[lucidreamer]

I found my own answer how to replace the Mundorf capacitor using the correct polarity for Elekit in regards to the 12AU7 tube on the schematics for TU-8200.

Here is the solution (if someone is interested) - based on several sources online the outer foil (shorter lead of Mundorf) always needs to be soldered to the plate the pre-amp tube that has the lowest impedance.

This is Pin 1 and 6 for the 12AU7 tube on the schematics and both capacitors (two per channel) are already connected to those pins, just need to make sure that they are connected with the shorter lead to those pins during the swap.

Easy fix!

Sources:
http://web.archive.org/web/20110826134445/http://www.aikenamps.com/OutsideFoil.htm
http://www.aikenamps.com/index.php/where-to-connect-the-outside-foil-on-capacitors
http://www.partsconnexion.com/capacitor_film_vcap_cutf1.html
http://www.laventure.net/tourist/caps.htm

 

[lucidreamer]

I got the Mundorf caps from Victor today that I ordered last week and just installed them into my Elekit replacing the C3, C4, C9 and C10 while changing DB107 to DB207.

Honestly I was initially skeptical about the coupling capacitor upgrade but after the swap there is a definite improvement in audio quality that I noticed right away. I compared using the same uncompressed which are familiar to me and the same music really opened up. It feels more transparent and effortless now with more space between instruments and better clarity for each note. The resolution is definitely improved too with more bass and high notes articulated. Interesting how they would sound after the break-in too, I would not

Overall I like how they sound, they have that pleasant touch to the high notes that can be rendered as some coloring to the sound maybe. But it does not sound too colored or syrupy at all, it just feels right by keeping the tubey character of the amplifier intact.

Not that the AMTRANS are bad capacitors but these German-made ones are really a step up and improve the quality of audio. I think they are worth the money and Victor sells them at a reasonable price and he would ship them fast. Some stores may take a few days to ship them out and it may be much longer to wait for them to arrive from Europe for those who live in the States like me.

 

[lucidreamer]

I just got a pair of identical NOS RCA 6L6GC blackplates w/bottom getters that I recently won on eBay. They cost pretty high but still lower than what the dealers would charge for those tubes these days.

They appear to be in great shape and only lightly used based on the overall condition, flashing, etc. I do not have the tester to confirm their readings but the seller said he would accept the return or work with me on issues with them. As usual the seller stated that they were new and tested as new but we all know. I doubt that it is possible to find real NOS RCA blackplates these days anyway which were never used. They came with original RCA carton boxes with a musty smell which was a good sign that they were sourced from the same place.

The sound is pretty nice and clean overall but compared to GE 6L6GC with large cooling fins that are my favorite ones - I do not really hear a dramatic difference that would justify the 3-4 times more price for them opposed to GE ones. Yes, the bass seems a bit tighter and the RCAs sound a little more dynamic and cleaner but there is no day-and-night difference as I thought it would be. They sound more like my new Philips EGG 7581A that I recently put on sale after switching to GE.

Should I give them a few days to burn-in and settle maybe? If they were laying in storage for 40-50 years, then it may take some time to 'wake them up' to sound best maybe. Is there a possibility that they were heavily used already and still showing the good flasher left? Should I keep them, suggestions?

 

[Effusion]

I agree with you regarding the RCA blackplate 6L6GCs, I also don't think they are really worth the extra coin, compared to the GE 6L6GCs, which can really be a deal if you search and are still my personal favorite 6L6GCs. Your impressions also sound very similar to mine as well, to me the RCA's are a bit cleaner, refined, with tighter bass, but at the same time, they sound a bit too clinical to me at times and generally have a lot less of a lush sound than the GE's tend to give. To me the GE's also have more bass impact, if a bit bloated at times, but I prefer the overall tone they give compared to the RCA's, which to me can sound a bit sterile and almost too clean. To generalize, to me the RCA's seem to be more solid state than the GE's, which may be a good or bad thing based upon the signal tubes, the headphones/speakers, and one's own preferences, but to me they always just took too much of tubey goodness out of the mix, where the GE's accentuate it. However, I for one really like the tube sound in general, so I tend to gravitate towards those.

