Dennis Had Inspire Amps

[pstrisik]

Originally Posted by Coltrane1

Hi Peter! Thanks for posting Dennis' thoughts. So is the 5Y3 "GT" an acceptable rectifier option one could consider for the 'fire bottle KT88'? I'm seeing a lot of NOS pairs on the 'bay.

Happy New Year!

Greg

Hi Greg,

My read is that the 5AR4, and other low voltage drop rectifiers like the 5V4, work with the KT88's to keep the preferable 2nd order harmonics dominant. I think Dennis is suggesting that a 5Y3, similar to 5U4, with the KT88 would allow odd order harmonics to be more present. It's safe since the 5Y3 doesn't drive the output tubes as hard as the 5AR4. Maybe the difference is more apparent at higher volumes when the distortion is stronger.

I've read that a primary reason tubes are considered warmer/smoother than solid state is because of the predominant 2nd order harmonic at distortion. Distortion with even order harmonics, especially the 2nd order, is more pleasing to our ears (or less displeasing) than odd order harmonics and SS produces more of the latter.

Ok.... I've probably said more than I know and something is off in that explanation, so feel free to correct.

Bottom line is that you can run the 5Y3 with the KT-88's but it may not be the best sounding combo, but our ears are the final judge. The 5Y3 is a good rectifier to have on hand, so I would grab one if it were me (and it was so I did! ). They are cheap enough. Even vintage RCA and Tung-Sol's are $10-$20.

[FloridaBoy]

Originally Posted by robert_kc

I’ve never heard the LaScala, Belle or Klipschorn (or Altec 19, etc). I’d like to hear them someday – driven by tubes, and playing classical music. (I did briefly own a Cornwall, but didn’t care for the sound – IIRC the bass sounded “muddy”.) Does anyone use these traditional horn-loaded speakers for classical music? If so, I’d like to hear your comments.

I’m also aware that some small companies manufacture up-grades to these classic speakers, and some manufacture entire speaker systems that they claim are superior to the originals. Again, I wish that I could hear them.

And some people say that the speakers to own are the Klipsch Jubilee.

Unfortunately I can’t accommodate speakers that are more than 2 feet wide (or in the case of Jubilee more than 3 feet wide) into my listening rooms, except perhaps in my basement (which is where my Klipsch RF-7s reside). I think that a lot of people are in the same boat, which is why tower speakers are so popular.

Maybe someday I’ll get to hear one of these classics …

I have Heresy III's due to space limitations. The Inspire gear is a great match for efficient speakers in general and horns in particular. However, if getting as close to reproducing large scale classical as possible is your goal horns are the answer. And the only way to decide what works for you is to trust your ears.

[FloridaBoy]

Originally Posted by pstrisik

Hi Greg,

My read is that the 5AR4, and other low voltage drop rectifiers like the 5V4, work with the KT88's to keep the preferable 2nd order harmonics dominant. I think Dennis is suggesting that a 5Y3, similar to 5U4, with the KT88 would allow odd order harmonics to be more present. It's safe since the 5Y3 doesn't drive the output tubes as hard as the 5AR4. Maybe the difference is more apparent at higher volumes when the distortion is stronger.

I've read that a primary reason tubes are considered warmer/smoother than solid state is because of the predominant 2nd order harmonic at distortion. Distortion with even order harmonics, especially the 2nd order, is more pleasing to our ears (or less displeasing) than odd order harmonics and SS produces more of the latter.

Ok.... I've probably said more than I know and something is off in that explanation, so feel free to correct.

Bottom line is that you can run the 5Y3 with the KT-88's but it may not be the best sounding combo, but our ears are the final judge. The 5Y3 is a good rectifier to have on hand, so I would grab one if it were me (and it was so I did! ). They are cheap enough. Even vintage RCA and Tung-Sol's are $10-$20.

Tubes in a single ended circuit clip 'softly' and the distortion is primarily second order so when clipping occurs it is not as obnoxious as solid state.

Another low voltage drop rectifier is the 83V, equivalent electrically to a 5V4 but you will need an adapter as it is a 4 Prong tube. They won't break the bank either.

VinylSavor: Tube of the Month : The 83V

[FloridaBoy]

Here is a link to a downloadable book that is great if you want to explore the tech side of tubes.

Tech Support

[FloridaBoy]

Dennis used .022uf Russian military K42 PIO (paper in oil) coupling capacitors in my amp. He used Auricaps in other builds. These are passive devices and sound different, just like tubes, and there are many types out there.

