Slow Blow pre?
- Thread starter therecordingart
- Start date
Help Support GroupDIY Audio Forum:
Hi, Sorry for non write to forum but i am really very busy and most of the time away from my city.
I wanna thank Sismofyt for those nice infos.
Yes i have them.
The 80VA =230/150mA, 12V/3A, 48V/100mA
The 150VA =250/300mA 12V/6A, 48V/100mA
I have paypal account so no problem for payment.
Cheers
fotis
I wanna thank Sismofyt for those nice infos.
Yes i have them.
The 80VA =230/150mA, 12V/3A, 48V/100mA
The 150VA =250/300mA 12V/6A, 48V/100mA
I have paypal account so no problem for payment.
Yes i finished but i didn't like so much. A guite dirty sound without dynamics... etc. You can read more of my test http://www.groupdiy.com/index.php?topic=10751&highlight=fotis
Cheers
fotis
mikeyB
Well-known member
Hello again Fotis, - can you give me dimensions of both transformers and chokes - I'm trying to keep things compact. How many channels will each of the transformers supply?
sismofyt
Well-known member
[quote author="Bluzzi"]Can we use with 110v on the primary?
jim[/quote]
i think fotis said it's no problem to wind one with dual 115VAC primaries. this will make it universal over the entire planet. connect the primaries in parallel in the us, series in the eu
jim[/quote]
i think fotis said it's no problem to wind one with dual 115VAC primaries. this will make it universal over the entire planet. connect the primaries in parallel in the us, series in the eu
sismofyt
Well-known member
eta, wrong info - sorry :roll:
sismofyt
Well-known member
[quote author="FotisGR"]Yes i have them.
The 80VA =230/150mA, 12V/3A, 48V/100mA
The 150VA =250/300mA 12V/6A, 48V/100mA
[/quote]
aren't both with _250VAC_ secondaries? there's no need to go down to 230VAC for the 80VA. just a typo? :wink:
The 80VA =230/150mA, 12V/3A, 48V/100mA
The 150VA =250/300mA 12V/6A, 48V/100mA
[/quote]
aren't both with _250VAC_ secondaries? there's no need to go down to 230VAC for the 80VA. just a typo? :wink:
sismofyt
Well-known member
note, that the currently proposed 12V heater Vreg will _NOT_ power more than two channels though. actually, i'm thinking about ditching that Vreg for a 13V zener + 2N3055 combo. that'll drive eight channels without any mods ... hmm .. cheaper too than getting a 3-6A Vreg
driving eight channles means you need to waste 35W though. and that is just the heater. total power consumption will be around 140W
and this is one of my more economic designs and ... wait, do i see black helicopters outside my window..?? oh, no, they're RED. argghhhhh, it's the green peace hit squad .. :green:
driving eight channles means you need to waste 35W though. and that is just the heater. total power consumption will be around 140W
and this is one of my more economic designs and ... wait, do i see black helicopters outside my window..?? oh, no, they're RED. argghhhhh, it's the green peace hit squad .. :green:
sismofyt
Well-known member
[quote author="mikeyB"]Sorry Fotis - forgot to ask for transformer and choke dimensions. I am interested in both the 80 and 150VA transformers.[/quote]
i don't have them, but standard unpotted toroids pretty much always have the same size, like these nuvotem talemas:
80VA = 93 x 38 mm / 0,9kg / M5 bolt
150VA = 105 x 42mm / 1,35kg / M6 bolt
allow a few millimeters for the topplate and rubber thingies ..
i don't have them, but standard unpotted toroids pretty much always have the same size, like these nuvotem talemas:
80VA = 93 x 38 mm / 0,9kg / M5 bolt
150VA = 105 x 42mm / 1,35kg / M6 bolt
allow a few millimeters for the topplate and rubber thingies ..
mikeyB
Well-known member
sismofyt - Thanks for the info :thumb:
sismofyt
Well-known member
ok, i did some calculations and updated my site regarding power consumption
80VA good for two channels only
150VA fine for four channels
80VA good for two channels only
150VA fine for four channels
Sorry to be late... but i will promise you for pics and dimensions tomorrow 
Yesterday i did some tests with my second channel slowblow. I changed the 5687 anode follower with a 12sn7. 15k anode R 390Ohm cathode R and 370VDC. It likes me. Full sound (a litle fat) but very nice. The interested is that i have 12 pieces of 12sn7 RCA and every tube has difenent sound :shock:
So what can i say? I don't know ...
I played also with cathode's cap and there was a big sonic diference. The best for my ears was a quite big 470uf/25V Black gate in parallel with a 1uf Jensen PIO. More capacitance = more fatness and a rise to mid-bass frequencies like harmonic enhancer. I think the balance will be 100-220uf but at 470uf my TLM103 sounds like a good tube mic :grin: .
