Yamaha DG 80 (A) / DG 100 (A)/ DG 130 (A)

[david.krause63]

Okay Adrian,

I'm assuming that the speakers are connected correctly and that you can't hear the slightest noise in front of them. Normally a relay inside the amplifier clicks shortly after power on. If you can't hear this either, then there really is a fault in the power amplifier!

The service documents can be found here:

viewtopic.php?t=14662

If you don't have the confidence to do it yourself, any radio or TV technician should be able to handle it. After all the power amplifier is no rocket science but common analog audio gear, and the more sophisticated digital part seems to work.

David

[Bustamelody]

No not at all!!

Thank you for being so kind as to detail the best approach, wise words and I appreciate the reply

[BassGuitarFreak]

Hi there,

I recently had the problem that my DG80-112 did not make any sound anymore. In my case the reason was one fuse on the power amp PCB which was blown. I just had to replace the fuse and the amp is working again! Perhaps it is the same on your device?

Roland

[Scott66]

Hi folks,

Brand new poster here and it's great to see conversation about the DG series still going. I owned a DG100-212A many years ago and foolishly sold it due to a somewhat misguided search for an amp that would fit in with the band I was in at the time.

Turns out that was a terrible idea, and ever since then I kept my eyes and ears open for another DG someone might be willing to part with.

Fast forward a decade or so and I see a DG100-212A pop up for sale not far from where I live , so straight down with a (very reasonable) fistful of dollars and the deal was done!

Now, I love my DG but the only thing that annoys me is seeing a blank spot where a chicken head knob should be...so...

Does anyone know any way, anyhow, anywhere, that I might be able to acquire just 1 knob

Yamaha apparently no longer stock them, and I've turned Google upside down to try and find one with no luck (although Google did lead me here so that's a win

Alternatively, is anyone aware of a suitable replacement knob? I know there are heaps of chicken head knobs available but I'm having trouble finding one with similar features as the original i.e. size, shape etc. Not concerned about the spline as that can be modified to fit and is hidden anyway.

Any help would be greatly appreciated.

[david.krause63]

These knobs are a real pain! There is still not much to add to this thread:

viewtopic.php?t=14927

David

[Rocketguitar]

Hello

I’m a long time user of the Yamaha dg amps, I’ve gigged exclusively with my dg80 since about 2003.

Recently, the power amp section of the dg80 failed (I’m getting it fixed) so I happened upon a dg100 locally so I’ve bought that while the other is repaired.

This one is different to my old dg. The trim control, when set to high and the light hits red, will distort (but not in a good way) the guitar sound. It’s a pre software update one (no chorus or vibrato). My other amp I could slam into the red and it’d make no difference to the sound (I used to have a dg130 and it was the same).

Any ideas what would cause it? Would the software update fix it?

Thanks in advance.

[david.krause63]

Some people keep their amplifier in the cellar or attic for years before they sell it. When they give it a final test before offering, they are sometimes faced with a E6 error (battery empty)! Often they change the battery after that, but don't realize that the RAM has already been partially deleted!

In that case a factory reset (turning power on while simultaneously pressing LEAD1 and RECALL switch) should solve the problem...

If that doesn't help, the build in test program (turning power on while simultaneously pressing MODE, REVERB and DRIVE2 switch) is described in detail starting on page 18 of the service manual.

viewtopic.php?t=14662

The software update would also fix it, as it overwrites all the data in the ROM and RAM. But I guess you will do that, after your DG80 is fixed, as you certainly don't want to end up with two bricked amps (when something goes wrong during the update process)...

David

[Rocketguitar]

Thanks for the reply, David. I appreciate it.

I’ve tried the lead 1 recall hold down , but no change, unfortunately.

I’ve looked at the manual regarding the test program, but it doesn’t explicitly talk about how to adjust the input limiter/gain. Perhaps I’m
Missing something?

I’ll probably wait until the dg80 is fixed and then
Have a go at upgrading the software to see if that will resolve the issue. I’ll talk to the amp tech when I drop it off, too.

The dg series amps are by far the best one ever played or owned. I love the sound, the dynamics and interactions between the guitar and amp. I’ve got two magic stomps and two ud stomps, so if worst came to worst I could still get that sound via another power amp.

[david.krause63]

I can confirm that there is no difference between a DG80 and DG100 in the input stage and that neither the gain nor the LEDs are adjustable. At least with firmware V2 both amps behave the same.

I must admit that i am no longer sure whether the test routines were even present in the original firmware V1! It will probably be best to update the firmware first and see if that solves the problem.

