• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

On Impulse I ordered a Boyuu Reisong A10 EL34, class A. Any experience? Add your opinion on it.

Old Guy8 said:
I wonder if a few capacitors were upgraded could it make a noticable sonic improvement. However subjective the evaluation of what's improvement. Would this be better area to try upgrades?
Click to expand...
I made a vain attempt to "improve" this TubeCube|7 that I have, and it made no difference. The cheap off-brand capacitors took a dump and the power supply wouldn't power it anymore until I recapped it. (Without fail, every cap I measured was right about at the lower limit of tolerances, and the one or two that were below the 20% tolerance probably prevented the switching power supply from working.) I made a couple of recommended capacitor substitutions while I had it open, but I still find it has a wicked rolloff past about 10kHz--it sounds like everything is under a blanket. It's a design flaw--another online review says the same thing. It's not bad for background listening but after a couple of years, I find I'm missing a lot.

I don't know which capacitors are used in this Reisong amp, but I would not be opposed to putting a few dollars into maybe bumping the caps up to Nichicons, even if it only improves stability and reliability. Wired as it is, it should be a simple job and might actually be fun to tinker with.
 
Wildcat, I asked the Amazon seller I bought mine from if it would be ok to use an adapter for 12AX7s and he said it was safe. I've also read elsewhere online that you can modify a 12AX7 to work by soldering jumpers between certain pins which I guess changes the voltage. Mind you, I have no actual electronics knowledge to back that up, just passing it along!
 
Got my new tubes installed, Running the same ones as Old Guy8 now. Voskhod Rocket 6N2P-EV / EB in the preamp, Tung-Sol EL34Bs and a vintage RCA 5Z4 for the rectifier. THe RCA 5Z4 has one more pin than the Chinese one but it fits in the socket and works and nothing is on fire yet.

I wasn't very scientific but I did one set of tubes at a time in case there were problems. I didn't detect a huge tonal difference with the new power tubes, but definitely heard a difference when I added the new preamp tubes. Bass is much less mushy. Tried several albums that I wasn't happy with before and they have all tightened up a bit. Don't think the rectifier changed the sound any but I figured I'd give it a try. Would love to continue to hear from other users. Particularly curious to hear if anyone tries out a 12AX7 adapter!

Marc
 

Attachments

  • IMG_5389.JPG
    IMG_5389.JPG
    100.5 KB · Views: 39
Marc Raley said:
Got my new tubes installed, Running the same ones as Old Guy8 now. Voskhod Rocket 6N2P-EV / EB in the preamp, Tung-Sol EL34Bs and a vintage RCA 5Z4 for the rectifier. THe RCA 5Z4 has one more pin than the Chinese one but it fits in the socket and works and nothing is on fire yet.

I wasn't very scientific but I did one set of tubes at a time in case there were problems. I didn't detect a huge tonal difference with the new power tubes, but definitely heard a difference when I added the new preamp tubes. Bass is much less mushy. Tried several albums that I wasn't happy with before and they have all tightened up a bit. Don't think the rectifier changed the sound any but I figured I'd give it a try. Would love to continue to hear from other users. Particularly curious to hear if anyone tries out a 12AX7 adapter!

Marc
Click to expand...
I too didn't notice a change with RCA rectifier.
As I previously posted, my rolled in tubes acquired better resolution over a couple weeks use.
 
My first tube amp is boyuu a10 which I bought five years ago from hifi exquis at Aliexpress. The amp arrived with one damaged shuguang el34 and they replaced it immediately. After a month of enjoying my amp with shuguang tubes, I upgraded it to mullard el34 and gz34. Then sometime in 2016 I installed a temporary switch for SE and UL mode that I saw from diyaudio. First thing I noticed is that salena jones sounded better on my coral beta-8s on SE mode.

By the way, this amp does not have enough power to drive my diatone r208 which is a 20watt 16ohm.
 
