@demoiree V1 gets full current regardless of tube. When it first happened (last month or so), I was using KT88. There's something wrong related to that valve position. I hope its an easy fix and that the transformer isn't damaged or something. Very nervous...

 

WOW - Well, since the R8 is broken, I plugged my A-S2100 integrated back in today. It is the first time I have listened solid state in several months. There's just no contest for holography, 3D mids, and air. The R8 absolutely smokes it in these regards. The A-S2100 has more detail and is quicker, but the soundstage sounds flat and boring by comparison and the midrange magic is not there. It doesn't reach out and grab you. Interestingly, the center image between the speakers seems much smaller too, though the peripheral width is about the same as the R8. The R8 has a more even and natural soundstage compared to it. Very interesting... Also interesting, I compared the stock R8 and A-S2100 on the first days of having the R8. Back then, the R8 had a smaller soundstage than the A-S2100 and was harsh. Plugging the A-S2100 back in today confirms that much has changed with the R8 since those first weeks. It all just makes me sadder that my R8 is down, though.

4 minutes ago, echorec said:

@demoiree V1 gets full current regardless of tube. When it first happened (last month or so), I was using KT88. There's something wrong related to that valve position. I hope its an easy fix and that the transformer isn't damaged or something. Very nervous...

 

WOW - Well, since the R8 is broken, I plugged my A-S2100 integrated back in today. It is the first time I have listened solid state in several months. There's just no contest for holography, 3D mids, and air. The R8 absolutely smokes it in these regards. The A-S2100 has more detail and is quicker, but the soundstage sounds flat and boring by comparison and the midrange magic is not there. It doesn't reach out and grab you. Interestingly, the center image between the speakers seems much smaller too, though the peripheral width is about the same as the R8. The R8 has a more even and natural soundstage compared to it. Very interesting... Also interesting, I compared the stock R8 and A-S2100 on the first days of having the R8. Back then, the R8 had a smaller soundstage than the A-S2100 and was harsh. Plugging the A-S2100 back in today confirms that much has changed with the R8 since those first weeks. It all just makes me sadder that my R8 is down, though.

 

I hope just a simple issue with resistors or caps ! 

 

maybe is a good time to swap out those willsenton caps to better ones mundorf or jantzen

 

 

 

3 minutes ago, demoiree said:

 

I hope just a simple issue with resistors or caps ! 

 

maybe is a good time to swap out those willsenton caps to better ones mundorf or jantzen

 

 

 

Not really, unless those caps are an issue. However I don't think those caps are the reason for this high current. There must be some faulty components in negative grid supply voltage specifically for V1 which is causing too much negative voltage in the grid causing high current. I suspect the filter caps/diodes on that circuit.

 

 

I wonder, since this problem previously went away and resurfaced, if there could be a cold/loose solder joint somewhere in the filter caps/diodes section. Perhaps the joint finally broken clean? I don't know what I talking about though ?

9 minutes ago, echorec said:

I wonder, since this problem previously went away and resurfaced, if there could be a cold/loose solder joint somewhere in the filter caps/diodes section. Perhaps the joint finally broken clean? I don't know what I talking about though ?

Oh dear.. I hope you can get it fixed. 

35 minutes ago, echorec said:

I wonder, since this problem previously went away and resurfaced, if there could be a cold/loose solder joint somewhere in the filter caps/diodes section. Perhaps the joint finally broken clean? I don't know what I talking about though ?

That is something you can try yourself if you are handy with soldering. Absolutely no harm in doing that. Just re-solder all the points around that valve base and bios pcb as I pictured above.

I decided to look myself and see if there is anything obvious. Check this out - There is NO SOLDER on one of the connections on the rear power tube selector switch. I don't suppose this could have anything to do with my problem could it?

 

 

By the way, is there any non invasive testing I can do to troubleshoot the V1 section using my multimeter? As I understand it, capacitors must be removed from the circuit to test them properly and I don't want to do that. But I'm wondering if there is anything else I can test without risking any damage (resistors or diodes?). I don't feel comfortable doing any soldering. Thanks so much for your time!

 

 

..................

Edited July 22, 20214 yr by muon*

1 hour ago, echorec said:

I decided to look myself and see if there is anything obvious. Check this out - There is NO SOLDER on one of the connections on the rear power tube selector switch. I don't suppose this could have anything to do with my problem could it?

 

 

The photo is not clear to me but if you see no solder there, that might be the issue. However, DON'T GO ON WITH MULITIMETER AND CHECKING STUFF UNDERNEATH IF YOU DON'T KNOW TUBE AMP. There are lethal voltages involved. Please be careful mate. 

.........................

