Group Buy Interest?

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redddog said:
Steve, we're still what appears to be a long way from these being serviceable. So in a way, none of us really have the pres yet. I'd wait it out if I were you. You really haven't missed anything.
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just to get an idea

of the prevalence

of these problems:

has anybody here

received a fully functional 1081?

(that is, no hum or buzz

or other extraneous noise

with the output gain at max

and the eq switches fully engaged)

or are we just

a few whiners here?



i'll ignore the mic gain switch

"pop"

for now and call it a non-issue
 
OK, so it seems a few of these are starting to head down-under now, so I will wait it out then reddog.........


redddog said:
Steve, we're still what appears to be a long way from these being serviceable. So in a way, none of us really have the pres yet. I'd wait it out if I were you. You really haven't missed anything.
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Is there any update on parts (transformers and circuit boards) for upgrades to the ACM 1200?
 
I'm wondering how the shipping is going as I'm still hoping to get ribbons, shock mounts, and resolution for items from the last two group buys. Chance had said he would take care of that once the shipping was complete.
 
eyeteeth said:
I'm wondering how the shipping is going as I'm still hoping to get ribbons, shock mounts, and resolution for items from the last two group buys. Chance had said he would take care of that once the shipping was complete.
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Last I heard, Chance was getting toward the end. He sent out a large number of invoices last week. He's been more active over at PSW.

:D
 
Eureka!

At long last, a GREEN YES!

Invoice paid and what not. Now to await gear, bone up on transistor swaps, and other such merriment. Oh, and buy a rack. (Teeheehee, I said "rack")

Jon M
 
jonmatthews said:
Eureka!

At long last, a GREEN YES!

Invoice paid and what not. Now to await gear, bone up on transistor swaps, and other such merriment. Oh, and buy a rack. (Teeheehee, I said "rack")

Jon M
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Well keep us abreast of your progress. (Teeheehee, I said "progress")


:D
 
Quick update on my experiments. First, I decided I wanted to figure out the hum I was hearing in my 73s. Upon bringing them into another room to test them, I'm not able to reproduce the hum. I suspect what I heard was environmental noise being picked up by the mic. So my 73s seem to be working reasonably well.

On a lark, I decided to try the 73's power supply in one of my 81s. No change. Not a surprise, but I figured it was worth a shot.
 
eyeteeth said:
I'm wondering how the shipping is going as I'm still hoping to get ribbons, shock mounts, and resolution for items from the last two group buys. Chance had said he would take care of that once the shipping was complete.
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Yikes. Are there a lot of people still waiting for stuff from this long ago?
 
Well, nobody i know here in Spain has their units or a shipping quote either.
 
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Anyone who wants two 1081's for $320 do 3 things [pre's haven't left chances warehouse yet]

1.pm me
2.get a hold of chance [i've tried emailing but have not heard back]
3.transfer me the funds
 
Hey Guys
Like I mentioned before, I have been BRUTALLY busy over the past few months. The pack/shippers notified me that the last of the Australia orders are packed and I will invoice them this afternoon. I just invoiced an order to AUS for over $1K. This bums me out because in actuality, they paid double shipping and double duty. If one person in each country could/would want to take it on in the future, I could have one single order shipped to each country directly from the manufacturer. That one person would have to do the distribution, but just think how much time and money that would save you guys. (me too) Another thing is for domestic orders, if there was a way to include domestic shipping in with the purchase price, that would cut the job and time in half! I had no idea this would be so big, but everything is almost finished. Once it is, I will take care of the ribbon material and shockmounts. For some reason I have stopped receiving notices of new posts here, but it seems that PSW seems to be a central meeting ground between here, GS, and prodigy. When I have time, I'll pop in to PSW and hope any news will get spread around. People are working to solve/work-around the hum/buz problems on the ACMP's. One other thing. I have 16 orders that have no shipping information in their users console. I have no idea where they are from, but will deal with them after everything else has shipped.
 
I've assumed that the custom transformers and electronics have been put on hold until shipping / fixing things are sorted out. Is this in fact the case? If not is there different contact / info pages other than what were posted on page 249?
 
I decided it would be entertaining to compare the design of the 73 (no EQ hum) with the 81 (massive hum). I haven't started comparing the actual circuit layout, but one HUGE difference immediately struck me the second I looked at the 73's circuit board: the 73 actually looks like it was laid out professionally by somebody who knows how to design PCBs....

The 81 (hum):

  • Probably 75% of the underside of the board contains no copper.
  • Traces all the same width regardless of purpose.
  • The inductor sits over an area of board that contains nothing but signal traces, with the signal traces from the switch running RIGHT under the middle of the inductor. Ugh.

The 73 (no hum):

  • Maybe 1% of the underside of the board contains no copper.
  • Signal/power traces are the same size as on the 81.
  • Ground traces occupy the entire remainder of the underside of the board.
  • The entire area under the inductor is a ground plane.

