dynacord BA300

[NoiseNinja]

I owned an old Dynacord Bass King T (as far as I remember) amp once, 50W or 60W I believe, with a solid state pre amp stage and tubes in the power amp stage.

It played quite fine, as far as I remember and had a pretty nice sound.

It had some troubles keeping up with the band, level wise, as it was, but you could push the pre amp stage quite hard, by adding some boost between the bass and the amp, without it clipping, so I used it for quite some time as my main amp.

Finally I parted with it though, while I was on a break from playing, and when I stated playing in band again I used my Ampeg B-15 60W (which had no problems keeping up with a very loud band (kind of a hardcore take om math-rock with noise-rock influences), pushing it hard to the point of overdrive, without it giving up and going into fart mode, since I was one of two bass players, and played with a considerably less bass heavy sound than usual and with more emphasis on the mids, as the other bass took care of the more traditional bass register, which apparently was easier for the amp to handle at high volumes).

 

[rust_preacher]

A little update on my Eminent EMT. I located the buzz originating from the metal top plate. There is a vertical piece of metal just underneath it that I can probably use to dampen the vibration with some heat-resistant silicone siding.

 

[Matthijs]

A short update on my B1000. I took my time to update the pre amp section. I planned to do it during Christmas, but had some family emergencies to take care of. I built a tube pre-amp with a ECC83, more or less to Beate's specs but without the tone stack, and managed to fit it in the amp. I still have some trouble getting rid of hum caused by the feed to the heater. I'm working on a dc supply now and looking at the possibility to use the dc supply for the transistor section.
As the Amp is still in bits and pieces I could only listen to it in livingroom conditions. The result so far is very clear and even "tube hifi". It all sounds very high end to my ears, but I'm sure there's a lot of wishfull thinking involved I'm not sure about the very low end though. It's hard to tell because of the slight 50hz hum that's still there and I did not use the 'big cab'. I've got the impression there's just a bit too much of a drop off below 100 hz.

I planned to use the tube pre to also add a master control, but probably won't. The tube pre does not add that much extra gain to really need a master to limit the input of the power amp and my goal is not to add tube-pre distortion.

 

[Martin Beer]

Here's an update on my mods to my Eminent II. I had already re-capped it and replaced the bias trimmers and the 10 ohm bias measurement resistors (which were about 10% off the nominal value), so that it was healthy and fully working. Rather than using the original type screw mount capacitors I made an eyelet board to hold MIEC axial capacitors, which are rather less "vintage correct", but are good quality parts.
I have removed two of the preamp channel boards (storing all of the removed parts carefully) and built a 6sl7 preamp in the space. I have used existing holes in the chassis to mount it using angle brackets. The preamp is based on a late-60s Ampeg B15n with a James tone stack following the two triodes. I tried running this via a 100k resistor to the junction of R400/C100 on the power amp board, and found that while it sounded good, the preamp did not have enough output. To remedy this I have added an additional gain stage using an LND150 FET, which has worked well. I have a master volume control following the FET stage, which allows for a little grit from the 6SL7. I used the amp at a rehearsal last night and it has plenty of volume and very enjoyable tone. The character of the 6sl7 preamp is quite distinctive, and I don't have any issues with hum or noise. The remaining two transistor input channels are still functional, so the original sound of the amp is still available.

The front panel bulbs are removed at the moment, as I was aware that the 6sl7 would place an additional 300mA draw on the filament supply. I have some wide-angle green LEDs which I'm going to experiment with to see if I can illuminate the front panel with those.

 

[beate_r]

I'm working on a dc supply now and looking at the possibility to use the dc supply for the transistor section.

It is not powerful enough for the tube heaters.

I am a bit surprised because of the hum. My amp does not hum. Is the reference of the heaters to the ground intact? It should be present in the old tube section.

As the Amp is still in bits and pieces I could only listen to it in livingroom conditions. The result so far is very clear and even "tube hifi". It all sounds very high end to my ears, but I'm sure there's a lot of wishfull thinking involved

Well, the amp has a pretty strong NFB and therefore comparatively small THD - please keep in mind that the technology had been developed with singing and organs in mind.

I'm not sure about the very low end though. It's hard to tell because of the slight 50hz hum that's still there and I did not use the 'big cab'. I've got the impression there's just a bit too much of a drop off below 100 hz.

I designed a 70 Hz highpass into the stages, and the possibility to bypass it (what You should not do if You are driving only one single 15" speaker). Dynacord specifies a corner frequency of 40 Hz, and that should be fairly reliable.

 

[NoiseNinja]

Doesn't know this particular amp personally.

But I did own a Dynacord Bass King T at one point, in fact my first bass amp ever.

It also had a solid state preamp stage and a tube driven poweramp stage, it was just 50W, and I must admit my knowledge and taste in tone has refined, unlike my memory.

But as far as I remember it actually was a pretty nice amp, and I have it's all tube predecessor Bass King arriving to me one of these days, which I plan to use alongside my solid state Trace Elliot combo.

Should be a great amp, if my memory serves me right, and if it's anything like the Bass King T.

Looks great as well.

 

[beate_r]

If You have a look at the schematics of Eminent, Imperator and Bassking T You find that the imperator and Bassking T simply use the Eminent's mixing stage as its preamp. The B-1000 as well. Imperator and B-1000 just are more powerful, especially the B-1000 and have an additional treble and bass boost.
And HiFi-Favorit and G-2000 have two of these channels plus a tremolo stage. G-2000 with more power.

