Just to be clear, the output transformers on these are massive. I swear the whole unit weighs like 60 pounds ( maybe an exaggeration but it hugely heavy to lift). And yes , guitar amps may allow some distortion, there is none present here or I would not use it.
Side note - input tube testing ( and I have done them all) but for sake of compare
rca mica black plates - clear and crisp but a little too crisp on the highs causing fatigue
mullard - original British made top of the line - smooth, buttery , relaxed but just a tad shy in the highs ( maybe rolled off slightly but very nice)
the winner - syvania black plate early 60’s rare - full spectrum enjoyment, deep lows, clean highs, mids perfectly setting the sound stage. You can literally hear a breathe in a mic.
there were many others. Never liked any Russian remakes. Baldwin organ ones were pretty nice but not as clear.
Side note - input tube testing ( and I have done them all) but for sake of compare
rca mica black plates - clear and crisp but a little too crisp on the highs causing fatigue
mullard - original British made top of the line - smooth, buttery , relaxed but just a tad shy in the highs ( maybe rolled off slightly but very nice)
the winner - syvania black plate early 60’s rare - full spectrum enjoyment, deep lows, clean highs, mids perfectly setting the sound stage. You can literally hear a breathe in a mic.
there were many others. Never liked any Russian remakes. Baldwin organ ones were pretty nice but not as clear.
I suspect that what Kay was getting at is that EL34's and 6L6GC's are in the same ball park and you can get similar power/performance from either one with minor mods to the amp.
Whereas replacing 6L6GC's (Capable of 55w in a P-P AB₁ amp) with EL84's (Capable of only 17w in a P-P AB₁ amp) defies logic.
Modify an amp to get 1/3 the power output with extensive mods including all new tube sockets for all output tubes..... not something any sane person would try, don't you think?
In a sense, you are fortunate and 60 pounds isn't that bad for a P-P Tube Amp rated at 95w/channel.
I'm looking at a BOM I've put together for an amp using Hammond transformers.
I'm already at 70lbs for just the two output and one power transformer. I figure by the time I add the chassis, components, tubes, chokes, etc. to it I'll be pushing 100lbs.
And yet… it works so beautifully… you can theorize all you like… but mine is proof in reality… amp required no modification to do so.. and the theory developed by one’s with more knowledge than you or I.
if you don’t try, how can you ever potentially succeed ? Not trying has a 0% success rate
Which McIntosh amp did you refer to? FIY, the MC-3500 or MI-350 tube amplifiers »only« weighed 125 lb per unit.
Best regards!
Best regards!
I was being funny ...the Velleman actually weights 51 lbs (but feels like 60...lol)
what has amazed me is the total disrespect I have seen here stressing TECH over sound (which the former is useless if the latter is not achieved) - but for those who like technical, these are damn fine. And the whole point of MY ORIGINAL post was not to say "its the greatest on earth " but to lend a hand to those who may have one and wanted past experience on making them sing
2 X 0 to 15 Wrms class A2 x 15 to 90 Wrms class AB
•Output impedance 4 or 8 Ohms
•Ultra linear output transformers
•Switch-on delay, to protect the output tubes: approx. 1 minute
•Standby circuit•Built-in bias current indicator
•Switch-on delay for the supply transformer: 0.5s
•Power bandwidth: 15 - 40kHz (-3dB, ref 50W)
•Frequency range: 8 Hz - 80kHz (-3dB, ref 1W)
•Harmonic distortion:0.1% (1 kHz/1W)0.7% (1 kHz/90W)
•Signal/noise ratio: > 105dB (A weighted wrt 90W)
•Channel isolation (75dB wrt 90W)
•Input impedance: 34Kohm•Input sensitivity (1Vrms) for 90W
•Damping factor (100Hz): > 10
Hi,
Thanks for sharing the results of your journey. Is this above the spec of the original amp, or did you measure them after your rolling?
Thanks for sharing the results of your journey. Is this above the spec of the original amp, or did you measure them after your rolling?
I've just reread your first post. Some quotes from that post:
- "... where they could be a 10, they designed as a 7."
- "Amazing...there was the 10....but wait there is more
- "Now it went from 10 to 11"
- "Nothing evokes the sweetness from my vinyl than this."
I'm intrigued by the toroidal output transformers.
In case you have the opportunity to run some distortion vs frequency plots, I'd love to see them.
In case you have the opportunity to run some distortion vs frequency plots, I'd love to see them.
Hi
In the mid nineties I built a K4040 kit -it worked ok but soon showed problems. The ht was way over spec and was caused by having an incorrect mains transformer - it was for European voltage not the 240v UK . I bought the kit from RS who arranged a replacement from the makers - I had to wait several weeks for this as they wanted the old one back to inspect. Eventually it arrived and fitted with expected levels of ht etc. Worked for several months until a loud bang and smoke was emitted from below chassis - caused by a faulty EL34 - burned a hole in the pcb, which was repaired and continued working. Must say, I have never been entirely happy with pcb mounted power valves - so later rebuilt the amp by removing the complete pcb and substituting a metal plate chassis hand wired - a lot of work, but gave many years of good service (and I could sleep at night!)
