"I will try to connect this preamp to Solid State Power amp I have Rotel RB-981. I don't know input impedance of RB-981. So I attach schematic of it."
There is a 33k from input to ground so at least <33k, normally solid state has standard 10k input impedance, so you also have to increase output cap C1 to 10u for best sound.
There is a 33k from input to ground so at least <33k, normally solid state has standard 10k input impedance, so you also have to increase output cap C1 to 10u for best sound.
C1 to 10uF 400V? wow I don't know how big is it? The K75-10 2.2uF 400V size is 10 centimeters. If 10uF 400V, I have to purchase other brand. Can you recommend other brand of 10uF 400V or I just need 10 uf 250V for smaller size?
I will try to find Wima MKP 10 first at Bangkok's Electronic shop.
Thank you Mr. Koonw. You are so kind. If you don't advice me, I will not know and just simply build as what diagram provide.
So I conclude that
- C1 shall be 10uF 400V (250V) to match with input impedance of Rotel RB-981
- C5 shall be 1uF 400V (250V) to linear the flat frequency to get more netural bass without phase shift to boost "fake" bass. I will get tight bass as it provide by my DAC (AKM4399 dual).
Can C1 & C5 be 250V rate? to get smaller size?
Thank you so much
Nut
So sad I bought 300VAC 500ma and 6.3V 4Amps and 5V 5 amps already.
Can I use them? The PCB states to be 300VAC. It is 50VAC higher than your recommendation.
See attached. There is little difference when the HT is increased by 50V or so. The distortion (0.82%/0.79%) has dropped a bit, and there are plenty of headroom.
"Can C1 & C5 be 250V rate? to get smaller size?"
DC now on the caps is at least 212V, so 250V is minimum, 400V is recommended. If you wire feedback cap 1u to output after output cap 10u, there is no more DC, so 1u can be as low as 50V. For 10u/400V, you can try high quality electrolytic cap which is smaller.
Attachments
Last edited:
Hi Mr. Koonw,
- Electrolytic might sound not as good as MKT or PIO (paper in oil).
- For PIO 10uF 400V will be too expensive and very big. I decide to use Vishay MKT 1813 10uF 250V. I think 250V can handle 212VDC in circuit.
- For 1uF 400V, I can find good PIO such as K75-10.
- Most Electrolytic @400V rate are polarity capacitors (+,-). How to know the direction of + and - in circuit. I attach picture on PCB whether it is correct direction.
Thank you.
- Electrolytic might sound not as good as MKT or PIO (paper in oil).
- For PIO 10uF 400V will be too expensive and very big. I decide to use Vishay MKT 1813 10uF 250V. I think 250V can handle 212VDC in circuit.
- For 1uF 400V, I can find good PIO such as K75-10.
- Most Electrolytic @400V rate are polarity capacitors (+,-). How to know the direction of + and - in circuit. I attach picture on PCB whether it is correct direction.
Thank you.
Attachments
Thank you so much Mr. Koonw. Let's start build this preamp.
This preamp will not be good if Mr.Koonw doesn't help me.
Mr. Koonw You are the best. Are you Malasian Guy? I think we are nearby.
Thank you so much Mr. Koonw. Let's start build this preamp.
This preamp will not be good if Mr.Koonw doesn't help me.
Mr. Koonw You are the best. Are you Malasian Guy? I think we are nearby.
Not problem, you're welcomed. I'm in Eastern Malaysia, have hays and hot weather, but ok I stay at home. Me too try to improve my own things so I am too learning from everybody.
Same hot weather here too. Now is 36C in Bangkok. I will evade to Moscow and St. Petersburg to get 12C.
I will try to find K75-10 1uF 400V there too if I have time.
Last question if I change 4 capcitors Left & Right (1uF & 10uF) I can plug directly to my Power amp ROTEL RB-981 with good sonic right?
I ever try to use volume via DAC (Dual AKM4399) and plug directly to Rotel RB-981.
I think it sound not as good as using E100 Headphone amp as preamp.
Why using Preamp between DAC & Power amp sound better and warmer than plug it directly from DAC to Poweramp?
I hope Cary will sound better than E100 as preamp.
Solid state DAC -> solid state amp has to have tubes in between to give you the harmonics or sonic you like, because in general solid state device has more odd harmonic. If DAC-> direct to tube amp, you can hear the difference too because the tube harmonic will dominate over the solid state harmonics. I don't have a tube preamp, my Denon 1815 just go directly to tube amp and I use variable electronic volume control. The harmonic distortion of power amp is very important also as it can take a long time to develop the preferred sonic just like the preamp. You can use PC sound card based spectrum analyzer such as WaveSpectra and microphone to help you to see what you're hearing from overall system. For tone source I just cut a CD with 1khz or other frequency even I have other test gears.
Last edited:
"tube harmonic will dominate over the solid state harmonics" I think that why DAC --> E100 tube HP --> ROTEL RB-981 sound better than DAC --> RB-981.
I think I prefer tube harmonic over solid state harmonic. It is warmer to my ears.
I have 14 tubes of 6SN7s to roll in the Cary AE-1 Preamp. I hope I will got tubes that suit my listening preference.
Thank you so much Mr. Koonw. You always provide knowledge to me and other people in this Forum.
You told me you live with "Hay". I envy you are in Rural with good atmosphere. I stuck in Bangkok which has a lot pollution. I will find new house in Rural when I have more money.
Hi Mr. Koonw
Sorry for bothering you again.
For 10uF 400V, I have a lot of good electrolytic 33uF 400V.
Can I replace 33uF 400V instead of 10uF 400V?
Is it still provide flat response with no phase shift?
Can you give me picture of frequency response and phase of 33uF 400V?
Thank you so much.
Sorry for bothering you again.
For 10uF 400V, I have a lot of good electrolytic 33uF 400V.
Can I replace 33uF 400V instead of 10uF 400V?
Is it still provide flat response with no phase shift?
Can you give me picture of frequency response and phase of 33uF 400V?
Thank you so much.
How about this: "Panasonic HFQ series. These capacitors boast good ESR and DA performance in a reasonably-sized package and don't cost as much as earlier high-performance electrolytics."
Last edited:
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.