Transformers for a Dr.Z Route 66
- gilmour_pugliese
- Resistor Ronker
- PokeyPete
- Resistor Ronker
Let's critique your choice of power transformers:
The transformer on the schematic has three sets of secondary windings:
.....740VCT w/ 50V (assumed) tap; current not given
.....5V; current not given
.....6.3VCT, current not given
Your transformer choices:
290GX.....690vCT @ 150mA (no 50V tap); 6.3VCT @ 5A.....(no 5V winding)
290LX.....600VCT @ 230mA (no 50V tap); 6.3VCT @ 4A; 5V @ 2A
Looking at the tube manual we find that the 5AR4 has a heater requirement of 5V, 1.9A.
The heater requirements of the 6.3V tubes are....EF86 0.2A, 12AX7 0.3A (parallel), KT66 1.3A (each) for a total of 3.1A.
I didn't do extensive research but I saw this transformer while checking the Mojo site.
http://www.mojotone.com/amp-parts/amp-t ... ransformer
The MOJO761 has the following characteristics and would be a closer match. Like I said, I didn't look very hard. I'm sure
there are even better matches if you search for them.
.....724VCT @ 150mA, with a 52V tap
.....6.3V @ 4A
.....5V @ 4A
Hope this helps a little on your journey down hwy 66
The transformer on the schematic has three sets of secondary windings:
.....740VCT w/ 50V (assumed) tap; current not given
.....5V; current not given
.....6.3VCT, current not given
Your transformer choices:
290GX.....690vCT @ 150mA (no 50V tap); 6.3VCT @ 5A.....(no 5V winding)
290LX.....600VCT @ 230mA (no 50V tap); 6.3VCT @ 4A; 5V @ 2A
Looking at the tube manual we find that the 5AR4 has a heater requirement of 5V, 1.9A.
The heater requirements of the 6.3V tubes are....EF86 0.2A, 12AX7 0.3A (parallel), KT66 1.3A (each) for a total of 3.1A.
I didn't do extensive research but I saw this transformer while checking the Mojo site.
http://www.mojotone.com/amp-parts/amp-t ... ransformer
The MOJO761 has the following characteristics and would be a closer match. Like I said, I didn't look very hard. I'm sure
there are even better matches if you search for them.
.....724VCT @ 150mA, with a 52V tap
.....6.3V @ 4A
.....5V @ 4A
Hope this helps a little on your journey down hwy 66
“No man is so foolish but he may sometimes give another
good counsel, and no man so wise that he may not easily err
if he takes no other counsel than his own. He that is taught
only by himself has a fool for a master.”
–Hunter S. Thompson
good counsel, and no man so wise that he may not easily err
if he takes no other counsel than his own. He that is taught
only by himself has a fool for a master.”
–Hunter S. Thompson
- gilmour_pugliese
- Resistor Ronker
Thank you Pokeypete
So:
-the power transformers from Hammond are not OK... According to your specifications, I've two choices: MOJO761, or give the specs to a manufacturer for a custom-wound PT... I've already used the second one for my Hiwatt DR504 clone
-the OT question seems to be more simple... this page:
http://www.hammondmfg.com/1608.htm
suggests a 1650PA for a max 60W 6,6k push-pull ultralinear... but any thought?
So:
-the power transformers from Hammond are not OK... According to your specifications, I've two choices: MOJO761, or give the specs to a manufacturer for a custom-wound PT... I've already used the second one for my Hiwatt DR504 clone
-the OT question seems to be more simple... this page:
http://www.hammondmfg.com/1608.htm
suggests a 1650PA for a max 60W 6,6k push-pull ultralinear... but any thought?
- gilmour_pugliese
- Resistor Ronker
I've contacted an Italian manufacturer:
http://www.inmadout.com/index.asp
and here's his proposal for a Route66:
PT: 360V-50V-0-360V@200mA, 3,15-0-3,15V@6A, 5V@3A
OT: 8K with 40% taps (or 6.6k, as used in the past in UL applications), 4-8-16ohm
This set is pretty good, but with 10V in less in the PT... So, a bit of headroom loss, right?
http://www.inmadout.com/index.asp
and here's his proposal for a Route66:
PT: 360V-50V-0-360V@200mA, 3,15-0-3,15V@6A, 5V@3A
OT: 8K with 40% taps (or 6.6k, as used in the past in UL applications), 4-8-16ohm
This set is pretty good, but with 10V in less in the PT... So, a bit of headroom loss, right?
- mojah63
- Breadboard Brother
some info here:
viewtopic.php?f=2&t=14124
I'd be more concerned getting the output tranny right. They all sound different..
some over-wound some are under-wound ect...
viewtopic.php?f=2&t=14124
I'd be more concerned getting the output tranny right. They all sound different..
some over-wound some are under-wound ect...
