[LingLing1337]

Class a tube amps and esp. Kt88s will put out quite a lot of heat.

 

[Effusion]

  The LD1+ is a good little budget amp, but for me.. and with Grado GS1000i's, I also felt it was not even in the same ballpark as the Elekit in terms of detail and soundstage.
 
In regards to the heat issues mentioned, any time you have tubes run at proper operating voltages and temps, there's no avoiding the amount of heat that will transfer into the amp via reflection and especially through the sockets.
I do worry about the long term effect of heat on some of the components and on my amp I drilled some holes at the back and fitted a little vent on the bottom to allow for some circulation to carry a bit of the heat away, and also I put a piece of thermal barrier material on the underside of the top part of the case where the tubes sit.
 

 
Very cool modifications!  Thanks for sharing the pic!
 
I would have to say that it's probably the best way to deal with the heat with this amplifier, at least that I can think of.  It would really be interesting to see the difference if we could take your modified unit versus another without, using similar types of tubes/time and check the temp both outside and inside the case.
 
I agree and while we do want our components to heat up to a good operating level for the best sound quality, almost all tube amps, maybe with the exception of those that just use a miniature buffer DAC stage, probably get a little too hot for comfort.  I'm sure that over time/use this can lead to premature deterioration of some internal components, especially around the sockets.  It is what leads to the end of most tubes, which is primarily heat over time causing the filaments to break down, but they also do get really hot!
 
Putting the mode switches on the bottom of the case looks great as well and probably functions better than on the top.  Great idea! 

 

 

[JK-47]

Nice mods Greg70 !!!
 
Any pics or directions on how you put the mode switches on the bottom? So obviously simple and effective at keeping the clean look of the amp, with the convenience of be able to quickly change the modes without dis-assembly.
 
My hat's off to you 

Very clever indeed.

 

[lucidreamer]

Yes, great mode switch and the vent cover modification, Greg70!!! I am seriously contemplating adding the two switches either at the back or at the bottom too. Probably at the back would be more practical, no need to lift the amp to change the settings, I like recessed button design like yours to avoid flipping them by accident when the power is on. Wonder is those wires should be shielded to reduce the possible issues with EMI.
 
Also, any thoughts/recommendations of maybe installing a small silent fan similar to a computer one to the back plate that would draw the heat out from the case for cooling the internal components and to prolong their life. There is an open space between above the speaker taps. Drilling some vent holes on the sides with dust screen or cloth would be needed for proper air circulation. That would involve taking the whole amp apart though to drill those holes and install the fan(s), I guess. But thanks to the modular construction - it should be a relatively easy fix.
 
One caveat to this is that a silent fan is a rare thing, I have not personally seen one yet. All of the motor fans still generate some sort of noise, especially after a couple of years when the bearings lose their lubrication and become looser. That would be annoying when listening to music through open design headphones. I bought a new cheap fanless ASUS laptop just because I hated that fan noise emanating from my i7 HP workstation laptop that was very audible between the songs. Even using a large external harddrive adds to the noise, the portable ones are the best and quietest.
 
I did some research for fans and this one looks promising: http://www.amazon.com/dp/B00VQLYT18?psc=1 claiming noise level of 24 dBA which is somewhere in between "quiet bedroom and TV studio background" based on this noise chart:
 

Sound sources (noise) Examples with distance	Sound pressure    Level Lp dB SPL
Jet aircraft, 50 m away	140
Threshold of pain	130
Threshold of discomfort	120
Chainsaw, 1 m distance	110
Disco, 1 m from speaker	100
Diesel truck, 10 m away	90
Kerbside of busy road, 5 m	80
Vacuum cleaner, distance 1 m	70
Conversational speech, 1 m	60
Average home	50
Quiet library	40
Quiet bedroom at night	30
Background in TV studio	20
Rustling leaves in the distance	10
Hearing threshold	0

 
This one is pretty cool too and has a top aluminum plate to look nice: http://www.amazon.com/AC-Infinity-AI-CFS120BA-Single-Cabinet/dp/B009COQYA0/ref=sr_1_22?ie=UTF8&qid=1434734689&sr=8-22&keywords=120mm+fan+grill
 
Probably installing the fan on top of the case may even be better if there is a good clearance above the amp. It will not require the complete disassembling, only taking off the top and the front cover to install the unit, plus drilling some holes. 

 

[Greg70]

The switching isn't hard to do, but I do understand why Elekit don't recommend it.. because they're worried that someone might try to switch it "on the fly" and do some damage.
It's important that it's only switched after the unit has been powered down for at least 10 minutes, which is why I put the switches on the bottom where no-one else would get to them. I also mounted the switches slightly recessed so that you have to use a fingernail to move it.
 
