DIY SVT tube bass amp

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okabass

Active member
Joined
Feb 17, 2006
Messages
43
Location
Lahti,Finland
HI

Here's some pics of my DIY SVT bass amp.

http://img205.imageshack.us/img205/4317/hpim1067fc2.jpg
http://img291.imageshack.us/img291/6258/hpim1071dx7.jpg
http://img291.imageshack.us/img291/3874/hpim1079it5.jpg
http://img291.imageshack.us/img291/4613/hpim1072cr2.jpg
http://img291.imageshack.us/img291/3746/hpim1078lx1.jpg

http://img393.imageshack.us/my.php?image=kopiosvtrakentaminen009lp3.jpg
http://img371.imageshack.us/my.php?image=kopiosvtrakentaminen019dp3.jpg
http://img351.imageshack.us/my.php?image=kopiosvtrakentaminen207zf8.jpg
http://img118.imageshack.us/my.php?image=kopiosvtrakentaminen095kk3.jpg
http://img114.imageshack.us/my.php?image=kopiosvtrakentaminen180bp5.jpg
http://img385.imageshack.us/my.php?image=kopiosvtrakentaminen040ne8.jpg
http://img385.imageshack.us/my.php?image=kopiosvtrakentaminen119wu5.jpg
http://img205.imageshack.us/my.php?image=kopiosvtrakentaminen176wl9.jpg
http://img205.imageshack.us/my.php?image=kopiosvtrakentaminen127fi4.jpg
 

SUPERMAGOO

Well-known member
Joined
Mar 12, 2005
Messages
348
Location
argentina
nice work!

wich schematic are used?

b+ voltage?

bias voltage?

this my first version of svt

http://groupdiy.twin-x.com/displayimage.php?album=topn&cat=-40&pos=2

and that is my finished svt version.

http://www.deremate.com.ar/accdb/ViewItem.asp?IDI=13538069

cheers!
 

okabass

Active member
Joined
Feb 17, 2006
Messages
43
Location
Lahti,Finland
[quote author="Ptownkid"]Hell yeah, that's a project that I will most likely embark on the the next 1-2 years.

How does it sound? Have you compared it to the real deal?[/quote]

HI

The sound is very subjective matter, but to me it sounds very good. I have played Ampeg SVT a few times, and can't tell which is better.
Mine is perhaps better made than new Ampegs. (fiber glass eyelet boards, teflon wire,polypropylene caps, metalfilm resistors, ceramic tube sockets and it's a handmade unit).
 

okabass

Active member
Joined
Feb 17, 2006
Messages
43
Location
Lahti,Finland
nice work!

>>>>>>>>>>Thanks!

wich schematic are used?

>>>>>>>>>I used several: original SVT, TUT 3 (London Power book), and my own experience as a bass player and tube enthuciast.

b+ voltage?

bias voltage?

>>>>>>>>> Around 685 volts and -43 volts . 80 mA per side. That makes c. 27 mA per tube (6550).

this my first version of svt

>>>>>> Yes, nice.
http://groupdiy.twin-x.com/displayimage.php?album=topn&cat=-40&pos=2

and that is my finished svt version.

>>>>>>>>>>Very nice, indeed.

http://www.deremate.com.ar/accdb/ViewItem.asp?IDI=1353806
 

okabass

Active member
Joined
Feb 17, 2006
Messages
43
Location
Lahti,Finland
[quote author="12afael"]that´s a big trafo!
you can read the Kilometers of the tour??? what do that counter?[/quote]

HI

The trafo is the Hammond W1650.

It counts the wrong notes. :grin:

Actually, its an hour meter: you don't have to guess, how long the tubes have been in use.
 

SUPERMAGOO

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Joined
Mar 12, 2005
Messages
348
Location
argentina
:? only -43 volts in bias???

screen voltage?

output ratio transformer?

my bass amps working w/ 560 b+

545 screen

-62 bias. w/less voltage bias the tubes are hot and destroy in my amps

im using svetlana 6550.

do you have link to see your schematic?

thanks and cheers! :grin:
 

okabass

Active member
Joined
Feb 17, 2006
Messages
43
Location
Lahti,Finland
only -43 volts in bias???

