JJ KT88 versus JJ KT88BG

Hi friend,

I am totally new to the tube world, but I have a solid experience of the DIY hobby...

I plan to build the Dynaco Mark III monoblocks (http://triodeelectronics.com/trmk3tuampki.html) but as I also have a secondary and smaller HiFi system to power, I will maybe start by smaller monoblocks (like thes ones : http://www.oddwattaudio.com/ow77-88.html).

Both of them can use the KT88 tubes, but for the second I have the choice between the JJ KT88 and the JJ KT88BG (or no tubes at all).

As I am a newbie in the tubes world, I have 3 questions:

a-/.for the Dynaco Mark III monoblocks, what would be the "best" tube from a sonic view point: the KT88 or the 6550 ?

b-/.what is the "best" tubes betwen the JJ KT88 and the JJ KT88 BG (BlueGlass) ?

c-/.In both cases, because I have eared that the KT 88 Gold Lion are the best available KT88 tube, I would like to know if the best deal is not just as simple as to order the KT88 Gold Lion separately (i.e to order the kit without any tubes ?)

Thanks for your help, the experts !

Bit early to lock in on a tube type ... keep your options open. Can't help with the JJ's, but I can tell you from personal experience, the Psvane KT88's are mighty fine.

That said, my favorite is the TungSol KT120's - IF your amp can drive them. Wouldn't think that would be a problem with the Mark III clones, but maybe an issue using the original transformers? You may, or may not need, closely matched tubes - depends on whether the amp can bias each tube independently. Basic matching isn't usually all that expensive anyway ...

PS ... from what I understand, the Winged C 6550's are alleged to be the cream of the crop for that type tube, but you'll want to jump fast if you're considering them. Out of production now, and the cost is starting to spike fast.

Sourcing your tubes is simply supply and demand. I know Bob offers some nice prices if you purchase tubes with a kit. nod nod wink wink nudge nudge, know what I mean?   

I believe he's currently supplying the Svetlana KT88's, which are also rumored to be quite nice.

I recently put together a pair of Mark III from Dynakitparts  http://www.dynakitparts.com/dynakit-products/amplifier-kits/MARK-III-KIT  I'm using the 6550 tubes in mine.

I used the octal driver board option from Roy's stuff and am very happy.

I did try a friends KT88's one evening last week. May have sounded a little boomy compared to the 6550's which I prefer at this point and one thing to consider if you plan on using the cases is the fatter KT88's are awfully close to the cover and to each other for that matter. It's a very tight fit which I just wasn't comfortable with. I was afraid the paint was going to  burn off the side of the case near the tubes.

https://2img.net/h/i103.photobucket.com/albums/m140/Elrick_02/Dynakit%20Mark%20III%20with%20Octals/DSC_2478_zps61fc7801.jpg

ThanKs Skizo. I am surprised than the 6550 C are no longer on production : so you mean that only the 6550C are out of production, or ALL the 6550 models are no longer on production ???

Regarding the KT120, what are the amp you use it on ?

They are not listed as compatible tubes on the Dynaco Mark III page (http://triodeelectronics.com/trmk3tuampki.html) , and as I am a newbir in the tube world (but a lot of experience in the DIY audio world), I absolutely do not know if the KT120 are compatible with the Dynaco Mark 3...

Anybody knows ??

Good point - the tube spacing was the main consideration for me going with a custom case ...



Plenty of room here for all the big trees ...

Something to consider if you're sticking with the stock chassis is adding ventilation holes around the base of the tubes and at least slotting the bottom of the case. That allows tube heat to draw up cooler air from below and creates a chimney effect right tight to the glass to improve heat dissipation ...

(This gives me a chance to show off my shiny new Mullard GZ37 too)   

Nounours18200 wrote:I am surprised than the 6550 C are no longer on production : so you mean that only the 6550C are out of production, or ALL the 6550 models are no longer on production ???

Just the Svetlana Winged C's ... last I heard even their website was dead. Still some in the pipeline, but I've heard some serious groans from price watchers. Lots of other 6550's still available from other sources, including NOS at ridiculous prices.

