Which do you prefer, KT88 or 6550, and which brand?

[Psilonaught]

I've just bought a pair of 100w KT88 monoblocks which are in fact my first foray into valve power amplification. I'll be using them for my tweeters and mid drivers.

Anyway, knowing what I'm like, I will want to replace all x8 power tubes almost immediately, and I wondered what the view round here was on the following questions

1) has anyone compared KT88 Vs 6550 in the same amp, which did you prefer and why?

2) what brands did you like best ?

I have my eye on x8  Shuguang nature Sound  KT88-T but at over £500 I better make sure I'm getting something that will be good!

I guess I should also consider KT120 too??

 

[Psilonaught]

So I'm told my new monoblocks won't accept KT120 so I'm resigned to KT88 tubes.

Anyone care to comment of what they think are the best ? Genalex GL reissues, Shuguang kt88-t or something else? 

The amps take x8 and are auto biasing.

 

[mac72]

Genalex reissue are possibly best new production KT88 tubes unless you want to spend silly money on EAT , second and a bit cheaper option - Electro Harmonix - not far behind Gold Lions . Shuguang tubes are quite good as well but you need to be careful at what conditions your amplifier works , they do not like to be put under too much stress (plate, screen voltage) also  buy from respected source - I bought few quads from Grant Fidelity in Canada , also Psvane tubes were good , definitely avoid buying from E-Bay . As to KT88vs6550 , I tried quite few 6550's and always came back to KT88 , 

 

[Psilonaught]

Genalex reissue are possibly best new production KT88 tubes unless you want to spend silly money on EAT , second and a bit cheaper option - Electro Harmonix - not far behind Gold Lions . Shuguang tubes are quite good as well but you need to be careful at what conditions your amplifier works , they do not like to be put under too much stress (plate, screen voltage) also  buy from respected source - I bought few quads from Grant Fidelity in Canada , also Psvane tubes were good , definitely avoid buying from E-Bay . As to KT88vs6550 , I tried quite few 6550's and always came back to KT88 , 

Many thanks. Grant Fidelity don't seem to have any KT88s for sale at the moment

 

[mac72]

Yes, it seems they don't sell Shuguang anymore and Psvane is gone , last time I bought tubes from them the owner was quite poorly and his wife started taking over the business .

Have a look at Hotrox they have few different brands of KT88 , I think they still sell Psvane but it's £200 for a pair.

 

[newlash09]

I've just bought a pair of 100w KT88 monoblocks which are in fact my first foray into valve power amplification. I'll be using them for my tweeters and mid drivers.

Anyway, knowing what I'm like, I will want to replace all x8 power tubes almost immediately, and I wondered what the view round here was on the following questions

1) has anyone compared KT88 Vs 6550 in the same amp, which did you prefer and why?

2) what brands did you like best ?

I have my eye on x8  Shuguang nature Sound  KT88-T but at over £500 I better make sure I'm getting something that will be good!

I guess I should also consider KT120 too??

Even Iam running 2 tube mono blocks with Mullard kt88's,  outputting 100 w into 8 ohms each. I got them with the express idea of only running mids and treble. While bass is handled by class D effeceint amps. However, the kt88 implementation in my particular amp due to its design doesn't sound as syrupy as some amps do. If one sat blind, they would wear they were hearing some high power class A amps. So I plan to replace the kt88's with EL34's, to add that syrupy smoothness and only use it for mid range. 

 

[Psilonaught]

Even Iam running 2 tube mono blocks with Mullard kt88's,  outputting 100 w into 8 ohms each. I got them with the express idea of only running mids and treble. While bass is handled by class D effeceint amps. However, the kt88 implementation in my particular amp due to its design doesn't sound as syrupy as some amps do. If one sat blind, they would wear they were hearing some high power class A amps. So I plan to replace the kt88's with EL34's, to add that syrupy smoothness and only use it for mid range. 

I've read then the KT88 is a very neutral tube and therefore I'm not surprised that you find it sounds like a class A. I'm about to receive my monos in the next few hours from Fedex, and I'll be comparing them to my class A plinius. I have no idea what to expect!

What monos do you have? I assume theu have signal tubes too, and therefore if you want more "syrup" then you will want to experiment with different kinds.

Personally I crave neutrality.

I've decided to order x8 Genalex GL reissues and x8 12AUT Psvane Art editions. £700  :dunno: Oh well. 

 

[newlash09]

I've read then the KT88 is a very neutral tube and therefore I'm not surprised that you find it sounds like a class A. I'm about to receive my monos in the next few hours from Fedex, and I'll be comparing them to my class A plinius. I have no idea what to expect!

What monos do you have? I assume theu have signal tubes too, and therefore if you want more "syrup" then you will want to experiment with different kinds.

Personally I crave neutrality.

I've decided to order x8 Genalex GL reissues and x8 12AUT Psvane Art editions. £700  :dunno: Oh well. 

Excellent...congratulations on your new tube amps

I too was using a class A krell power àmp before going to my present TAD1000 tube mono blocks from USA.  And with the KT88's the amps were sounding exactly like the krell. So i sold off the krell.

I did change the driver tube a 12AU7 electro harmonix to a gold lion. It brought about slight but noticable improvement in clarity and a clearer back ground. But in the bargain, the sound become leaner. So i changed back to EH. So now I plan to try EL 34's in place of kt88's as I like a more romantic sound

edit : I think it is called as the input tube and not the driver tube as might have wrong mentioned

 

[Psilonaught]

sounds like we have very similar amps.

