Alctron CP540 Neve 2254/33609 Clone

[kingkorg]

@Ruud, not the cleanest comp i agree. However, LF area was actually cleaner with stock output transformer, these measurements are with Carnhill.

@r2d2
It seems to be the same thing, with some tweaks/changes. The diodes are closely matched, pretty surprising.

I guess it could benefit from cap upgrade in the signal path, i am not 100% sure that Nichicon branded ones are originals. Some are lower values compared to Igor's.

Switchable Zobel is a nice feat.

Igor mentions some blue aged tantalums are better option. Sounds bit esotheric to me, but...

Mentions also old Motorola transistor, i might try one.

Both CP540 and MP73eq do the same thing i can't get with any plugin.

With no compression/eq enabled when driven harder they do wonders on stereo busses.

I don't have pairs sadly, but i just run L&R chanels individualy and bring them back in DAW. No compression, just driven until i hear first clue of distortion, and then dial back couple db. It does wonders this way, both eq and compressor.

Btw i sold LA610 and Liquid Chanel in the meanwhile and never regreted. I am actually surprised both units got good reviews at Gearslutz as well as their 500 series

 

[r2d2]

…….Btw i sold LA610 and Liquid Chanel in the meanwhile and never regreted. I am actually surprised both units got good reviews at Gearslutz as well as their 500 series  

really no "fan" with liquid channel ?

…….Not that i care for what they write there, but when they praise Chinese gear non affiliated to any US company i tend to pay attention.

the n*1 cloners in the world  ?

cheers

ps
lack of the limiter on the Igor 54 comp
it's like a car without a wheel

 

[kingkorg]

I am actually huge fan of Liquid products. However the problem with Liquid Chanel is when it gets pushed, it does deliver fixed maximum saturation/character that is sampled, and can't get any further. There is no interraction/variation when input and output are pushed in different ways.

I get the same effect with Liquid Mix i still have and love. For 50$ they sell now it can't be beaten.

Liquid Chanel is superb clean preamp when emulations are not used. And people overlook that part often. Add variable impedance transformer/no transformer input, AD converter and it's really a killer. But in the end i was going for ''color", Alctron has that for sure. And for the price of LC i can get a lot of great of clean pres and still have LM for emulations.

I used LC for live as well, and there is no thing like it for that application.

 

[Matt C]

Is there anyone still selling the CP540? Seems to me like they're all sold out

 

[kingkorg]

Well, i did get them directly from Alctron. Just try that way. There is a guy on ebay and reverb "noelthemusician" that sells their gear. You can try Aliexpress and Alibaba as well.

The price vary a lot, but i would say that somwhere about 250$ is fair ptice. I would not by any means pay 500$ what advertised price seems to be.

Golden Age Comp54 seems to be the same thing, but different package.

 

[r2d2]

Golden Age Comp54 seems to be the same thing, but different package.

……. the chineses also  clone themselves ;D
cheers

ps
(…how they do with wifes ?  :  )

 

[kingkorg]

I believe Alctron produces them for Golden Age.

 

[r2d2]

I believe Alctron produces them for Golden Age.

After checked various images about
have to say that are soooooooooooooo  similar to Igor designs
marconi knobs too , are sooooo similar to that for sale here around…

cheers

ps
how many " suckers"  around…  :-\

 

[kingkorg]

Thanks for confirming that!

 

[living sounds]

So I got a couple of the second generation Alctron CP540V2 2254 inspired compressors.

They are surprisingly heavy and quite well-build. Mechanical construction is not perfect though, some screws don't fit perfectly and you can get into trouble if you unscrew and screw them back together a few times. I also had to fasten screws that had come loose on one of the units big output trafo.

Lot's of attention to detail, like 7 individual through-hole LEDs lined up behind the meter for an even glow.

The unit gets its power from an external switchmode +24VDC supply, and there's a filter with a big choke inside the unit to get noise down to a reasonable level.

Everything on the main board is through hole, only resistor ladders on the front panel PCB are surface mount. Switches used for everything except the output gain pot.

Lot's of dry tantalum caps used, some WIMA caps, transitors that look like Fairchild brand, many 184's so the circuitry might stem from the revision E of the 2254.

The blocks that are made up of individual PCBs in the original are clusters of parts surrounded by emptyness on the PCB here.

The output is returned inverted, but this is easily fixable by carefully taking off the output trafos secondary connector in its entirety from the PCB and reattaching it turned 180 degrees. No soldering iron needed.

There's a relay bypass, a link option, a switchable high pass filter with a 7 khz (De-Esser) mode. A lot more attack/release settings than on the original or the AML.

Mechanical switches are pretty good (I prefer these bigger ones to the Behringer, for example), but don't align perfectly with the front panel markings. No big deal IMO.

It sounds good and very useable, but probably not as detailed and sweet as my AML 2254s. I will have to do a shootout. Tantalums and cheap electrolytics might play a role, and maybe the semiconductors. The trafos look good and the output trafo is a big one. The unit works the way you would expect from a diode bridge compressor/limiter. It sounds much more balanced and nicer than the aggressive, midrange heavy Behringer. It also feels better with the big easily set switches.

Some unlabelled trim pots. The one for setting bias is easily identified and bias can be set correctly. Overall calibration was very good, but the output vs. unit gain is 7 dB or so too hot. And there was a 0.8 dB difference between both units, that got down to 0.3 dB once compression was turned on (with threshold set so there is no compression action).

