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Post by dandeurloo on Apr 13, 2017 7:44:31 GMT -6
I have the comp 54's. I upgraded the transformers in mine. I have recently been thinking they could maybe be upgrade a bit more with some part swaps and a real PSU.
I don't really mind the meter in its wonky state. These comps are cool. I bet for 200 bucks and some better transformers they could be really useful. Keep in mind the input and output transformers are gonna cost almost as much as the comp. But these already have what looks to be a better PSU built into it. At least its not a wall wart like the Comp54's.
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Post by winetree on Apr 13, 2017 13:45:14 GMT -6
"At least its not a wall wart like the Comp54's."
The Cp540 has the 24volt wall wart. No room for an internal power supply. Another week goes by. I'll try to hook my CP540 up next week.
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Post by dandeurloo on Apr 13, 2017 15:18:51 GMT -6
oh, boo. I hate wall warts. I think these would probably sound better with real full wave PSU's. I may make a external for my pair of Comp54's. I'm guessing that would help.
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Post by donr on Apr 13, 2017 23:12:47 GMT -6
At what point does an external PS stop being a wall wart? The in line PS for the Stam 1073 feels like a brick with wires on each end.
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Post by winetree on Apr 13, 2017 23:21:51 GMT -6
When there's no lump in the power cord?
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Post by svart on Apr 14, 2017 8:15:36 GMT -6
At what point does an external PS stop being a wall wart? The in line PS for the Stam 1073 feels like a brick with wires on each end. When they take the transformer and rectifier out of the little box at the end of the cable, and put it in the chassis of the unit allowing all the glorious EMI to radiate all over the boards.. Because that's really the only difference between a linear wall-wart and an internal linear supply. When most people complain about wall-warts, they are not really complaining about the topology used, as much as they are unknowingly complaining about the under-specing of the supply, or the lack of proper filtering in the unit itself. If the wall-wart is specified properly and the filtering needs are satisfied, then a wall-wart is a perfectly viable solution for powering just about anything.
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Post by schmalzy on Apr 14, 2017 8:47:43 GMT -6
Well, I pulled the trigger on two of these. I saw the ebay listing last night and took a swing. I've been wanting to hunt down some Comp 54s for a while but hadn't seen them at a price I was comfortable with in the event I didn't like 'em or they sucked.
Worst case scenario, I'll use 'em live with uneven bass players that need a few layers of compression, on trashy drum mics, on software instruments that require some analog scuzz in the chain, and on synths that need a little taming.
I'll report back with my findings!
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Post by Tbone81 on Apr 14, 2017 9:54:48 GMT -6
At what point does an external PS stop being a wall wart? The in line PS for the Stam 1073 feels like a brick with wires on each end. When they take the transformer and rectifier out of the little box at the end of the cable, and put it in the chassis of the unit allowing all the glorious EMI to radiate all over the boards.. Because that's really the only difference between a linear wall-wart and an internal linear supply. When most people complain about wall-warts, they are not really complaining about the topology used, as much as they are unknowingly complaining about the under-specing of the supply, or the lack of proper filtering in the unit itself. If the wall-wart is specified properly and the filtering needs are satisfied, then a wall-wart is a perfectly viable solution for powering just about anything. I think I'm speaking for a lot of people when I say I don't like warts of any kind. Wall warts just happen to be annoying because they take up too much space in my power strip. It's never a deal breaker though.
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Post by dandeurloo on Apr 14, 2017 11:00:32 GMT -6
At what point does an external PS stop being a wall wart? The in line PS for the Stam 1073 feels like a brick with wires on each end. When they take the transformer and rectifier out of the little box at the end of the cable, and put it in the chassis of the unit allowing all the glorious EMI to radiate all over the boards.. Because that's really the only difference between a linear wall-wart and an internal linear supply. When most people complain about wall-warts, they are not really complaining about the topology used, as much as they are unknowingly complaining about the under-specing of the supply, or the lack of proper filtering in the unit itself. If the wall-wart is specified properly and the filtering needs are satisfied, then a wall-wart is a perfectly viable solution for powering just about anything. Agreed. I also prefer a full wave rectified PSU rather then the half wave of most wall warts. That gets you some serious gains in my experience.
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Post by stam on Apr 14, 2017 12:50:23 GMT -6
At what point does an external PS stop being a wall wart? The in line PS for the Stam 1073 feels like a brick with wires on each end. When it's grounded, like the power supply on the Stam 1073
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Post by svart on Apr 14, 2017 12:56:33 GMT -6
When they take the transformer and rectifier out of the little box at the end of the cable, and put it in the chassis of the unit allowing all the glorious EMI to radiate all over the boards.. Because that's really the only difference between a linear wall-wart and an internal linear supply. When most people complain about wall-warts, they are not really complaining about the topology used, as much as they are unknowingly complaining about the under-specing of the supply, or the lack of proper filtering in the unit itself. If the wall-wart is specified properly and the filtering needs are satisfied, then a wall-wart is a perfectly viable solution for powering just about anything. Agreed. I also prefer a full wave rectified PSU rather then the half wave of most wall warts. That gets you some serious gains in my experience. Most of the ones I've hacked apart over the years have been full wave. Most older tube guitar amps are halfwave rectified and folks don't seem to complain too much though. It's all about getting ripple down to acceptable amounts. Just multiply the bulk capacitance on your DC input and you'll be good with halfwave rectifiers.
