Is Ultra Linear the Way to Go For Hi Fi?

[gingertube]

Don't know why anyone would recommend an ST70. Every ST70 I've heard, worked on, regardless of the upgrades done, has sounded as cold sterile and boring as most SS Amps. Too much NFB.

The "cheap" 845 SET amps out of China are pretty ordinary too. I had one of the Music Angels, OK at low volume but was sickly sweet with chocolate on top when turned up even a bit, excess 2nd harmonic - upchuck material.
Again, this was despite tube rolling, power supply upgrades and coupling cap upgrades - better than how it came out of the box but still objectionable.

That is why I developed that Baby Huey circuit I posted above, in its 8th generation and now good enough that I can set the vinyl tracking weight and anti-skate just by listening.

I am building a new amp but OZ$3000 in parts, PPP 300B monoblocks with Plitron Toproidal Output Trannies, Chokes and Power Trannies.

The Baby Picture: Built in a cheap chassis from MabelAudio

[gingertube]

http://www.oestex.com/tubes/1955%20Radiotronics.pdf
Articles on Ultralinear by AR Chesterton and Fritz Langford Smith (Editor of Radiotron Designers Handbook).

Fritz says that the THD and IMD values of the Ultralinear Connection are lower than for either Pentode or Triode Mode and in fact lower than can be accounted for from basic feedback theory alone.

The EL84 Datasheets confirm the claims on THD and IMD.

Cheers,
Ian

[Structo]

Wow lots of information to digest.

Thanks guys!

[Aurora]

Most PP HiFi amps are ultralinear - a trade off between power and cost, really. Depends on what speakers you intend to use.
There's quite a number of 6550 or KT88 PP ultralinears in the 60W +/- range. Others swear by SE, - 300B, 2A3 or 845s being the most common ones. In the medium quality range ( as concidered by some) old Dynacos or look alikes are quite commen. Old McIntosh, Marantz and some Harman call big bucks in the used market.
There are quite few designs that are concidered quite good in the 20-25W +/- region, - paired with reasonably sensistive speakers, they're certainly loud enough!
That PPP 300B thingie will cost you BIG bucks - guessing 2-3000$ in iron alone...

[David Root]

I recently began digging into tube hi fi and am planning two amps that cover the two most popular styles.

1) 2x70W PP 6550 monoblocks using RCA 6CG7s and old '60s Tung-Sol 6550s.

2) 2x7W parallel SE parafeed 2A3 monoblocks with choke fed PS. JAN RCA US Navy 2A3s with D3A drivers.

Why monoblocks? Besides the fact there is no channel crossover with separate PSs, the other (more important) fact is these amps built on a single chassis are just too friggin' big and heavy to be moved around.

Should have all the parts for #1 in a couple of weeks. This is aimed at rock music not string quartets. I call them Rockoblocks.

#2 will be more toward the jazz/classical side but with a bit of bass push tweaking built in so they should rock out too.

Problem is I really need two very different speaker pairs and that's not in the budget at this point. So I'll have to compromise for a while I guess.

[Clyde]

Hi David,
I'd be interested in how you configure the D3A's as I have a handful also, curious to see how they sound. Thanks.

[renshen1957]

I recently began digging into tube hi fi and am planning two amps that cover the two most popular styles.

1) 2x70W PP 6550 monoblocks using RCA 6CG7s and old '60s Tung-Sol 6550s.

2) 2x7W parallel SE parafeed 2A3 monoblocks with choke fed PS. JAN RCA US Navy 2A3s with D3A drivers.

Why monoblocks? Besides the fact there is no channel crossover with separate PSs, the other (more important) fact is these amps built on a single chassis are just too friggin' big and heavy to be moved around.

Should have all the parts for #1 in a couple of weeks. This is aimed at rock music not string quartets. I call them Rockoblocks.

#2 will be more toward the jazz/classical side but with a bit of bass push tweaking built in so they should rock out too.

Problem is I really need two very different speaker pairs and that's not in the budget at this point. So I'll have to compromise for a while I guess.

Hi David,

My dream was to experiment with the EL156 as produced in Octal Base from China. The original tube was used when cutting analog masters for LPs. Although I couldn't afford let alone find the 10 pin version, a conservatively run Class A circuit might sound sweet.

From CE EL156 - Chinese Inspection Condition: Filament Voltage = 6.3 V Filament Current = 1.9 A Plate Voltage = 440 V Plate Current = 100 mA Screen Grid Voltage = 350 V Screen Grid Current = 16 mA Control Grid Voltage = S-bias Load Resistance = 4000 ohms Transconductance = 13.0 mA/V Maximum Data: Plate Voltage = 800 V Screen Grid Voltage = 450 V Plate Power = 50 W Screen Grid Power = 8 W Cathode Current = 180 mA

Dual SE Mono Blocks, run as triodes. I have some other ideas with other lower power Triodes, but as my work is in production mode (8 days a week), all I can do is dream and draw schematics in my mind's eye. (Sighs )

Best regards,

Steve

Best regards,

[JazzGuitarGimp]

He's bbbbbbaaaaaaaaaaccccccccckkkkkkkkk...

[galtjunk]

Check out Decware's Triode Zen.
5u4g, 2x SV83 and a 6n1p.
2 watts per channel of corksniffer Hi-Fi on a beer budget.
He sells kits, boards or completed amps.
I built mine for about $250.
You will need efficient speakers.

[ic-racer]

Anyone interested in HiFi tube circuits might be interested in this 1957 book by Crowhurst on high fidelity tube circuit design:

http://www.tubebooks.org/Books/Atwood/C ... Design.pdf