ndevamp

Responses from ndevamp

EAR founder has cancer
Oh. Poor Tim!Better go and see him properly soon, he’s here in the UK. But chatting to him isn’t straight forward, I’ve learned. We’ve had some great chats over the decades. I was only wondering the other day after seeing him at Munich last year w... 
Sansui CA 2000 preamp
Should be a nice preamp. It was one of the first to incorporate low distortion transistor circuitry, and had a unique volume control circuit that reduced noise to very low levels. They don’t make them like that anymore and from that standpoint, it... 
What's wrong with variable bias?
Looking at the schematic, the TA-A1ES switches the quiescent bias current from low to high depending on volume output. At low volume it uses low bias to save on heat output from the output transistors. Both halves (both NPN and PNP output transist... 
Nakamichi CA-7A & CA-7E difference
Looking at the schematic, there were a few versions made of the CA-7E. The UK one was set for 240V, the German and European one set for 220V (can be changed to 240V internally). Both those can’t be set for 120V operation. Only the Saudi Arabia ver... 
impedance matching buffer
Perhaps try a transformer volume control. It’s passive and because it’s a transformer, it will maintain low output impedance. Antique Sound Labs make a nice one, T2 DT. 
Review: Sansui AU-7700 Amplifier
I’ve had a few Sansuis over the years. The AU-9500 was superb and a pleasure to use. It needed restoring a few years back, some of the transistors became noisy so I replaced them. The switches all needed cleaning, and the volume control needed rep... 
Anyone done A / B listening to compare vintage stereo receivers with today’s Amps/Preamps?
Echolane, +1 for moving the switches regularly to keep them working well.I help maintain a studio mixing console with hundreds of mechanical switches. The advice given in the service manual is to do just that, operate them regularly to keep tarnis... 
Anyone done A / B listening to compare vintage stereo receivers with today’s Amps/Preamps?
Just keep a spray can of switch contact cleaner handy when you notice a switch giving issues. 
Anyone done A / B listening to compare vintage stereo receivers with today’s Amps/Preamps?
I agree with mrdecibel, there are generally lots of switches with the audio signal going through them in older gear. There are some issues with that.Apart from the extra wiring needed to get the signal from the circuit board to a front-mounted swi... 
Anyone done A / B listening to compare vintage stereo receivers with today’s Amps/Preamps?
Things that have changed over the years are: solid state parts were designed as through-hole components, now mostly surface mount and integrated circuits. That makes the assembly a lot more compact and so eg. circuit board inductance reduces, allo... 
12BZ7 ///12AX7
The BH/BZ/AX data sheets all look similar in the same way that a bicycle is similar to a motorbike. They have the same number of wheels and you need to balance to ride them.Well if nothing else you’re enthusiastic about it all! But don’t be disapp... 
12BZ7 ///12AX7
7308 is a 6dj8 equivalent, not 12au7.The Defy 7 has the 12au7 as input tube, the 12ax7 is the driver tube. The extra current capability of a 12bh7 is unused in this circuit. Same for a 12bz7 in place of the 12ax7 at the same operating current. The... 
12BZ7 ///12AX7
Just looked at the Defy 7 schematic, audio section. It looks like the 12bz7 would work ok for the audio circuit voltage settings. BUT there is a danger it will draw too much heater current from the filament winding, along with the E80CC, which als... 
12BZ7 ///12AX7
The 12bz7 is basically a double 12ax7, ie. Each 12bz7 triode is similar to two 12ax7 triodes in parallel. It draws double the heater current of a 12ax7 (600mA vs 300mA) and has twice the transconductance. It has a gain of 100, like the 12ax7. Not ... 
Hana SL or ML?
It’s most likely system dependent, so I’m not totally surprised you like yours set at 400 ohms. On my system 390 ohms made it sound a little clamped down, probably with better focus and more neutral overall, but I couldn’t go back from 2.2k on my ...