 

 

Edited July 22, 20214 yr by muon*

Bummer to read of your issue @echorec. Hoping you get it sorted quickly.  I guess this will test the warranty follow up etc too.  I am sure Yong will be helpful but yes, the geographical distance will push options available.  The website does clearly state warranty is no issue outside of China so if thats through their preferred fixxer or your preferred fixxer with the cost being covered I am sure will explored. 

 

On a happier note, mine finally arrived.  Packaged like a champion and the smell of fresh paint once I unboxed it was insanely strong.

 

All plugged in and working perfectly.  Checked the bias, was a bit high and just pegged it back a bit and now all good.

About 5hrs of listening thus far, very nice.  I am sure it will get better after maybe 20-30hrs as a minimum.  But right out of the box I am happy with the bass and also the higher frequencies, nothing brittle and bass is quite stong.  Wouldnt say soundstage is mind blowing just yet but I can hear the depth in it, just need it to open a little and then the width will be there too.

All tubes are standard, the KT88 I was unsure whether to go for based on some reviews saying the EL34 is a slightly smoother sound but I went with KT88 and will over time roll through the varying options.

As this was a unexpected gift I just plan to enjoy it for a while and leave it as it is till its all burnt in and operating at capacity. Unless the tubes foul up I dont expect to change anything until maybe early next year, but with all the rolling in this thread already it will be a great reference bank on what tubes power and pre to consider when I do decide to go shopping!

 

Here are some pics...

 

 

 

 

 

Edited October 19, 20205 yr by 08Boss302

Thanks, everyone! I double checked that solder connection pictured above and there must be a very tiny amount of solder holding the wire to the post as the wire does not move. It definitely needs to be resoldered though. I just closed it up and am planning on taking it in for repair locally on Tuesday. I'll let the local expert take it from here.

 

@08Boss302 Congrats! Let us know what you think as time goes by. It will get better!

 

 

@echorec

Hey mate,

Here are schematic. I have attached Original as well as one I drew after opening. The values are different nothing else and some details of Tube switching is not included in both but that does not matter much as it only changes the grid voltage.

R8原理图-NO SHARE.pdf

Thank you so much!

 

 

@Atmaj thanks for sharing the schematics! 

 

just curious have you done some measuring if the B+ voltage? is it around 445V? so when biasing KT88 should be around 55ma(70% dissipation)  ? 

 

 

2 minutes ago, demoiree said:

@Atmaj thanks for sharing the schematics! 

 

just curious have you done some measuring if the B+ voltage? is it around 445V? so when biasing KT88 should be around 55ma(70% dissipation)  ? 

 

 

I did measured all the B+ voltages (with 244V grid supply) which are there in the schematic however, I haven't noted down the Bias current measurements. Should have done that but it took long time to note values of all components and draw schematic. I roughly recall it to be 47ma but not 100% sure about it.

1 hour ago, 08Boss302 said:

 

On a happier note, mine finally arrived.  Packaged like a champion and the smell of fresh paint once I unboxed it was insanely strong.

 

 

 

 

 

Congrats on your purchase!! I was also impressed with the packaging, esp the foam cut out that fits all the tubes snugly. But man.. that smell was insane. I had to put the box and all its trimmings in the sideyard and the machine had enough juice to perfume the room for the next few days. 

 

Having that tube database is a good idea. 

I am feeling so lucky that like some of you guys, I did not have hot tube issue or any noise issue even after rolling so many tubes.

 

The best part is that smell...... I did have tiny bit smell first time I turned it on for about 10 to 15 mins but nothing so bad (or do I really need to see a nose specialist? ?)

 

These replaciable tubes are listed in the user manual as well. However there are few more you can use like 6L6 in EL34 mode. Ideally EL34 and KT88 are kind of family of tubes and there are few interchangeable tube types available for each family. 

Hahahaha No need to see a nose specialist but our house pets were so intrigued with the smell that they kept sniffing the amp and the tubes (when they're not on). Think they were getting a bit high. 

 

Its great that this thread is now 5 pages!! Well done @Atmaj!!

 

My humming 6SL7 tubes are finally resolved. Originally China HiFi sent replacements but they hummed at both speakers rather than just the right side. I just resigned myself and today a package came from China with another set of 6SL7s!! The missus was like.. what did you buy again?? 

 

Hooked them up and both speakers are silent. 

 

Strange and I wonder if the tube measurements play a part or its just a quality issue. The first set of tubes measured 2.5mA, second set was 1.5mA and now 2.2mA. So much variability.. 

 

THE SMELL... It made me feel ill for a couple of days, but it is a necessary initiation into the brotherhood/sisterhood of R8 owners

 

Glad to hear those replacement tubes are quiet @2Dculture.

?

The smell was super strong out of the box, these things clearly are being packed not long after assembly. The paint is dry but not aired right out ?