Regarding the KT120, what are the amp you use it on ?

I recently built the Latino ST120 with a few minor mods. Pictured above. Only real hardware changes were larger chokes and the Russian PIO capacitors.

They are not listed as compatible tubes on the Dynaco Mark III page (http://triodeelectronics.com/trmk3tuampki.html) , and as I am a newbir in the tube world (but a lot of experience in the DIY audio world), I absolutely do not know if the KT120 are compatible with the Dynaco Mark 3...

Reason I mentioned, check first with the mfg of whatever kit you settle on. A stock Dynaco doesn't have what it takes to drive the KT120's, but the ST120 has plenty reserve due to upgraded iron. Apparently Triode doesn't feel quite as confident. They're also verified by Bob & Co as good to go in the Latino monoblocks.

sKizo wrote:I recently built the Latino ST120 with a few minor mods. Pictured above. Only real hardware changes were larger chokes and the Russian PIO capacitors.

This could be a good alternative for me : did you get the larger chokes and Russian caps (and the proper schematics) directly from bob ? (I mean that I am skilled enough to build this kit, but I cannot define the appropriate new chokes value by myself, nor the schematics: I have to be guided).

sKizo wrote:A stock Dynaco doesn't have what it takes to drive the KT120's, but the ST120 has plenty reserve due to upgraded iron. Apparently Triode doesn't feel quite as confident. They're also verified by Bob & Co as good to go in the Latino monoblocks.

I have always been interested by these monoblocks , but they are 115V only and when I have asked the question I have been replied that they are not available in 230V version and that they are shipped only to USA & Canada... Did you mean that there is maybe a possibility to get them in 230V for Europe with the KT120 ?

Thanks very much for your reply,

I got the Russian PIO capacitor upgrade that Bob sells, but had to purchase the larger chokes elsewhere ... schematics weren't an issue as they were basically straight substitutions for the standard parts.

You can see there's a slight difference between the C17x chokes and what comes with the kit.



http://www.onlinecomponents.com/triad-magnetics-c17x.html?p=12695244

Although not necessarily required, I figured as long as I had the room, why not? One thing you need to keep in mind is that too large a choke can cause hummmmm, but that's not an issue on mine.

~~~

Wasn't aware you were on the other side of the big pond from my stomping grounds in Michigan USA. You can probably get a step down transformer and run that in line with an amp to convert from US to Euro current requirements, but that can be a bit of a problem due to the current draw. Something in the 2kW range should give you plenty to work with, even with monoblocks. Reasonable price and opens up a lot of extra possibilities maybe.



http://www.amazon.com/Bright-VC2000W-Voltage-Transformer-converter/dp/B000MXW85A/ref=pd_sim_lg_3

The Amazon link is just for more info, but I'm sure you could find something similar in your area. One caution ... you COULD get some noise due to the extra conversion step without proper filtering, so maybe check with some locals first to find out what works best. It's also possible you could get some mechanical noise with an extra transformer ... easy fix for that would be to locate it somewhere away from the listening area.

... as far as getting Latino amps overseas ... that's between you and Bob ...  

sKiZo wrote:Good point - the tube spacing was the main consideration for me going with a custom case ...



Plenty of room here for all the big trees ...

Something to consider if you're sticking with the stock chassis is adding ventilation holes around the base of the tubes and at least slotting the bottom of the case. That allows tube heat to draw up cooler air from below and creates a chimney effect right tight to the glass to improve heat dissipation ...

(This gives me a chance to show off my shiny new Mullard GZ37 too)   

Skizo this is EXACTLY what I am trying to do with my system. I have 2 sets of Thiels (CS1.2s and CS2.3s) which are power hungry at 87db, I've never owned a tube amp but auditioned 1 with my speakers and my world changed forever......just couldn't justify $6,600 for the amp. Next week I am ordering Bob Latino's VTA ST-120 with his upgraded capacitor options, but I've been wondering about the tubes. I was going to go with Gold Lion KT88s, but have been curious about the KT120s. Bob said the KT120s would work fine, but he did not have enough experience to say how they performed. What has been your experience with 88s versus 120s?