Cambridge Audio Solo Phono Preamplifier Review

[sergeauckland]

Can you please describe what "overload" is? How can I tell how much overload a specific preamp/phono pre has? I've never heard about overload so no idea what this referances.

Overload is another way of saying clipping. A phono cartridge has a nominal output of, say, 1mV per cm/sec recorded velocity so the output is typically quoted as being 5mV. However, LPs are cut with an arbitrary level, (unlike CDs which can only ever go to 0dBFS) and according to Shure, can have levels more than 20dB (10x) above 5cm/sec. This means that the cartridge will output more than 50mV on peaks on the LP. If the phono stage has a gain of, say, 40dB (100x) then the phono stage will output 500mV on a nominal 5mV input, but has to be able to output more than 5V (100x 50mV) on peaks. If the phono stage can't do that, it will overload (i.e. clip) and distort heavily. Back in the 1970s, phono stage designers knew that, and designed the phono stages in amplifiers to have very good overload levels. From what I've seen of some modern designs, that's been forgotten, and in an attempt to get better noise numbers, the overload point is lower now than it was then.

This isn't made easier by today's phono stages being run from low voltage USB ports, or small wall-warts, whereas in the past they were integrated in the amplifier and had much higher voltage rails available, which made getting more output a lot easier.

S.

 

[SPOautos]

Overload is another way of saying clipping. A phono cartridge has a nominal output of, say, 1mV per cm/sec recorded velocity so the output is typically quoted as being 5mV. However, LPs are cut with an arbitrary level, (unlike CDs which can only ever go to 0dBFS) and according to Shure, can have levels more than 20dB (10x) above 5cm/sec. This means that the cartridge will output more than 50mV on peaks on the LP. If the phono stage has a gain of, say, 40dB (100x) then the phono stage will output 500mV on a nominal 5mV input, but has to be able to output more than 5V (100x 50mV) on peaks. If the phono stage can't do that, it will overload (i.e. clip) and distort heavily. Back in the 1970s, phono stage designers knew that, and designed the phono stages in amplifiers to have very good overload levels. From what I've seen of some modern designs, that's been forgotten, and in an attempt to get better noise numbers, the overload point is lower now than it was then.

This isn't made easier by today's phono stages being run from low voltage USB ports, or small wall-warts, whereas in the past they were integrated in the amplifier and had much higher voltage rails available, which made getting more output a lot easier.

S.

How can you tell what phono pre/phono stage are designed in a way not overload/clip? Is there a certain spec to pay close attention too?

 

[sergeauckland]

How can you tell what phono pre/phono stage are designed in a way not overload/clip? Is there a certain spec to pay close attention too?

The only meaningful specs for that are the gain and the maximum output level. That will tell you what the overload point will be with any particular cartridge. If a manufacturer doesn't quote that, then I would be very suspicious and not bother.

S

 

[SPOautos]

The only meaningful specs for that are the gain and the maximum output level. That will tell you what the overload point will be with any particular cartridge. If a manufacturer doesn't quote that, then I would be very suspicious and not bother.

S

So I've recently got this turntable (Kenwood kd550) and it came with a AT Series viii cartridge and I replaced the stylus because it was damaged. Here are the specs....

Audio-Technica Series VIII Phono Cartridge Specifications
- Output voltage: 3.0 mV
- Frequency response: 10-27,000 Hz
- Channel separation: Average 31 dB @ 1 kHz | 21 dB @ 10 kHz
- Channel balance: 1 dB
- Vertical tracking force: 1.0 g- 1.5 g
- Vertical tracking angle: 20°
- Stylus type: Linear Contact
- Cantilever: Tapered alloy tube
- Load impedance (ohms): 47 k
- Load capacitance (pF): 100-200

I recently replaced the stylus and it has these specs.....

Frequency response: 12Hz-27kHz
- Output voltage @ 1kHz,5cm/sec: 3mV
- Channel balance: 1dB
- Channel separation @ 1kHz/10kHz: 29/19dB
- Stylus type: Highly polished vivid line diamond
- Stylus tip: .0002 x .0029 inch
- Cantilever: Thin-wall metal alloy tube
- Tracking force: 1.0-1.5g


I see the output is 3.0 mV but I do not see "gain". Oh I suppose the 3.0 mV is at 1kHz,5cm/sec so not really the maximum because your saying that vinyl is not always at 1kHz,5cm/sec so as it changes, the output changes and what I need to know is the maximum....correct? I guess I need to email AT to ask about that.

 

[sergeauckland]

So I've recently got this turntable (Kenwood kd550) and it came with a AT Series viii cartridge and I replaced the stylus because it was damaged. Here are the specs....

