buildafriend
Well-known member
emrr said:
Noted. thanks very much.
Could I trouble you to point me in the direction of a fair tube dealer?
RCA BC-2B
- Thread starter buildafriend
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Help Support GroupDIY Audio Forum:
Noted. thanks very much.
Could I trouble you to point me in the direction of a fair tube dealer?
www.tubesandmore.com
for high end sonics>
KCA Tubes
and a million dealers in europe, i used to have a thick binder full of tube dealers, but ended up using the back of the pages for scrap paper, you only need 1 or 2 good tube dealers,
hey OT:
anybody know about the output tranny for an Ampex single-ended 350 12SJ7/6F6- type record amplifiers?
The code or model number is B-6300.
cj
for high end sonics>
KCA Tubes
and a million dealers in europe, i used to have a thick binder full of tube dealers, but ended up using the back of the pages for scrap paper, you only need 1 or 2 good tube dealers,
hey OT:
anybody know about the output tranny for an Ampex single-ended 350 12SJ7/6F6- type record amplifiers?
The code or model number is B-6300.
cj
emrr said:
+10 and X 100.
It's also worth repeating that regardless of what their tube tester readings are, the reality is that one will still have to test and sort for noise. The ones with high hiss and hum will likely be useless for the critical position they are most commonly used in.
I think it's important that sellers and vendors understand the practical realities instead of just latching on the "famous tube" nonsense and expecting the $$ to roll in with complete absolvence. So if you're inclined, give the hucksters on ebay an earfull every once in a while. If they know enough people aren't willing to pay their high prices they may change their ways. With the growing overpopulation of guests on this forum, there just may be some lurking and on the lookout for trends.
Sorry for the mini-rant guys.
This is a 250Vac center-tapped secondary; in other words it's 2x125Vac, resulting in about 150Vdc. You need 450-500Vac CT in order to get 250-300Vdc B+.buildafriend said:
buildafriend
Well-known member
CJ said:
Okay so tubesandmore.com is a very trusted site. Got it. I have heard this from other people, but I figured that they would not have old tubes like the 1620 and that I would have to find them on ebay. I guess not!
The only thing that scares me is that I don't see any picture of the tube on the tubesandmore site. They are $11.75 each.. thats 175 pennies more than $10.
http://www.tubesandmore.com/products/t_1620
There is no datasheet. I know that I am dealing with a pentode but I don't have any kind of reference for the tube socket pin out. I might not even need a tube socket depending on the construction of the tube body.
buildafriend
Well-known member
abbey road d enfer said:
Hmm about this guy?: hammond 269JX
http://angela.com/search.aspx?find=269JX
http://www.hammondmfg.com/263.htm
Buildafriend,
Jim Cross down in Florida has all the old types you need.
http://www.vacuumtubesinc.com/
I have been using him for years, he does tubematching for $2/pair and often ships same day.
If you check out the prices he is nearly always less than the others.
The 1620 is $10 there
best
DaveP
Jim Cross down in Florida has all the old types you need.
http://www.vacuumtubesinc.com/
I have been using him for years, he does tubematching for $2/pair and often ships same day.
If you check out the prices he is nearly always less than the others.
The 1620 is $10 there
best
DaveP
The only thing I would be on the lookout for is - be sure and tell them:
1) You want a NOS tube - and ask what their confidence level is that it is an unused tube. It's a reasonable question.
2) NO PULLS! It happens. Sometimes they may not even be aware of it. Some may consider a tube that looks barely used on a tester as essentially new. Maybe so, but it should be sold as USED.
Do you plan using a valve rectifier? If yes, the JX is correct. If you were using solid-state rectifier, the GX would be more appropriate.buildafriend said:
buildafriend
Well-known member
DaveP said:
Ah thanks Dave! I will send him an email with lassoharp's specifics. I am going to ask for a snapshot of the tubes as well.. I think I might be a little annoying in doing so but I think it's fair.
I really appreciate how you guys steer me strait and look out for my wallet.
I found a cool little article on there about how some 1620's were marked as 1622's.
buildafriend
Well-known member
abbey road d enfer said:
I've never built a valve rectifier but.. yeah tubes all the way!
buildafriend
Well-known member
lassoharp said:
NO PULLS is right! thanks for the heads up.
I'd really doubt a real tube dealer would bother with taking pictures of a $10 tube, only if he were trying to mark them up on ebay at $70/pair.
Ebay isn't reality. Repeat three times.
Speaking of ebay again, one used to get the best deals bidding on the items that didn't have pictures. Remember when most didn't have pictures? Another lesson.
Ebay isn't reality. Repeat three times.
Speaking of ebay again, one used to get the best deals bidding on the items that didn't have pictures. Remember when most didn't have pictures? Another lesson.
buildafriend
Well-known member
emrr said:
It's a shot in the dark! But I can see where your coming from! ;D
buildafriend
Well-known member
Get ready for the novice BOM....
R1 and R2 are hard to read! take them with a grain of salt.
all resistors are 2 watt.
R1 = 680
R2 = 820
R3 = 120k
R4 = 100k pot
R5 = 2K
R6 = 270 ohm
R7 = 470k
R8 = 3k9
R9 = 3k3
R10 = 10K
R11 = 33k
mouser cart for resistors
http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=34d3d9c264
it is noted next to C-8 that the cap is "330 MMFD" I am going to assume that this is 330 pF. it looks like a tone stack. maybe I can throw a pot in here near or as R11 and have a tone control? I am guessing that R4 is the gain pot.
