AD797 Phono Stage Build and Help Desk Thread
- Thread starter HypnoToad
- Start date
Your figures are correct. I haven't done a real-world study of these, but it appears that you should get 40-45 hours of use before recharge (with the 5ah batts). I charge mine once a month if needed, or if I forget to turn the preamp off before bed a couple of times. :nono:
A multi-stage charger will give you more cycles, not sure what the cheap chargers discussed do?
Thanks for the kinds words, I literally jumped off my seat when I first heard it working properly, I would have been happy for it to be equal or just nudge out the HTMCPS but it beats it easily.
I would charge them once a month at least, just to be sure, with heavy usage probably every two weeks.
37.5ma is the current draw so for 5ah batteries it's not a lot.
I have been checking mine and they were 12.75 when I got them and 12.65 now so they are not like the dry cells where the voltage goes way down.
GreatTone
Super Member
Mine are the 5ah batteries -- cost $5 each on Amazon, $20 to ship them...I bought the multi-stage charger ($25) after reading about the bad things the "non-intelligent" chargers might do. Also, after melting the wires on my HTMCPS when I hooked the batteries up wrong and shorted them, I am paranoid about fires etc and wanted the safest charger I could get.
Has anyone tried other output caps?
I did a comparison between the Panasonic's and the Wima's listed in the BOM.
The difference is huge, the Panasonic's have a syrupy midrange with more pronounced bass and a slightly rolled off top end. They remind me of when I tried out Grado carts a while back, warm and lush. You can always open up the top end by adding a similar 0.1uf cap in parallel.
The Wima's have more detail and are more even top to bottom, bass is not as pronounced as the Panasonic's, they are probably more accurate and they allow you to see into the music more. In direct comparison the Wima's sound thin but it's more a case of the Panasonic's lushness making them sound that way.
If you like a more tube like sound, have a bright cart or system the Panasonic's are definitely are a viable option.
I did a comparison between the Panasonic's and the Wima's listed in the BOM.
The difference is huge, the Panasonic's have a syrupy midrange with more pronounced bass and a slightly rolled off top end. They remind me of when I tried out Grado carts a while back, warm and lush. You can always open up the top end by adding a similar 0.1uf cap in parallel.
The Wima's have more detail and are more even top to bottom, bass is not as pronounced as the Panasonic's, they are probably more accurate and they allow you to see into the music more. In direct comparison the Wima's sound thin but it's more a case of the Panasonic's lushness making them sound that way.
If you like a more tube like sound, have a bright cart or system the Panasonic's are definitely are a viable option.
Last edited:
sachu888
Spare the tigers, kill me
I suggest everyone to try Russion PETP K73-16 caps.Tey are inexpensive and will outperform most of the exotic caps.They are available here http://www.ebay.com/itm/2-2uF-63V-P...642?pt=LH_DefaultDomain_0&hash=item5d3011027a
I have no affiliation with the seller just a happy customer.I have suggested these caps to few members and they all have found vast improvement over Wima's or Panasonic.There is a good read here abut these caps http://www.diyaudio.com/forums/parts/143675-petp-capacitors-one-best.html
Regards,
Sachin
Last edited:
sachu888
Spare the tigers, kill me
I will post here if I find any other source.They must be available with some East Europian tube online shops.
Regards,
Sachin
sachu888
Spare the tigers, kill me
Hi,
I just found PETPs on this site http://www.sovtube.com/en/17-petp
I don't have any experience with this seller,just found this source while google.
Edit: They are little bigger in size,so anything above 63V would be difficult to fit on PCBs.
Regards,
Sachin
I just found PETPs on this site http://www.sovtube.com/en/17-petp
I don't have any experience with this seller,just found this source while google.
Edit: They are little bigger in size,so anything above 63V would be difficult to fit on PCBs.
Regards,
Sachin
Last edited:
Regarding the cheap 24v charger discussed earlier, an AK member just told me he had his 5Ah batts on his until they got warm and made a hissing sound! He measured over 13 volts on the batteries! This is bad news for them folks!
Be very careful with these chargers and monitor the charge level carefully!