I set mine up to only switch between Ultra Linear and Pentode, so I used this DPDT switch for it's high current rating which is overkill I'm sure when switched properly after power has dissipated, but a switch like this would never handle the 275V DC if it were switched while powered up:
http://au.rs-online.com/web/p/slide-switches/1759703/
 
Each channel only needs one set of contacts, so you really only need a SPDT switch. A DPDT like the one I used could be wired to change both channels at once.
 
If you want to switch all 3 modes, I believe you'll need something like this:
http://au.rs-online.com/web/p/toggle-switches/7109876/
 
Wiring is simply a matter of connecting the "common" hole used for the jumper on the circuit board - that is, the hole directly connected to R17 or R18, to the common terminal on the switch.. and then the hole for the mode you want, to the corresponding terminal on the switch. I hope that makes sense.
 

 
Lucidreamer
I did consider a fan, but besides the audible noise, I was also worried about introducing electrical noise.. so I decided that convection was the safe bet.
Theoretically the air can enter through the bottom under the boards, and flow either up and past the sockets and tubes, or over the power supply and out the back.

 

[JK-47]

Thanks Greg70

 

[Effusion]

Good idea about the fan, I like it.  However, Greg70 is correct, some oscillation noise would/could seep into the line of the Elekit, especially if the fan was hooked up to the amp's power source.  Similarly, if you're using a usb DAC that has it's own power source, cutting the power lead or buying a cable that only sends the data feed can even make a difference, if your DAC allows it (to test, use a cheap cord and cut the power lead).  I do like the one with the aluminum top plate, and you would be able to run it separately from the amps source, so that would help.  As long as the fan isn't creating too much of a magnetic field around the rotating fins, than it could be okay, if it turns out to be an issue, than you could just use the screen and take the fan out.  Probably best to use the power plug option as too many usb connections could cause issues, if their all on the same circuitry on the motherboard.  Crazy to think how noisy our computers can be, with fans and hard drives and all the such; it has prompted many to go towards more minimalistic silently passive cooled systems, such as the Mac Mini and various media servers.
 
I did look up Psvane's return policy and it is pretty much a "sold as is" policy.  However some of the language in the link below indicates that exceptions can be made, but again only if they want to and probably only for how much extra they think you are willing to pay.
 
http://psvanetube.com/wordpress/psvane-tubes-warranty-return/
 
As a result, I would have to say that it is probably not a good bet for others to offer a grace period as well.  Another shop, Upscale Audio, sells quite a few of the more reasonably priced new production, as well as some nice NOS 12au7s, but all at a bit of a cost more than others.  They also do not offer returns though.  However, they do "burn-in" their tubes by running them for I believe 48-72 hours before matching/shipping, so it is a good shop for quality new production.  Overall, unfortunately it would appear like ones only reasonable option is to sell them, if you find you don't care for them.
 
http://www.upscaleaudio.com/vacuum-tube-warranty-information/
 
Greg70, thanks for info, very useful and probably the way I'll go down the road.  Right now I've been enjoying the Triode mode the most, but have switched back in forth and auditioned once before and I did enjoy the Ultra-linear mode at that time quite a bit.  I'll need to do some more auditioning of the two in the near future, especially once I start using my speakers again; however it is a bit difficult to do the switch, regardless of the 10 min. cool down, when you have to open the darn case.  It really makes this mod invaluable to auditioning as well as using multiple modes at different times.
 
Great ideas and implementation!

 

[lucidreamer]

Has someone tried the Tube Amp Doctor (TAD) 6L6GC STR power tubes with Elekit TU8200 by chance? I just placed an order for a pair on Amazon for $50. They seem to be well regarded for great bass and overall dynamics and some people even rank them over =C= Winged 6L6GC that cost 2x than TAD ones. Once they arrive, I will give them a try and post my thoughts.
 
I just got a pair of Psvane 12AU7 MKII and KT88 both in Grade A from Grant Fidelity this weekend. The 12AU7 MK2 do sound a little better and smoother than the stock 12AU7. As for KT88 - I actually liked them at first but then switched back to stock 6L6EH. The KT88 are extremely detailed, smooth and airy with deep bass and extended highs, very much like a solid state amplifier, however, I find them a little fatiguing after listening for awhile. They do have a reference like sterile, cold(ish) and fast sound quality that some people may enjoy, but to me they are missing some of that tube character and rich harmonics that even the 6L6EH stock tubes had. I would enjoy a little more warmer and mellifluous touch instead of fast attack maybe more. It could be my HE-560 planar headphones that I use or the lack of the recommended tube burn-in time. I am really doubtful that after the recommended 150-300 hours of burn-in they will be sounding richer and become sounding more tube-like, usually the initial character is there or not from the first few hours of breaking in the tube. I should also try them in UL mode just for the sake of testing. The Grant Fidelity claim burning in tubes before matching.
 