These are what I bought - balanced Melody M88Q monos. X4 KT88 and X4 12AU7s. Assuming I prefer them over my Plinius, I'll be having the caps and wiring upgraded too

 

 

[newlash09]

sounds like we have very similar amps.

These are what I bought - balanced Melody M88Q monos. X4 KT88 and X4 12AU7s. Assuming I prefer them over my Plinius, I'll be having the caps and wiring upgraded too

 

Wow...they look gorgeous ...absolutely lovely. Hearty congratulations sir

Please do share your listening impressions, once you have them up and running.

 

[mac72]

I've decided to order x8 Genalex GL reissues and x8 12AUT Psvane Art editions. £700  :dunno: Oh well. 

These amps come with no tubes ? 
I’ve heard good things about Melody amps, hope you enjoy them. Power tubes don’t affect sound as much as small signal tubes , I’d start with these first IMO

 

[Psilonaught]

They just arrived. After a good clean the first this I did was pop the underside. Wow  :x

Look at the craftsmanship and more importantly the components used. 

Aluminium paper in oil Jensen, coke can sized nichicon and decent MKP caps.

 

[Psilonaught]

Power tubes are totally unbranded however which isn't a good sign...signal tubes are original melody which will be. Chinese I'm sure.

Can the power tube brand be decerned from this photo? Probably cheap Chinese ?

View attachment 79123

 

[rabski]

Svetlana I think. Most others have round holes rather than oblong cutouts. Actually, the Svets aren't at all poor. Well worth keeping as spares and as a comparison with the Gold Lions.

 

[Psilonaught]

So I've had a chance to listen to my first KT88 setup. The dealer I bought these from saw fit to replace the tubes on one side with Russian tubes ( X3 round hole, unbranded, and x1 square hole) Vs the stock melody tubes which I'm fairly certain are kt88-98 tubes (x4 oval holes).

Once I phoned them to complain that the amps had been supplied with three different tube types...they replaced the square with another unbranded round hole.

Due to the dealer's sloppy tube installation I'm fortunate enough to be able to compare each type by playing one channel at a time and comparing.

The Russia round holes are quite rolled off and lack sparkle or air. Not nice. Also, I noticed that they get a lot hotter than the kt88-98 (or they take a lot longer to cool down). The ruskies were burning hot after a few minutes powered down Vs warm to touch for the kt88-98.

The kt88-98 sound very nice overall, with a lot nicer top end - more air and sparkle.

Conclusion, ruskie unbranded round holes are not good, at least not in this setup. 

 

[pmcuk]

For the input tubes have a look at this...

https://www.effectrode.com/knowledge-base/the-12au7-tube/  Read the carefully. Check heater voltages and pinouts to be sure from Frank's Tube database or google the tube in question and see the radiomuseum.org or r-type.org

The 12AU7 is an OK tube, nothing special. The E80CC, however, is nice and gets a lot of love. Undoubtedly an upgrade. HOWEVER... the heater is 600mA instead of 300mA. Four together adds 1.2 amps, which is not trivial. You'd need to clear that with the designer. May be OK, may not be. 

https://forums.stevehoffman.tv/threads/tubes-12au7-vs-5814a.17898/ 5814 is OK - 300mA but check which version, A etc. since they have different heater voltages

https://forums.stevehoffman.tv/threads/are-5963-tubes-a-true-substitute-for-a-12au7-tube.727709/ 5963 is OK, 300mA

https://www.thetubestore.com/genalex-gold-lion-ecc82-b749 if you can find them the B749 are reputed to be best of all, bit of a legend. 

https://www.hotroxuk.com/genalex-gold-lion-12au7-ecc82.html A later copy version, not the original B749. I'm assuming the B749 is 300mA but can't see any data. 

 

[Psilonaught]

Hiya

I've bought some NOS clear top RCA from a US dealer so will see how those go.

I've decided to order another set of the kt88-98 since I like their sound and leave it as that for now. I don't need to sink £500 on "better" power tubes right now. Tis a slippery slope, tube rolling...

 

[Psilonaught]

For the input tubes have a look at this...

https://www.effectrode.com/knowledge-base/the-12au7-tube/  Read the carefully. Check heater voltages and pinouts to be sure from Frank's Tube database or google the tube in question and see the radiomuseum.org or r-type.org

The 12AU7 is an OK tube, nothing special. The E80CC, however, is nice and gets a lot of love. Undoubtedly an upgrade. HOWEVER... the heater is 600mA instead of 300mA. Four together adds 1.2 amps, which is not trivial. You'd need to clear that with the designer. May be OK, may not be. 

Audio Emotion, the UK melody dealer, is contacting the company owner and trying to find out if the units are KT120 compatible (a US dealer told me not, but he was v rude and isn't the manufacturer, so getting a second opinion!).

I'll try and find out about the signal tube heater voltage. I've been told to try 12BH7 if the higher heater voltage is supported.

Ps the dealer I referenced earlier in isn't Audio Emotion, they are just kindly helping me as good dealers do

 

[mac72]

E80cc and Ecc82 are bit different beasts , they do differ not only when it comes to heater current draw but work at different conditions at 250V plate voltage , 6mA vs 10.5mA also plate resistance 10kohm vs 7.8kohm and amplification 27 vs 17 .  
 

Ps the dealer I referenced earlier in isn't Audio Emotion, they are just kindly helping me as good dealers do

Audio Emotion are definitely  good guys ,