Having said all that, I was always happy with the massive toroidal transformers!
In the mid nineties I built a K4040 kit -it worked ok but soon showed problems. The ht was way over spec and was caused by having an incorrect mains transformer - it was for European voltage not the 240v UK . I bought the kit from RS who arranged a replacement from the makers - I had to wait several weeks for this as they wanted the old one back to inspect. Eventually it arrived and fitted with expected levels of ht etc. Worked for several months until a loud bang and smoke was emitted from below chassis - caused by a faulty EL34 - burned a hole in the pcb, which was repaired and continued working. Must say, I have never been entirely happy with pcb mounted power valves - so later rebuilt the amp by removing the complete pcb and substituting a metal plate chassis hand wired - a lot of work, but gave many years of good service (and I could sleep at night!)
Having said all that, I was always happy with the massive toroidal transformers!
Hi
In the mid nineties I built a K4040 kit -it worked ok but soon showed problems. The ht was way over spec and was caused by having an incorrect mains transformer - it was for European voltage not the 240v UK . I bought the kit from RS who arranged a replacement from the makers - I had to wait several weeks for this as they wanted the old one back to inspect. Eventually it arrived and fitted with expected levels of ht etc. Worked for several months until a loud bang and smoke was emitted from below chassis - caused by a faulty EL34 - burned a hole in the pcb, which was repaired and continued working. Must say, I have never been entirely happy with pcb mounted power valves - so later rebuilt the amp by removing the complete pcb and substituting a metal plate chassis hand wired - a lot of work, but gave many years of good service (and I could sleep at night!)
Having said all that, I was always happy with the massive toroidal transformers!
In the mid nineties I built a K4040 kit -it worked ok but soon showed problems. The ht was way over spec and was caused by having an incorrect mains transformer - it was for European voltage not the 240v UK . I bought the kit from RS who arranged a replacement from the makers - I had to wait several weeks for this as they wanted the old one back to inspect. Eventually it arrived and fitted with expected levels of ht etc. Worked for several months until a loud bang and smoke was emitted from below chassis - caused by a faulty EL34 - burned a hole in the pcb, which was repaired and continued working. Must say, I have never been entirely happy with pcb mounted power valves - so later rebuilt the amp by removing the complete pcb and substituting a metal plate chassis hand wired - a lot of work, but gave many years of good service (and I could sleep at night!)
Having said all that, I was always happy with the massive toroidal transformers!
To me the "Tech" is very important with this amp. I have a fairly good sized collection of all the articles, mods, improvements, etc. that can and have been done on these amps.
One thing that showed up in several articles was their tendency to turn themselves into space heaters as the EL34's went into meltdown due to bias failures. Many of the mods deal with that in various ways. Some of these issues seem (to me) to have been design flaws but that may be more limited to the K4000 and not so much the K4040.
The tech becomes very important for this amp it seems, from a longevity standpoint. Once you fix that, tech to improve the sound then becomes beneficial.
And that "hand" is appreciated.
The specs are what attracted me to this amp in the first place. Plus having read numerous articles regarding the torroidal output transformers, especially Modern high-end valve amplifiers Based on toroidal output transformers by Menno Van Der Veen.
I didn't have the money to buy one new (kit) 10 years ago when I believe they were around $1,300 (CAD).
Now I really would like even one that needs repairs to tinker with but they are scarce in the used marketplace.
Love my amp. The changes were not hard because they were all on the board ( desolder, replace, etc.). One thing if I don’t put it in the instruction you may or may not have to do is run an extra wire from the ground to the chassis. I did and it eliminates the very faintest of him ( faint as in your had to hold your ear to the speaker to hear it). It is now quiet as a mouse. Also, I just did a new tube review on audio karma - lol been 8 years since I tried other input tubes. I did it just because, no other reason
instructions are easy because the manual clearly marks every spot ( it had to because originally it was a build) so you don’t even have to know how to read a schematic
So you experienced the el34 problem first hand. This why I went to the NOS 6l6gc’s. Don’t go new build … slovtecs and the like are like nails on a chalk board. Smooth as a razor… lol
BY the way , as I was testing tubes today (input tubes in this case are the Matched Pair GE JAN 5751/12AX7 Black Plate Triple Mica Square Getter 1969 Strong
Beautiful sound and I filmed a clip (sorry, with an Iphone) but if you use headphones or earbuds you get the idea. I dont think I have ever heard an ambient sound recording that does justice but this one is not bad ....linked on my one drive
https://1drv.ms/v/s!AoQ15fY-JFvS-fhnpMxqXcucKVhx2w?e=KqDABl
Beautiful sound and I filmed a clip (sorry, with an Iphone) but if you use headphones or earbuds you get the idea. I dont think I have ever heard an ambient sound recording that does justice but this one is not bad ....linked on my one drive
https://1drv.ms/v/s!AoQ15fY-JFvS-fhnpMxqXcucKVhx2w?e=KqDABl
I think you may have missed my point regarding Kay's comment.
He mentioned using EL84's in the amp and said it wasn't a typo.
IE: Put EL84's in it and you'd have to put 9 pin miniature sockets in place of the Octal's to start with. And end up with 1/3 the amp you started with.