With that said, generally I've found that many of the NOS versions of tubes that many people rave are the best online are in fact just a bit more solid state sounding overall than their less raved about counterparts. That is they tend to give a tighter, more controlled, and precise sound. I also believe that many who go from say something like a GE to a RCA 6L6GC automatically believe they are superior because of their tightness and overall cleaner sound, even though it isn't by much, translating this into a perceived higher quality. Taking this into account, it is still really hard to tell unless you try them out for yourself, but knowing this generality and where you typically land on the continuum of tubey versus solid state, can help determine if the cost is worth it to you beforehand. Don't worry though, so many are crazy about the RCA blackplates, especially those who read up on them online, that you should have no trouble selling them if you ultimately determine they are not for you. Another option is to hold on to them for a bit if you don't need the cash right away, get them properly tested, and sell them in a year or two down the road. The prices are only go up these days, especially for those that have large followings online or are talked about more. As more and more folks get into tube amplifiers, the ones that are considered the cream of the crop get snatched up quickly, at almost any price it seems nowadays.

I tend to find that burn-in on tubes, while necessary, isn't like their solid state counterparts, in that they don't take as long, but still require some time. I would say that generally a couple of hours of burn-in is really all that is needed for most tubes, with 24 hours being the absolute max to cause any real difference in my opinion. Now, this isn't just for true NOS, but also for those that haven't been used in many years, so it is always best to wait a couple of hours before judging critically, even if they are used when you purchased, as you never know when the last time they really saw some use was.

As a side note, I'm glad you are liking the Mundorf's! I like them as well, as do several others here on this forum, and your impressions are once again, similar to mine. The caps seem to open up the sound a bit, giving more definition between the notes, a bit more of a cleaner sound, a bit more detail, and to me, sound a bit more natural than the AMTRANS overall. To me the highs seem to be more extended and a bit more present, but it is hard to tell now as it has been so long since I did the upgrade and it was the highs that seemed to have changed a bit after about 30 hours or so of break in. In addition, prior to the upgrade I wasn't able to use my amp for several weeks, so my reference at the time wasn't great. It seems like you really got a baseline and were able to get better impressions than I was. It would be nice to compare a stock version to one whose only difference is the Mundorf caps, but generally I also think it is a worthwhile upgrade for those on the fence, especially considering what some NOS tubes cost, even quality new production, and if you think about it, this upgrade will affect every tube you use with it, whereas the tubes are strictly self-contained. Give it a bit of time and see if you notice any differences as they burn-in a bit.

As another side note, to those that are interested in the 8600, I'm hoping to get some good impressions of it this weekend when I see Victor at RMAF. I spoke with Victor a few days ago over the phone and he really likes it! He told me that it is so quiet that it's scary and that the tone is absolutely amazing, especially with piano. I'm really excited to hear it and spend some time with Victor again. More to come...

 

[lucidreamer]

Thanks Effusion, great points! I will probably keep the RCAs to myself, both GE and RCA tubes are superior and possess that nice tubey tone that makes everyone want to listen to the music for hours, it is both transparent and warm without being dark or too bright and fatiguing. The tendency is that those NOS tubes will be very hard to come by regardless of price.

I agree 100% that if the tube sounds too solid-state and bright, it may appear as a benefit at first, but after a while one realizes that it is a too fatiguing to listen to that setup for longer periods of time. I remember experimenting with solid-state PPA headphone amps a few years ago and based on some online suggestions I experimented with video opamp chips that have frequency of several hundred mHz. After dealing with oscillation issues at first, I finally made it work and it did sound like nothing I ever heard before, very quiet and extremely resolving. But it was discomforting and fatiguing, after a while you get a sensation of tiny ringing in your ears like after taking a plane. It was not a pleasantly-sounding setup at all, I pulled those chips out later and put the audio ones back in, it is still laying around in the drawer, the PPA amp after coming across Elekit. I think the problem with the video opamp chips was too much high-frequency and ultrasonic noise creeping in that would need to be specially filtered out or something.