Probably 6L6GC is what I am after in the long run.... I have not had a chance to listen to EL34 yet but based on the numerous reviews, this type of power tubes have a great rich midrange and are a little shy on bass and highs(supposedly), where 6L6GC is very well balanced overall. To my understanding EL34 is a great choice for headphones/speakers with pronounced bass/high notes, such as Grado or Beyer 990. But for more flat sounding headphones 6L6GC may be a better choice for more linear response.
 
Any possible recommendations regarding the NOS or production 6L6GC tubes (besides TAD that I just purchased) that have that special magical, euphonious analogue tube sound. The stock 6L6EH sound pretty good to me already in terms of response and rich harmonics with less than 100 hours on them.
 
Thanks everyone!

 

[lucidreamer]

Just found a good article elaborating on different flavors of 6L6 NOS tubes:
 
http://www.audiotubes.com/6l6.htm
 
Looks like the best ones are RCA black plate and next comes the GE 6L6 (bold blue):
 
OK, SO TELL ME HOW THEY SOUND!!
Everybody keeps saying "you have to get (fill in the blank) brand of tubes or you are just not cool!" But do they sound good? The tube needs to sound good to your ears and deliver the kind of sound you are looking for, and nobody can tell you exactly which tube this may be! Here are some general observations:
 
350B, KT66, and EL37 types These are generally in a class by themselves. The 350B is the king of the 6L6 types with an incredible, palpable air and depth to the sound with razor sharp focus and dynamic power. It is not always compatible with all amps due to its different current draw and filament demands. The British NOS KT66 also rule in this category and are usually compatible with any 6L6GC circuit, ditto the EL37. Warm and rich, like most of the British tubes, again with nice power reserves. The EL37 only a little less powerful and getting harder to find every day. There is a USA KT66 called the 7581A and it is virtually the same as a 6L6GC, and are found mostly made by GE. Clean, detailed, airy, and powerful. The beige base version made for amps is superb and the rarest of this type. These types listed here are usually used in hi-fi applications, but the KT66 is sometimes favored for a British sound in guitar amps that call for a 6L6GC. There is a very nice KT66 version being made by Groove Tubes which sound similar to the Genalex, available in various hardness ratings. One of the best current production KT66 tubes available.
 
6L6GC types Most needed for guitar amps but these make a fine hi-fi tube in any amp calling for a KT66, 7581, or even 5881. The blackplate RCA are the stars, and rightly so. They are rich, warm, detailed, creamy, and powerful. No other tube comes close except possibly the NOS GE 6L6GC. The GE is a bit more linear from top to bottom and lacks some of the RCA richness, but we are still talking about the two best NOS tubes in this class! The GE is often much less costly, but this may change as they become scarce. Sylvania made this tube for many other brands. They are typically bright and sparkly, if a bit leaner in the bass. Usually the Sylvania made NOS tube is the winner when it comes to bargain performance. Do not overlook some of the current production tubes. The few that deserve attention are the JJ from the Slovak Republic, and the Winged C from SED, St. Petersburg, Russia. Both have near-NOS sonics at a much lower price. The 6L6GC type can substitute for any of the types below, but may require a bias adjustment or modification to operate at peak performance. Consult an amp tech whenever substituting tube types.
 
5881 and 6L6WGB types The Tung Sol is the most asked for tube here. The original 1950s and 1960s brown base tubes, often found made for the military (JTL5881 or JAN 6L6WGB used interchangeably) are smooth, detailed, and nearly as powerful as the 6L6GC types. They have great warmth yet balanced by smooth airy highs and wide dynamics. The GE and Sylvania are the next best thing and the choice if cost is a consideration. These brownbase tubes often have a silver getter spot on the side only, and both USA and Canada versions are equally excellent. These are brighter and leaner sounding, but often one-third less costly than the Tung Sol. Finally, the JAN Philips 6L6WGB with the green or blue labels are a super bargain but are getting hard to find. They were late 1970s made in the USA, and are somewhat bright sounding, but often priced far lower than either of the above types. This may change as stocks become depleated. Generally, guitar amps that call for a 6L6GC cannot use these tubes without bias circuit adjustments or even modifications. Consult an amp tech if you are unsure.
 