The difference was so night-and-day that I'm still trying to get my jaw off the floor. Not only is the entire underside of the board below the inductor is a solid chunk of grounded copper, but also there are places where they extended a thin ground trace as much as a couple of inches away just to fill the space between two other traces. It's like the difference between a board laid out by professional engineers and a board laid out by a second year EE major....
 
I also just noticed another huge difference. The power line filter caps on the individual boards on the 73 (no hum) are 1000uF, while the ones on the 83 (hum) are just 100 uF. Unfortunately, I don't have any parts that big handy to see if upping the size of the cap helps. All my parts are single digit uF and under except for a few that don't have bendable leads, and thus can't be wired in too easily. :) I'll get some parts tomorrow. (Radio Shack and Fry's close way too early on Sunday.)

I noticed one other thing that everyone with a 73 should note: on the 73 (no hum), the power filtering capacitors on four of the audio boards are SEVERELY under-specified in their voltage rating. They are 1000uF caps rated at a mere 25V. This is on a 24V power rail.... That means these parts are running right up against their MAXIMUM voltage rating. For safety, these parts should have been specified with at LEAST a 30V rating, and ideally 35V. Chance, please make SURE this gets fixed for future revisions. Using caps this close to their maximum voltage is absolutely unacceptable even in devices with cooling fans. In rack-mount devices with no cooling whatsoever, it is absolute suicide.

I can't say this strongly enough: for anyone who owns a 73, you should IMMEDIATELY replace ALL THREE of those 1,000uF capacitors and the one 2,200 uF capacitor with capacitors of the same value and at LEAST a 35V rating. I doubt the 73s will run for more than about 2-3 months of continuous use before these parts explode, if that long. Rubycon caps are good caps, but their use doesn't excuse running them right at the limit.... The good news is that Radio Shack carries 1,000uF capacitors with both 35V and 50V ratings, either of which should be fine, so you shouldn't have any trouble finding this part. Same goes for the 2,220uF caps.

The parts in question are:

  • C4
  • C13
  • 3C21
  • 5C11

They're really obvious; they are the largest black cans on each of the four main audio boards in the 73.

The good news is that the 81's power filtering capacitors are at least a reasonable voltage (35V), albeit possibly too small a value. :)

There are also four capacitors on the lefthand board that are 25V. I don't think that they are likely to come close enough to 25V to worry about them, but if you're paranoid, you might consider replacing those as well. Despite the boards being seemingly identical, the parts are numbered differently as follows:

73 Number/81 Number: rating
  • 1C5/1C5: 220uF
  • 2C5/1C15: 220uF
  • 2C2/1C12: 470uF
  • 1C2/1C2: 470uF
 
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dgatwood said:
I also just noticed another huge difference. The power line filter caps on the individual boards on the 73 (no hum) are 1000uF, while the ones on the 83 (hum) are just 100 uF. Unfortunately, I don't have any parts that big handy to see if upping the size of the cap helps. All my parts are single digit uF and under except for a few that don't have bendable leads, and thus can't be wired in too easily. :) I'll get some parts tomorrow. (Radio Shack and Fry's close way too early on Sunday.)

I noticed one other thing that everyone with a 73 should note: on the 73 (no hum), the power filtering capacitors on three of the audio boards are SEVERELY under-specified in their voltage rating. They are 1000uF caps rated at a mere 25V. This is on a 24V power rail.... That means these parts are running right up against their MAXIMUM voltage rating. For safety, these parts should have been specified with at LEAST a 30V rating, and ideally 35V. Chance, please make SURE this gets fixed for future revisions. Using caps this close to their maximum voltage is absolutely unacceptable even in devices with cooling fans. In rack-mount devices with no cooling whatsoever, it is absolute suicide.

I can't say this strongly enough: for anyone who owns a 73, you should IMMEDIATELY replace ALL THREE of those 1,000uF capacitors with a capacitor of the same value and at LEAST a 35V rating. I doubt the 73s will run for more than about 2-3 months of continuous use before these parts explode, if that long. Rubycon caps are good caps, but their use doesn't excuse running them right at the limit....

The 81's power filtering capacitors are at least a reasonable voltage (35V), albeit probably too small a value. :)

There are also four capacitors on the lefthand board that are 25V. I don't think that they are likely to come close enough to 25V to worry about them, but if you're paranoid, you might consider replacing those as well. Despite the boards being seemingly identical, the parts are numbered differently as follows:

73 Number/81 Number: rating
  • 1C5/1C5: 220uF
  • 2C5/1C15: 220uF
  • 2C2/1C12: 470uF
  • 1C2/1C2: 470uF
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Thanks for this valuable heads up! I've got 2 73's (and getting 2 more!). I really like 'em and would hate to see them blow up or melt down anytime soon!
 
dgatwood said:
I doubt the 73s will run for more than about 2-3 months of continuous use before these parts explode, if that long.
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First fire, then explosion -- kickass! Maybe a car chase next?

Are these caps of the variety that you should drain before futzing with?
 
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