So I tried to set it to unity gain and failed. There is one unlabelled trimmer left that has the right size (5k), right setup (used as a variable resistor as in the original) and is in the right location at the output stage. The resistor values next to it are off (should be 220-1k ohm in series but is 4.7k ohm; should be 1.8k ohm to ground but is 2.2k ohm) and turning the pot and even changing the resistors to the stock values doesn't give the desired outcome. So they have either deliberately or accidentaly changed the gain structure for some reason. In order to get unity gain I would have to knock the resistor level so high I might increase overall noise or cause other unforeseen consequences. Lacking a schematic, I will keep it as it is.

I will probably build a linear PSU to feed both units at some point.

I can post photos if folks are interested.

 

[thomasdf]

Interesting ! Thanks for the very detailled review. Where did you get them, to have them shipped in Europe ? How much did you pay ?

 

[living sounds]

Interesting ! Thanks for the very detailled review. Where did you get them, to have them shipped in Europe ? How much did you pay ?

From Swamp Industries in Australia. I took advantage of their 20% discount in June and payed around 620 EUR for the pair, including shipping, taxes and customs. These are a much better deal than the Behringer IMO. The only caveat is the gain issue with the set gain pot doing next to nothing.

 

[chrispbass]

I found Igor's schematic, and even though there are some differences it seems like the same thing. I will dig deeper when i get some extra time.

@Ruud, i was a bit slow with THD measurements, but i did get scary similar results.

100ms 2.79%
400ms 0.81%
800ms 0.428%
1500ms 0.368%

Even though it doesn't show, the cursor was placed at 50hz. I used soundcard and REW.

Hi Kingkorg

Any chance of sharing the schematic if you still have it please?

I’ve got one Igors 2254’s to complete and it may come in handy.

Cheers

 

[kingkorg]

Hi Kingkorg

Any chance of sharing the schematic if you still have it please?

I’ve got one Igors 2254’s to complete and it may come in handy.

Cheers

Sorry, no. But it has to be somewhere out there.

 

[chrispbass]

Sorry, no. But it has to be somewhere out there.

No probs, and yes it should be, but no luck so far. May not need it anyway, and can always get the jist from the original.

Cheers

 

[r2d2]

Hi Kingkorg

Any chance of sharing the schematic if you still have it please?

I’ve got one Igors 2254’s to complete and it may come in handy.

Cheers

Hey what docs do you need ?

 

[living sounds]

I shot out the CP540V2 with the AML 2254.

Apart from the difference in gain the overall sound is quite different.

The AML sounds very nice and hifi, with a classy sheen in the high end and a big low end.

The CP540 in contrast has more distortion (measured with sine waves) and a less open high end, but a deeper low end and a much more obvious color to it. A little crusty, thickening, evening out resonant sources. Somewhat similar to what the GAR1731 op amp does, but more classy and less intrusive.

I could not match the compression behaviour like I was able to do with the Behringer. Apparently the CP540 does its own thing.

For me the AML is the better choice for well-recorded detailed sources like close miked string instruments, vocals and even the mixbus. The CP540 shines on individual drum tracks, the drum bus, anything with a midrange that needs evening out like electric guitars, string sections. The wider range of attack/release settings makes it very versatile. I just did a mix where I had it inserted in the drum bus, not just in parallel like the Behringer I had patched in there before, and it performed brilliantly.

In terms of noise the CP540 was even a little quieter than the AML, probably due to the gain staging being different (distortion is a lot higher for the CP540).

A very useful piece of gear I wouldn't mind having a few more of.

 

[blue_luke]

Geoff Tanner, one of the Neve designers, always says 'do not replace the tants!!!'
("Those tants aren't there without a reason")
I know that opinions differ, but it seems they do change the sound.

I may agree or not, I would have to hear the beast. But one lesson I've learned from my days as a service tech for AIWA in the early '80's, my boss was a component engineer and explained to me that tantalums get a bad rap because they blow short quite often and takes with them the circuits they are connected to.
The problem, so it seems if I remember correctly, is that tants are notorious to be sensitive to voltage spikes. He also told me to never use a tant at less than 35V rating and his rule of thumb was to use at least twice the Vdc rating than required.... and we designed circuits where the tants were used at only 25% of their rating.
Just my two cents (Canadian )

 

[Tekay]

The GAP 54 was more or less based on our Vintagedesign C1 compressor. I provided a compressor schematics to GA. I left out some features as the HPF, just 3 attack settings and I also left out the 25 and 50mS recovery but it ended up at their version anyway including the line/mic transformer footprint which were a custom versions at the time, I guess they just reverse engineered our C1 which they were distributing for us at the time. Google vintagedesign C1 and you'll see that they are more or less identical

 

[living sounds]

The GAP 54 was more or less based on our Vintagedesign C1 compressor. I provided a compressor schematics to GA. I left out some features as the HPF, just 3 attack settings and I also left out the 25 and 50mS recovery but it ended up at their version anyway including the line/mic transformer footprint which were a custom versions at the time, I guess they just reverse engineered our C1 which they were distributing for us at the time. Google vintagedesign C1 and you'll see that they are more or less identical

Very interesting, thank you. Do you have any idea what happened with regards to gain structure / set gain trimpot configuration in the CP540V2 as described in my post #30 above?