Yes, the Mundorf upgrade was definitely 100% worth the money, no regrets whatsoever. After about a week - they seem to relax a little bit and sound even better and a little laid back. Maybe that was after I switched to Mark Levinson 360S DAC recently which really sounds amazing and vinyl-like despite the age. On a side note, the iFi Micro iDSD DAC that I used before with Elekit is also very fine-sounding DAC. I spent like 3-4 hours doing some A/B tests between the Mark Levinson and iDSD and despite the huge price differences the iDSD rivals the ML in all aspects. The ML indeed has better bass and wider soundstage and sounds more fluid maybe; it has some unique mellifluous voice with a higher authority found in serious equipment. But as for details and transparency - they are both on par as I did not notice much or any differences between both DACs and I can surely tell the difference. It is really amazing how audiophile technology progressed in the last dozens of years and became affordable for everyone and not just for rich guys and gals. The latest version of iDSD Black is around $400 new and it is a great portable DAC/headphone amp that sounds way better its price range, I think. I now use it as a USB -> SPDIF converter only with external DAC.

I think I am going to stop the upgrade journey for now and settle on that existing setup to just enjoy the music.

 

[Effusion]

For those who are interested, I was able to briefly audition the new Elekit TU-8600, Victor's version, last weekend at RMAF. Here is a link to my impressions (which are towards the bottom): Link

I also took a few photos of the 8600 as well as the other equipment at Victor's table while I was there this year, so I've posted them below as well. It was really great to see Victor again this year and I enjoyed the time I was able to spend with him and at his table.



As far as more direct comparisons to the 8200, it's really hard to tell and I would need more time with the 8600, plus at least two options with the tubes for it. I think ultimately the 8600 may have better layering, resolution, and resolve, with a slightly quieter background, but I would really need each side by side and with different tube types for the 8200 to get a better idea. However, I did notice that the 8600 unit needed a bit more time to break-in towards the end of my listening, which was confirmed right after by Victor. It sounded very nice as it was and all I'm thinking now is how it will settle in with a bit more time, plus what other makes of 300Bs would adjust the sound. As it was though, I can say that it was as good as the 8200, even a bit better in several places, so comparable and close to me with really nice sets of more dynamic tubes, such as the KT-66/88, 6550, and 807, in the 8200. While there were places that I would have liked better, even some that I would have liked better if they were more like the 8200 at times, overall it definitely impressed me in several ways. I would say that if one was looking for a punchy, versatile, and great seductive sounding amp, without feeling the need to swap out the tubes like I do at times, this may be a great model for you. Ultimately I would need more time with it and in my own chain. I also really like the options of tubes I have for the 8200 currently, in addition to its size, however if I could ever finally decide on which pair of single drivers I want to try, I think this amp would be both very fun and sound great in this type of setup. Being able to fully take advantage of both speakers and headphones at the same time on some really nice 300Bs sounds pretty good to me!

My thanks to Victor and all at Elekit who keep making all of this great gear! I'm keeping my eyes on this one...

 

[sotto123]

Has anyone had the chance to compare the TU-8200 to the Mogwai?

I'm curious because both take 6L6GC tubes.

I generally prefer a warm, rich sound which I think both would offer.

 

[fccn75]

Hello All,

Been enjoying this amp for awhile now since my FET catastrophe last year. Three questions I like to throw out: DC offset from source to TU8200 input, using12BH7, and using 12AX7.

According to our amp's schematic, it is DC from input connectors to output transformer. How high of a DC offset from i.e. DAC output can it take? I know common knowledge is less than 100mV for typical designs, but this input appears to right at the grids after the 50K pot. Can it take more than 100mV without any consequences?

There were posts regarding the use of 12BH7 awhile ago, that it was quite preferred over the 12AU7. I am thinking of trying it but the higher current drain at the heater and different plate resistance is a concern for longevity of the amp. How has it been for those who have used this tube after all this time?

12AX7 - high gain tube. I have a passive I/V stage using a current injection and a single low value resistor on my TDA1541 diy DAC that only puts out 70mV or so. On headphone out using the standard 12AU7, I can get pretty decent sound when I push the volume close to 4:00 which on a standard DAC would be damaging to both headphone/ear! Instead of using another line-stage in-between, just toying with the idea of using a high gain tube like the 12AX7. What do you all think?

