Hiraga 30W vs. Le Monstre

[JohanH]

Today I listened to my 3 Monstres.

All are built with original transistors: one has Kiwame resistors, one has tantalum resistors and the last one I bought already made so I don’t know which type of resistors are used.
The first two are powered by the same PSU, which has about 900000 uF capacitance and a 160VA transformer. The last one has the same capacitance and a 300VA transformer.

Because the Monstres do not like my ESLs (more on that later) I listened to them on a Focal 2-way system housed in a drainage-pipe Daline type enclosure.

To cut a long story shorter, I didn’t like the Kiwame version. It had an edgy feeling and didn’t have the smoothness and natural sound of the other 2. Don’t get me wrong: it sounds very good, but the other 2 were just better.
I will try Jazz’s mods on this one and let you know if and how it improves.

The tantalum and 300VA version were very close: closer than I had expected. The 300VA version exhibited more detail, air and sounded more natural. The difference was minute but noticeable. Yet the tantalum version sounded cleaner, less edgy. In the end I think I would prefer the tantalum version.

My feeling now is that of the resistors I have tried until now in the Monstre, I prefer tantalum. I also feel that the Monstre benefits from using a larger transformer. Next step will be building a tweakable PSU based on a 300VA transformer for the tantalum version to further explore the influence of the PSU on the Monstre. Again, I will keep you posted.

In another thread I mentioned my problems with the Monstre and my ESL. I think I solved that now. A short while ago I measured the impedance of the ESLs and it falls to about 0,8 ohms at 20 kHz. My 30W Hiraga doesn’t seem to mind but the Monstre does. After some experimenting with correction filters I now have a LR filter that puts the 20 kHz impedance at about 4 ohms; more Monstre-friendly.
Because the 300VA Monstre is in a presentable housing I hooked it up to the ESLs instead of the Hiraga.
Wow. It does everything the Hiraga does and then some. Voices and instruments sound more natural, less grainy/edgy. Again, the Hiraga does this very, very well: the Monstre is just better.
The impedance correction filter also takes away some of the highs so next step is decreasing the resistance until the Monstre can’t cope anymore.

So my first question is answered: the 30W Class A will be / is replaced with a Monstre. Some further tweaking will be done to get the most out of it.

Am I done?
No, of course not.
A friendly forumner sent me some JLH PCBs, which I will first stuff with tantalum resistors and then see how it compares in my system with the Monstre.
I will keep you posted.

Johan

[ggta]

I have all the components exept transformer to built a 30W class A (original nec transistors).

How much VA would you suggest for the transformer. one or two transformer?

I have 12 caps of 22000 µF each. Do you think it is necessary to use all of them?

Have you compared such amps with a Zen, an Aleph or another class A amp?

[JohanH]

Hello ggta,

If memory serves me well I used a 500VA transformer; minimum would be in the neighborhood of 200VA but Hiraga (and many others) liked to play safe in this area and at least doubled the wattage available.
I think building it dual mono (2 transformers, rectifier bridges, capacitors) would be best, but more expensive. Single PSU works well enough.

I would use all those caps; mine has 12 times 78000. You could start with the ones you have and add more later to test the benefits.

There are others on this forum that have compared the Hiraga and Monstre to e.g. the JLH and others (see posts on amplifier ranking, favorite amps etc.)
Unfortunately I don't have first hand experience with the Pass amps, but I'd love to compare them.

[ggta]

Thanks for your answer.

I think I will start by 2*225 VA with 6*22000 µF for each transformer.

I will certainly build a BOZOZ as preamp. Have you tried symetrical entries on your Class A?

[JohanH]

Hello ggta,

with those fairly low (ahum) capacitance per channel, be sure to add the resistors in the PSU to avoid hum.

[Upupa Epops]

After my thirty years experience in electronic I hear at first time about tantalum resistors. What is this ?

[ggta]

Originally posted by JohanH
Hello ggta,

with those fairly low (ahum) capacitance per channel, be sure to add the resistors in the PSU to avoid hum.

Which value would you recommand for the resistors?

Do youy think it is better to reduce the hum to have:

- one transformer of 500 VA with 12 * 22 000 µF (total of 264 000 µF) for all the amp

or

-two transformers of 225 VA with 6 * 22 000 µF for each channel (total of 264 000 µF for all the amp)

[analog_sa]

After my thirty years experience in electronic I hear at first time about tantalum resistors. What is this ?

Amazing. Was that industrial electronics? I used tantalums for the first time in 1984.

[Upupa Epops]

Any type for searching ?

[MikeW]

Pass mini-a compares very well with these amps. It depends on what material you listen to. I have built all three and like them all.