to a mic pre. i don;t know which source he used for the vintage gear (maybe he did it himself) but the response curve is as identical as you would expect from two different, like units. I would imagine manufacturing variances would produce bigger differences many times.

I wonder how Brent's would stand up in the same test. I'm not bashing the Averill's at all since they certainly have a fantastic reputation! I have heard complaints about the D. Alexander pres too, but from the pictures they look sufficiently well made to me so I guess it's a matter of opinion in the end.

Shane

there's nothing different going on in a 1272 than a 1073 below about 40 something dB

Click to expand...

Well, in concept there's not much different, true, but to avoid confusion, of which there seems to be much regarding a 1272 as a mic preamp, 1272's were generally fixed gain on both stages with a pot to adjust level between preamp and output stages.

The typical mic preamp conversion is to add a 2-stage switch to contol a pad in front of the input trafo and the gain of the preamp stage. The output stage generally remains fixed. It is easy to make a 1272 mimic pretty exactly a 1073-type preamp in this manner, up to 50dB of gain. After that your gonna have to increase the gain beyond what Neve did.

Tim's N72 is unique among the various commonly found '1272' clones in that it uses the Neve approach of using a 3-pole gain switch to control attenuation and two gain stages. Splitting the gain duties between both stages definitely changes the sound, apparently for the better according to comments made here and elsewhere. Neve used 1272's for talkback mic preamps with 70dB of gain by increasing both stages.

FWIW, I would argue that you could get a little higher gain from a 1272-type design and not really violate Neve's guidelines by dropping the lowest gain-set resistance for the preamp stage down to 91-ohms, which gives around 31dB total from this stage instead of the 28dB of the 120-ohm that is typically used here. Neve used a 91-ohm resistor on an identical preamp section for the third stage in the three-stage mic preamps. Beyond that your requiring more from the amps than Neve used in this application.

If you still need higher gain and want to maintain excellent LF response, increase the caps coming off the power rails (connected to pins M and N) to higher values. Neve used the highest values they could physically fit in these positions, typically a 470u or 640u or a couple of these in parallel if space allowed. Caps are now much smaller, so you can increase them easily. I use 1500u to 4700u depending on space available.

JC

The main thing, tim's kits spec regular electrolytics where a real neve used tantalums, so the N72 sounds a bit more open and its because of that. He used to package the kits with panasonic FC caps which would produce an even more open and hifi sound than if you used tantalums like neve did.

Click to expand...

Nope, the N72 uses tantalum coupling capacitors (Panasonic EF series, 22uF) in the same places that Neve did. The power supply decoupling and shunt capacitors are aluminum electrolytics, also like Neve.

You make a good point about the DI implementation on most of the racked 1272s I've seen. Sticking a hunk of coax and a 1/4" switched jack between the trafo and first stage input strikes me as bad practice. Also, the impedance looking into the first stage is high, but it's not high enough to load a single coil pickup the way I'd prefer. My DI (it's coming, I swear) will be a JFET buffer that has enough oomph to drive the input transformer.

[quote author="soundguy"]they also package the stuff with power one supplies which are really terrible for neve's IMO, I changed those out in a pair of 33114's I had and it made a tremendous difference in depth with the eq's.[/quote]

You are correct about the power supply comment. I have a pair of API 550s in an Averill rack w/ no phantom power option. I'm bought a pair of Baumans's API boards and was thinking that if I can add phantom power to the Averill supply, then I wouldn't need to build a PS for Bauman's boards. However, when I opened up the Averill power supply is was simply a Power One supply in a little black box.