Bud basically they all sounded very similar.

 

[rust_preacher]

I have played my G-2000 exclusively (through a Peavey Black widow 18" speaker) in band practice using a Precision strung with flats. Occasionally I have taken a roundwound-strung bass with me, as I did yesterday. This Precision-style bass has a DiMarzio pickup, much hotter than the Van Zandt in my regular P... I didn't do any other adjustments besides turned down the volume on the bass to compensate for the added volume, and played through the rehearsal that way, until the last song, Neil Young's "Cinnamon Girl" for which the lead guitarist said "I need more grit for this"... I turned the volume back to full on the bass...

The sound was thunderous. I could feel my pant legs flap as the punch of the Precision hit me from behind. The distortion was also very tasty. Overall, the volume was too much for the rehearsal, but I got what I wanted from the experience.

 

[Matthijs]

Hi Beate,

I solved the hum problem with some help from Marble amps. A small boutoque guitar amp builder. It took an extra cap in the power supply and a different placement for the pre amp. But the main problem remained in the transistor pre stage. So I also removed both stages and it now is a full tube amp. I used your basic design and added a b15 two band tone stack with a bypass switch, and it has a gain and master control. I added the bypass because I like the straight voicing. I kept the 70 hz dropoff in your design, but might still change that after some real time experience. The high control on the tone ampeg tone control interacts well to control the clear voicing of the amp. I have my doubts about the bass, but I need some live experience with db before I make up my mind.

 

[Muziekschuur]

In the market for a Dynacord Eminent. We'll see if the deal can be done.

 

[Matthijs]

Small update on my b1001:
I changed some cap values in the pre to get a little more bass below 70hz. And I built a very small closed 2*10. As a matching cab for the head. But I like the sound with my 2*12+5 the best. With the eq bypassed and a headway infront it does really well with db. Dead quiet, and a audiophile like warm but still hifi sound.

 

[beate_r]

Small update on my b1001:
I changed some cap values in the pre to get a little more bass below 70hz. And I built a very small closed 2*10. As a matching cab for the head. But I like the sound with my 2*12+5 the best. With the eq bypassed and a headway infront it does really well with db. Dead quiet, and a audiophile like warm but still hifi sound.

Yes, i can well understand that sometimes the 70Hz is a bit limiting. That's why i made it switchable. (In contrast to the smaller amps where it increases the usable headroom a lot.

BTW: at present i am planning to tweak an Epiphone Valve Junior which has already modded for use with a bass guitar toward the limits possible with the power supply. It looks as if 8 W might possible with a 6L6GC in the power stage and a more or less fully renewed preamp. But that is pretty tricky because of the limited rail voltage. A nice side effect is lots of ideas to improve the 2nd Valve Junior ...

 

[Muziekschuur]

I took the Dynacord BC800 from my storage to my house. Nice 8x10 cabinet. Any big Dynacord bass cabinet owners here?

 

[Matthijs]

I never see those big cabs anymore. Back then they were the stuff I’d dream about owning one time. Right now my back is hurting just by the thought of getting one out of the car.

How does it sound? Does it hold up to modern times?

 

[Muziekschuur]

I think 8x10's are muddy by nature.. I have a 4x12 by Hiwatt. It sounds better. Due to the 12's. I bought it primarily because it would complete my BA300. It looks amazing.

 

[beate_r]

Well, a bit old. But i did some successful work on my two gold cages. A simple mod, and a ground loop built in durint production (!) is finally gone.

I just love love those Echolette M40's. You just can't beat the looks of those...

M40 on a 215 stack. Loud as hell... regarding its 32W.
Input tube replaced by a ECC82/1AU7 - it was too sensitive for modern powerful pickups.
(The G2000 keeps silent; it need new output tubes).

 

[Muziekschuur]

That just takes the cake. What a look.

 

[Deleted member 271037]

Lots of great info about Dynacord amps in this thread!

Perhaps someone can help me with the following question:

I just got a Bass-King 1 for free and I'm not sure about the position of the preamp tubes. The schematic doesn't seem to list the tubes in the order they're currently installed inside the amp.

I'm pretty rubbish at reading schematics so I might be reading this wrong but the previous owner said he thought the amp had some issues (it hasn't been used for years...). I want to make sure the tubes are at least in the correct positions before powering it up.

Looking at the attached pic, are the red or the green tube positions correct?

At least I know from the schematic that the first two preamp tubes (not labelled in this pic) should be ECC808 but I haven't opened up the chassis enough to see what's actually in there yet.

 

[Arrow]

Great to see there's a Dynacord club going on! Not much activity but a good read!

I have 2 1969 Dynacord amps, a Bassking T and a Hifi Favorit 2. 40 Watts and 80 watts. Both are serviced completely and sound so good!
I finally found my sound after having owned lots of amps. This is a sound of its own, I'm totally in love!

Especially connected to the 15 inch 1974 Dynacord Basscab I just bought an hour drive from my home in The Netherlands.

Since I play with IEM, the amp doesn't need to be cranked up. Our soundtech said it is the best sounding amp I ever took with me.

I can leave the cab at home cause I use the head going in a loadbox. That works great!

I hope there are a lot more Dynacord users that respond to keep this thread alive!

Here are my beauties: