What to do with a 60s Dynacord Twen??

[ToneFerDayz!!1!]

So I posted this on another forum, but I figure this is also a good place to see some ideas, given the amount of amp gurus who are familiar with Euro amps here. (Paging Racing! Racing, to the courtesy phone!)

So, I have a 1966ish Dynacord Twen. It's a 2x6v6, 1x12" amp with tremolo and a decent amount of output. However, it doesn't sound as good as my old Harmony 306a, which is very close to a 6G3 Brown Deluxe, and that's a sound that I absolutely adore. Would it be possible/worth it to get a local amp tech to mod my Dynacord to get it in the ballpark? The Twen isn't really collectable at all, and it's in some rough cosmetic shape. I'm looking to get the trem a little stronger and to get a bit more gain out of it, but I don't necessarily need super high hard rock/metal gain.

Here are the circuits, for reference:

Dynacord Twen:



Fender 6G3:



Harmony 306a:

[Racing]

Of course.

https://www.youtube.com/watch?v=KEhLr131ajo

There´s loads that can be had from it. First up though you HAVE to replace the speaker. It´s that simple. The stock old Dynacord speakers,often Elbau ones,simply ain´t manufactured to cope with what we´re doing with guitars these days.

Then.
It is a true point to point amp. Good enough.
Basically you´ll need to rip the innards out of it. Stock it carries with it a few design flaws even,which is rather odd for a German made amp. First up it does NOT adhere to "the golden rule". Ie;make sure that the centertap of the HT winding of the power transformer is hooked directly to the grounding of first hit e-lyte. NOTHING else is to touch that point. Ground to chassis AFTER that. In turn ground the rest of the amp (preamp and PI) to a point close to the input jacks.



The input jacks in turn needs to be reset to become "floating". I just replace them with regular Cliff ones. Stock they head directly for ground,which creates a ground loop=hiss and hum.
There´s a ground bus bar running the length of the chassis. Feel free to use that but make sure it hits ground in one point and one point only.

In turn,in stock form,the cathode resistor for the powertubes and its decoupling cap is just a few millimeters apart. Separate those two as much as technically possible. The stock setup will boil the innards of that cap to crap in notime. Hence why non serviced Twens are often low on power.

Then.
To REALLY get those things going they need yet another tube. Dynacord in their wisdom supplied a hole for that already,and that is the hole that keeps a solder support for the input grid resistors stock.



So. Basically i wipe them clean. What remains,in essence,is the chassis...the x-formers and the powertube sockets.



I turn it into a tagboard design as such. Board i use in this case is a "Vox style" one as they´re a direct fit,sort of. 10mm stands for it works a long way.



Main smoothing caps get replaced,of course. That means using a cone drill to accept this day n era stuff.



All said and done this one got a Vintage 30 speaker. One major culprit with ALL Dynacord combos is that they are to shallow to be closed up. So..didn´t really free tone up until i removed the back plate. Then it really came to life.

All said and done they are great performers if you just take to heart that they need a different component topology. Basically all of the Dynacord amps sound the same. Very "German",ie;cold..hard..n shrill.
IOW there´s IMO no point in noodling around with them. Just wipe them clean and start over,components are cheap after all. With like 50€ invested in materials (if tube and what not are kosher) and a little know how you get yourself a true,vintage,screamer. Light and compact..that´ll run with the big boys need be.
Always always use zener diodes vs the g2/screens for amps this limited in power. It makes them able to run WAY WAY WAY closer to their edge without folding and starting to sound compressed and mushed.

[ToneFerDayz!!1!]

Of course.

https://www.youtube.com/watch?v=KEhLr131ajo

There´s loads that can be had from it. First up though you HAVE to replace the speaker. It´s that simple. The stock old Dynacord speakers,often Elbau ones,simply ain´t manufactured to cope with what we´re doing with guitars these days.

Yeah, that's first on the to-do list for sure.

Then.
It is a true point to point amp. Good enough.
Basically you´ll need to rip the innards out of it. Stock it carries with it a few design flaws even,which is rather odd for a German made amp. First up it does NOT adhere to "the golden rule". Ie;make sure that the centertap of the HT winding of the power transformer is hooked directly to the grounding of first hit e-lyte. NOTHING else is to touch that point. Ground to chassis AFTER that. In turn ground the rest of the amp (preamp and PI) to a point close to the input jacks.



The input jacks in turn needs to be reset to become "floating". I just replace them with regular Cliff ones. Stock they head directly for ground,which creates a ground loop=hiss and hum.
There´s a ground bus bar running the length of the chassis. Feel free to use that but make sure it hits ground in one point and one point only.

In turn,in stock form,the cathode resistor for the powertubes and its decoupling cap is just a few millimeters apart. Separate those two as much as technically possible. The stock setup will boil the innards of that cap to crap in notime. Hence why non serviced Twens are often low on power.

Then.
To REALLY get those things going they need yet another tube. Dynacord in their wisdom supplied a hole for that already,and that is the hole that keeps a solder support for the input grid resistors stock.



So. Basically i wipe them clean. What remains,in essence,is the chassis...the x-formers and the powertube sockets.



I turn it into a tagboard design as such. Board i use in this case is a "Vox style" one as they´re a direct fit,sort of. 10mm stands for it works a long way.



Main smoothing caps get replaced,of course. That means using a cone drill to accept this day n era stuff.



All said and done this one got a Vintage 30 speaker. One major culprit with ALL Dynacord combos is that they are to shallow to be closed up. So..didn´t really free tone up until i removed the back plate. Then it really came to life.

All said and done they are great performers if you just take to heart that they need a different component topology. Basically all of the Dynacord amps sound the same. Very "German",ie;cold..hard..n shrill.
IOW there´s IMO no point in noodling around with them. Just wipe them clean and start over,components are cheap after all. With like 50€ invested in materials (if tube and what not are kosher) and a little know how you get yourself a true,vintage,screamer. Light and compact..that´ll run with the big boys need be.
Always always use zener diodes vs the g2/screens for amps this limited in power. It makes them able to run WAY WAY WAY closer to their edge without folding and starting to sound compressed and mushed.

This is interesting, Racing, lots of stuff to think about here. I'm leaning towards letting a tech gut it and put in a Fender 6G2 circuit actually.

Also, does the stock baffle suffice for the speaker swap or am I going to need to cut a new one too?

[ToneFerDayz!!1!]

For reference, here's the 6G2 circuit (which I absolutely adore):



It certainly looks much closer to the stock Twen's circuit, but I'm not really well versed the details of amp circuits.

[Racing]

Yes.
The stock baffle works just fine. Issue is that the stock speaker uses a different bolt pattern vs what´s a standard today. Hence,what you need to do is "undress" the baffle from its fabric,unbolt the stocker and the drill for a modern day n era pattern.
Then staple that fabric back where it belongs.
Takes a little while but that done...you can toss and turn as far as speakers to hearts desire.

..again.
Them Twens are great platforms to build something of your own. IF you wanna try it out with a stock circuit and a modern speaker just at least add a massive gridstopper for the entry grid of the concertina PI.
Just solder a 1M resistor between the concertina grid and it´s inbound driver stage. What that´ll do is calm the behavior of the PI down and you´ll get rid of that rather "jagged edge" part of the sound.

But..TBH..the stocker doesn´t sound all that IMO. Just wipe the thing clean and be done with it already..if u ask me.

[ToneFerDayz!!1!]

An update for Racing and others:

So, a few weeks ago, I took the Twen in to get it overhauled for some new concerts and my tech did a bunch of changes:

1) Apparently the amp had new tube sockets installed and biased for 7581s, which I never really noticed. We took those out and brought it back to the stock 6v6 configuration, plugged some pretty good sounding Tung Sol RIs in there. The amp sounds fuller, breaks up a bit earlier, and has more of that 6v6 snarl I love. I'm frankly a little mystified why someone wanted 7581s there, unless they were trying to cop an Ampeg Jet vibe or that was all they had lying around.

2) Got rid of the stock speaker. We put in an Eminence Legend 12" that had been sitting around the shop and the difference is night and day. Even though it's not broken in, the Eminence is night and day better than the no-name West German 12"- louder, clearer, handles gain better. It IS a touch bright with the Twen circuit, but that's what the treble and tone knobs are for, I suppose.

3) Swapped out some microphonic preamp tubes with some other NOS ECC83s I had lying around.

4) Fixed the cab so that it wasn't rattling anymore.

There's still a few changes I'm contemplating-- bringing the amp more in line with the 6G2 circuit, for example, but I'd say the first two changes were the most important. Now this thing screams, and all said and done, for under $300.