My amp still says "Processing in progress" (as of Monday). I know there are worldwide delays in shipping so I'm not too concerned. Plus, I paid with a credit card through PayPal, so I have some protections in case it never ships or doesn't arrive. I'm debating opening it up upon receiving it, just to see what quality of parts are used inside of it.
 
I’ve been using the amp for 3-4 weeks now and the right channel cathode bypass cap just blew. A short pop from the speaker followed by a nice puff of magic blue smoke. Going to replace the 220uF/63V capa with 220uF/160V high reliability Nichicon ones. Hopefully no other damage.
 
Duncan99 said:
I’ve been using the amp for 3-4 weeks now and the right channel cathode bypass cap just blew. A short pop from the speaker followed by a nice puff of magic blue smoke. Going to replace the 220uF/63V capa with 220uF/160V high reliability Nichicon ones. Hopefully no other damage.
Click to expand...
Duncan,
Sorry to hear. Drop back in when you get it fixed. Good luck.
OG
 
Mine arrives Wednesday, apparently--it's en route. But my rectifier tube has not shown up yet--the other tubes arrived a week ago. (I ordered the model without tubes.) Maybe after this amp runs in for a bit, I may see which capacitors it uses and replace all of them. This crummy Tube Cube 7 I'm using had one of the caps go bad, which killed it--all the off-brand caps I tested after removing them were either right on the -20% tolerance limit or completely out of spec. Unfortunately replacing the caps didn't make the little turd sound any better.
 
While back I bought a Schiit Modi Multibit DAC. Within first 5 minutes, pop, smoke. It happens. Replacement was quickly sent.
 
The amp arrived today in all its chromed-out glory, very nicely packed. Just awaiting the Mullard rectifier tube I ordered, and I'll be able to fire it up.
 
No tube today. I wish I knew someone locally I could borrow one from until mine arrives.

I found this in another thread, re: converting the 6N2 to 12AX7. The rewiring looks fairly simple, and I would imagine this is what the socket adapters also do.

convert-6n2-to-12ax7.gif
 
Wildcat said:
Five hours away...in one direction. Thanks for the offer though! Mine will probably arrive within the next few days.
Click to expand...
In the grand scheme of things five hours away is really just a hop, skip, and a jump. Not suggesting you should make that drive for a rectifier tube, tho. :thumbsup:
 
ctjetta said:
In the grand scheme of things five hours away is really just a hop, skip, and a jump. Not suggesting you should make that drive for a rectifier tube, tho. :thumbsup:
Click to expand...
For a single tube, no. :D But if I were buying something larger? Five hours is nothing. I drove 8½ each to pick up my current speakers. I figure 10-11 hours daily is my limit, if the item is worth it. An overnight stay isn't an issue either--I get a small road trip out of it!
 
Old Guy8 said:
Duncan,
Sorry to hear. Drop back in when you get it fixed. Good luck.
OG
Click to expand...

IMG-2841.jpg IMG-2843.jpg IMG-2844.jpg
Successfully fixed the amp. The left channel cathode bypass cap blew as I thought (see photos: blown cap and blown cap vs replacement cap). After I replaced the cap it still didn't work so I replaced both EL34's with some Tung-Sol's I had ordered from Amazon. I had been waiting to replace the tubes until I could do some listening tests, but oh well. After replacing both tubes all is good. But that leaves me with the question, did the tube short and take out the cap, or did the cap short and take out the tube? While unhooking everything I noticed that I was using the 8-ohm tap for my Klipsch RP600-M's instead of the 4-ohm tap. Not sure if the higher plate load the tube was seeing as a result could have caused the OT to saturate or something? My best guess is the cap shorted and took out the tube. The original cap was a Rubycon 220uF 63V device so not exactly low quality. I replaced it with a Nichicon 220uF 160V high reliability cap (Digikey pn 493-13277-1-ND). With the hand assembled point-to-point wiring it was very easy to work on this amp!
 
You must log in or register to reply here.
Back
Top Bottom