I did my best at choosing capacitor types.. I can only seem to find these 40uF caps at around 15 bucks each! OOUUCH. thats 75 bucks just in capacitors.. I feel like thats wayy too much money.
C1 = 40mfd 400V Volt electrolytic
C2 = 0.5mfd low voltage wima film
C3 = 40mfd 400V Volt electrolytic
C4 = 40mfd 400V Volt electrolytic
C5 = 40mfd 400V Volt electrolytic
C6 = 40mfd 400V Volt electrolytic
C7 = 10 mfd 400V Volt electrolytic
C8 = 330pf low voltage cermic disc cap
hammond steel chassis 10" x 12" if you order the chassis from angela make sure that you order the bottom of the enclosure too... it is sold seperately
hammond 269JX PSU xfrmr
Cinemag CMMI-10C mic input xfrmr
NOS UTC A-25.
6X5- GT/G NOS tube
2 matched 1620 NOS tubes
Tube sockets for all three tubes
hookup and PSU wire
2 XLR connectors. one male, one female
Fender pilot lamp
Fuse holder and Fuse
IEC inlet
2 small 8 pin turret boards
1 or 2 knobs depending on the tone pot option that I am still unsure of.
Here is what I have so far. I still need the audio transformers, tubes, and capacitors.
am I forgetting anythinggg?? :
I hope this works!!
SCHEMATIC http://www.coutant.org/ba2c/index.html
R1 and R2 are hard to read! take them with a grain of salt.
all resistors are 2 watt.
R1 = 680
R2 = 820
R3 = 120k
R4 = 100k pot
R5 = 2K
R6 = 270 ohm
R7 = 470k
R8 = 3k9
R9 = 3k3
R10 = 10K
R11 = 33k
mouser cart for resistors
http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=34d3d9c264
it is noted next to C-8 that the cap is "330 MMFD" I am going to assume that this is 330 pF. it looks like a tone stack. maybe I can throw a pot in here near or as R11 and have a tone control? I am guessing that R4 is the gain pot.
I did my best at choosing capacitor types.. I can only seem to find these 40uF caps at around 15 bucks each! OOUUCH. thats 75 bucks just in capacitors.. I feel like thats wayy too much money.
C1 = 40mfd 400V Volt electrolytic
C2 = 0.5mfd low voltage wima film
C3 = 40mfd 400V Volt electrolytic
C4 = 40mfd 400V Volt electrolytic
C5 = 40mfd 400V Volt electrolytic
C6 = 40mfd 400V Volt electrolytic
C7 = 10 mfd 400V Volt electrolytic
C8 = 330pf low voltage cermic disc cap
hammond steel chassis 10" x 12" if you order the chassis from angela make sure that you order the bottom of the enclosure too... it is sold seperately
hammond 269JX PSU xfrmr
Cinemag CMMI-10C mic input xfrmr
NOS UTC A-25.
6X5- GT/G NOS tube
2 matched 1620 NOS tubes
Tube sockets for all three tubes
hookup and PSU wire
2 XLR connectors. one male, one female
Fender pilot lamp
Fuse holder and Fuse
IEC inlet
2 small 8 pin turret boards
1 or 2 knobs depending on the tone pot option that I am still unsure of.
Here is what I have so far. I still need the audio transformers, tubes, and capacitors.
am I forgetting anythinggg?? :
I hope this works!!
SCHEMATIC http://www.coutant.org/ba2c/index.html
http://taweber.powweb.com/store/capord.htm
EC5050 8.50. Takes care of 1st two. Using a 2nd one covers the last 40mf and ups C7 from it's original value which I see no problem in doing as you want the 1st stage as clean as possible. I've seen much worse overkill on other SE design power supplies
C2 should not be "low voltage". Rate it for the max supply voltage it will see at start up.
C3 and C1 are a 25V part. 35V or 50V is fine there too. So is 100 or 470uf.
buildafriend
Well-known member
abbey road d enfer said:
Thanks very much
I was on the phone with Cinemag selecting an output transformer for this BA-2. Dave was nice enough to look at the schematic and said:
"Hi Jon;
I think that you can live with a turns ratio of 4:1. The CM-2810 with steel laminations and butt-stacked should work well. $40.55 If you know how much dc current it will take, that can help me figure out the amount of gap it needs.
-David"
Should I assume that the DC current that the the OP transformer will be taking is the exact amount that the PSU is dishing out? 250-300V DC.
buildafriend
Well-known member
lassoharp said:
Thanks very much. 8) I wonder how big of a deal it would be to replace the 40uF caps with 47uF caps..
dmp
Well-known member
If using the tube rectifier (6X5) the capacitance should not exceed a max value, a spec of the rectifier, due to too much in-rush current I believe. I'm not sure what this is for the 6X5, but I have read that the 6X5 has some critics as a robust tube.
In my current build I used a 33uf / 47uf / 47uf for the filtering caps. Maybe I should go higher though.
The datasheet for 6X5 indicates a 4uF head capacitor. The RCA choice of using 40uF is justified by the fact that it runs at 2/3 of the rated voltage and that the transformer has 700 ohms DCR for each half-secondary. I bet you could fit a 47uF without further ado, but, as always, there's the risk of optimism, so you could use a 33uF. Remember that very often, elcap values were overrated because designers knew that the value would decrease with age. Today, elcaps are much more stable, so your 33uF will be equivalent to a 5 years old 40uF of period technology. And anyway, you're free to compensate the relatively feeble value by incresing the other caps that follow. C4=33uF and C5=C6=47uF should be adequate.
