So.... Finally I got some time and energy to go to the first stage of tweaking. I did one channel first, and the next day the second one. First step means just some changes in the power supply and two capacitors on the main board.
Having a closer look at the power supply board I realized that there is additional space for extra blade terminals:
So it is rather easy to add additional wiring to the existing one and so doubling up on wire size from the power supply to the amplifier and also to the speaker outputs. Conveniently there are also solder pads on the amplifier board.
I also added 2 220uf 100V Nichicon KZ to the power supply as Niekos did before.
Then I replaced two 330uf caps with Elna Silmics, they are right at the input transistors, so they should have quite some impact on the sound.
As they are pretty long I put tape on top to avoid some short circuit with the power supply board, but it turned out to be unnecessary later on.
Last step was to use copper end sleeves for the speaker output wire, they are crimped and then firmly screwed down in the speaker terminals. The original brass rings were also crimped by the way, which is always a better connection than soldering.
Having a closer look at the power supply board I realized that there is additional space for extra blade terminals:
So it is rather easy to add additional wiring to the existing one and so doubling up on wire size from the power supply to the amplifier and also to the speaker outputs. Conveniently there are also solder pads on the amplifier board.
I also added 2 220uf 100V Nichicon KZ to the power supply as Niekos did before.
Then I replaced two 330uf caps with Elna Silmics, they are right at the input transistors, so they should have quite some impact on the sound.
As they are pretty long I put tape on top to avoid some short circuit with the power supply board, but it turned out to be unnecessary later on.
Last step was to use copper end sleeves for the speaker output wire, they are crimped and then firmly screwed down in the speaker terminals. The original brass rings were also crimped by the way, which is always a better connection than soldering.
So, big question ist of course: how does it sound?
Honestly I didn't expect that much of a change and was surprised how much I was wrong.
The amp sounds bigger, more effortless and smoother now. This is especially noticeable in complex passages, and with demanding music like tenor saxophone, high piano notes and female voices.
The days before I put in my EL34 ppp circlotrone amp, which has a beautiful tonality and can sound really seductive while still being clear.
The clone has now made a good step towards that tube amp sound without the downsides, still very good control, deep bass and huge space, maybe even bigger than before.
I guess that the Elna Silmics are responsible for the beautiful tone, it sounds a little darker than before with the tonal balance shifted a little bit towards the lower mid range.
But because I will swap the input caps for the Miflex this will be balanced out again, because those should be far more transparent than the Wima MKS.
But also without changing the input caps I like it much more than without those tweaks. It just fits to the music I'm listening to which is jazz, classical music, experimental and sometimes some Electro. If someone prefers techno or something like that snappier sounding caps could be the ticket for these 330uf.
In any case they have a big impact I'm sure. Don't know about the wires, but the more powerful bass could well be a result of those.
Second step will be then replacing the input caps and resistor.
And on a final note I'm wondering what the purpose of those fuses is. They did nothing to protect the amp of Neiljd, and they are rated for 16A 250V, does that even make sense? I guess I will bypass them, the original amplifier doesn't have them as well.
Honestly I didn't expect that much of a change and was surprised how much I was wrong.
The amp sounds bigger, more effortless and smoother now. This is especially noticeable in complex passages, and with demanding music like tenor saxophone, high piano notes and female voices.
The days before I put in my EL34 ppp circlotrone amp, which has a beautiful tonality and can sound really seductive while still being clear.
The clone has now made a good step towards that tube amp sound without the downsides, still very good control, deep bass and huge space, maybe even bigger than before.
I guess that the Elna Silmics are responsible for the beautiful tone, it sounds a little darker than before with the tonal balance shifted a little bit towards the lower mid range.
But because I will swap the input caps for the Miflex this will be balanced out again, because those should be far more transparent than the Wima MKS.
But also without changing the input caps I like it much more than without those tweaks. It just fits to the music I'm listening to which is jazz, classical music, experimental and sometimes some Electro. If someone prefers techno or something like that snappier sounding caps could be the ticket for these 330uf.
In any case they have a big impact I'm sure. Don't know about the wires, but the more powerful bass could well be a result of those.
Second step will be then replacing the input caps and resistor.
And on a final note I'm wondering what the purpose of those fuses is. They did nothing to protect the amp of Neiljd, and they are rated for 16A 250V, does that even make sense? I guess I will bypass them, the original amplifier doesn't have them as well.
I forgot to mention for one evening I had two different channels and could compare them, the difference was clearly audible with the same music. I could mute each channel separately, so I could switch in seconds between channels.
Good idea! I also noticed the extra blades, but did not check to see if these could be used. What kind of wiring did you use?
