[ACMP investiupgradifications] All things PREAMP
- Thread starter clintrubber
- Start date
Help Support GroupDIY Audio Forum:
diyfanatic
Well-known member
I think that nobody give a f*ck but there is a lot of people waiting for you to get some work done...
dustbro
Well-known member
Del said:
?? what good work?
willowhaus
New member
- Joined
- Feb 20, 2009
- Messages
- 2
Maybe try this: http://recforums.prosoundweb.com/index.php/mv/msg/16069/0/2928/18558/ That'll get you to the current page. According to compasspnt they have working units burning in. Take it for what it's worth.crazydoc said:
I don't really care much either way until somebody actually comes up with something useful, instead of a lot of promises. Looks like things here aren't much different from there, though...
okgb
Well-known member
Hmm sounds like a stand off
spend money sending it ,to risk not getting it back
or sit on something that isn't usefull
Funny how they posted it's taking time because there is no profit
in the repairs [ but there surely was in the sales , maybe enough
to cover the repairs ? ]
curious to see if they open up a return system and how many take them up
on it ? they could probably buy new boards from the chinese for less and
just send them to people , no soldering .
Chance said he wanted to do some good to make up for his past ,but
that needs fixing as well
spend money sending it ,to risk not getting it back
or sit on something that isn't usefull
Funny how they posted it's taking time because there is no profit
in the repairs [ but there surely was in the sales , maybe enough
to cover the repairs ? ]
curious to see if they open up a return system and how many take them up
on it ? they could probably buy new boards from the chinese for less and
just send them to people , no soldering .
Chance said he wanted to do some good to make up for his past ,but
that needs fixing as well
Back to the subject at hand...
Has anybody successfully mounted their power toroid in an external box? I was playing around with my pair of 81s last night and confirmed that I should probably do that if I want to get rid of the induced buzzing at the inductors. I may try some mu-metal shielding first. I have a couple sheets of 3M Ultraperm on their way. If that doesn't work though, anybody have a suggestion for a connector and/or wiring to use for the 10 leads necessary to remotely mount the toroid?
Has anybody successfully mounted their power toroid in an external box? I was playing around with my pair of 81s last night and confirmed that I should probably do that if I want to get rid of the induced buzzing at the inductors. I may try some mu-metal shielding first. I have a couple sheets of 3M Ultraperm on their way. If that doesn't work though, anybody have a suggestion for a connector and/or wiring to use for the 10 leads necessary to remotely mount the toroid?
Steve Hogan,
You are once again not responding to my emails. You did send me the message below on 6/4/2010. I paid for two kits nearly 1.5 years ago. There is no reason for you to delay my shipment. Just put them in a box and send to me. Easy. Done.
----------------
Hi Tom,
I will be working on the ACMP's next week -- I am hoping to finalize my mods
at that time. Then I can start shipping stuff.
This last week I did some work on 2 Neve 1084 modules. I did comprehensive
measurements on all the inductors. I now have accurate info on what they
are SUPPOSED to be. Working on the real thing will bring new perspective on
the clones. By the way, there were some real eye-opening problems with the
original circuitry including excessive HF (-3dB down at 20kHz) and LF
rolloffs. There is also a 12 dB peak at 1 Hz in some of the eq sections
using the original Neve values.
I expect to be able to send you a care package by the end of the month.
Steve
-------------------------
==============
==============
0kgb,
No, Terry made it perfectly clear by saying that the repairs would result in the end users having gear that resulted in a net loss to the seller but they were still trying to make it happen. He also mentioned elsewhere that there was not one penny of profit.
You are once again not responding to my emails. You did send me the message below on 6/4/2010. I paid for two kits nearly 1.5 years ago. There is no reason for you to delay my shipment. Just put them in a box and send to me. Easy. Done.
----------------
Hi Tom,
I will be working on the ACMP's next week -- I am hoping to finalize my mods
at that time. Then I can start shipping stuff.