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Post by dandeurloo on Apr 14, 2017 13:18:23 GMT -6
Yeah, tubes are different because they don't require as much filtering as solid state designs. I find the full wave PSU's really do help on solid state designs. But again IMO.
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Post by aamicrophones on Apr 15, 2017 21:09:15 GMT -6
Hi Guys, I ordered in a GA-54 about a year ago. I had a couple of GA-73's that I changed all 7 caps in the audio chain to tantalums and the input transformer to a Carnhill/St Ives used in the original 1073.
I have a friend across the lake from me who had a nice 1073 and there was no audible difference I could hear with my old ears between the real 1073 the upgraded GA-73.
I didn't have a 2254 available to compare to the GA-54 but I have used one in the Neve console at the old Little Mountan Sound and in the Neve at Total Sounds West in Vancouver over 20 years ago. Now, these studio don't exist anymore.
Maybe something was wrong with the GA-54??? However, when I patched it into the inserts of the MXP3036 it was very disappointing, it seemed to "suck the life" out of the vocal even when the compressor was bypassed???
It didn't sound anything like the 2254 compressor that I have used in Neve consoles???
Its still sitting on my "needs investigation" shelf. It seemed to be more than changing the transformers. The GA73 sounded more useful and more "HiFi" before it was upgraded compared to the GA-54.
I would be happy to know if anyone finds the CP-54 from Alctron to be more useful. Looking inside from the pictures that Ragan attached the transformers look different than those in the GA-54.
if you guys get a more positive result from the CP-54 then I might find the inspiration to put the last couple of old Neve transformers I have left into the GA-54 and tweak it out.
To my ears the GA-54 was not even in the ballpark of being "modifiable". Hopefully, the CP-54 has been improved over the GA-54 build.
The GA-54 was no where in the ballpark of the WA-76 from Warm Audio. The WA-76 sounded just like my original 1176F and maybe a db or two quieter.
Cheers, Dave aamicrophones.com
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Post by dandeurloo on Apr 15, 2017 22:11:04 GMT -6
The transformers in the GAP stock are total garbage. Replacing those helps a lot. I am about to take out all the caps in one of my units and replace them with higher quality parts and see if that helps.
I wish I had a schematic for this thing.
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Post by indiehouse on Apr 16, 2017 6:33:07 GMT -6
Wondering if it wouldn't be easier (and maybe cheaper?) to buy/build one of Colin's kits from AML?
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Post by aamicrophones on Apr 16, 2017 13:54:48 GMT -6
Hi Dan, I just found the Schematic for the 2254e and I always thought there was one intermediate transformer ( between the input transformer and output transformer) but according to the schematic there are 2 intermediates.
The GA-73 has one intermediate so they circuit will not be exactly the same. I will take a look at the original schematic when I get a chance and see what might be done to the GA-73. The lovely thing about the 2254 was that it had a 1.5:1 ratio.
With a 2:1 ratio if the signal tries to rise 10db the compressor will only allow it to rise 5db above the threshold. With 1.5:1 ratio if the signal rises 10db the compressor will only allow it to rise 3.4db above the threshold.
The Ward Beck M466 compressor also had a 1.5:1 ratio and I really like those compressors. I think I still have a couple around here and one day will get around to racking them.
The Ward Beck was not a optical, VCA or FET type compressor it used a bridge of 4 transistors to control the gain reduction. Ward Beck designed it to compete with the 2254 for their 70's broadcast consoles.
With my 4-upgraded LA4 compressors, my 1178 (stereo 1176F), the Warm Audio WA-76 compressor and 3-upgraded LA-610/La2 compressors I haven't found the urgency to get the dissapointing GA-73 working properly.