5932, 1614, 6L6Y, and other glass 6L6G/A/B types The metal 1614 and 6L6Y types enjoy a fine reputation in some McIntosh amps. The RCA are the ones most often requested, with fine dynamics, rich warmth, and detailed, airy highs. The 5932 glass military type can often be used in place of these (or any other except for the GC, KT66 or the 5881) and in this case the Sylvania is what is often found. They are powerful for their size, with a nice punchy and lively sound. Finally, the lower power 6L6 metal, 6L6GA and 6L6GB come in many NOS brands. The RCA is the warmest, the GE fairly balanced, and the Sylvania the brightest of these. The large G shapes are said to be the most musical. Like the 5881 types, these cannot be used in an amp calling for a 6L6GC or KT66 without at least bias adjustment or more likely, circuit modifications. Consult an amp tech if you are unsure.

 

[JK-47]

lucidreamer,
 
Try I pair of vintage GE 6L6GC's, very nice for a reasonable price. The RCA "Black Pates"  are nice, but I don't think they justify the premium. Sylvania 6L6GC's (not the STR 387's or 415's) are a little drier sounding and sound more analytical, they almost sound like solid state (they also lack a little on the bottom end). I have Philips 7581A's (basically the miltary version of the Sylvania STR387/415 6L6GC)  in my amp quite often and enjoy them (very punchy, and accurate without sounding too analytical). The limited time I have had with various new production tubes always have left me wanting more out of them.

 

[Greg70]

lucidreamer
 
Psvane make some of the best modern tubes you can get. They are accurate tubes with a good frequency response, and I guess they could be considered analytical and almost solid state if you're chasing a tubey tone.
 
I wouldn't write off the EL34s. They are a very musical tube, and you might be surprised to find that you like them.
I resisted them for a long time based on what I read, and then when I finally tried a pair I knew they were the ones for me in the Elekit.. admittedly with Grados.
It might be worth trying a reasonably priced pair of modern EL34s just to see if the flavour appeals to you. I started with re-issue Mullards, and IMO they are similar in character to the fantastic NOS mullards and have maybe 80% or more of that tone so they're a good place to start to see if that tube suits you.
In Ultra Linear mode they still have excellent bass response, although a little less than the 6L6 and KT-88 types.
 
From the description of the sounds you're chasing, I think you might like Mullard or Amperex pre-amp tubes too
 
Good luck in your quest.

 

[Effusion]

Sorry to hear that you're not diggin the Psvane KT88s so much, they are highly regarded, however I have yet to actually be able to properly audition a pair myself.  I don't doubt that they may seem a little more solid state, as most new production tend to do, when compared to other types, even NOS.  There seems to be something with these NOS tubes; many find that they tend to give more bloom, sounding a bit more like a "tube" in general and compared to more recent batches.  This probably isn't always the case, but many have agreed so.
 
JK-47's suggestion is a really good one.  I've also found that the GE 6L6GC can be worth the money, they are fairly inexpensive in comparison to others and sound pretty darn good.  I would have to say that the RCA Black Plate 6L6GCs I have tend to be a bit more solid state when compared to their GE counterparts, which can also be had much cheaper than the RCAs.  Below is a nice pair, similar test results, maybe not exactly matched on mutual conductance, but same date codes nonetheless; could be worth it:
 
http://www.ebay.com/itm/Two-GE-6L6-GC-vintage-tubes-test-great-see-pics-/171829439472?pt=LH_DefaultDomain_0&hash=item2801d52bf0
 
Greg70's recommendation is also a very good one and may actually be close to what you're looking for.  The EL34s are nice sounding tubes and I feel tend to be more laid-back and bloomy, generally with great mid-range and air/soundstage.  I really like the Mullards, Teslas, Amperex, and Siemens... all have a slightly unique sound to each other.  An inexpensive, but highly regarded, newer production version is the SED Winged "C" EL34s.  Below is a nice pair that I think would give you at least an idea of what the EL34 can do:
 
Better hurry if you want them though!
 
http://www.ebay.com/itm/SED-Winged-C-EL34-Tubes-Matched-Pair-/281726799211?pt=LH_DefaultDomain_0&hash=item419839cd6b
 
