SSS a Hartman Manning Affair

Overdrive Special, Steel String Singer, Dumbleland, Odyssey, Winterland, etc. -
Members Only

Moderators: pompeiisneaks, Colossal

Post Reply
User avatar
dreric
Posts: 962
Joined: Mon Dec 01, 2008 3:15 pm
Location: SF East Bay

SSS a Hartman Manning Affair

Post by dreric »

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?
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
amplifiednation
Posts: 2070
Joined: Sun Dec 26, 2010 6:19 pm
Location: Boston
Contact:

Re: SSS a Hartman Manning Affair

Post by amplifiednation »

Those boards look great!!
Amplified Nation
www.amplifiednation.com
@ampnation
User avatar
Mr. dB
Posts: 261
Joined: Sat Jun 10, 2006 6:58 pm
Location: Little Rock, Arkansas

Re: SSS a Hartman Manning Affair

Post by Mr. dB »

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?
User avatar
martin manning
Posts: 13079
Joined: Sun Jul 06, 2008 12:43 am
Location: 39°06' N 84°30' W

Re: SSS a Hartman Manning Affair

Post by martin manning »

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.
User avatar
pompeiisneaks
Site Admin
Posts: 4222
Joined: Sat Jan 14, 2017 4:36 pm
Location: Washington State, USA
Contact:

Re: SSS a Hartman Manning Affair

Post by pompeiisneaks »

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

tUber Nerd!
User avatar
martin manning
Posts: 13079
Joined: Sun Jul 06, 2008 12:43 am
Location: 39°06' N 84°30' W

Re: SSS a Hartman Manning Affair

Post by martin manning »

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.
I believe you would need to increase primary impedance by miss-matching the speaker load though.
User avatar
jelle
Posts: 2372
Joined: Sat Feb 04, 2006 7:55 pm
Location: New Jersey

Re: SSS a Hartman Manning Affair

Post by jelle »

Hi,

UL operation is a form of NFB. So if you do that, reduce or ditch the global NFB, and the presence control.

Jelle
User avatar
martin manning
Posts: 13079
Joined: Sun Jul 06, 2008 12:43 am
Location: 39°06' N 84°30' W

Re: SSS a Hartman Manning Affair

Post by martin manning »

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.
User avatar
dreric
Posts: 962
Joined: Mon Dec 01, 2008 3:15 pm
Location: SF East Bay

Re: SSS a Hartman Manning Affair

Post by dreric »

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?
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
User avatar
dreric
Posts: 962
Joined: Mon Dec 01, 2008 3:15 pm
Location: SF East Bay

Re: SSS a Hartman Manning Affair

Post by dreric »

Also, I replaced the bias supply photo with the correct one.
Eric
1949 Zenith, Zenith Toggle Recoil, Zenith 55 & 440
User avatar
martin manning
Posts: 13079
Joined: Sun Jul 06, 2008 12:43 am
Location: 39°06' N 84°30' W

Re: SSS a Hartman Manning Affair

Post by martin manning »

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.
User avatar
jelle
Posts: 2372
Joined: Sat Feb 04, 2006 7:55 pm
Location: New Jersey

Re: SSS a Hartman Manning Affair

Post by jelle »

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
User avatar
martin manning
Posts: 13079
Joined: Sun Jul 06, 2008 12:43 am
Location: 39°06' N 84°30' W

Re: SSS a Hartman Manning Affair

Post by martin manning »

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.
User avatar
jelle
Posts: 2372
Joined: Sat Feb 04, 2006 7:55 pm
Location: New Jersey

Re: SSS a Hartman Manning Affair

Post by jelle »

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. :D :twisted: :D

jelle
User avatar
didit
Posts: 976
Joined: Thu Sep 25, 2008 3:37 pm
Location: Canada

Re: SSS a Hartman Manning Affair

Post by didit »

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
You do not have the required permissions to view the files attached to this post.
Post Reply