 

[fccn75]

Whoops, meant to say amp is DC from input to before the power section!

 

[Dimu]

Hello All,

Been enjoying this amp for awhile now since my FET catastrophe last year. Three questions I like to throw out: DC offset from source to TU8200 input, using12BH7, and using 12AX7.

According to our amp's schematic, it is DC from input connectors to output transformer. How high of a DC offset from i.e. DAC output can it take? I know common knowledge is less than 100mV for typical designs, but this input appears to right at the grids after the 50K pot. Can it take more than 100mV without any consequences?

There were posts regarding the use of 12BH7 awhile ago, that it was quite preferred over the 12AU7. I am thinking of trying it but the higher current drain at the heater and different plate resistance is a concern for longevity of the amp. How has it been for those who have used this tube after all this time?

12AX7 - high gain tube. I have a passive I/V stage using a current injection and a single low value resistor on my TDA1541 diy DAC that only puts out 70mV or so. On headphone out using the standard 12AU7, I can get pretty decent sound when I push the volume close to 4:00 which on a standard DAC would be damaging to both headphone/ear! Instead of using another line-stage in-between, just toying with the idea of using a high gain tube like the 12AX7. What do you all think?

Regarding DC- what do you mean "DC from input connectors to output transformer"? There are tubes and coupling caps in the amp.

I would not stick 12AX7 into this amp- not a good idea. Read the thread on what's involved in using 12BH7 or E80CC. I tried Brimar 12BH7 and even though I liked them more than 12AU7 I much rather prefer E80CC. It seems like I am not alone in appreciating E80CC- somebody just bid up a rare version of E80CC to $599 for a single tube! That would be $1200 to drive this amp, before you even pay for the output tubes which are usually costlier than driver tubes

https://www.ebay.com/itm/E80CC-6085-PHILIPS-tube-PINCH-DISC-getter-SMOOTH-plates-46-WKB/311998787509

 

[fccn75]

Hello Dimu, I was trying to convey that this amp is direct coupled from input (rca jacks on back) to the 12AU7 grids after the volume pot. The only signal coupling cap is between the output of the 12AU7 to the next stage taken over by the 6L6 power section.

No go for 12BH7...no go for 12AX7 but ok for E80CC, I'll do some research on this tube. OMG, $599 for a single tube, no thanks!!!

 

[Dimu]

If you can run E80CC you can also run 12BH7.

 

[gasmonkey]

Noob question, I own a Tu-8200 (love it), and have the opportunity to get a used tu-8500 at a good price locally. I use a line in only, (Chord Mojo -> tu-8200), dont own a cd player or record player. All digital files.


Would this be of benefit too me? I'm failing to see how it would benefit me, but have have a couple people tell me a preamp will always improve my sound.

 

[vkung]

Yes.. you use TU-8500 as a tube buffer...

 

[Dimu]

Noob question, I own a Tu-8200 (love it), and have the opportunity to get a used tu-8500 at a good price locally. I use a line in only, (Chord Mojo -> tu-8200), dont own a cd player or record player. All digital files.


Would this be of benefit too me? I'm failing to see how it would benefit me, but have have a couple people tell me a preamp will always improve my sound.

I enjoyed building TU-8500 even though I wish there was more room in the case to be able to upgrade more components. It certainly does not hurt having this preamp, I always use it with my TU-8200. As for how much it helps- if you only feed it with your DAC the only difference is going to be more second harmonic distortion than TU-8200 alone. The way this works is that you crank volume up on TU-8500 and attenuate it way down with TU-8200 volume pot. In fact for that configuration I would replace TU-8500 volume pot with a fixed 50k resistor soldered in so that those preamp tubes get to produce maximum distortion.

If you are not building it yourself I would say your money is better spent on some nice tubes for TU-8200 than getting preamp, and also on upgrading components in TU-8200. A well upgraded TU-8200 alone will sound better than stock TU-8200 paired with stock TU-8500. Of course when I say nice tubes I mean real tubes, not the stuff that communist factories produce today.