Be very careful with these chargers and monitor the charge level carefully!
GreatTone
Super Member
I was very tempted to get the cheap charger, as it was only about $5 compared to $25 for the multi-stage, protected version. But after reading some things like this (and worse!), I decided $20 more was worthy insurance against burning my house down...
When I got mine I tried it with the batteries new and it went from red charging to green charged in less than a minute.
On the weekend I tried charging them again and had a red light for about 2 hours then went to green for fully charged, I then checked the voltages and they were both 12.9volts each.
The batteries never got warm, I got this one and it has many good reviews:
http://www.amazon.com/Betterstuff-L...Charger+For+eZip+4.0+400+500+750+900+Mountain
That being said, you can't be too careful and as Jim said you should closely monitor any charging.
On the weekend I tried charging them again and had a red light for about 2 hours then went to green for fully charged, I then checked the voltages and they were both 12.9volts each.
The batteries never got warm, I got this one and it has many good reviews:
http://www.amazon.com/Betterstuff-L...Charger+For+eZip+4.0+400+500+750+900+Mountain
That being said, you can't be too careful and as Jim said you should closely monitor any charging.
Last edited:
I suspect this is a high-rate 'fast' automatic charger, a series resistor would be a good idea with small batteries, one sufficient to limit initial charging current to within the upper limit of the batteries being used as I am trying now. I have used selected incandescent series current limiting lamps as dynamic charging ballasts thus in the past to prevent overloading the chargers or batteries beyond rating limit. Ideally you would want a lamp rated for the voltage of the charger and wattage calculated for the max initial rating of the battery being charged. Once the charged bucking voltage of the batteries come up toward the max output of the charger the lamp will dim until the end-charge is reached.
Last edited:
Steve I have used both the 4006 which is 4" wide, 1.5" high and 6" long and the 4012 when I couldn't get the 4006 which is 4" wide, 2.5" high and 6" long.
The PCB won't slide into the side slots of either, I don't like that idea at all, I use standoffs, if you use the 4006 with the Wima output caps you need standoffs that are no more than 8mm or the caps are too tall.
Here is a link to Context Engineering, you can see all the dimensions of their enclosures.
http://contextengineering.com/split_body_enclosures.html
Here is a pic of Jim Reeves enclosure which is the 4006:
Last edited:
GreatTone
Super Member
I used this Hammond enclosure, which was big enough to work in, but not too big:
http://angela.com/hammonddiecastaluminum739x472x206enclosure1590d.aspx
It's 7.39" x 4.72" x 2.06" -- it's pretty plain aluminum, but works for me. I do kind of like that other case with the top that bends over the sides. Seems like it would provide easy access.
http://angela.com/hammonddiecastaluminum739x472x206enclosure1590d.aspx
It's 7.39" x 4.72" x 2.06" -- it's pretty plain aluminum, but works for me. I do kind of like that other case with the top that bends over the sides. Seems like it would provide easy access.
dodog
Addicted Member
I wish I had a Fry's nearby......
I've had to order all my cases online and I've found the Hammond 1455N to work quite well. 4.6" wide, 2.1" tall, 6.3" long. Gives you a bit more breathing room over the 4006 but the tradeoff is that it's not a split enclosure, rather it requires the top to be slid into tracks/grooves, then the front/back get screwed on. Makes changing opamps, etc. a bit more work but I tend to build my project and stop fiddling (as I tend to break things if I fiddle too much).
(No Affiliation)
http://www.amazon.com/1455N-Silver-...=1361979283&sr=8-6&keywords=hammond+enclosure
I've had to order all my cases online and I've found the Hammond 1455N to work quite well. 4.6" wide, 2.1" tall, 6.3" long. Gives you a bit more breathing room over the 4006 but the tradeoff is that it's not a split enclosure, rather it requires the top to be slid into tracks/grooves, then the front/back get screwed on. Makes changing opamps, etc. a bit more work but I tend to build my project and stop fiddling (as I tend to break things if I fiddle too much).
(No Affiliation)
http://www.amazon.com/1455N-Silver-...=1361979283&sr=8-6&keywords=hammond+enclosure