If not, the test routines 81 and 82 check the digital processing including gain and sensitivity. There is also a RAM and FLASH-ROM check routine (just in case).

David

[Rocketguitar]

I’ve got my dg80 back from the amp repair (sickamps.co.uk in Harlow, Essex). The problem was a big capacitor right before the speaker output had blown. The repairer said it was an odd design to put such a capacitor there, it considering the amp is almost 30 years old, I think it’s done pretty well!

Now to try and update the software on the dg100!

[david.krause63]

The design of the power amp part is 50 years old by now! It was used almost unchanged since the appearance of the G100 amp in the early 70ies!

The design of the amp is very odd indeed. It is not voltage drive like solid state HiFi amps but current driven like tube amps! That design and the fact that the 2200µF capacitor (which was probably blown in your case) is in series to the loudspeaker results in a very poor damping factor which lets the speakers breathe freely and produce their own specific sound.

No transistor amplifier that I know of reacts in such a way to different loudspeakers. You can check this by swapping the speakers from the dg80 with the DG100. You will never get such a different sound between the V30 and the Celestion-G100 with any usual voltage driven transistor amp. There is no need for a speaker simulation (which you need with voltage driven linear amps with a very good damping factor, which is good for HiFi when you don't want to colour the sound.)

Regards, David

[Stefan Markowitz]

No transistor amplifier that I know of reacts in such a way to different loudspeakers. You can check this by swapping the speakers from the dg80 with the DG100. You will never get such a different sound between the V30 and the Celestion-G100 with any usual voltage driven transistor amp. There is no need for a speaker simulation (which you need with voltage driven linear amps with a very good damping factor, which is good for HiFi when you don't want to colour the sound.)

I partly disagree to that:
The power amp of the DG100 is different to the DG80 and DG130 - it (DG100) has a different sizing of the feedback loop, which does not emphasize the effect of a somehat current drive characteristic as much as on the 80 and 130. This leads to a smoother sound IMHO. I realized that years ago, when I bought a DG130 (I already hat the DG100) and was unhappy with it's sound. As a simple solution I swapped the amp chassis from the (to me) better sounding DG100 into the case of the DG130. Meanwhile I changed the feedback circuit so that they are identical in sound.
I play the DG amps through different power amps, sometimes the built-in, sometimes tube amps, and often through a cheap class D power amp, wich is in my 19" rack, initially bought as backup, but it is really good sounding.
BTW, the Marshall Valvestate power amp utilizes the same principle in order to exhibit a tube-like current drive to the speakers. But It is dimensioned too strong for my taste, I installed a potentiometer to be able to adjust it from to HiFi to Valvestate, so I can adjust it to a sweet spot..

[Stefan Markowitz]

Now to try and update the software on the dg100!

It will be interesting to see whether the distortion problem goes away after the update.
I tried how my DG80 responds when turning the TRIM to max.
When playing a clean sound it behaves like an slightly overdriven tube amp (strong humbucker, hard strumming, red LED on), not at all bad sounding.
But when using a distorted sound (Drive2), it gets an ugly sound when the red LED flashes strong, this seems to be the typical behaviour.

[david.krause63]

I'm aware of the different feedback parameters. I always thougt it's due to the different speaker impedance. Both DG80 and DG130 usually feed into 8 ohm speakers (DG80 into a single celestion G100 and DG130 into a s412v cabinet with four celestion V30, where two are parallel connected in series to the other pair). The DG 100 is the only one which has to feed into 4 ohm (two V30 in parallel) , which is compensated by the different feedback circuit.

I also did some tests many years ago to find out why there are 3 different software updates although they use the same PCB with only minor differences. In my opinion, the only difference is the speaker simulation for the line out, matching the respective speakers.

And yes, I'm also very curious to see if the software update will solve the distortion problem!

David

[Stefan Markowitz]

I also did some tests many years ago to find out why there are 3 different software updates although they use the same PCB with only minor differences. In my opinion, the only difference is the speaker simulation for the line out, matching the respective speakers.

Maybe I wrote this already years ago, there are also small differences in the FX loop. The level is different for DG100 and DG130. But this does not affect the sound, the difference in sound is only related to the difference in the PA's feedback loop. I never compared the software versions.

BTW, when talking about amp sounds it's always interesting to hear something. On my Youtube channel there are some cilps, on all of them I'm playing through a DG amp (DG1000, DG130, DG80) with different combinations of speakers and power amps (DG130 usually sitting on a 4x12 cab and using it's built-in power amp). It is very convenient to be able to clone the settings from one amp to another.
https://www.youtube.com/@dex-livevideo9115/videos

Stefan