This last week I did some work on 2 Neve 1084 modules. I did comprehensive
measurements on all the inductors. I now have accurate info on what they
are SUPPOSED to be. Working on the real thing will bring new perspective on
the clones. By the way, there were some real eye-opening problems with the
original circuitry including excessive HF (-3dB down at 20kHz) and LF
rolloffs. There is also a 12 dB peak at 1 Hz in some of the eq sections
using the original Neve values.
I expect to be able to send you a care package by the end of the month.
Steve
-------------------------
==============
==============
0kgb,
No, Terry made it perfectly clear by saying that the repairs would result in the end users having gear that resulted in a net loss to the seller but they were still trying to make it happen. He also mentioned elsewhere that there was not one penny of profit.
okgb
Well-known member
they won't lose money on me cause i don't trust spending more money
sending it to them . At the very least they / he had originally sat on the
1/4 mil for some time claiming production was held up because some
units didn't pass QC of which there obviously was none .
[ i don't think they've fostered an atmosphere of any trust at all ]
there have been allot of untruths not all from the chinese
and t & c had many opportunties to handle things better
are they going to contact all the buyers ? or be happy about all the people
who have cut their loses & given up ? [ can you tell i feel very ripped off ? ]
terry talking more sounds like damage control minmizing distrust of chance
Is it the Karma of all the people who got bad deals with these guys ?
are they still trying to salvage a business ?
Still the idea get the chinese to make better boards in a tighter deal
and see how much that would cost the end user , less labour on they're part
Back to the task at hand , wmtunate email me and i'll send compilation
of the thread & idea's
i believe Alex C , got more milage from replacing the inductors & shielding
making moving the transformer minimal for the effort but with modest gain
at that point
reagrds Greg
sending it to them . At the very least they / he had originally sat on the
1/4 mil for some time claiming production was held up because some
units didn't pass QC of which there obviously was none .
[ i don't think they've fostered an atmosphere of any trust at all ]
there have been allot of untruths not all from the chinese
and t & c had many opportunties to handle things better
are they going to contact all the buyers ? or be happy about all the people
who have cut their loses & given up ? [ can you tell i feel very ripped off ? ]
terry talking more sounds like damage control minmizing distrust of chance
Is it the Karma of all the people who got bad deals with these guys ?
are they still trying to salvage a business ?
Still the idea get the chinese to make better boards in a tighter deal
and see how much that would cost the end user , less labour on they're part
Back to the task at hand , wmtunate email me and i'll send compilation
of the thread & idea's
i believe Alex C , got more milage from replacing the inductors & shielding
making moving the transformer minimal for the effort but with modest gain
at that point
reagrds Greg
crazydoc
Well-known member
Greg
I don't think there is any profit motive at work here, certainly not at this point. It's damage control.
The problem started with the big lie, that Chance's "tech" designed these units and sent the design to China for manufacture. Subsequent events have pretty much shown that these were unusable preamps (poor design, eq inductor and other noise,) already designed in China, waiting for someone to bite. Chance and some "engineer friends" apparently took a quick listen one afternoon to the prototypes they sent him (which may have been preselected to have no obvious faults) and approved their manufacture, without even opening them up. You'd think the "tech" would have wanted to see the quality of manufacture, etc.
So we got these boxes of crap. Steve Hogan, without ever evaluating the preamps completely, designed and apparently manufactured a number of replacement power transformers, assuming this was the root of the problem. He spent all the money he was sent on these and some other components, but has been unable to fix the problem(s), which have turned out to be multiple with no easy complete fixes. Apparently he is so anal that he can't let go of this until he feels the problems are completely solved, so here we sit, out our money and our equipment, probably for the indefinite future, despite intermittent empty promises to get them back "next month".
TnC foolishly inserted a warranty into the user manual, so there is probably some legal requirement to try to do something about repairing the non-functional units (about 100% I'd say.) They sent out a call for guinea pig units last April, and have apparently been trying to fix these for the last 6 months. Latest word (Sept 9, a month ago) is
To me this means "Goddamn, every time we think we've got them fixed, something else doesn't work right."
Maybe they will be fixed soon, and folks can send (at their own shipping expense) their pres for repair. I hope so, though I won't be one of them - good money after bad and all that.
I found multiple manufacturing defects in my units - several connectors not connected, deteriorating resistors, fuse installed wrong, a washer trapped under soldered components. I have fixed one of my 81's, and my 73 to usable condition, with the transistor swap on the 81, inductor and power transformer shielding on both, gain switch mods on both (one mechanical and one optoelectronic.) I sent one 81 to Steve Hogan so he'd have a unit to start working on ASAP, and so that I could compare his mods to mine sonically. It looks like I'll never have that chance.
I don't think there is any profit motive at work here, certainly not at this point. It's damage control.
The problem started with the big lie, that Chance's "tech" designed these units and sent the design to China for manufacture. Subsequent events have pretty much shown that these were unusable preamps (poor design, eq inductor and other noise,) already designed in China, waiting for someone to bite. Chance and some "engineer friends" apparently took a quick listen one afternoon to the prototypes they sent him (which may have been preselected to have no obvious faults) and approved their manufacture, without even opening them up. You'd think the "tech" would have wanted to see the quality of manufacture, etc.
So we got these boxes of crap. Steve Hogan, without ever evaluating the preamps completely, designed and apparently manufactured a number of replacement power transformers, assuming this was the root of the problem. He spent all the money he was sent on these and some other components, but has been unable to fix the problem(s), which have turned out to be multiple with no easy complete fixes. Apparently he is so anal that he can't let go of this until he feels the problems are completely solved, so here we sit, out our money and our equipment, probably for the indefinite future, despite intermittent empty promises to get them back "next month".
TnC foolishly inserted a warranty into the user manual, so there is probably some legal requirement to try to do something about repairing the non-functional units (about 100% I'd say.) They sent out a call for guinea pig units last April, and have apparently been trying to fix these for the last 6 months. Latest word (Sept 9, a month ago) is
To me this means "Goddamn, every time we think we've got them fixed, something else doesn't work right."
Maybe they will be fixed soon, and folks can send (at their own shipping expense) their pres for repair. I hope so, though I won't be one of them - good money after bad and all that.
I found multiple manufacturing defects in my units - several connectors not connected, deteriorating resistors, fuse installed wrong, a washer trapped under soldered components. I have fixed one of my 81's, and my 73 to usable condition, with the transistor swap on the 81, inductor and power transformer shielding on both, gain switch mods on both (one mechanical and one optoelectronic.) I sent one 81 to Steve Hogan so he'd have a unit to start working on ASAP, and so that I could compare his mods to mine sonically. It looks like I'll never have that chance.
Hi all,
Here is what i got.
I have almost no experience with electronics.
Location is USA.
I've bought 2 81's way back from one of the members here on our forum...
One of them - "the good one", had a small click on gain switch, same position as all of you and less noise, hum and buzz compared to second one - "the bad one" has crap loads of wrinkled resistors, big gain pop, bent pins on bass IC and a lot of noise, hiss and hum with or without EQ (toroid rotation does not help at all). Some Q switches and phase are hard to press out (from what I can see, too much paint in holes and also hole angle might be a problem - nice round file can fix paint problem).This "bad one" is off since may 2009.
Fixes I did on "good" unit:
Rare Ultraperm 80 Shielding Sheet
http://www.goldmine-elec-products.com/prodinfo.asp?number=G16600A
I cut the sheet to size i need, electrical tape on both sides and after that made it into desired shape. Used more el. tape to connect parts together. I made 2 layers around, top and bottom and that lowered drastically problem with noise, buzz and hum. I did rotate the toroid. Rotation has to be done few times...outside the rack with lid on and off and than correction inside the rack, lid on and off. It took some time to do this. I also used same shielding around inductors - 2 layers made into cap, isolated with electrical tape. No "naked" contact anywhere.
Replaced the Q4 and Q5 transistors on all 4 EQ boards, and now is almost silent if you don't use EQ. Noise is present but much less than what it was.
While doing all this fixes, I used Roger Nichols Digital Inspector XL as tool for checking noise and frequency response.
What I remember, from FFT analyzer display in InspectorXL, all "sound crap" is down for about 30-40dB after all fixes i did. Also Spectragram analyzer showed "hotest" (showing bright red color) dead on 60Hz without fixes...suggesting that power was issue. After fixes and toroid rotation, analyzer 60Hz region was not as hot as it was. Now is showing just a shade of yellow color that is more close to no color at all. Hope that this info means something to all of you electronics educated people.
What I also noticed is after using shielding and transistor replacement, gain switch "click" is almost gone...it is so low that it is safe to use gain switch without turning output down... There has to be total silence in the room to notice click now. It sounds more like a "dust" in the pot. Much better than when i received the units. Can be used now. I have been using it now for almost year with fixes i did and can tell you that bass guitar sounds really nice - low end is with much better definition. Vocals also sound nice.
EQ on...hiss is on certain frequencies..not on all. It sounds nice but I can imagine how it would sound when all fixed.
I generally don't use EQ when recording.
This is all on MIC in.
There is a problem with line in...level is very low even if I dial it hot. Headroom problem. Never checked line in after all this fixes cause I have few other pres. I don't use line in on 81...i can live without it. Would like to fix it tho!
This is my experience with KuNg Fu ChNeVez!
I am so sad about all of you that were fooled by "mighty Mr. Fix it".
I feel for you all...I just hope that he will be honest and at least return your gear back.
There is a big lesson for all of us here.
All best to all of you!
Regards,
Tasa
Here is what i got.
I have almost no experience with electronics.
Location is USA.
I've bought 2 81's way back from one of the members here on our forum...
One of them - "the good one", had a small click on gain switch, same position as all of you and less noise, hum and buzz compared to second one - "the bad one" has crap loads of wrinkled resistors, big gain pop, bent pins on bass IC and a lot of noise, hiss and hum with or without EQ (toroid rotation does not help at all). Some Q switches and phase are hard to press out (from what I can see, too much paint in holes and also hole angle might be a problem - nice round file can fix paint problem).This "bad one" is off since may 2009.
Fixes I did on "good" unit:
Rare Ultraperm 80 Shielding Sheet
http://www.goldmine-elec-products.com/prodinfo.asp?number=G16600A
I cut the sheet to size i need, electrical tape on both sides and after that made it into desired shape. Used more el. tape to connect parts together. I made 2 layers around, top and bottom and that lowered drastically problem with noise, buzz and hum. I did rotate the toroid. Rotation has to be done few times...outside the rack with lid on and off and than correction inside the rack, lid on and off. It took some time to do this. I also used same shielding around inductors - 2 layers made into cap, isolated with electrical tape. No "naked" contact anywhere.
Replaced the Q4 and Q5 transistors on all 4 EQ boards, and now is almost silent if you don't use EQ. Noise is present but much less than what it was.
While doing all this fixes, I used Roger Nichols Digital Inspector XL as tool for checking noise and frequency response.
What I remember, from FFT analyzer display in InspectorXL, all "sound crap" is down for about 30-40dB after all fixes i did. Also Spectragram analyzer showed "hotest" (showing bright red color) dead on 60Hz without fixes...suggesting that power was issue. After fixes and toroid rotation, analyzer 60Hz region was not as hot as it was. Now is showing just a shade of yellow color that is more close to no color at all. Hope that this info means something to all of you electronics educated people.
What I also noticed is after using shielding and transistor replacement, gain switch "click" is almost gone...it is so low that it is safe to use gain switch without turning output down... There has to be total silence in the room to notice click now. It sounds more like a "dust" in the pot. Much better than when i received the units. Can be used now. I have been using it now for almost year with fixes i did and can tell you that bass guitar sounds really nice - low end is with much better definition. Vocals also sound nice.
EQ on...hiss is on certain frequencies..not on all. It sounds nice but I can imagine how it would sound when all fixed.
I generally don't use EQ when recording.
This is all on MIC in.
There is a problem with line in...level is very low even if I dial it hot. Headroom problem. Never checked line in after all this fixes cause I have few other pres. I don't use line in on 81...i can live without it. Would like to fix it tho!
This is my experience with KuNg Fu ChNeVez!
I am so sad about all of you that were fooled by "mighty Mr. Fix it".
