audio-talk

chris661 wrote: ↑Mon May 14, 2018 6:34 pm ...I'm thinking about bringing a different amp... Crown MA12000i, anyone?

Chris

Wahey! Cue "Liquid Spirit (Claptone Remix)"

Thermionic Idler wrote: ↑Mon May 14, 2018 1:56 pm That's this Saturday isn't it. I could bring along my 15W OTL and AMB linestage?

Thinking out loud, the Rozenblit 15W OTL is going to love these speakers. Single driver, 8 Ohm, what's not to like?

Cressy Snr wrote: ↑Mon May 14, 2018 7:07 pm
Thinking out loud, the Rozenblit 15W OTL is going to love these speakers. Single driver, 8 Ohm, what's not to like?

Your's 'n Phil music taste fer starters.... hehehehehehehheheheheheheh (etc).

Cressy Snr wrote: ↑Mon May 14, 2018 7:02 pm

chris661 wrote: ↑Mon May 14, 2018 6:34 pm ...I'm thinking about bringing a different amp... Crown MA12000i, anyone?

Chris

Wahey! Cue "Liquid Spirit (Claptone Remix)"

Torn between the two amps. Crown MA5002VZ, or MA12000i...

Sod it, I'll bring both. I'll bring some wheels to move the MA5002VZ. To say it's heavy would be an under-statement.

I've also got the old Akai AM-2250 that I'm using for the home stereo at the moment, but I wouldn't call it HiFi.

Chris

Cressy Snr wrote: ↑Mon May 14, 2018 4:16 pm Yep, this Saturday afternoon.
You're welcome to turn up Dave, no probs.

It'd be brilliant to hear an OTL amp through them.
I feel an NVA vs pro vs OTL bake off coming up

Cheers Steve, I'll be there, about what time should I aim for?

I'd be interested to see what you think of the active linestage too, although I know the NVA is designed more for use with passives. God I hope the OTL isn't completely outclassed, I've sunk quite a lot into the design and build of the full fat "Beasts".

Thermionic Idler wrote: ↑Mon May 14, 2018 9:29 pm

Cressy Snr wrote: ↑Mon May 14, 2018 4:16 pm Yep, this Saturday afternoon.
You're welcome to turn up Dave, no probs.

It'd be brilliant to hear an OTL amp through them.
I feel an NVA vs pro vs OTL bake off coming up

Cheers Steve, I'll be there, about what time should I aim for?

Chris is aiming for 1:00, so around 1 to 1:30 would be great.

Brill, thanks. I'll bring along some LP's as well, just recently got some lovely Speakers Corner reissues of Maria Callas and some Decca-recorded Handel.

Thermionic Idler wrote: ↑Mon May 14, 2018 10:03 pm Brill, thanks. I'll bring along some LP's as well, just recently got some lovely Speakers Corner reissues of Maria Callas and some Decca-recorded Handel.

Look fwd to hearng these records.

I'm listening to a lot more of my classical recordings now I've got the Fanes up and running. I find that interesting in itself, as the driver is supposed to be a PA unit.

Have, over the past few days been simplifying the pink SET down some more.

The input and driver stages are now in a self contained triode-pentode of the PCL86 variety.
This is basically half an ECC83 and a lower (9w) dissipation version of the EL84, in one bottle, but with a 13V heater.
It runs fine on 12.6V heaters. I've had four of these kicking around for years, so I thought I might as well put them to use.

The high gains of this little lot mean that all the cathode bypass caps were able to be removed whilst keeping the same overall gain in the whole amp. This means that the output impedances of all stages is higher than normal but nothing seems to have suffered. It'll be an extra amp to use with the Fanes on Saturday.

So the amplifier lineup is:
NVA A20
DIYNVA, which Richard tells me is roughly equivalent to the A60
Pink, JJ 2A3-40 SET amp
Rozenblit Son of Beast 15W OTL
Crown MA5002VZ pro amp
Crown MA12000i pro amp
AMB active linestage.

This is shaping up to be quite a good do.

Cressy Snr wrote: ↑Wed May 16, 2018 6:12 pm The input and driver stages are now in a self contained triode-pentode of the PCL86 variety.
This is basically half an ECC83 and a lower (9w) dissipation version of the EL84, in one bottle, but with a 13V heater

Ah yeah but no but yeah but (etc)... 13V heater y'say, isn't that PCL heater usually specified as a 300mA heater chain device like they do/did on TV's rather than a specific voltage?

Dave the bass wrote: ↑Wed May 16, 2018 6:34 pm

Cressy Snr wrote: ↑Wed May 16, 2018 6:12 pm The input and driver stages are now in a self contained triode-pentode of the PCL86 variety.
This is basically half an ECC83 and a lower (9w) dissipation version of the EL84, in one bottle, but with a 13V heater

Ah yeah but no but yeah but (etc)... 13V heater y'say, isn't that PCL heater usually specified as a 300mA heater chain device like they do/did on TV's rather than a specific voltage?

Yes it is, but it works fine on 12.6V, parallel.
The datasheet specifies Vf = 13.3V with the If at 300mA. ECL86 is expensive compared to the PCL86.

IIRC MJ did a comparison of series and parallel heaters with these sorts of series designed valves and concluded that there was no practical difference in performance between series and parallel operation.

We'll be missing the Royal Wedding of course. Oh the horror!

Listening to the SET with the Fanes, it was very nice, but after a while on some recordings, the bass began to get on my wick: basically it was crap!
Bass instruments were ill-defined and loose, certain notes being emphasised at the expense of others.
Put the bypasses back on the 2A3 cathodes; gain up, output impedance down, bass, ten times better.
It might stand more of a chance now against the other amps.

IIRC, the Fane units are pretty high-Q to start with, so a high output impedance would tend towards a one-note boom sound wherever the low-frequency impedance peak is. Probably in the 70-80Hz range if I had to guess.

I'll bring stuff to measure the impedance curve - only takes a minute.

Chris

Yes,
High sensitivity does not necessarily mean a speaker is valve amp friendly. Many folk seem to miss this.
Zobel network would sort it of course, but I'm not really that bothered with valve amps these days, so can't be arsed with a Zobel.