There are better options near this price point.
The review is simply a consumer warning.
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Pro-ject Phono Box MM Review
- Thread starter amirm
- Start date
There are better options near this price point.
There is also the cable capacitance...The capacitor is not in series, of course.
View attachment 298792
There is a old video where the problem is explained. Other users also have reported about this later. I am not sure if they have fixed it with the LP5X.
I also had the problem with a Hanpin DJ-Turntable and had detected it by my own already. It made a big difference in high frequency response.
restorer-john
Grand Contributor
Here you go. My old girl has been sitting in a box since the late 1980s. She got an identical arm (the counterweight decoupling rubber had perished resulting in the counterweight sagging badly) pulled from a parts donor APQ-50. Had her deteriorating phono leads and power lead replaced, a replacement antiskate spring from the donor and a full alignment and setup to spec. I also cleaned out and re greased (with special ultra high viscosity 500,000wt silicone oil) the damped cue cylinder to have the arm raise and lower perfectly.
Love that funky 1980s "quartz lock" printing.... Single point strobe, neon lit from PLL QL IC. The single point strobe is also monitored by an IR LED/TR interrupter to give feedback to the main IC.
Optical sensed lift of via LED/LDR and solenoid operated auto return shut off. No physical arm contact.
Arm lower base is alloy
Headshell is magnesium alloy with the original PC-90 (AT) dual magnet cart. Stylus was replaced in the 1980s. Zero wear under high powered magnification.
Fun fact:
The APQ55 has an inbuilt overhang set point built into the rubber platter mat. Of the three concentric inner rings, you centre the stylus above the middle one when the cart is moved over the spindle. Brilliant!
Other fun fact2:
Many other Japanese 1970s and 1980s TTs have overhang gauges moulded into the backside of their original platter mats- turn them over to see.
Fun fact 3:
Some brands also built in overhang set points on strobe lights upper bodies.
restorer-john
Grand Contributor
The MM phono stage in a Sony TA-3650 integrated from 1977.
It came in at number six in terms of overload when I tested 13 or so phono stages I had lying around. The best was 320mV...
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computer-audiophile
Major Contributor
Thank you, very nice - and with a slightly better pickup you could definitely get a better sound out of it.
restorer-john
Grand Contributor
I have a heap of cartridges here. I just leave that TT original as it reminds me of my youth.
computer-audiophile
Major Contributor
I see. You could check the tracking ability with a test record and see how high you still get with this pickup. Also your pickup was certainly more flexible in his youth.I have a heap of cartridges here. I just leave that TT original as it reminds me of my youth.
At what frequency?
The schematic suggests that this is a very non-optimal design for MM.
As I have pointed out in the past, S/N past (say) 80dB (I'm excluding discrete frequency, like hum) brings no benefit since the cartridge's Johnson noise will then dominate. With a stage like this and an MM, the noise would be much worse than any measurement Amir would present since his test method is almost completely insensitive to current noise.
There's more than a 40dB swing in gain over the audible range, so it's a vital bit to specify. Of course, advertising specs tend to be quite vague...
restorer-john
Grand Contributor
The 40 year old stylus will easily track the bass drum tests at +4db, +8dB, +12dB perfectly and +16dB with some distortion at 1.5grams VTF. There appears to be no more or less deflection as can be the case when the elastomers dry out/or go soft and collapse. Most ATs seem to last many more decades than some of the other, more esoteric brands. I use several test records, and for tracking the old W&G 24,2434 is a great way of sorting the wheat from the chaff. I have a few copies of that test record.
restorer-john
Grand Contributor
Phono overloads were pretty much always specified and tested at 1kHz.
That's what I do. I drive my phono stages with a 1kHz sine (600R source), vary level until the output clips, then wind it back a touch, check the THD and read the input applied voltage (in mV). I can also sweep also using an attenuated inverse RIAA filter to see if there's any reason to revisit the 1kHz number.
The Sony amp I mentioned above was one I had sitting on a pile of unused subwoofers within easy reach, so it got used with the TT. Its rated MM overload was 210mV. I measured ~220mV (217mV) on a rainy day several months back when I was amusing myself with phono stages on gear that was laying around...
The units with the highest overloads necessarily run much higher rails than is typical to accommodate the swings/gains needed. The Denon can swing almost 20V RMS out the tape outs. I've got a Kenwood LO7C here which has +/-47V rails for the MM and MC stages and its overload capability is over 350mV (1kHz/0.003%).
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computer-audiophile
Major Contributor
You know very well, better than many others, I am aware of that! I would like to say that in advance.
I have had old AT cartridges of this type, where the needle suspension had become harder after decades, not softer. I therefore prefer to use new pickups.
To explain: I always do a trackability test first with new or unknown cartridges. It gives information about the trackability of my tonearm/cartridge combination. The higher the achieved value (micron), the better the respective tonearm / cartridge combination is able to sample difficult groove modulations without distortion. I aim for a value above 80 µ.
LtMandella
Member
it was just a generic china manufactured ultrasonic tank. I got mine from Amazon. The vendors bundle the ultrasonic cleaner with a simple device that has mounts on the side of the tank with a motor mount to rotate the LPs in the bath. The vendor name would not mean anything really since it was just a relable of a generic tank cleaner.
LtMandella
Member
MQA encoding is lossy. The marketing hype from that company about MQA sound quality I believe has been discredited.
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