I feel for you all...I just hope that he will be honest and at least return your gear back.
There is a big lesson for all of us here.
All best to all of you!
Regards,
Tasa
This debacle can be analysed again and again, but it isn't going to get you any further.
For those of you with some knowlege in electronics, fix these units yourself. This is a DIY electronics forum! I fixed mine in a couple of days after doing a fair amount of research. There is enough info here; remove the boards, replace whatever components you feel necessary, inspect all solder work and re-wet where necessary, rotate toroid for minimum hum, add toroid shielding if transformer still causes interference.
For those who don't feel confident, either sell them and cut your loss, or pay someone say, three or four tech hours to get these useable. But not me!
For those of you with some knowlege in electronics, fix these units yourself. This is a DIY electronics forum! I fixed mine in a couple of days after doing a fair amount of research. There is enough info here; remove the boards, replace whatever components you feel necessary, inspect all solder work and re-wet where necessary, rotate toroid for minimum hum, add toroid shielding if transformer still causes interference.
For those who don't feel confident, either sell them and cut your loss, or pay someone say, three or four tech hours to get these useable. But not me!
okgb
Well-known member
right , the fixes are not a big mystery , just a drag
and substantial .
I compliled / distilled the thread and clintrubber was going to
fix the first page to find it there .
just galling , the perpetuation of " we're going to make it right ? "
yeah right
and substantial .
I compliled / distilled the thread and clintrubber was going to
fix the first page to find it there .
just galling , the perpetuation of " we're going to make it right ? "
yeah right
crazydoc
Well-known member
rodabod said:
ACMP 81 for sale, condition unknown, $300. Send money to me, contact Steve Hogan for shipping. ;D
dustbro said:
Well I for one chose to believe that Steve is doing good work and will complete this project. Scarcasism and ridicule will not help. Nor will it get anyone anywhere. If one cannot say something nice, then its best not said at all.
Just my oinion however.
Del
okgb
Well-known member
Question is , what can motivate steve ?
people have been more than reasonable
so thanking him for something he long should have done
is productive ?
Until someone gets their promised unit back ,
he's not much better than chance
people have been more than reasonable
so thanking him for something he long should have done
is productive ?
Until someone gets their promised unit back ,
he's not much better than chance
maxwall
Well-known member
- Joined
- Nov 17, 2004
- Messages
- 1,134
Paul G said:
RE: Phantom power upgrades in ACMP 73,84, 81 Power supply.
2SD1978 NPN darlington might replace 2N5551 NPN pass transistor in Phantom supply and 20 + 32 (52v) Zener diodes in
series to replace D18 1N978 51v zener. , The D18 can be left in place , but overall voltage will drop marginally. So this
is an optional mod.
any ideas on other Darlington pass types or others that will work here with a NPN T0-92 footprint ? Lets investigate ....
Reason : 2N5551 might be stressed by presence and upgrade of C21 from 100uf/63v to 220uf/100v.
2N5551 datasheet: http://www.fairchildsemi.com/ds/MM%2FMMBT5551.pdf
Question : which darlington NPN will work to replace the 2N5551 NPN pass transistor with T0-92 pinout ?
Darlingtons have double junction voltage drops or dropout voltage (~1.5 - 2.4v minus 52v, yielding ~50-51V ) too,
unlike the 2N5551 which has dropout voltage of ~.7 to 1.5v
" R5 resistor replaced with 1N5313 current blocking diode to further reduce ripple "
" Also , It is suggested to remove C22 and C23 as they are not of any real benefit "
Here is a example where current capability can be increased (FIG 1,2) , where Q1 in the above diagram may need increased
capability to keep up with demands current demands with upgraded parts. Use 2SD1978 as a starting point , pay attention to leg
orientation on the transistor before trying this. The legs may not match the original Q1 (2N5551) part , make sure , consult
datasheet on your device. Also, can use your DMM with transistor tester socket to verify.
Similar threads
Latest posts
-
-
-
FEELER - Solid-state microphone upgrade boards (OpAmp, JFET, U87A, FET847, ORS87-Plus)
- Latest: wanderingengineer
-
-
-