Audio-Technica Series VIII Phono Cartridge Specifications
- Output voltage: 3.0 mV
- Frequency response: 10-27,000 Hz
- Channel separation: Average 31 dB @ 1 kHz | 21 dB @ 10 kHz
- Channel balance: 1 dB
- Vertical tracking force: 1.0 g- 1.5 g
- Vertical tracking angle: 20°
- Stylus type: Linear Contact
- Cantilever: Tapered alloy tube
- Load impedance (ohms): 47 k
- Load capacitance (pF): 100-200

I recently replaced the stylus and it has these specs.....

Frequency response: 12Hz-27kHz
- Output voltage @ 1kHz,5cm/sec: 3mV
- Channel balance: 1dB
- Channel separation @ 1kHz/10kHz: 29/19dB
- Stylus type: Highly polished vivid line diamond
- Stylus tip: .0002 x .0029 inch
- Cantilever: Thin-wall metal alloy tube
- Tracking force: 1.0-1.5g


I see the output is 3.0 mV but I do not see "gain". Oh I suppose the 3.0 mV is at 1kHz,5cm/sec so not really the maximum because your saying that vinyl is not always at 1kHz,5cm/sec so as it changes, the output changes and what I need to know is the maximum....correct? I guess I need to email AT to ask about that.

Gain isn't a function of the cartridge, but of the phono stage. The maximum cartridge output will depend entirely on how hot the LP was cut. According to Shure, that can be as much as 22dB above 5cm/sec, if I remember correctly, so any phono preamp has to have at least 20dB of overload capability if it's to handle anything except the very hottest LPs. In your case, with a cartridge giving 3mV output at 5cm/sec recorded velocity, your phono pre-amp has to be able to take at least 30mV input without clipping. If it can handle 50mV, then you're most unlikely ever to clip the phono stage on music peaks.

As an aside, one real benefit of a large overload margin is that clicks and pops on LPs can generate far greater levels than even a hot cut on the LPs, and whilst the phono stage might not clip on the loudest music passages, if it clips on clicks, then that'll make the clicks so much more noticeable.

S.

 

[SPOautos]

Gain isn't a function of the cartridge, but of the phono stage. The maximum cartridge output will depend entirely on how hot the LP was cut. According to Shure, that can be as much as 22dB above 5cm/sec, if I remember correctly, so any phono preamp has to have at least 20dB of overload capability if it's to handle anything except the very hottest LPs. In your case, with a cartridge giving 3mV output at 5cm/sec recorded velocity, your phono pre-amp has to be able to take at least 30mV input without clipping. If it can handle 50mV, then you're most unlikely ever to clip the phono stage on music peaks.

As an aside, one real benefit of a large overload margin is that clicks and pops on LPs can generate far greater levels than even a hot cut on the LPs, and whilst the phono stage might not clip on the loudest music passages, if it clips on clicks, then that'll make the clicks so much more noticeable.

S.

So is this where the benifit of adjustable gain comes into play? Such as the Art DJ Phono ii that has a gain adjustment knob. Not really supposed to be used as a 'volume' or to turn up all the way to get extra volume.....but rather set it based on the output level of the cartridge so that theres no clipping....but keep it as low as possible (without clipping) because the distortion may go up as the gain goes up?

Am I thinking of that correctly?

 

[sergeauckland]

So is this where the benifit of adjustable gain comes into play? Such as the Art DJ Phono ii that has a gain adjustment knob. Not really supposed to be used as a 'volume' or to turn up all the way to get extra volume.....but rather set it based on the output level of the cartridge so that theres no clipping....but keep it as low as possible (without clipping) because the distortion may go up as the gain goes up?

Am I thinking of that correctly?

Yes, you're thinking the right way, but the Art DJ stage seems a poor implementation

Specifications
Frequency Response10Hz -50KHz, +/-.5dB
Phono EQ StandardConforms to RIAA Curve
Total Harmonic Distortion.01% Typical @ 1kHz
Hum and Noise> 90dB below clipping
Input Impedance 47k Ω in Parallel with Either 100pF or 200pF
Maximum Input Level 40mVrms @1kHz
Maximum Gain 45dB @1KHz
In / Out Connections RCA
Maximum Output Level+6dBu (1.4Vrms)
Filter Type/Response Switchable, Low Cut,-3dB @ 22Hz

If you look at the maximum input level being 40mV, that would be a good number, but if the gain is set for 40dB, which is typical for a phono stage, then the output level would need to be 4.0V and the ART DJ stage clips at only 1.4v output. So, what this means is that you can either have enough gain, or you can have a decent input level, but not both. For a decent home phono stage, you really need at least 40dB of gain, and a maximum input level of, say, 50mV, which requires a maximum output capability of 5V. If you're using a lower output cartridge like the AT that gives out 3mV at 5cm/sec, then you can relax the maximum input to say 30mV, but then you'd need more than 40dB of gain to provide the same output level into your amplifier, so the maximum output level still needs to be around 5V to avoid clipping on all but the hottest LPs. Bearing in mind the earlier comment about audibility of clicks, the higher the output level the better, 8-10V isn't unreasonable (+20-22dBu).