- PokeyPete
- Resistor Ronker
Hi gil',gilmour_pugliese wrote:I've contacted an Italian manufacturer:
http://www.inmadout.com/index.asp
and here's his proposal for a Route66:
PT: 360V-50V-0-360V@200mA, 3,15-0-3,15V@6A, 5V@3A
OT: 8K with 40% taps (or 6.6k, as used in the past in UL applications), 4-8-16ohm
This set is pretty good, but with 10V in less in the PT... So, a bit of headroom loss, right?
That set looks very nice. I've included a link to the KT66 from duncan amps. As you can see from
the chart they list the load resistor as being 8K when the KT66 is setup as normal tetrode; but when
set up as ultra-linear tetrode that the load resistor given is 7K. This would lead me to believe that
the OT from the set or the 1650PA would both be satisfactory in this build.
http://tdsl.duncanamps.com/dcigna/tubes ... t66-3h.gif
I'll include another link from duncan amps (just one layer above the link I just posted) so that you
can see the KT66 stats listed for different setups......tetrod, triode, etc.
http://tdsl.duncanamps.com/dcigna/tubes ... /kt66.html
“No man is so foolish but he may sometimes give another
good counsel, and no man so wise that he may not easily err
if he takes no other counsel than his own. He that is taught
only by himself has a fool for a master.”
–Hunter S. Thompson
good counsel, and no man so wise that he may not easily err
if he takes no other counsel than his own. He that is taught
only by himself has a fool for a master.”
–Hunter S. Thompson
- gilmour_pugliese
- Resistor Ronker
thanks Pokeypete... I prefer the Inmadout option because the set has a resonable price (150€) and the manufacturer is italian (speak the same language is important in those cases). BTW, if I choose Inmadout I'll ask a 6.6/7k for OTPokeyPete wrote:Hi gil',gilmour_pugliese wrote:I've contacted an Italian manufacturer:
http://www.inmadout.com/index.asp
and here's his proposal for a Route66:
PT: 360V-50V-0-360V@200mA, 3,15-0-3,15V@6A, 5V@3A
OT: 8K with 40% taps (or 6.6k, as used in the past in UL applications), 4-8-16ohm
This set is pretty good, but with 10V in less in the PT... So, a bit of headroom loss, right?
That set looks very nice. I've included a link to the KT66 from duncan amps. As you can see from
the chart they list the load resistor as being 8K when the KT66 is setup as normal tetrode; but when
set up as ultra-linear tetrode that the load resistor given is 7K. This would lead me to believe that
the OT from the set or the 1650PA would both be satisfactory in this build.
http://tdsl.duncanamps.com/dcigna/tubes ... t66-3h.gif
I'll include another link from duncan amps (just one layer above the link I just posted) so that you
can see the KT66 stats listed for different setups......tetrod, triode, etc.
http://tdsl.duncanamps.com/dcigna/tubes ... /kt66.html
You'll probably find your filament village will drift closer to 7VAC because your only drawing 3.1A of current and it's spec'ed for 6.3V @ 6A. PT voltages are spec'ed under load; If the load is less than spec'ed, the voltages go up a little.
It's nothing major, but you'll want to check the filament voltage when the amp is built and running to see if you need to correct it down to 6.3V.
It's nothing major, but you'll want to check the filament voltage when the amp is built and running to see if you need to correct it down to 6.3V.
I am currently building a hybrid route 66 with Maz preamp second channel. I looked at transformers and the closest I could come to without resporting to custom built was the following:
Power: Hammond 374BX 750V C.T.@ 201ma. 50v bias tap, 5V C.T. @ 3A, 6.3V C.T. @ 6A
OP: Hammond 1650HA 40watt, 6,600 ct, Push-Pull (2 Tubes), 6L6GC, 807, 5881, EL34
These are readily aailable
My only real concern is the PT is on the edge regarding current but as long as the hammonds can run hot it should be ok.
Thoughts please
Power: Hammond 374BX 750V C.T.@ 201ma. 50v bias tap, 5V C.T. @ 3A, 6.3V C.T. @ 6A
OP: Hammond 1650HA 40watt, 6,600 ct, Push-Pull (2 Tubes), 6L6GC, 807, 5881, EL34
These are readily aailable
My only real concern is the PT is on the edge regarding current but as long as the hammonds can run hot it should be ok.
Thoughts please
- PokeyPete
- Resistor Ronker
I am very curious to know how you came to the conclusion that "the PT is on the edge regarding current".ukbrightonbloke wrote:I am currently building a hybrid route 66 with Maz preamp second channel. I looked at transformers and the closest I could come to without resporting to custom built was the following:
Power: Hammond 374BX 750V C.T.@ 201ma. 50v bias tap, 5V C.T. @ 3A, 6.3V C.T. @ 6A
OP: Hammond 1650HA 40watt, 6,600 ct, Push-Pull (2 Tubes), 6L6GC, 807, 5881, EL34
These are readily aailable
My only real concern is the PT is on the edge regarding current but as long as the hammonds can run hot it should be ok.
