New PP Pentode Monoblocks

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Mike H
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#196 Re: New PP Pentode Monoblocks

Post by Mike H »

Actually when I said "often", more truthfully "occasionally" ... can't keep it up forever. :D
 
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#197 Re: New PP Pentode Monoblocks

Post by Paul Barker »

My amps which is the original Barbaric is far from fatiuing, it actually gets better the longer it stays on.
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#198 Re: New PP Pentode Monoblocks

Post by Mike H »

Seems like it's simply a personal taste thing. Ain't going to be resolved to suit everybody all of the time. :D
 
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#199 Re: New PP Pentode Monoblocks

Post by Cressy Snr »

Mike H wrote:
pre65 wrote: Is that relevant to the amps Steve and Mike exhibited at Owston ?
Certainly if it's same o/p stage, which I'm assuming it is. :D
Nah, the "pentode" Elektor amp DTB mentions is just cheap ass ultralinear.
Not in the same league :wink:
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#200 Re: New PP Pentode Monoblocks

Post by pre65 »

Cressy Snr wrote:
Mike H wrote:
pre65 wrote: Is that relevant to the amps Steve and Mike exhibited at Owston ?
Certainly if it's same o/p stage, which I'm assuming it is. :D
Nah, the "pentode" Elektor amp DTB mentions is just cheap ass ultralinear.
Not in the same league :wink:
I had a suspicion that would be the case. :)
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#201 Re: New PP Pentode Monoblocks

Post by Mike H »

Actually I'm beginning to remember he put a topic on here about it? Doing it up? Making it work?

So no, ultra-linear?, pah .. :D
 
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#202 Re: New PP Pentode Monoblocks

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By "he" I mean floppybootstomp (Tony) not DTB.....
 
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#203 Re: New PP Pentode Monoblocks

Post by Cressy Snr »

Have sorted the fronts of the amps out. The solid front rail underneath the bottom edge of the wood panel, made the amps a bit heavy looking and were a temporary measure, just to get them going for Owston.
I've now put that right with some tapered feet at each end of the front panel:
Image
This has lightened the frontal aspect of the amps and provided a bit more ventilation to the undersides.
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#204 Re: New PP Pentode Monoblocks

Post by Paul Barker »

Shoddy.
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#205 Re: New PP Pentode Monoblocks

Post by Mike H »

What's the round silver thing with red LED ?
 
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#206 Re: New PP Pentode Monoblocks

Post by Paul Barker »

It's an old technology that pre-dates the dac. Something called a phono stage. Totally obsolete these days.
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#207 Re: New PP Pentode Monoblocks

Post by Cressy Snr »

Am hearing some great sounds from vinyl and the AppleTV, courtesy of a set of General Electric 6550A.
Lovely old valves. Now they have cathode followers driving them, they sound beautiful with widescreen soundstaging and a great tonal balance from top to bottom and super rendition of both male and female voices.

The EH 6CA7s are great valves for the money, but set up at 400Va with 270Vg2 running at 50mA per valve, the old 6550s are a real class act. :D
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#208 Re: New PP Pentode Monoblocks

Post by Cressy Snr »

And now we have a quad of JJ KT88s that Paul gave me, running in the amps.
Strangely or maybe not as the case may be, these are the best sounding valves among the ones I have tried.
They just seem to work best with the rest of the system.
I have three quads suitable for these amps.

6CA7 Electro-Harmonix, these are detailed, well balanced but a bit matter of fact in their presentation.

NOS GE 6550A - These are powerful sounding, fat juicy and full-bodied; a bit in 'yer face long term.

Then the KT88 JJ which seem to be the best all rounders. Their treble performance in these amps is clean, sweet and liquid.
Vocals are very good, with a presence that the other two sets of valves can't quite match and overall, the midrange performance is excellent. The bottom end is nicely controlled and extended; not quite as powerful as the bottom end of the 6550As but better balanced with the rest of the frequency spectrum.

The JJs are keepers with these amps I think. It's taken a while, but now vinyl has been successfully integrated with the digital and I'm more than satisfied with the performance of the pentode monoblocks, I think that apart from a phono stage I'm pretty much done now.

I'm looking now at a design I have worked out for a pair of half height, folded, quadratic tapered Metronome speakers, using the Fostex FF225WK plus ribbon tweeter. I'm aiming for the same performance as the present Mets, but in a less tall form factor, but same line length and still keeping the elegant looks. Just need to work out how the fook I'm going to build them. The current design is ten years old now and I'm looking at re-connecting with the concept and refreshing the design a bit.
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#209 Re: New PP Pentode Monoblocks

Post by Cressy Snr »

I've run quite a few valves in these amps up to now, to check its versatility - El34, KT88 and 6550A and all have given a good account of themselves.
I've recently given the GE NOS 6550As back to Steve S, as although I love them to bits, they're not mine and worth too much money to keep hanging round at home (TBH I was a bit scared of buggering them up or breaking one of them to be confident with them)
Steve had additinally lent me a set of old used KT66 to have a play with. I had them in the old gold stereo Barbarik of Paul's for a short while, but again was a bit scared of using them in anger. I've never felt that comfortable using somebody else's stuff, but talking with Steve, he did try to encourage me to try them in the new setup, so here they Steve, playing in the mono Barbariks.

Image

I must say they are really nice valves in these amps, once set up properly; very organic and human sounding.
I am using matched Tube Amp Doctor EL34Bs as workhorses at the moment as these are what the amp was designed to use in the first place, The old KT66s stack up beautifully and there's just something about them that puts you that bit more closer to the music than modern production stuff.
We were talking about how the really old pre-war valves are even better and just do the biz, and that it is a shame that the amps we build have potential that is only fully released when the older valves are brought out.

I've been doing this for ten years now and over that time period, I think that the modern production valves have come on a lot and are now getting very, very close to what the old stuff was achieving, which is encouraging and modern valves can, these days, be used largely without the worry that you might be missing out on something; those KT66s still have that nth degree of magic, but the performance gap is not as wide as it used to be.

I'll definitely keep using these, for a while yet.
Though the Barbarik monos can use the higher powered KT88/120/6550 family and make a good sound with them, it does perform better with the lower-powered EL34/6CA7s and KT66s. The '66s also look great against the grey powder coat casings of the monoblocks. :)
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#210 Re: New PP Pentode Monoblocks

Post by Mike H »

I must say I do like KT66's, if they're decent quality ones. :thumbleft:
 
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