S.

 

[AudioSceptic]

Yes, you're thinking the right way, but the Art DJ stage seems a poor implementation

Specifications
Frequency Response10Hz -50KHz, +/-.5dB
Phono EQ StandardConforms to RIAA Curve
Total Harmonic Distortion.01% Typical @ 1kHz
Hum and Noise> 90dB below clipping
Input Impedance 47k Ω in Parallel with Either 100pF or 200pF
Maximum Input Level 40mVrms @1kHz
Maximum Gain 45dB @1KHz
In / Out Connections RCA
Maximum Output Level+6dBu (1.4Vrms)
Filter Type/Response Switchable, Low Cut,-3dB @ 22Hz

If you look at the maximum input level being 40mV, that would be a good number, but if the gain is set for 40dB, which is typical for a phono stage, then the output level would need to be 4.0V and the ART DJ stage clips at only 1.4v output. So, what this means is that you can either have enough gain, or you can have a decent input level, but not both. For a decent home phono stage, you really need at least 40dB of gain, and a maximum input level of, say, 50mV, which requires a maximum output capability of 5V. If you're using a lower output cartridge like the AT that gives out 3mV at 5cm/sec, then you can relax the maximum input to say 30mV, but then you'd need more than 40dB of gain to provide the same output level into your amplifier, so the maximum output level still needs to be around 5V to avoid clipping on all but the hottest LPs. Bearing in mind the earlier comment about audibility of clicks, the higher the output level the better, 8-10V isn't unreasonable (+20-22dBu).

S.

The Pro-ject seems to have got this nailed at 9.5V. https://www.henleyaudio.co.uk/shop/product/viewfile?FileId=4933&ProductId=999

[edit]From that review, the relevant figures

Output overload measured 9.5V. That equates to 95mV input overload for MM and 9.5mV for MC, both good figures our measurements of cartridge output show; the unit will not suffer overload.

 

[SPOautos]

Yes, you're thinking the right way, but the Art DJ stage seems a poor implementation

Specifications
Frequency Response10Hz -50KHz, +/-.5dB
Phono EQ StandardConforms to RIAA Curve
Total Harmonic Distortion.01% Typical @ 1kHz
Hum and Noise> 90dB below clipping
Input Impedance 47k Ω in Parallel with Either 100pF or 200pF
Maximum Input Level 40mVrms @1kHz
Maximum Gain 45dB @1KHz
In / Out Connections RCA
Maximum Output Level+6dBu (1.4Vrms)
Filter Type/Response Switchable, Low Cut,-3dB @ 22Hz

If you look at the maximum input level being 40mV, that would be a good number, but if the gain is set for 40dB, which is typical for a phono stage, then the output level would need to be 4.0V and the ART DJ stage clips at only 1.4v output. So, what this means is that you can either have enough gain, or you can have a decent input level, but not both. For a decent home phono stage, you really need at least 40dB of gain, and a maximum input level of, say, 50mV, which requires a maximum output capability of 5V. If you're using a lower output cartridge like the AT that gives out 3mV at 5cm/sec, then you can relax the maximum input to say 30mV, but then you'd need more than 40dB of gain to provide the same output level into your amplifier, so the maximum output level still needs to be around 5V to avoid clipping on all but the hottest LPs. Bearing in mind the earlier comment about audibility of clicks, the higher the output level the better, 8-10V isn't unreasonable (+20-22dBu).

S.

How does this all come into play with a phono pre that has no adjustments such as this Cambridge Solo? Does it just have a generic margin built in that should cover most cartridges?

 

[sergeauckland]

How does this all come into play with a phono pre that has no adjustments such as this Cambridge Solo? Does it just have a generic margin built in that should cover most cartridges?

Yes, the Solo has been designed properly with a generous overload margin, but still keeping noise low and with accurate RIAA equalisation. With the exception of slightly low gain, it's pretty near perfect. Even the slightly low gain isn't that much of a problem given that most amplifiers have too much gain, and the noise from the Solo is very low.

S

 

[EJ3]

I happen to think both LPs (with their cover art and liner notes, photographs) are things of beauty. And I think my TT is gosh darn pretty, too. Watching it spin around brings me joy.

As for watches, yes, there are alternatives in the forms of cell phones.

Anyway, time will tell.....

(pun intended)

Back to the regular thread.

Both my TT's are things of beauty when just sitting (sometimes I sits & thinks, sometimes I sits & listens to music & sometimes I just sits): Dual 1229 in a custom American Walnut plinth and a TECHNICS SL-M3 (from the factory in rosewood veneer). A higher end (for the manufacturer) mid-fi KENWOOD cassette deck also sounds good with type II or IV tape. & a SONY W-500 (bit perfect) to make CD's. Now I am trying to get ready to digitize but haven't figured out what hardware I want to do it with yet.