Do you think changing the PS for my APIs would make a difference at all?

very cool thread guys.

oh !! and Hi to Tim.

carry on.

hey tim-

I built my n72's with all aluminum EE's but I think I had one of the first kits eons ago. The DI on the averill racks shouldnt be labeled "DI" simply because its not, its just a transformer bypass switch. Its fine for keyboards, but its NOT an instrument DI as there's no way as you said, a guitar pickup could be properly loaded. That said, its IMO moronic to add all that extra cable capacitence when the only thing doing that is REALLY useful for can be equally or arguably better achieved by putting a pad before the input transformer for use with keyboards... You could still label it DI and all that and have the same advertisable features, etc, but most of the DI's out there are not DI's at all. I will say though, plugging a guitar directly into an API 325 works really well in my experience, but Ive never had luck with anything neve doing that.

Greg- so far as power supplies go, I didnt get a unit that slipped through quality control, all the averill boxes use those shitty supplies. I got a vintech x73 today and it uses the same cheap open frame supplies and I'll bitch about that box in another thread. Ive changed supplies and heard differences on some gear and not heard boo of a difference on others, so you'd have to try and see. I dont know if its my particular modules or what, but to date, anything I have that is neve or a copy of a neve has noticably benefitted from going from a power one to something a little better. And FWIW, I wound up using tim's ps1 for a lot of neve stuff, thats a really great power supply. Neve amps sound a little stiffer with that supply compared to a power one, and anything to control the mush factor in the bottom end of an average neve thing is something Im gonna do, so...

dave

So could the difference between the Averill 1272 and the N72 be attributed mainly to the Power One supply vs the SCA supply? Does the Averill in fact use the 3 pole switch or the two? I remember reading a post by Geoff Tanner stating that the N72 was one of the very few Neve clones that used the correct circuit and gain structuring (as prescribed by RN himself). Are the Averill and D. Alexander clones not in that category as well. the N72 certainly sound more open and full range than the Vintech 1272, and the Averill clone. Of course, this could all be psychological, or perhaps the others are more heavily loaded on the secondary of the output transformer.

Shane

So here are the pics:
http://img.photobucket.com/albums/v292/chrissugar/BRENT-AVERILL/DSCF6897X.jpg
http://img.photobucket.com/albums/v292/chrissugar/BRENT-AVERILL/DSCF6899X.jpg
http://img.photobucket.com/albums/v292/chrissugar/BRENT-AVERILL/DSCF6900X.jpg
http://img.photobucket.com/albums/v292/chrissugar/BRENT-AVERILL/DSCF6903X.jpg
http://img.photobucket.com/albums/v292/chrissugar/BRENT-AVERILL/DSCF6906X.jpg
http://img.photobucket.com/albums/v292/chrissugar/BRENT-AVERILL/DSCF6908X.jpg

chrissugar

The DI is a 100K resistor from the input jack to the gain switch after disconecting the input transformer. :?
Panasonic FC glued to the box. :green: :green: :green:
Also the transistors are diferent in the two channels. May be it is not a tragedy but they sell a stereo pair so it would be good to be matched.

chrissugar

I discovered an interesting thing. From my own tests and after reading posts at diferent forums my idea was that the default input impedance for the 1073 type preamps is 1200 ohms. I mean most of the mikes give good results with this impedance and the low Z is for ribbons or some dynamic mikes.
If you look to this picture you can see that the input transformer has the windings conected in paralell, so it is always low Z.
Maybe Dan Kennedy can confirm about the input Z ?

Look at the four pins from the left side, pin1 shorted with pin2 and pin3 shorted with pin4.
http://img.photobucket.com/albums/v292/chrissugar/BRENT-AVERILL/DSCF6903X.jpg

chrissugar

Looks not so great
Peter

Actually, gluing that cap to the panel is probably something I could have done myself. Maybe used a zip tie instead. That cap used to be mounted where the gain switch now is on that unit, so they had to stick it somewhere and that seems like a good enough place to me.

I wouldnt compare two completely different units and suggest that its the power supply that makes them sound different. I can only claim that on the same circuit, there are times when power it with one supply vs. another can make a noticable difference, thats all. You'd have to experiment with your stuff to see, some circuits, like my neve stuff, I was able to get improved performance with better supplies, other stuff nothing noticable so I kept the power ones.

dave