SSS a Hartman Manning Affair
Moderators: pompeiisneaks, Colossal
SSS a Hartman Manning Affair
I though I start a build thread about my latest build.
It's a SSS from the Hartman threads:
Original thread:
http://ampgarage.com/forum/viewtopic.php?f=4&t=20662
A couple of layout errors got corrected in this thread:
http://ampgarage.com/forum/viewtopic.php?f=4&t=29722
With the "alternate power supply for the driver stage" modification described by Martin Mannning in this thread:
http://ampgarage.com/forum/viewtopic.php?f=4&t=29882
Because there's a hole in the chassis, there will be a presence pot:
http://ampgarage.com/forum/viewtopic.php?f=4&t=30090
There will be a FET, again the chassis has a hole for the FET pot. Seeing that space is not an issue, I grabbed the Ceritone layout.
Chassis is an old thing that RJ worked up.
Heyboer twin reverb PT, stand-up mount.
NOS Sunn 3-60T output transformer.
Due to the OT I'm going to be running 2 6550 for output.
Here's a question for the group. The OT is a ultra linear and the Sunn amps were wired in UL. I'm toying with the idea of wiring the amp UL but I'm not sure if this is a good thing or a not so good thing. I'm not aware of any Dumble's wired UL so it would be a break in tradition. Opinions?
It's a SSS from the Hartman threads:
Original thread:
http://ampgarage.com/forum/viewtopic.php?f=4&t=20662
A couple of layout errors got corrected in this thread:
http://ampgarage.com/forum/viewtopic.php?f=4&t=29722
With the "alternate power supply for the driver stage" modification described by Martin Mannning in this thread:
http://ampgarage.com/forum/viewtopic.php?f=4&t=29882
Because there's a hole in the chassis, there will be a presence pot:
http://ampgarage.com/forum/viewtopic.php?f=4&t=30090
There will be a FET, again the chassis has a hole for the FET pot. Seeing that space is not an issue, I grabbed the Ceritone layout.
Chassis is an old thing that RJ worked up.
Heyboer twin reverb PT, stand-up mount.
NOS Sunn 3-60T output transformer.
Due to the OT I'm going to be running 2 6550 for output.
Here's a question for the group. The OT is a ultra linear and the Sunn amps were wired in UL. I'm toying with the idea of wiring the amp UL but I'm not sure if this is a good thing or a not so good thing. I'm not aware of any Dumble's wired UL so it would be a break in tradition. Opinions?
You do not have the required permissions to view the files attached to this post.
Last edited by dreric on Tue Oct 24, 2017 4:44 am, edited 1 time in total.
Eric
1949 Zenith, Zenith Toggle Recoil, Zenith 55 & 440
1949 Zenith, Zenith Toggle Recoil, Zenith 55 & 440
-
- Posts: 2070
- Joined: Sun Dec 26, 2010 6:19 pm
- Location: Boston
- Contact:
1 others liked this
Re: SSS a Hartman Manning Affair
Those boards look great!!
Amplified Nation
www.amplifiednation.com
@ampnation
www.amplifiednation.com
@ampnation
Re: SSS a Hartman Manning Affair
If the output transformer is from a Sunn 2x6550, is it a Dynaco A431?
Some of the early Dumbleland amps used Dynaco iron didn't they? If so, maybe there is some Dumble history of ultralinear outputs after all?
Some of the early Dumbleland amps used Dynaco iron didn't they? If so, maybe there is some Dumble history of ultralinear outputs after all?
- martin manning
- Posts: 13356
- Joined: Sun Jul 06, 2008 12:43 am
- Location: 39°06' N 84°30' W
Re: SSS a Hartman Manning Affair
Looking good! I think I would wire up the output stage in the conventional way, and then you can easily experiment with using the screen taps. With that in mind you could run separate leads from each side of the pp stage to the screen node so that separating them for UL would be easier. That could be switched even, if you like the different qualities of the sounds. The bias should not need to be adjusted since the screen voltage will be nearly the same either way with the screen resistors on the sockets.
I'm very interested to see how this comes together.
PS: Above I note the attached picture shows the modified layout I drew for the CF driver supply that uses a separate transformer. The link goes to the layout that you have actually used, where the driver is powered from the 60V bias tap. A bit of silicone at the top of each of the two pairs of radial caps would be a good idea to keep them from moving.
I'm very interested to see how this comes together.
PS: Above I note the attached picture shows the modified layout I drew for the CF driver supply that uses a separate transformer. The link goes to the layout that you have actually used, where the driver is powered from the 60V bias tap. A bit of silicone at the top of each of the two pairs of radial caps would be a good idea to keep them from moving.
- pompeiisneaks
- Site Admin
- Posts: 4222
- Joined: Sat Jan 14, 2017 4:36 pm
- Location: Washington State, USA
- Contact:
Re: SSS a Hartman Manning Affair
Me being very far from an expert, but wasn't one of HAD's primary goals for the power section, especially for the SSS, to have an extremely clean power section? UL provides this even more than non, so I'd think it fits, but you definitely can experiment with both and see. Maybe add an UL switch?
Sent from my LG-H872 using Tapatalk
Sent from my LG-H872 using Tapatalk
tUber Nerd!