 

[watchnerd]

Both my TT's are things of beauty when just sitting (sometimes I sits & thinks, sometimes I sits & listens to music & sometimes I just sits): Dual 1229 in a custom American Walnut plinth and a TECHNICS SL-M3 (from the factory in rosewood veneer). A higher end (for the manufacturer) mid-fi KENWOOD cassette deck also sounds good with type II or IV tape. & a SONY W-500 (bit perfect) to make CD's. Now I am trying to get ready to digitize but haven't figured out what hardware I want to do it with yet.

Mine is one of these, although with a different arm (I use an SME M2-9R):

The newer Technics decks would have better wow, flutter, and speed consistency specs (although maybe not much of an audible difference given imperfections in LP manufacture), but as an art object, I can't really part with the Michell.

 

[milosz]

Turntables are mechanical, and can be built to a fine standard and superb finish. As objects, they can be beautiful and intriguing. The 19th century method of storing and playing back music is quaint, and using this apparatus involves entertaining ritual. Playback can sound OK, and some people even prefer the coloration this type of transduction imposes on the signal.

That said I find the whole process fussy and I like to hear music without the antique SINAD, so although I do have a large vinyl collection and a good VPI setup, I seldom use it.

 

[watchnerd]

Turntables are mechanical, and can be built to a fine standard and superb finish. As objects, they can be beautiful and intriguing. The 19th century method of storing and playing back music is quaint, and using this apparatus involves entertaining ritual. Playback can sound OK, and some people even prefer the coloration this type of transduction imposes on the signal.

That said I find the whole process fussy and I like to hear music without the antique SINAD, so although I do have a large vinyl collection and a good VPI setup, I seldom use it.

Like mechanical watches.

 

[murraycamp]

Overload is another way of saying clipping. . . . From what I've seen of some modern designs, that's been forgotten, and in an attempt to get better noise numbers, the overload point is lower now than it was then.

This isn't made easier by today's phono stages being run from low voltage USB ports, or small wall-warts, whereas in the past they were integrated in the amplifier and had much higher voltage rails available, which made getting more output a lot easier.

S.

Excellent. Was always a bit confused about this. Thanks @sergeauckland

 

[milosz]

Like mechanical watches.

Another affectation and form of conspicuous consumption, yes. I understand the appeal of fine craftsmanship, but I've never felt the need to wear a gaudy Oyster.

(I don't wear a watch, actually. )

 

[watchnerd]

Another affectation and form of conspicuous consumption, yes. I understand the appeal of fine craftsmanship, but I've never felt the need to wear a gaudy Oyster.

(I don't wear a watch, actually. )

Oysters are the mechanical watches for those who don't know much about watches.

I prefer vintage Seiko dive watches.

 

[Bob from Florida]

Overload and the phono stage - look at the above graph. The blue dot graph is how the music is filtered to cut the grooves on the record. The blue dot graph also represents the way the frequencies playback through your cartridge. The red line represents the correction to flatten the frequency response that takes place at some point in the phono preamp. As you can see, from 1KHZ to 20 KHZ the signal from your cartridge gets jacked up as much as 20 db at 20KHZ. So if your phono stage has the minimum headroom of 20 db at say 3.5 mv once your cartridge exceeds that value you can clip your phono stage. The more headroom the better. Usually if the first gain stage is low gain - uncorrected signal - then is passively corrected before stage two yields goods results. When I had the Schiit Mani you can set all kinds of gain combinations. There was one setting that minimized the gain in the stage before correction and that sounded the best. This is one area where a well designed vacuum tube phono moving magnet stage has an inherent advantage. Lots of voltage swing available before clipping. One way to get an idea of where your solid state phono stands is the power supply voltage. Higher is better = more swing available before clipping. A 24 volt input supply might be regulated down to 18 volts which is much better than a 5 volt supply. Vinyl can be a pain to set up but can be very rewarding. It also encourages minor exercise since you have to get up every 20 minutes to flip sides or change records.

 

[watchnerd]

Usually if the first gain stage is low gain - uncorrected signal - then is passively corrected before stage two yields goods results. When I had the Schiit Mani you can set all kinds of gain combinations. There was one setting that minimized the gain in the stage before correction and that sounded the best. This is one area where a well designed vacuum tube phono moving magnet stage has an inherent advantage. Lots of voltage swing available before clipping. One way to get an idea of where your solid state phono stands is the power supply voltage. Higher is better = more swing available before clipping. A 24 volt input supply might be regulated down to 18 volts which is much better than a 5 volt supply.

Perhaps an argument for using SUTs with MCs.

 

[SIY]

Perhaps an argument for using SUTs with MCs.

The best argument is that it allows you to run the MC balanced.