Cheers, Dave aamicrophones.com
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Post by aamicrophones on Apr 16, 2017 14:07:40 GMT -6
Agreed. I also prefer a full wave rectified PSU rather then the half wave of most wall warts. That gets you some serious gains in my experience. Most of the ones I've hacked apart over the years have been full wave. Most older tube guitar amps are halfwave rectified and folks don't seem to complain too much though. It's all about getting ripple down to acceptable amounts. Just multiply the bulk capacitance on your DC input and you'll be good with halfwave rectifiers. The Wall Wart for the GA-73 and GA-54 is just a transformer that supplies 24v A/C. All the rectifying, filtering and regulation is done on the internal circuit board. So, unless that transformer can't hold the ac at 24 volts when the circuit is energized it will make no difference to the sound. I have upgraded several GA-73 preamps and never found a problem with the external 24 volt transformer being able to supply the 24v a/c under load. The GA-73 Wall Wart has a power cord also so it doesn't take up three positions in the power bar. The Wall Warts that are problematic usually have the rectifiers and filtering inside the Wall Wart plastic case and its usually impossible to repair them. The other advantage is the "power transformer" is removed from the chassis far enough away that it can't induce hum into the input transformer. In the the Studer A80 every set of channel electronics had its own 24v a/c transformer located in the bottom of the multi-track. This removed the a/c EMI magnetic field from being located near the input transformer to the bottom of the tape machine. Cheers, Dave
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Post by ragan on Apr 16, 2017 14:29:59 GMT -6
Hi Dan, I just found the Schematic for the 2254e and I always thought there was one intermediate transformer ( between the input transformer and output transformer) but according to the schematic there are 2 intermediates. The GA-73 has one intermediate so they circuit will not be exactly the same. I will take a look at the original schematic when I get a chance and see what might be done to the GA-73. The lovely thing about the 2254 was that it had a 1.5:1 ratio. With a 2:1 ratio if the signal tries to rise 10db the compressor will only allow it to rise 5db above the threshold. With 1.5:1 ratio if the signal rises 10db the compressor will only allow it to rise 3.4db above the threshold. The Ward Beck M466 compressor also had a 1.5:1 ratio and I really like those compressors. I think I still have a couple around here and one day will get around to racking them. The Ward Beck was not a optical, VCA or FET type compressor it used a bridge of 4 transistors to control the gain reduction. Ward Beck designed it to compete with the 2254 for their 70's broadcast consoles. With my 4-upgraded LA4 compressors, my 1178 (stereo 1176F), the Warm Audio WA-76 compressor and 3-upgraded LA-610/La2 compressors I haven't found the urgency to get the dissapointing GA-73 working properly. Cheers, Dave aamicrophones.com The GAP doesn't have the limiter portion, is that what the extra transformer would be for?
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Post by aamicrophones on Apr 16, 2017 15:27:16 GMT -6
Hi Ragan, thanks you are right. I just took a quick look at the front of the GA-73 and the 2254 schematic and the 2nd "intermediate" transformer is used for the limiter section.
Cheers, Dave
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Post by dandeurloo on Apr 16, 2017 18:06:22 GMT -6
Dave thanks for the info. I just opened one of mine up. I do see some rectification happening inside the unit. I am guessing it is full wave since it is using a bridge.
The GAP Comp 54's do have 3 audio transformers total. So, the original 2254 had a total of 4?
Do you know what version of 2254 these are suppose to be based on. I have to admit after swapping transformers this thing really does sound pretty good.
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Post by Guitar on Apr 16, 2017 18:16:23 GMT -6
Did you do anything to yours, or are they OK stock?
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Post by winetree on Apr 16, 2017 23:38:40 GMT -6
"I have to admit after swapping transformers this thing really does sound pretty good."
Which ones did you swap and with what?
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Post by svart on Apr 17, 2017 8:19:42 GMT -6
Did you do anything to yours, or are they OK stock? I rock mine stock. I don't think there is enough difference to warrant modding. They have the "Vintage neve sound" thing going on. The only difference is that they seem to have less headroom, and will distort earlier if you turn them up high. Other than that, the difference in sound isn't much more than the difference between other name-brand clones, or the difference in real Neve modules. You gotta remember that the real vintage modules used 20% tolerance parts that age and change over time and their transformers were not that tight tolerance either. One module to the next would sound somewhat different. With vintage preamps, you get high-distortion, high noise devices that are mojo monsters. Worrying about specs is not something I would do with old Neve modules.
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Post by svart on Apr 17, 2017 8:25:10 GMT -6
Dave thanks for the info. I just opened one of mine up. I do see some rectification happening inside the unit. I am guessing it is full wave since it is using a bridge. The GAP Comp 54's do have 3 audio transformers total. So, the original 2254 had a total of 4? Do you know what version of 2254 these are suppose to be based on. I have to admit after swapping transformers this thing really does sound pretty good. 2254/33609 had 3 transformers. First was the input which stepped down the signal level to very low levels going into the zener attenuator section. The second transformer steps the signal back up to a somewhat usable level into the output amplifier section (exactly like a 1073). Finally the last transformer is the output transformer, which is the same as any vintage neve output tranny. The 2254/33609 has two sidechains, both of which are almost identical in design but have different RC time constants for attack and release. They are hooked up in parallel, so it would be easy to take one out without affecting the action of the other.
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Post by svart on Apr 17, 2017 8:31:02 GMT -6
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