AFAIK, all the Inspire amps I have seen here have .022uf caps in them. It is a small value capacitor and even most of the boutique brands in that size are affordable. There are two of them in the circuit and they are easy to change even if you, like me, are an average solder slinger. I have Klipsch speakers and I have always liked PIO caps with them because of the smooth yet detailed presentation of music. So after the K42's settled in I ended up preferring a .01uf V-Cap copper foil and a .015uf Vitamin Q in parallel. .025uf is not a big difference and cap values usually have a +/- 10% variance. The Vitamin Q's are very smooth and the Copper foil V Cap is a bass champ. Me likey. BUT THIS COMBO MAY NOT WORK FOR YOU. Because, like tubes, we have personal preferences and our systems are different.

I have experimented with capacitors for many years and it is no different than rolling tubes and the results may surprise you.

Google capacitor comparisons and you will find a wealth of info.

[FloridaBoy]

Originally Posted by nhparrot

Rectifier Question, which will drive the output tubes harder and why?

Tube -------- Fvolt - Famp - Vdrop - MaxPmA - MaxPv
5AR4/GZ34 -- 5.0 --- 1.9 --- 17 ---- 250 ----- 450
5Z4 --------- 5.0 --- 2.0 --- 20 ---- 125 ----- 350

Is it the voltage drop (Vdrop) or the plate voltage/output current (MaxPV/MaxPmA) to be concerned with?

From another post but by Dennis:

Just one more thought ... personally I prefer the sonic presentations of the directly heated (5y3,5U4) rectifier tubes vs the indirectly (5AR4 type) in my amplifiers. If one wants to push the amps to the limit then the indirect cathode type (5AR4) would be the choice. Just a personal listening choice. Some times the sonic presentation preferred choice defies engineering parameters.

The 5AR4 would push a given power tube harder...but possibly past the sweet spot of the tube in the Inspire circuit.

[Coltrane1]

Originally Posted by pstrisik

Hi Greg,

My read is that the 5AR4, and other low voltage drop rectifiers like the 5V4, work with the KT88's to keep the preferable 2nd order harmonics dominant. I think Dennis is suggesting that a 5Y3, similar to 5U4, with the KT88 would allow odd order harmonics to be more present. It's safe since the 5Y3 doesn't drive the output tubes as hard as the 5AR4. Maybe the difference is more apparent at higher volumes when the distortion is stronger.

I've read that a primary reason tubes are considered warmer/smoother than solid state is because of the predominant 2nd order harmonic at distortion. Distortion with even order harmonics, especially the 2nd order, is more pleasing to our ears (or less displeasing) than odd order harmonics and SS produces more of the latter.

Ok.... I've probably said more than I know and something is off in that explanation, so feel free to correct.

Bottom line is that you can run the 5Y3 with the KT-88's but it may not be the best sounding combo, but our ears are the final judge. The 5Y3 is a good rectifier to have on hand, so I would grab one if it were me (and it was so I did! ). They are cheap enough. Even vintage RCA and Tung-Sol's are $10-$20.

Thanks Peter!

I'm so loving the KT88-LP2 combo with the Sophia 274b rectifiers that I'm tempted to leave well enough alone...for now. I've not had better "tube" sound in my system...I can't believe this little 'fire bottle' KT88 drives my electrostats to more than satisfying levels....I let the LP2 and the KT88 sit for nearly 2 years...well, better late than never. Enjoy!

[Cohibaman]

Originally Posted by Musica Amantem

I thought it would be useful for the discussion to show my subjective tube-rolling results so far. The first group is the inventory of tubes I currently have, followed by my perceived relative results.

The first three columns of the configuration below relate to the preamp (LP-27a) and the rest are the amp's (SET), following the order: Input, Rectifier and Output tube in each case:

Output Tubes

NOS Russian 6L6 GT
NOS RCA 6V6 G ST
NOS RCA 6V6 GT
NOS TungSol 6AR6WA w/Adptr
Genalex Gold Lion KT-88
NOS Philco Globe-Type 27
NOS Philco 27
NOS RCA 27
NOS Sylvertone Globe-Type 56
NOS RCA-Radiotron 56

Rectifier Tubes

Sophia Electric 274-B, Octal
NOS RCA Radiotron 80
NOS Sylvania 80
NOS RCA Victor 80
NOS RCA Cunningham 80
NOS Sylvania JAN 80
NOS RAD-TEL 5Z3 (4-Pin)
NOS RCA 5Z3 (4-Pin)
NOS Brimar 5Z4 (Octal)
NOS Westinghouse-Holland 5AR4

Input Tubes

NOS RCA 6SN7 GT
NOS Sylvania 6SN7 G/B
NOS Sylvania 6SN7 GTA
NOS Super Radiotron 6SN7 GTA
NOS GE 6SL7 GT
Tung-Sol 6SL7 GT
NOS Sylvania 6SL7 GT
NOS Phillips JAN 6SL7 WGT
NOS Tung-Sol 6SL7 GT
NOS GE 6BX7 GT (got only one)