The Mullards can be expensive, same with the Telefunken, but re-brands can be had at great prices!  Below is a pair of Valvo's, a Mullard re-brand, that look nice; notice the etchings in the glass near the base, the "xf" means it was made in the Blackburn factory in England, and I believe the 3 indicates the 3rd generation, made in the early '70s, so a little later production than others (generally less in-demand):
 
http://www.ebay.com/itm/2x-VALVO-MULLARD-EL34-6CA7-O-GETTER-XF3-TUBES-TESTED-STRONG-/291497006704?pt=LH_DefaultDomain_0&hash=item43de935670
 
These Amperex "Bugle Boys" also look very nice; they have a different flavor than the Mullards, however mine aren't Bugle Boys though, so I can't say for sure... slightly different date codes, but test really good:
 
http://www.ebay.com/itm/2-NOS-NIB-Amperex-Bugle-Boy-EL34-6CA7-Tubes-Dual-Top-D-Getters-Tested-/371357014576?pt=LH_DefaultDomain_0&hash=item56769a5a30
 
With all the examples above, please research the sellers/listings and buy at your own risk, although eBay has the best prices, it can sometimes be a miss.  Vendors may have similar types in stock, but I've found that with NOS, sometimes it isn't worth the extra price of their service, plus many times I can't actually see them until they arrive.  Most eBay sellers at least offer refunds if they are damaged in transit or if they do not work the first time you turn them on, but other than that though, you are stuck with them and would have to resell them if necessary.  If they sell a lot of tubes and have great feedback than usually they are honest with their test results and will work with you if you have issues.  I did not do this research myself for any of the links above, just quickly found them as examples.
 
A great resource for information on NOS tubes in general is Tube World; they have some really useful info and a ton of pictures to boot!
 
https://www.tubeworld.com
 
Maybe even giving the Psvane a wee bit more time may prove beneficial, as the sound may loosen up after a few more hours of burn-in.  I am, of course, just assuming that Grant Fidelity only burnt them in for a day or two, so they can better match them before sale, and that they were completely unused prior to this.  I haven't purchased many new production, but even some of my NOS were a little tight sounding in the beginning.

 

[lucidreamer]

You guys are awesome, thanks so much for your suggestions and recommendations!!! It may actually take me some time to sift through the information to decide which NOS tubes would be a good choice. There are quite a few of them to figure out what may be the best bet, plus the lack of trying/testing them before buying makes is like gambling.
 
Just found some good comparison between RCA and GE NOS 6L6, it seems to be in line with what Effusion mentioned as well and the GE is a winner here (GE is more tubey sounding compared to RCA):
 
The GE 6L6GC Grey Plates are smoother and more laid back sounding, which I like a lot. Horns are tamed a little, with less brashness & edge compared to the RCAs. The GEs are not quite as transparent as the RCAs, but still by any measure they are nicely transparent, with superb imaging & soundstaging, but perhaps not quite as an obvious sense of layering back into the depths of the soundstage as the RCAs possess. The GEs don’t have quite the same prowess as the RCAs when it comes to tempo, melody lines, and rhythm, but do best the RCAs in terms of timbre and tone color.

The verdict: I like the GE 6L6GC Grey Plates the best in my MC30s. They have a smoothness and richness that makes them easy on the ears, and as a side benefit they’re almost half the price of the RCA 6L6GC Black Plates. You might come to the opposite conclusion, and favor the RCAs for their superior low frequency performance, and snappy renditions of tempo, melody, and rhythm. All I can say is I’m glad I’ve got a set of both.

http://jeffsplace.me/wordpress/?p=5569

 

 

[lucidreamer]

This listing says only a few hours were put on the EL34, but the seller does not really post any test data/results, pretty risky.... Maybe someone already bought from that seller and has good experience.
 
http://www.ebay.com/itm/281726799211?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT
 
 
Is this listing basically for the same exact tube as =C= EL34 just branded as Marshall?
 
http://www.ebay.com/itm/SVETLANA-WINGED-C-EL34-DUET-MARSHALL-/201369627557

 

[JK-47]

Thanks for the article

 
There are also different GE 6L6GC's depending on the year of manufacture.... Similar to the RCA's in the article, the height of the bottle changed somewhere in the mid to late 1960's. Square or circle getters, and round or oval spacers. Making for an interesting mix within the same GE family of 6L6GC's... I tend to prefer the earlier short bottle GE's myself, but I'm sure everyone will have their own preference. I almost forgot to mention that GE's 7581A is also a dead ringer for a late production (1970's-1980's) tall bottle 6L6GC (I'm sure they are one and the same). And to make matters worse GE made RCA'a 7581A's.... I have or have had examples of all the above mentioned tubes. They all sound very similar, with subtle nuances differentiating them.