Great, thank you!
What is C21? It says MKT, but is it an electrolytic or is the mark just where the foil ends or begins?
Location: Tallinn
Posts: 6
I'm Thomas.
Great, thank you!
What is C21? It says MKT, but is it an electrolytic or is the mark just where the foil ends or begins?
If it says MKT it's a film cap, metalised polyester. They're non-polar.
Kuzma Stabi/S 12", (LP12-bastard) DC motor and optical tacho psu, Benz LP, Paradise (phonostage). MB-Pro, Brooklyn dac and psu, Bruno Putzeys balanced pre, mod86p dual mono amps, Yamaha NS1000m
Location: Tallinn
Posts: 6
I'm Thomas.
OK, found it on the schematic, a 10 uF output cap of the treble amp. I'll order a MKP.
The mid amp in one of the speakers has an awful noise, like static but changing in volume every now and then.
Any ideas of the likely culprit(s)?
Here is info on offset voltage and bias for this amplifier.
Analogue: Thorens TD 160 Super, Micro Seiki CF1 arm, Toshiba SR-370, Micro Seiki MA-505 arm, Nagaoka MP-50, Ortofon S 15-TE
Source: JRiver 20, RME 9632 sound card, cd Micromega Drive 1, Hegel HD2 dac, Asus Xonar STX
Pre-amp: Quad 33, Audiolabor VV2020
Amps: Quad 522, Quad 405, Nakamichi Amplifier 1, CEC Amp 3300
Speakers: Kef 104/2, ESS Amt 1 Monitor, Magneplanar 2.5/RT, Yamaha NS1000M - Active Genelec, cable Mogami 2513 "Blue Rocket"
Location: Tallinn
Posts: 6
I'm Thomas.
Noticed that one of the amps doesn't have the 100 pF ceramics across collector and base (I assume) on the power transistors of the mid amp. Found only 120 pF in my junk box. I suppose they are there to stop high-frequency ringing so 20 pF up wouldn't harm? Or what is yr opinion?
Location: Seaford UK
Posts: 1,861
I'm Dennis.
In about '74 I took my Nelson-Jones 10+10 into work and it was criticised for the wide bandwidth, they saying that it was asking fro parasitic oscillations at HF. (Went to 1Meg -3dB I think)
The technician bloke, with whom I was equally qualified, put a few puff across a collector and base in a signal section of each shannel. I used it for years like that until one day I questioned his decision.
Then when I removed it a veil was lifted, and the sound opened up, never had an oscillation except with expensive Litz speaker cables much later, and when going from Tannoys to ESS Monitors. Removed the cables and returned to thick mains cable, no problems.
Location: Tallinn
Posts: 6
I'm Thomas.
Has anyone got a spare amp for these to sell or borrow? One speaker (following the amp) has a lot of scraping noise. Now mostly from the bass speaker, but earlier from the mid or all speaker. Suspect the protection circuit.
Another option might be to make them passive again, with the original filters or the Danish modded filter. Dunno if it is worthwhile, because these speakers have been stored in a humid place for very long, no idea how corroded the domes really are and how it affects their speed.