Yes it is but I changed several things which yielded big improvements. In order of significance:
Tent labs heater boards on the 300B's. This brought my audible noise down to barely being able to discern that its turned on with 106db spl speakers. (La Scalas)
Intact audio autoformers on the volume controls. This lifted a veil and revealed much more detail.
Power supply is 100% film caps. Yes they are the size of soup cans. I also adjusted a few resistor values to bring the B+ to 390V and 180v on the D3a's.
Coupling caps are 4.7uf Deulund cast copper. The 4.7uf greatly improves bass response vs the .47 his schematic shows.
I am using the Linlai WE300B clones and have nothing but good things to say about them. I can't tell the difference to a pair of modern Western Electrics and at $580 a pair thats a bargain. I love this amp.I would like to A/B it against some of the high end professionally built models sometime. Very curious how it would fair. But I can recommend this build to anyone. Esp with the changes I made. The film caps didn't make much difference that I could tell but the heater boards and the volume controls are a must have IMO.
Tent labs heater boards on the 300B's. This brought my audible noise down to barely being able to discern that its turned on with 106db spl speakers. (La Scalas)
Intact audio autoformers on the volume controls. This lifted a veil and revealed much more detail.
Power supply is 100% film caps. Yes they are the size of soup cans. I also adjusted a few resistor values to bring the B+ to 390V and 180v on the D3a's.
Coupling caps are 4.7uf Deulund cast copper. The 4.7uf greatly improves bass response vs the .47 his schematic shows.
I am using the Linlai WE300B clones and have nothing but good things to say about them. I can't tell the difference to a pair of modern Western Electrics and at $580 a pair thats a bargain. I love this amp.I would like to A/B it against some of the high end professionally built models sometime. Very curious how it would fair. But I can recommend this build to anyone. Esp with the changes I made. The film caps didn't make much difference that I could tell but the heater boards and the volume controls are a must have IMO.
I am building the same amplifier and I am also making some changes to it:
I am also looking for higher grade OPTs than the Lundhals, but I am having a hard time to come to a decision about which one would be the best substitute.
- DC filaments with Rod Coleman's power supplies
- High current (>300mA) cathode led bias for the D3a
- Fixed high voltage LED anode bias for the 300B
- Film capacitors for the PSU (Wima DC-Link)
- 1uF Duelund Cu/Ag coupling caps.
I am also looking for higher grade OPTs than the Lundhals, but I am having a hard time to come to a decision about which one would be the best substitute.
I have used a pair of Amplimo (= same as Plitron) toroid transformers. Massive, 5,4 kilos each. I might sell them.
See also: https://pearl-hifi.com/06_Lit_Archi...n_der_Veen_Menno/SE_300B_Amp_w_Plitron_OT.pdf
See also: https://pearl-hifi.com/06_Lit_Archi...n_der_Veen_Menno/SE_300B_Amp_w_Plitron_OT.pdf
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@banpuku sold his SX-11 Nano:
https://www.diyaudio.com/community/threads/monolith-magnetics-chokes-pt-and-opt.388522/#post-7574747
It has a little different parameters: 22H, 203R RDC.
I have S-9 and S-15, both of them very good OPT ... but measured parameters does not fully match published data.
@jwags81818 I will share the updated schematic later this morning, when I get back to my computer.
On the D3a I came up with the idea of using a combo of LED bias and filament bias. In that way I am basically flooding a large LED (with very low differential resistance dV/dI<0.5 ohm) and obtain high ac rejection on the cathode voltage, without using a capacitor. I haven't built it yet, so I haven't been able to validate how it performs but I believe it should work well.
Regarding the coupling capacitor, I also thought that 0.47u was too small, based on the simulation I ran. But I didn't dare to go past 1uF because, in my past experience, I noticed that some amps sound sluggish when the coupling capacitor gets too big. But it's good to hear that with this amp I can indulge with the coupling capacitor size if necessary!
I am far from you, in Fremont CA unfortunately, but if one day I pass by where you live I'll definitely let you know!
On the D3a I came up with the idea of using a combo of LED bias and filament bias. In that way I am basically flooding a large LED (with very low differential resistance dV/dI<0.5 ohm) and obtain high ac rejection on the cathode voltage, without using a capacitor. I haven't built it yet, so I haven't been able to validate how it performs but I believe it should work well.
Regarding the coupling capacitor, I also thought that 0.47u was too small, based on the simulation I ran. But I didn't dare to go past 1uF because, in my past experience, I noticed that some amps sound sluggish when the coupling capacitor gets too big. But it's good to hear that with this amp I can indulge with the coupling capacitor size if necessary!
I am far from you, in Fremont CA unfortunately, but if one day I pass by where you live I'll definitely let you know!
You are going to LOVE this amp. I have spent the past 4-5 years tweeking it. Spend the money on the autoformer volume controls. It reveals so much more detail than a resistive one does. Your amp should also be dead silent. Granted I built a PCB for mine but your point to point build should be silent as well. Even with my 106 db spl speakers you can';t hardly tell its turned on. Also its not sluggish at all. On his web site he has response plots of .47 and 4.7. check them out. You will want the bigger caps.
Unfortunately. I managed to pick up a level one opt near the end. It’s very good.
I noticed this the least in all the changes I made to my amp. Granted I was using Soviet mil-spec PIO caps prior to the switch to all film but I didn't notice a big change. Now transformer volume controls are another story. I don't see how anyone that has tried them could ever use anything else. It was like pulling 2 thick bed sheets off my speakers. You just hear so much more. Very good low volume performance as well. I would love to try some silver ones. But even the copper variety is a tremendous improvement. FYI I used the ones from Intact Audio. Worth every cent.
I've noticed a big improvement by bypassing e-caps with film caps, with a ratio 1:100 approximately (220u e-caps and 2u2 film caps).
I tried film caps only a long time ago and I kept e-caps with film paralleled as the difference wasn't that evident.
Do you feel full film cap PSU is it that way better than paralleled 'litics & film caps?
Hi Everyone. Regarding iron, I have owned a few over the years. Monolith SX-11 Nano, IntactAudio Nickel, J&K Audio. I sold these units, not because they were poor sounding. They are very good products. Rather, in my opinion, the finest are produced by Muse Coils (Alexander). His Minotaur series is the creme de la creme. Just one man's opinion. Here is a photo of lastest product using all Muse Coils. Simply the best in my experience.
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