With these subjective assessment results:

6BX7 80 56 6SL7 274 B KT88 9.0 Great sound!
6BX7 80 56 6SL7 5Z3/Adpt KT88 9.0 Great sound!
6BX7 80 56 6SL7 5Z4 KT88 9.0 Great sound!
6BX7 80 56 6SL7 5AR4 KT88 8.0 Somewhat thick-sounding
6BX7 80 27 6SL7 5Z3/Adpt KT88 9.5 Great sound!
6BX7 80 27 6SL7 5Z4 KT88 10.0 Best sound!
6BX7 80 56 6SL7 274 B 6V6 GT 7.0 Lacking weight & body
6BX7 80 56 6SL7 5Z3/Adpt 6V6 GT 9.0 Great sound!
6BX7 80 56 6SL7 5Z4 6V6 GT 9.0 Great sound!
6BX7 80 56 6SL7 80/Adpt 6V6 GT 7.0 Lacking weight & body
6BX7 80 56 6SL7 5AR4 6V6 GT 9.0 Great sound!
6BX7 80 27 6SL7 5Z3/Adpt 6V6 GT 9.0 Great sound!
6BX7 80 27 6SL7 5Z4 6V6 GT 9.5 Great sound!
6BX7 80 56 6SL7 274 B 6AR6 6.0 Not neat. Lacks soundstage
6BX7 80 56 6SL7 5AR4 6AR6 7.0 Narrow soundstage
6BX7 80 27 6SL7 5Z3/Adpt 6AR6 9.0 Great sound!
6BX7 80 27 6SL7 5Z4 6AR6 7.0 Not neat. Lacks SPL
6BX7 80 56 6SL7 80/Adpt 6V6 GST 9.0 Great sound!
6BX7 80 27 6SL7 80/Adpt 6V6 GST 9.0 Great sound!
6BX7 80 56 6SL7 274 B 6L6 GT 8.0 Slightly less bass
6BX7 80 27 6SL7 5Z3/Adpt 6L6 GT 9.0 Great sound!
6BX7 80 27 6SL7 5Z4 6L6 GT 9.0 Great sound!
6BX7 80 27 6SL7 5AR4 6L6 GT 9.0 Great sound!

Obviously YMMV, and I still need to confirm some of the values again, but so far this combination of Dennis's preamp/amp is phenomenal as most everything in it sounds great.

I'll revise the suggested combinations from Dennis concerning the 5U4 (5Z3) & 6V6's vs 5AR4 & KT88's. Any suggestions/comments are welcome. My speakers are Tekton Lore 2.0's and I use a Yggdrasil DAC coupled to my laptop and Foobar as a player.

Truly impressive feat of tube rolling!!! Well done!

[lsquaredb]

Musica Amantem, that's a lot of tube rolling! Have you tried the old globe or balloon shaped 27's in the LP-27a? I tried some Everready Raytheon balloons and there was more richness and texture than with shouldered 27's, but the balloons hummed a lot.

Since you're using a preamp, you probably don't need the extra gain from the 6SL7 amplifier input tube. Have you tried the 6SN7 in the amp?

I'm using an RCA 6SN7 and NOS Tung Sols 27 shoulder tubes in the preamp. What's in the amp varies, but the input tube is usually a 6SN7 or 7AF7 with an adaptor. The power and rectifier combinations that have worked the best so far are Popes + 5U4, 6V6G + 5Y3 or new production Gold Lion KT-88 with 5U4 or 5AR4. The 6V6's sound best, the KT88's sound a little bit soft, but with large-scale orchestral music I need the extra power.

[Musica Amantem]

Interesting. I can see your points, indeed. For one thing, I'm correcting my initial judgement on the KT88 / 5AR4 and I'm giving it top marks. It seems the 5AR4 needed more settling time. This, along with the Brimar 5Z4 make the KT88's sing. My Electric Sophia 274-B also make the KT88's sound great.

I also love the RCA 6V6 GT's paired with either the 5Z3 or 5Z4. I need to listen back again to my RCA G ST (big bottle) with the RCA 80 and compare that against the above.

I received ballon type 27's from Dennis originally but one went noisy so I asked for a new pair and these are here but have not had the opportunity to try them. I'm currently using the shouldered 27's, but liked the ballon 56's very much also.

Never tried a 6SN7 yet, although I have a few ... Not enough time for all possible combinations, but the bottom line is, most everything in this preamp/amp combo sounds great! So many good choices and so little disappointments, a true tube-rolling platform indeed.