Thoughts please
Please explain (and show your work).
“No man is so foolish but he may sometimes give another
good counsel, and no man so wise that he may not easily err
if he takes no other counsel than his own. He that is taught
only by himself has a fool for a master.”
–Hunter S. Thompson
good counsel, and no man so wise that he may not easily err
if he takes no other counsel than his own. He that is taught
only by himself has a fool for a master.”
–Hunter S. Thompson
Hi Pokey Pete
Like most enthusiasts we get facts (debabtable) and figures from the internet or books. I know basic ohms law etc and thank god I have a calculator.
My work is research, and looking at other designs, datasheets etc and it looks like the current draw on 2 x kt66 in ultra linear mode is between 135 ma and 160ma depending on wattage output (30W - 50w). Adding in the smaller tubes, preamp & driver (I have 2 extra ecc33 tubes) I could be looking at about 175ma, add the desired 20% overhead prefered to not push transformer too hard, makes 210ma. The Hammond transformer is rated 201ma. I may be wrong but I believe Hammonds are not military spec and only have about 2% headroom which means I dont have much overhead.
Please by all means put me straight with this because it will make me stop worrying that my transformer may meltdown!
I have not been able to find a definitive answer to how much current a Rout 66 draws at peaks. I know we should not take everything we read as the truth, especially when looking to build a clone of an amp that dosent have any official plans or data of voltages, currents and tranformer specs.
(shhh dont tell Dr Z i am building one a MAZZ66)
Cheers
Like most enthusiasts we get facts (debabtable) and figures from the internet or books. I know basic ohms law etc and thank god I have a calculator.
My work is research, and looking at other designs, datasheets etc and it looks like the current draw on 2 x kt66 in ultra linear mode is between 135 ma and 160ma depending on wattage output (30W - 50w). Adding in the smaller tubes, preamp & driver (I have 2 extra ecc33 tubes) I could be looking at about 175ma, add the desired 20% overhead prefered to not push transformer too hard, makes 210ma. The Hammond transformer is rated 201ma. I may be wrong but I believe Hammonds are not military spec and only have about 2% headroom which means I dont have much overhead.
Please by all means put me straight with this because it will make me stop worrying that my transformer may meltdown!
I have not been able to find a definitive answer to how much current a Rout 66 draws at peaks. I know we should not take everything we read as the truth, especially when looking to build a clone of an amp that dosent have any official plans or data of voltages, currents and tranformer specs.
(shhh dont tell Dr Z i am building one a MAZZ66)
Cheers
- PokeyPete
- Resistor Ronker
It seems like you have done your homework!
When you disclosed your transformer specs I thought it was a terrific selection. I even thought it was a little overkill,
but I liked that. If I were going to build a "66" amp, I would definately consider using it. The specs in one of the links
that I provided above uses a similar voltage and load resistor value as the schematic above. It gives a 145mA reading
at maximum signal level. In my mind I was thinking that pre power triodes had plate resistors in the 100k to 220k range
yielding only several hundred microamps to 1 or 2 milliamps per triode. It looked to me like it would take a lot of tubes
to use up all of that 56mA available headroom. That's why I asked you about it. I admit that I haven't looked at the MAZ
schematic so I don't know what is involved. You may be right about it being on the edge. But for the "66" it looks great!
My thinking is that unless the MAZ preamp is some kind of current hog you should be fine with this transformer. Hopefully
one of our "Amp Masters" will step forward and give you proper advice. Best of luck on your project!
When you disclosed your transformer specs I thought it was a terrific selection. I even thought it was a little overkill,
but I liked that. If I were going to build a "66" amp, I would definately consider using it. The specs in one of the links
that I provided above uses a similar voltage and load resistor value as the schematic above. It gives a 145mA reading
at maximum signal level. In my mind I was thinking that pre power triodes had plate resistors in the 100k to 220k range
yielding only several hundred microamps to 1 or 2 milliamps per triode. It looked to me like it would take a lot of tubes
to use up all of that 56mA available headroom. That's why I asked you about it. I admit that I haven't looked at the MAZ
schematic so I don't know what is involved. You may be right about it being on the edge. But for the "66" it looks great!
My thinking is that unless the MAZ preamp is some kind of current hog you should be fine with this transformer. Hopefully
one of our "Amp Masters" will step forward and give you proper advice. Best of luck on your project!
“No man is so foolish but he may sometimes give another
good counsel, and no man so wise that he may not easily err
if he takes no other counsel than his own. He that is taught
only by himself has a fool for a master.”
