Duncan,
Great your back in operation. And wasn't hard to work on.
I hardly used the original el34s before I changed to Tungsols.
Hopefully your past troubles. I'm listening to mine now.
On Impulse I ordered a Boyuu Reisong A10 EL34, class A. Any experience? Add your opinion on it.
- Thread starter Old Guy8
- Start date
Great your back in operation. And wasn't hard to work on.
I hardly used the original el34s before I changed to Tungsols.
Hopefully your past troubles. I'm listening to mine now.
I've got a nice, shiny doorstop of an amp, just waiting on my rectifier tube. It shipped almost a month ago from the UK but given the uprooted global mail situation right now, who knows when it will get here?
Would a 5AR4 work in place of a 5Z4G? I hate to buy another tube but I can keep one for a spare, and get one in the US so it arrives in some reasonable amount of time. My limited research makes me think it might work, but I don't know much about tubes (except for those I use in other equipment).
5AR4: http://www.r-type.org/exhib/aaa0997.htm
5Z4G: http://www.r-type.org/exhib/aaa0094.htm
Would a 5AR4 work in place of a 5Z4G? I hate to buy another tube but I can keep one for a spare, and get one in the US so it arrives in some reasonable amount of time. My limited research makes me think it might work, but I don't know much about tubes (except for those I use in other equipment).
5AR4: http://www.r-type.org/exhib/aaa0997.htm
5Z4G: http://www.r-type.org/exhib/aaa0094.htm
Duncan99
New Member
I'm not an expert, put it sure looks to me like it will work. 5AR4 can handle more voltage and current, same pinout, both are 5V heater, indirectly heated, full wave rectifier tubes. This link (read the last entry) agrees. https://forum.audiogon.com/discussions/5z4-half-wave-rectifiers-replacement-suggestion
Small world. That was the post that led me to look for a 5AR4.
I really don't see it offered as a substitute in many places, which is why I thought I'd ask about it here. But I came to the same conclusion that you did, plus I believe the heater current draw is very slightly less. The pinout certainly seems to be the same, as you say. Wish I had looked into it earlier, as I'd have skipped the 5Z4G.
FlaCharlie
Super Member
Please post the schematic. Schematics for the lower cost Chi-Fi offerings are uncommonly difficult to find.
The amps seller supplied the schematic to me (buyer) with the caveat that I not post it on the net.
A pm is a legal out.
FlaCharlie
Super Member
No problem. If you were given the schematic under that agreement I respect that.
That said, in order for it to be someone's intellectual property they would have to have a patent. The patents that were issued years ago for some designs have long since expired and are considered public domain. There's not much new in the world of tube audio, just variations of past designs.
As a result almost all "modern" (commercially available) tube circuits are generally considered to be based on "prior art" and cannot be patented as a result.
I did read about a piece of modern gear a while back which advertised that their power supply was patented. Being patented doesn't mean it's secret. It only means you can't reproduce it commercially without a license. Patented designs are available to the public online and, as far as I know, individuals can legally build them for their personal, non-commercial, use.
Anyway, a quick search turned up this schematic which was posted on AliExpress.
FlaCharlie
Super Member
Are you commenting on my posting the schematic and saying that I should have just kept it to myself?
If so, the whole point of forums like this is to share helpful information. For instance . . .
The schematic shows that it does operate in UL mode as you can see that the screen of the output tube (Pin 4) is tied to an ultralinear tap on the output transformer through a 100 ohm resistor. You can also see that, in stock form, there is no switch that allows you to run it in either triode mode or pentode mode. So if you wanted triode or pentode you would need to modify the amp.
While I don't own one of these amps I am curious about different designs. If you own one it's always a good idea to have a schematic.
As one would expect, there is nothing really innovative about the circuit. It's pretty much the same as the other Chinese SE EL34 amps out there. The main differences I noticed are the use of a different input tube and the fact that they are using a hybrid PS.
Apparently they got a good deal on PTs that don't have a center tap so they created an artificial center tap using diodes in order to use a tube rectifier. I've done this myself with a couple of amps I built from scratch. It works just fine, although I'd use quieter diodes than the 1N4007s.
BMC
Active Member
I have had this amp for a few days. It has been a ride for sure.
This is my first low powered tube amp. I’ve always been a user of high power and lower efficiency speakers (Magnepans, acoustic suspension boxes). So I was a little skeptical that this would work for me. I have used 100 watt Frazier 106c tube monos, Sherwood tube integrateds, Dynacos, etc.
I received the amp on Tuesday. Took a week for shipping. I first tried it on my large Advents, and it severely lacked dynamics and seemed veiled with rolled off treble and bass. I have a sub, so not really needing bass out of my mains. But the lack of air and treble was worrisome.
So I swapped Advents for my old KEF Coda III’s. They are 87db, and were even worse with dynamics on this amp. The mids were sounding really nice though, so I just played light classical tracks for a while.
I then hooked the Advents up again and played Dark Side of the Moon. It was sounding the same as before, when all of a sudden the sound just opened up in the middle of the 2nd track. It sounded like the amp just acquired a set of balls! Then it reverted back to the more veiled sound. This kept happening randomly here and there. At this point I figured the tubes must be burning off gas still?
