I'm thinking about trying a pair of the Sunbuck 2A3 monoblock amps that I have found on AliExpress and I wonder if anyone has any experience with them. Right now I'm using BRZ HiFi 300b monoblocks on the squawkers of my LaScalas and ACA monoblocks for the tweeters. The new amps would be for the tweeters, obviously.
I'm very impressed with my 300b amps and even more so now that they are just tasked with the mid-range. I replaced the WIMA coupling caps with nice Audio Note copper foils and took them to a whole 'nother level. Buying this sort of cheap equipment from China is something of a risk but I've had good luck so far.
Pete
I'm very impressed with my 300b amps and even more so now that they are just tasked with the mid-range. I replaced the WIMA coupling caps with nice Audio Note copper foils and took them to a whole 'nother level. Buying this sort of cheap equipment from China is something of a risk but I've had good luck so far.
Pete
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"I'm very impressed with my 300b amps and even more so now that they are just tasked with the mid-range."
Does that mean the bass response is poor? There doesn't look like a whole lot of iron in the output transformer.
Does that mean the bass response is poor? There doesn't look like a whole lot of iron in the output transformer.
I used the BRZ amps full range for a while and couldn't get the bass bins to integrate properly with the squawkers and tweeters -- there was too much bass in my room. I was happy enough with the quality of the bass but I wanted less of it. So, I started bi-amping the speakers, just using the crossovers for passive bi-amping. I had already been bi-wired so it wasn't difficult. The system sounded much better with the 300b amps just trying to drive the high pass section of the squawker crossover rather than a woofer, but I recently got a MiniDSP so now the 300b monoblocks are connected directly to the squawkers. With no crossovers and restricted frequency demands, I'm getting all of the mid-range magic that they have to offer, I think.
The output transformers are small but something like my LaScalas are an easy load for them, especially at the moderate levels that I tend to. I don't know about the Sunbuck amps but my plan is to just use them for the tweeters so an undersized OT won't be much of an issue.
BTW, the OTs look to be about the same size as the 'properly sized' AudioNote iron. Most amps tend to go up a size or two, and for good reason.
Pete
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Well, I bit the bullet and ordered a pair. They should be here by the end of the week.
I ordered the 115v version and plan to plug them directly into the wall outlets. I have a dedicated power panel going to my listening room and the outlets generally run around 124v. They come with 5U4G rectifiers.
My BRZ amps have 110v power transformers so I'm using bucking transformers, and I have switched to 5AR4 rectifiers. I like the slower turn on that they provide and the slightly higher plate voltage suits the 300b tubes.
My dilemma is whether or not to change the rectifiers in my new amps. The heaters should be okay with the higher line voltage but I wonder about the output tubes. The 30 volts or so from the 5AR4s plus the 8% or so from the wall sounds like it will be getting close to the limit.
What do you guys think?
Thx,
Pete
I ordered the 115v version and plan to plug them directly into the wall outlets. I have a dedicated power panel going to my listening room and the outlets generally run around 124v. They come with 5U4G rectifiers.
My BRZ amps have 110v power transformers so I'm using bucking transformers, and I have switched to 5AR4 rectifiers. I like the slower turn on that they provide and the slightly higher plate voltage suits the 300b tubes.
My dilemma is whether or not to change the rectifiers in my new amps. The heaters should be okay with the higher line voltage but I wonder about the output tubes. The 30 volts or so from the 5AR4s plus the 8% or so from the wall sounds like it will be getting close to the limit.
What do you guys think?
Thx,
Pete
My power mains run from 117VAC to 123VAC. I design my amplifiers to run off of 120VAC center, so the mains voltage is within + /- 3V.
Your mileage may vary.
Your mileage may vary.
Pete,
I use variAC on my Chinese tube amps. The correct voltage save the tube from burning out.
I use variAC on my Chinese tube amps. The correct voltage save the tube from burning out.
My monoblocks arrived safely a week ago.
I ordered them with tubes for an extra $165 and assumed that I would need to get better ones.
The output transformers seem tiny but these are 3.5 watt amplifiers and I'm just using them for the tweeters so I can't imagine that I'm anywhere near saturating them. They seem quite well put together and are in the same cabinets as the Wright Mono 8 amps that I have, but these guys are nicely ventilated. They couldn't be simpler inside and the solder joints look pretty good.
After the first night of listening I had decided that they are going to work well. I replaced the SAMR polypropylene coupling capacitors with some AuriCaps that I had on hand and now with 50 hours or so on them I'm very happy.
I had been using a pair of ACA amps as bridged monoblocks for the tweeter horns and these new 2A3 amps are a nice step in the right direction. They are more 3D and sweeter sounding but still a bit closed-in on top. As the tubes settle in the top octave is opening up nicely.
I got Chinese 300B amps last year with $150 worth of tubes included and they only came alive when I put in better tubes. I thought that I would need to get better 2A3s but at this point I'm not sure, the included tubes sound pretty wonderful.
Pete
I ordered them with tubes for an extra $165 and assumed that I would need to get better ones.
The output transformers seem tiny but these are 3.5 watt amplifiers and I'm just using them for the tweeters so I can't imagine that I'm anywhere near saturating them. They seem quite well put together and are in the same cabinets as the Wright Mono 8 amps that I have, but these guys are nicely ventilated. They couldn't be simpler inside and the solder joints look pretty good.
After the first night of listening I had decided that they are going to work well. I replaced the SAMR polypropylene coupling capacitors with some AuriCaps that I had on hand and now with 50 hours or so on them I'm very happy.
I had been using a pair of ACA amps as bridged monoblocks for the tweeter horns and these new 2A3 amps are a nice step in the right direction. They are more 3D and sweeter sounding but still a bit closed-in on top. As the tubes settle in the top octave is opening up nicely.
I got Chinese 300B amps last year with $150 worth of tubes included and they only came alive when I put in better tubes. I thought that I would need to get better 2A3s but at this point I'm not sure, the included tubes sound pretty wonderful.
Pete
Attachments
Pete,
Happy to hear you like the 300B blocks
I use a Sylvania 6sn7 preamp tube and it's sound very good in these amps.
I will change WIMA MKP 10 0.1 250V to WIMA MKP 10 0.1 1000V.
Did you replace any other caps to improve the sound?
BTW, I am loving my new Elekit TU-8400. I am considering install KT-170's
Happy to hear you like the 300B blocks
I use a Sylvania 6sn7 preamp tube and it's sound very good in these amps.
I will change WIMA MKP 10 0.1 250V to WIMA MKP 10 0.1 1000V.
Did you replace any other caps to improve the sound?
BTW, I am loving my new Elekit TU-8400. I am considering install KT-170's