–Hunter S. Thompson
good counsel, and no man so wise that he may not easily err
if he takes no other counsel than his own. He that is taught
only by himself has a fool for a master.”
–Hunter S. Thompson
Thanks Pete for feedback, this is what makes a good forum!
I feel much better about the hammond, i just wont turn it up to 11!
I will post my build pics and diy drawings soon.
Again, thanks and hope others find our post useful
I feel much better about the hammond, i just wont turn it up to 11!
I will post my build pics and diy drawings soon.
Again, thanks and hope others find our post useful
I forgot to add, if anyone uses the Hammond 374BX make sure you check the current. They changed it from 175ma to a 201ma version about a year half ago, so if you buy one, make sure its a later version rated at 201ma and some companies are still showing it as 175ma on their data sheets.
Cheers
Cheers
Waiting for Tubes, then final testing
The amp is a two channel with switching amp a Route 66 with a MAZ Junior channel added
WIll mess with some of the values to tweak it once tubes have arrived. So far no smoke!
Teh tramsformers are the hammonds I suggest in previous post.
CM
Matched Pair Russian Genalex Gold Lions KT66
2 x JJ ECC83s (for maz channel)
1 x TUNGSOL EF806 (for 66 channel)
1 x TUNGSOL Re-Issue 12AX7 (phase splitter tested)
Sovtek 5AR4
The KT66's are massive! if you are going to use these in a project, make sure you leave airspace between them!
All from HOTROX in UK who have a great selection and so far a great service.
Had to tweek the bias supply resitors as couldnt get the bias violtage high enough to get the right bias, which i set at 37ma.
The amp spunds gorgeous, sparkle on the top ends with nice warm low end, and thats with a crappy 1x12 cab I have! Cant wait to get the new 2 x12 cab made up with a vintage 30 and one of the new 'celestion cream back' speakers.
The tranformers seem to be ok, need to push them for a while to see how warm they get.
- PokeyPete
- Resistor Ronker
You did a terrific job with your amp build.....looks Wonderful !!!ukbrightonbloke wrote: The tranformers seem to be ok, need to push them for a while to see how warm they get.
You stated earlier that you were thinking that "the PT is on the edge", and apparently you are still
holding on to that belief. You've had a chance to crank it up a bit ( I assume ). Do you still have
reservations about this PT when adding the MAZ front end? I would love to hear a sound sample
featuring both MAZ and "66" inputs! Since the two amps normally use different power tubes, how
satisfied are you with the sound of the Maz? Would you mind showing us how you combined the
two preamps?
“No man is so foolish but he may sometimes give another
good counsel, and no man so wise that he may not easily err
if he takes no other counsel than his own. He that is taught
only by himself has a fool for a master.”
–Hunter S. Thompson
good counsel, and no man so wise that he may not easily err
if he takes no other counsel than his own. He that is taught
only by himself has a fool for a master.”
–Hunter S. Thompson
Hi Pete, thanks for message.
I have cranked it and to be honest it seems all ok! the PT seems to be working fine and not getting hot, only warm from the massive gold lions (which are great!)
Here is the final schematic with switching and bias component change. I had to tweak the resistors in the bias circuitry to get the desired bias (38ma for me at mo)
The 66 chanel sounds pretty much like the 66 i tried at a local shop. the Mazz chanel sounds great too, harder than the 66, and much more like a jtm 45/plexi with kt66
I am waiting on the cab to be made for the amp and speaker (from cabs by chris, ampmaker)
will be fitting into this
The cab will be based on the Drz 2 x 12 which has a mix of a vintage 30 celestion and a 12h greenback but i will be using the vintage 30 (50w) and one of the new creambacks (60w)
Hope all this info helps
Chris
I have cranked it and to be honest it seems all ok! the PT seems to be working fine and not getting hot, only warm from the massive gold lions (which are great!)
Here is the final schematic with switching and bias component change. I had to tweak the resistors in the bias circuitry to get the desired bias (38ma for me at mo)
The 66 chanel sounds pretty much like the 66 i tried at a local shop. the Mazz chanel sounds great too, harder than the 66, and much more like a jtm 45/plexi with kt66
I am waiting on the cab to be made for the amp and speaker (from cabs by chris, ampmaker)
will be fitting into this
The cab will be based on the Drz 2 x 12 which has a mix of a vintage 30 celestion and a 12h greenback but i will be using the vintage 30 (50w) and one of the new creambacks (60w)
Hope all this info helps
Chris
- snofla1900
- Breadboard Brother
Looks great!
What I like to do in fixed bias amps is make the biascontrol double and feed them to the 220 K gridresistors of the outputtubes so you can bias them seperately.
Could you perhaps post a soundclip ?
What I like to do in fixed bias amps is make the biascontrol double and feed them to the 220 K gridresistors of the outputtubes so you can bias them seperately.
Could you perhaps post a soundclip ?