 

Mine lasted about a day then went away, the boxes are in the garage, I haven't checked them but I suspect the fumes would be in the foam and cardboards after a 5week boat ride couped up and sealed.. 

 

 

Hi All..

Upto about a dozen hours now and all is good.

I am very happy with lows, I am finding the mids/highs  a bit forward and even maybe brittle, maybe even distored is a good word but its not true distortion. More so a sound presentation that is not my preference.  

Further burn in might settle this down but reading around it could also be the KT88 doing what they're designed to do.  Maybe they're not as forgiving with hard rock and metal as I was aiming for.  That small and very fixable thing aside  I have no humming or any other noise to raise any unwanted suspicions.   Its great. 

I have read around online with regard to tubes  to allow about 40hrs of burn in but am wondering if the KT88 will settle to the sound signature I like or if I need/should consider rolling these out sooner than my initial plan?

To provide clarity I am after a fat "laid back" sound.  Lows I like to have some kick,  mids dont need to be overly pronounced but a flat mid quite ok.. With highs, a sweeter sound, nothing overly exaggerated or glassy, even slightly rolled off is better than bright!!!  I am new to this rolling caper and also have some confusion about rolling the pre tubes or the power tubes first and which is going to have influence.

 

Based on reading through this thread and the rolling already done I am not sure the KT77 or 6550 are quite what I am after but also happy to advised otherwise.

I am thinking maybe the Tung Sol EL34B will be good. Most suggest its mids are clean and full, plenty of bass and slightly softer but well detailed top end all without being a forwardly accentuated presentation. 

For the 6SN7 I am thinking the Tung Sol GTB or the EHGold Pin both seem to be well regarded - not sure of any distinct SQ signature being vastly different.

For the 6SL7 I am thinking the Tung Sol or the Sovtek, again, pretty well regarded and not much to suggest much difference. 

 

Whilst I wont be pulling the trigger on any of the above this week or so I am happy to get some opinion on the above options.  I can keep playing music with all the stock tubes and if still itching for change I can make some purchases.

 

Cheers.

4 minutes ago, 08Boss302 said:

Hi All..

Upto about a dozen hours now and all is good.

I am very happy with lows, I am finding the mids/highs  a bit forward and even maybe brittle, maybe even distored is a good word but its not true distortion. More so a sound presentation that is not my preference.  

Further burn in might settle this down but reading around it could also be the KT88 doing what they're designed to do.  Maybe they're not as forgiving with hard rock and metal as I was aiming for.  That small and very fixable thing aside  I have no humming or any other noise to raise any unwanted suspicions.   Its great. 

I have read around online with regard to tubes  to allow about 40hrs of burn in but am wondering if the KT88 will settle to the sound signature I like or if I need/should consider rolling these out sooner than my initial plan?

To provide clarity I am after a fat "laid back" sound.  Lows I like to have some kick,  mids dont need to be overly pronounced but a flat mid quite ok.. With highs, a sweeter sound, nothing overly exaggerated or glassy, even slightly rolled off is better than bright!!!  I am new to this rolling caper and also have some confusion about rolling the pre tubes or the power tubes first and which is going to have influence.

 

Based on reading through this thread and the rolling already done I am not sure the KT77 or 6550 are quite what I am after but also happy to advised otherwise.

I am thinking maybe the Tung Sol EL34B will be good. Most suggest its mids are clean and full, plenty of bass and slightly softer but well detailed top end all without being a forwardly accentuated presentation. 

For the 6SN7 I am thinking the Tung Sol GTB or the EHGold Pin both seem to be well regarded - not sure of any distinct SQ signature being vastly different.

For the 6SL7 I am thinking the Tung Sol or the Sovtek, again, pretty well regarded and not much to suggest much difference. 

 

Whilst I wont be pulling the trigger on any of the above this week or so I am happy to get some opinion on the above options.  I can keep playing music with all the stock tubes and if still itching for change I can make some purchases.

 

Cheers.

 

Here is my observation.....

 

Tung Sol EL34 has very good base and excellent mids but highs are rolled off

KT77 has too much mid but I haven't broken them in to check further

Tung Sol 6SN7 is an excellent current production tube which is almost at par with NOS tubes.

There is nothing in current production for 6SL7 which can match NOS tubes (except . Don't even  bother to try Sovtek, it is same chinese tube what you have, just re-branded.

 

Stock KT88 are good tubes and suits to the taste what you mentioned, I think you will get the sound what you want by rolling pre-amp tubes. If you go to any EL34 family tube, mids will be pronounced one and you will loose base (except TS EL34B).

@08Boss302 The nice thing, IMO, is that this amp can be tweaked to accommodate most preferences. First, what speakers do you use and what is/are your sources? I definitely recommend waiting a few weeks to make any moves. The character of the amp will change, I promise!