Nice! I am waiting for the parts to arrive to replace the capacitors as well, curious how this will affect the sound. I think most impact will be the input caps, I will use the miflex as well (MKP-10), thanks for that tip. I am not sure about the resistor yet, what type will you use? Have you ever used the vishay/charcroft z-foil resistors? I am thinking of using these (also in my tube preamp, I read some good experiences with these. And they also look cool 😎)
Good question, but why add them when not needed? It would add to the total cost unnecessarily?
I will also replace the white resistors with Futaba MPC 71 that you recommended.
When you placed the Elna caps, did you remove the amp board from the cooling chassis? Did you encounter any problems in doing that?
This is all great info thanks a lot. My system has been getting leaner and leaner as I've added silver and rhodium interconnects, cables and plugs and I want to get bit of warmth back so there Silmic capacitors might do the trick. I was going to go with Audio Note Kaisei but I think the Elna's may be a better match. Just still waiting on the amp to get back me.
Hey Niekos that must be me from the Stereonet thread. The Zfoils in the MP701 where a noticeable improvement but as I mentioned above it was another step towards leanness that I'm trying to reverse without sacrificing the considerable amount of detail I have gained fro recent component changes. Maybe the zfoils in the D5 might be too much but I'll be throwing them in and posting my experiences!
I am in the process of following in Jogi's footsteps - just not sure about those additional 220uF Nichicons though. When it comes to the 51R resistors: in another project I replaced those Zfoils with AN Tantalums and found them tonally more pleasing (less leans?) and those Niobiums are even more "colourful" which I find very pleasing to the ear - and no, I do not find them less transparent.
@ Niekos
I just used plain vanilla 1,5mm² speaker litz wire for 3€ at 10 meters.
Never used those Z foil resistors, from what i read about them they should be very transparent but also a little bit too much on the neutral side for some.
As the amp sounds warmer now they could be an option though. Interestingly it sounds more transparent at the same time by the way.
And for the fuses: the original amplifier doesn't have any protection circuit, so they are not really necessary. The clone has relais for DC protection I assume, should be suffice. And also at 16 ampere my house fuse kicks in anyway.
And I did not remove the amplifier board, because I'm lazy as I mentioned before already. I am reluctant to dismantle the whole amp as the risk of screwing up something is increased a lot. I just pulled the capacitor bodies off, so the legs stayed in and I could desolder them easily and pull them out. Then I soldered the Silmics in from above with a thin solder tip, so there is 5mm space between the caps and the board.
@Neiljd
That is exactly the reason I will go for audio note tantalums, because they've have a warm tone while still been very transparent. So the Silmics should be the medicine for you here for sure, maybe even for the two 100uf 100V ones as well.
For a more neutral touch I would use the green Nichicon bipolar ones or even Audio Note Kasei.
It's like cooking, there are many different recipes and also taste is very individual.
And... Really important to double and triple check, of course I soldered one Nichicon with reversed polarity, would have been a nice firework.
Also make sure that nothing touches the heat sink when things are soldered from above, capacitor legs or wire.
One reason I did it in two sessions is not to become tired and sloppy. That's exactly when the magic smoke is released🙂
I just used plain vanilla 1,5mm² speaker litz wire for 3€ at 10 meters.
Never used those Z foil resistors, from what i read about them they should be very transparent but also a little bit too much on the neutral side for some.
As the amp sounds warmer now they could be an option though. Interestingly it sounds more transparent at the same time by the way.
And for the fuses: the original amplifier doesn't have any protection circuit, so they are not really necessary. The clone has relais for DC protection I assume, should be suffice. And also at 16 ampere my house fuse kicks in anyway.
And I did not remove the amplifier board, because I'm lazy as I mentioned before already. I am reluctant to dismantle the whole amp as the risk of screwing up something is increased a lot. I just pulled the capacitor bodies off, so the legs stayed in and I could desolder them easily and pull them out. Then I soldered the Silmics in from above with a thin solder tip, so there is 5mm space between the caps and the board.
@Neiljd
That is exactly the reason I will go for audio note tantalums, because they've have a warm tone while still been very transparent. So the Silmics should be the medicine for you here for sure, maybe even for the two 100uf 100V ones as well.
For a more neutral touch I would use the green Nichicon bipolar ones or even Audio Note Kasei.
It's like cooking, there are many different recipes and also taste is very individual.
And... Really important to double and triple check, of course I soldered one Nichicon with reversed polarity, would have been a nice firework.
Also make sure that nothing touches the heat sink when things are soldered from above, capacitor legs or wire.
One reason I did it in two sessions is not to become tired and sloppy. That's exactly when the magic smoke is released🙂