Next, I bought a pair of Klipsch R-51M bookshelves that I got open box at Best Buy. Figured I could return them if they weren’t to my liking (never owned Klipsch before). So since they were new, they also required breaking in! Once hooked up, I could tell right away that this was going to work just fine. The dynamics were already way better right out of the box.
After a couple of days of breakin, and more sound fluctuations out of the El34’s, it permanently opened up with the “balls”. Wow the veil is off. This is a great match with the Klipsch. HUGE soundstage. Pretty good imaging. Now I can play 2112 and it actually sounds dynamic. Playing Floyd’s Welcome to the Machine was immersive!
So I am really happy with this setup, and still am using the stock el34b’s. I did swap in the Russian rocket tubes I already had on hand. Have some NOS el34s coming my way in a couple of weeks. But in the meantime, I’m just gonna sit back and enjoy.
Final setup:
Apple Airport express optical out
TubeDac09 with GE five star tube
Reisong A10
Klipsch R-51M
Velodyne 1012 sealed sub
Thanks to oldguy8 for starting this thread - it helped me make the decison.
This is my first low powered tube amp. I’ve always been a user of high power and lower efficiency speakers (Magnepans, acoustic suspension boxes). So I was a little skeptical that this would work for me. I have used 100 watt Frazier 106c tube monos, Sherwood tube integrateds, Dynacos, etc.
I received the amp on Tuesday. Took a week for shipping. I first tried it on my large Advents, and it severely lacked dynamics and seemed veiled with rolled off treble and bass. I have a sub, so not really needing bass out of my mains. But the lack of air and treble was worrisome.
So I swapped Advents for my old KEF Coda III’s. They are 87db, and were even worse with dynamics on this amp. The mids were sounding really nice though, so I just played light classical tracks for a while.
I then hooked the Advents up again and played Dark Side of the Moon. It was sounding the same as before, when all of a sudden the sound just opened up in the middle of the 2nd track. It sounded like the amp just acquired a set of balls! Then it reverted back to the more veiled sound. This kept happening randomly here and there. At this point I figured the tubes must be burning off gas still?
Next, I bought a pair of Klipsch R-51M bookshelves that I got open box at Best Buy. Figured I could return them if they weren’t to my liking (never owned Klipsch before). So since they were new, they also required breaking in! Once hooked up, I could tell right away that this was going to work just fine. The dynamics were already way better right out of the box.
After a couple of days of breakin, and more sound fluctuations out of the El34’s, it permanently opened up with the “balls”. Wow the veil is off. This is a great match with the Klipsch. HUGE soundstage. Pretty good imaging. Now I can play 2112 and it actually sounds dynamic. Playing Floyd’s Welcome to the Machine was immersive!
So I am really happy with this setup, and still am using the stock el34b’s. I did swap in the Russian rocket tubes I already had on hand. Have some NOS el34s coming my way in a couple of weeks. But in the meantime, I’m just gonna sit back and enjoy.
Final setup:
Apple Airport express optical out
TubeDac09 with GE five star tube
Reisong A10
Klipsch R-51M
Velodyne 1012 sealed sub
Thanks to oldguy8 for starting this thread - it helped me make the decison.
Last edited:
BMC
Active Member
Small world. That was the post that led me to look for a 5AR4.
I asked the seller on the phone if 5AR4 could be substituted, and he said no. He also said it would not be worth doing anyway, since it would not have any effect on the tone.
I totally get what he was saying, but I went ahead and ordered a NOS 5Z4 just to have a more reliable tube. I would also suspect the dynamics could benefit from having a better tube.
Your welcome, BMC.
Here to share audio gear and music.
I too only had experience with 100 wpc tube gear, Cronus Magnum and Sphinx hybrid.
Is it the end all amp? No, but IMO, it can do justice to vocals and small group jazz, I listen to.
In my setup, the amp has a nice softness. If recordings already have distortion this may add a little fuzz. Nice build quality also.
If I happen upon some higher efficiency speakers than my 92 db spl ADS L470/2. Would love to listen.
The two tubes are close enough to work--the heater current is only slightly less, and the 5AR4 has a slightly lower voltage drop. Pinout is the same. So, the tube will work fine.
https://audiokarma.org/forums/index.php?threads/would-5ar4-work-as-a-5z4g-substitute.916649
https://audiokarma.org/forums/index.php?threads/would-5ar4-work-as-a-5z4g-substitute.916649
BMC
Active Member
These little 93 db Klipsch are fun to listen to. Very musical little guys. The speakers seem to match the warmth of this amp well. Great with a sub.
BMC
Active Member
Thanks! That is good to know.
Verified--it's a
The 5AR4 came a day early, and the amp fired up with no problems.I bought this amp with no tubes, which was an option from the seller I used. I have to say the amp was packed like a fortress, arrived in flawless condition, and it worked on the first try.
For tubes, I decided on the ElectroHarmonix 6CA7, Voshkod Rocket 6N2P, and the Tung-Sol 5AR4. It is sounding fairly good right now, even though the amp and tubes haven't broken in yet. Dead quiet too! Its main use will be on my desktop feeding a pair of KEF LS50s and a small powered sub beneath the desk. Once it breaks in, I may give it a try in my big system.
The KEF LS50 shows a nominal impedance of 8Ω with a minimum of 3.2Ω. I'm guessing I should keep these on the 8Ω taps.