You know it's a matter of taste. :thumb:
Later
fotis
Yesterday i did some tests with my second channel slowblow. I changed the 5687 anode follower with a 12sn7. 15k anode R 390Ohm cathode R and 370VDC. It likes me. Full sound (a litle fat) but very nice. The interested is that i have 12 pieces of 12sn7 RCA and every tube has difenent sound :shock:
So what can i say? I don't know ...
I played also with cathode's cap and there was a big sonic diference. The best for my ears was a quite big 470uf/25V Black gate in parallel with a 1uf Jensen PIO. More capacitance = more fatness and a rise to mid-bass frequencies like harmonic enhancer. I think the balance will be 100-220uf but at 470uf my TLM103 sounds like a good tube mic :grin: .
You know it's a matter of taste. :thumb:
Later
fotis
sismofyt
Well-known member
you got 370VDC with that transformer and a 100ohm resistor in the B+? that seems a little high. what is your voltage drop across that resistor? and on the first cap after the diodes? not that there's anything wrong with 370VDC. it's better actually. both the 12SN7 and the 5687 SRPP likes that better
with 320VDC which is what i'm aiming for, you need a little higher cathode resistor for the 12SN7, 500ohm instead. you're pushing a bit more than 12mA through it (asuming around 182V at the plate), i specced it out at 10mA. iyou're running a little more than two watts through. fine and within limits. i would like to run 15mA through it, but with a low 15kohm plate resistor, i'd need a 450V B+ which goes past the magic '400V' mark. above that components become very expensive. it's more important with the low plate resistor. 2,5-3x Rp is my majic spot for these tubes. at that point the tube really sings. 2C22 types further benefit from a 600V B+ (they can take 500V _at_ the plates)
if you raise the plate resistor significantly (and change the cathode resistor accordingly) you'll get less 2nd order harmonic distortion and a little more gain. sounds gets boring quick though
you could also try to lower the resistors in the 5687 SRPP. 820ohm works better
odd, jazzy liked the 12SN7 _with_ the cathode cap as well. i generally do not like it. the bass tends to get to phat and uncontrolled. but it's a nice sonic variation i guess. one could just throw in a switch :wink:
12 RCAs yummy. one could do serious gear with those suckers
with 320VDC which is what i'm aiming for, you need a little higher cathode resistor for the 12SN7, 500ohm instead. you're pushing a bit more than 12mA through it (asuming around 182V at the plate), i specced it out at 10mA. iyou're running a little more than two watts through. fine and within limits. i would like to run 15mA through it, but with a low 15kohm plate resistor, i'd need a 450V B+ which goes past the magic '400V' mark. above that components become very expensive. it's more important with the low plate resistor. 2,5-3x Rp is my majic spot for these tubes. at that point the tube really sings. 2C22 types further benefit from a 600V B+ (they can take 500V _at_ the plates)
if you raise the plate resistor significantly (and change the cathode resistor accordingly) you'll get less 2nd order harmonic distortion and a little more gain. sounds gets boring quick though
you could also try to lower the resistors in the 5687 SRPP. 820ohm works better
odd, jazzy liked the 12SN7 _with_ the cathode cap as well. i generally do not like it. the bass tends to get to phat and uncontrolled. but it's a nice sonic variation i guess. one could just throw in a switch :wink:
12 RCAs yummy. one could do serious gear with those suckers
sismofyt
Well-known member
damn, that is dissapointing fotis .... i had hoped that you somehow had made a device that could turn 250VAC into 380VDC. that would solve the worlds energy problems :razz:
380VDC is real close to 400VDC, you must have quite a stable grid down there
but like i said the higher the voltage the better
380VDC is real close to 400VDC, you must have quite a stable grid down there
but like i said the higher the voltage the better
mikeyB
Well-known member
Has anybody used the brand "LCR" axial polypropylene capacitors - any good?
sismofyt
Well-known member
are you thinking about the yellow ones from rs / farnell? if so, they're fine, but not as good as solen / scrs. about same price. i use them a lot for PSU bypass duties though as they come up to 1kV
if you got a bunch you can always start with these and swap later. good tubes + lcr caps is better than shit tubes + expensive hifi caps :wink:
if you got a bunch you can always start with these and swap later. good tubes + lcr caps is better than shit tubes + expensive hifi caps :wink:
Jazzy_Pidjay
Well-known member
HS to Sismofyt :
Hi my man !!!!!! happy to see you back !
check your mail, i suspect a Gmail fuc**d up !!
We have a lot of things to discuss !!
miss you !
Hi my man !!!!!! happy to see you back !
check your mail, i suspect a Gmail fuc**d up !!
We have a lot of things to discuss !!
miss you !
ubxf
Well-known member
Is the Lundahl 1577 a good alternative to the 1538xl for this preamp
Thanks
francois
Thanks
francois