>>>>>>I might just remember me wrong, cause I set the bias by measuring voltage against 1 ohm cathode resistor, as in original Ampeg power amp. The SVT schema says -47 volts bias on grid 1.

screen voltage?
>>>>>>>>around 440 volts

output ratio transformer?
>>>>>>>>Didn't need to calculate it . It is the Hammond W1650. From the data sheet I sew it suits for six 6550. Ra is 1,9k ohm.

my bass amps working w/ 560 b+

545 screen
>>>>>>>>>>Yes. The g2 max voltage is 450V. That's abit over that.

-62 bias. w/less voltage bias the tubes are hot and destroy in my amps

im using svetlana 6550.

>>>>>>>>>>Good tubes. Mine are EH6550.

do you have link to see your schematic?

>>>>>>>I dont have a complete schema, cause I've dealt tubestuff -and SVT- enough, that I don't need complete schema.

thanks and cheers!

>>>>>Yes. Same to You! :grin:
 

warpboy

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Joined
May 25, 2006
Messages
242
Location
France
hello,
I have a ampeg svt cl to repair because nothing operate only the fan.
visibly the transfo that gives voltage to the differents boards has voltage at the primary but not at the secondary. A thermal resetable fuse is inside the trnasfo but i do't no how be sure of the state of the protection abd if I have to reset it.
for info it a SLME transfo (no info on the web!) part number : 94-602-35
thank by advance
 

okabass

Active member
Joined
Feb 17, 2006
Messages
43
Location
Lahti,Finland
[quote author="warpboy"]hello,
I have a ampeg svt cl to repair because nothing operate only the fan.
visibly the transfo that gives voltage to the differents boards has voltage at the primary but not at the secondary. A thermal resetable fuse is inside the trnasfo but i do't no how be sure of the state of the protection abd if I have to reset it.
for info it a SLME transfo (no info on the web!) part number : 94-602-35
thank by advance[/quote]

HI

I'm not sure what to say. First, I'm not sure, if I understand you correctly. Secondly, I don't know, how much you know about tube amps. SVT power supply is much more powerful (=dangerous) than a normal guitar amp PSU.
An old trick is to put a normal 60-100 W light bulb in series with the mains. It'll limits the current, when you reset the fuse. If the bulb shines all the time brightly, there's something wrong with the amp. If its first bright, and then dim, it's probably ok. At least: it doesn't have a shorted circuit. Hope that helps. Good luck!
 

warpboy

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Joined
May 25, 2006
Messages
242
Location
France
hello, thank for the infos Okabass :thumb:
What i doesn't understand it's how to reset the resetable thermal fuse in the transfo?
thank for all
 

okabass

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Joined
Feb 17, 2006
Messages
43
Location
Lahti,Finland
[quote author="warpboy"]hello, thank for the infos Okabass :thumb:
What i doesn't understand it's how to reset the resetable thermal fuse in the transfo?
thank for all[/quote]

HI
I'm not familiar that kind of Ampeg transformer resettable fuse. Is there some kind of pushbutton? I think usually the thermalfuses in transformers are not resettable; you must replace the fuse. Perhapse you must remove the transformer "bells", and see if you can do something to the fuse? Perhapse the very last method is to bypass the blown fuse with a wire, but that might be dangerous. Is there any SVT CL manual or schematic, or any information somewhere?

Well, now I remember me better: I once fixed SVT CL. Do you mean the protection circuit? You "reset" it simply by making sure, that the tubes are ok.
 

okabass

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Joined
Feb 17, 2006
Messages
43
Location
Lahti,Finland
okabass said:
[quote author="warpboy"]hello,
i have found these informations :
http://www.freeinfosociety.com/electronics/schemview.php?id=42
http://www.freeinfosociety.com/electronics/schemview.php?id=40
Do you have any infos about this transfo (voltages at primary and secondary)?
Thank
:thumb:

HI
Those schems are from early seventies version, not SVT CL. You ask:voltages at primary and secondary? Sorry, I might not understand, but why can't you read the voltages by yourself from the schematics?

How about : http://www.fliptops.net/index.htm
 
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