- martin manning
- Posts: 13356
- Joined: Sun Jul 06, 2008 12:43 am
- Location: 39°06' N 84°30' W
Re: SSS a Hartman Manning Affair
I believe you would need to increase primary impedance by miss-matching the speaker load though.martin manning wrote: ↑Mon Oct 23, 2017 10:33 amI think I would wire up the output stage in the conventional way, and then you can easily experiment with using the screen taps. ... The bias should not need to be adjusted since the screen voltage will be nearly the same either way with the screen resistors on the sockets.
Re: SSS a Hartman Manning Affair
Hi,
UL operation is a form of NFB. So if you do that, reduce or ditch the global NFB, and the presence control.
Jelle
UL operation is a form of NFB. So if you do that, reduce or ditch the global NFB, and the presence control.
Jelle
- martin manning
- Posts: 13356
- Joined: Sun Jul 06, 2008 12:43 am
- Location: 39°06' N 84°30' W
Re: SSS a Hartman Manning Affair
Hold on, I read more carefully... You are using the Sunn OT and and Twin PT, for about 450V on the plates, yes? What is the primary impedance of the OT? From our discussion in the power supply thread I see the Sunn had 485V. Probably fine as I said there, but it would be nice to know the Zpri. It should be 4k3, according to the Triode Store spec sheet for Dynaco A431-S/Sunn 3-60T. In any case start with a UL power stage since that is what the transformer is designed for. You might be able to run it in conventional p-p and miss-match the speaker impedance, but going that direction might result in red-plating.
Re: SSS a Hartman Manning Affair
I wanted to thank everyone for their replies and suggestions.
I'm going to wire the OT in ultra linear to start. As Martin pointed out that's what it's made for. The primary impedance is 4k3.
Any problems if I just wire them the way it's shown on the Sunn schematic?
I'm going to wire the OT in ultra linear to start. As Martin pointed out that's what it's made for. The primary impedance is 4k3.
Any problems if I just wire them the way it's shown on the Sunn schematic?
You do not have the required permissions to view the files attached to this post.
Last edited by dreric on Tue Oct 24, 2017 5:13 am, edited 1 time in total.
Eric
1949 Zenith, Zenith Toggle Recoil, Zenith 55 & 440
1949 Zenith, Zenith Toggle Recoil, Zenith 55 & 440
Re: SSS a Hartman Manning Affair
Also, I replaced the bias supply photo with the correct one.
Eric
1949 Zenith, Zenith Toggle Recoil, Zenith 55 & 440
1949 Zenith, Zenith Toggle Recoil, Zenith 55 & 440
- martin manning
- Posts: 13356
- Joined: Sun Jul 06, 2008 12:43 am
- Location: 39°06' N 84°30' W
Re: SSS a Hartman Manning Affair
In the Sunn scheme the choke is ahead of the plate node, so it's rated for the total amp current. I'm assuming that your power supply is like the Hartmann SSS, where the choke is between the plate and screen nodes, and it is a 90 mA Fender Twin type. I think that will be ok, as you have more filtering on the plate node and common-mode cancellation in the OT for the screens. Just connect the power tube screens to the OT UL taps and leave the choke where it is in the Hartman schematic.
Interesting NFB in the Sunn power amp. I'm not sure what the 390p off one of the screen taps is for; maybe a stability fix. Since you are using a LTP inverter you can follow the usual Fender topology, and adjust the level to your liking. You will have the presence control to play with too.
Interesting NFB in the Sunn power amp. I'm not sure what the 390p off one of the screen taps is for; maybe a stability fix. Since you are using a LTP inverter you can follow the usual Fender topology, and adjust the level to your liking. You will have the presence control to play with too.
Re: SSS a Hartman Manning Affair
If it were me:
Have it run in normal non UL mode. 4.3K for two 6550s is fine.
NFB, presence control. Done.
But that's just me.
jelle
Have it run in normal non UL mode. 4.3K for two 6550s is fine.
NFB, presence control. Done.
But that's just me.
jelle
- martin manning
- Posts: 13356
- Joined: Sun Jul 06, 2008 12:43 am
- Location: 39°06' N 84°30' W
Re: SSS a Hartman Manning Affair
You could do that, but you'd be leaving a lot of output power on the table, and the load line would be far below the Vg1 = 0 knee so I'd worry about overdissipation on the screens. Miss-matching down to 2k15 would avoid that, but might redplate. Worth trying out both ways, but UL will be solid.
Re: SSS a Hartman Manning Affair
True, increasing the Plate voltage by adding a small B+ transformer would stop secondary emission and the over dissipation of the screens.
Or a 5K or so choke resistor would too. And will decrease power. The first method does not decrease power.
jelle
Or a 5K or so choke resistor would too. And will decrease power. The first method does not decrease power.
jelle
Re: SSS a Hartman Manning Affair
Puzzled now. That would have been my view, based on limited KT77 experience and some reading. Pulled up a 6550 datasheet and saw the relative "pentode" vs "UL" operation columns.
Best .. Ian
http://www.nj7p.info/Tubes/PDFs/Frank/135-GE/6550A.pdf
Best .. Ian
http://www.nj7p.info/Tubes/PDFs/Frank/135-GE/6550A.pdf
You do not have the required permissions to view the files attached to this post.