The No.1 Website for Pro Audio
Cleanest 500 series preamp on the market? - Welcome to Camden 500
Old 28th June 2018
  #1
Gear Maniac
Cleanest 500 series preamp on the market? - Welcome to Camden 500

Cranborne Audio have finally completed the Camden 500 preamp and signal processor for 500 series, and it’s a bit of a beauty.

We’ve generated the final specs, and whilst we were expecting great performance, we’ve actually ended up with (probably) the cleanest, most transparent 500 series mic preamp on the market; and we’re going to sell it for a price that everyone can afford - $349 US Retail / £299 RRP IncVat.

Thanks to its Mojo circuit, it’s also a lot more than just a clean preamp. Mojo is a 100% analogue saturation circuit that can be dialled-in to be one of the most saturated and ‘transformer-like’ preamps in your arsenal. Or Mojo can be bypassed completely to reveal the cleanest, frequency/phase-linear preamp you've ever heard.

We know these are bold claims that we would be skeptical of… but we have the Technical Specs for you guys to analyse taken straight from our APx555 Audio Analyzer. You'll see that the Camden 500 pushes the theoritical limit of linearity, noise and distortion. With Mojo bypassed - the Camden 500 is not colouring or influencing your mic, mic placement, or source in any audible way, shape, or form - it will also continue to perform at these extraordinarily low performance figures at all gain settings.


THD+N:
<0.0004%, 1kHz, 35dB gain, 24dBu out

Equivalent Input Noise (EIN):
<-129.5dBu, 150 ohm source, unweighted - (that’s pretty much the theoretical limits of EIN).
<-131dBu, 150 ohm source, A-weighted
<-135.5dBu, Inputs common, unweighted

Frequency Response:
±0.25dB, <5 Hz to >200 kHz, 35dB gain
<±1dB, <5 Hz to >200 kHz, max gain - (most preamps have dramatic frequency roll-off at max gain)

Phase Shift:
<2.25°, 40dB gain, 20Hz to 20kHz
<4°, Max gain, 20Hz to 20kHz - (4° at max gain is pretty much unprecedented, it’s not uncommon to see 10-30° of phase shift on the very best preamps at max gain)

Intermodulation Distortion:
<0.0008%, 50Hz and 7kHz, 35dB gain, 20dBu out
<0.0006%, 50Hz and 7kHz, 35dB gain, 15dBu out

Max Input Level:
Mic = 17.6dBu (<0.003% THD)
Line = 26.5dBu (<0.02% THD)
Hi-Z = 24dBu (<0.02% THD)

Max Output Level:
27.5dBu (<0.002% THD, 30dB gain)

CMRR:
>70dB, typ >85dB, 35dB gain, 10-20kHz, 100mV Common mode

Input Impedance:
Mic= 8.9kOhms 48v Off, 5.4kOhms 48v ON,
Line = 24.3kOhms
Hi-Z= 1.5MOhm unbalanced, 3MOhm balanced

Output Impedance:
150 Ohms

Current Draw:
120mA per rail - idle
140mA per rail - typical use case

Slew Rate:
20V/uS, 35dB gain, 25dBu out

The complete technical specifications (with AP graphs) can be found here: https://www.cranborne-audio.com/hubf..._TechSpecs.pdf

We’re really excited to get these out into the wild. The Millennias, Grace Designs, Forsells, Earthworks of the world are great bits of kit - we’ve all used them before - but they are not what we consider affordable, certainly not for engineers and musicians like ourselves.

We’ve truly designed a preamp that will stand shoulder-to-shoulder with those great preamps whilst costing less than half the price. We haven’t cut corners… we’ve just started from scratch by developing our own custom topology, sourcing components that have never been seen in the audio industry before, and tuning the design to the nth degree (and then some more…).

If you guys have any questions, or would like us to take a look at another preamp to see how Camden 500 compares, let us know!
Old 28th June 2018
  #2
Lives for gear
 
gainreduction's Avatar
 

Really cool to see someone doing something new in these times of clone-the-classics.
Old 28th June 2018 | Show parent
  #3
Gear Maniac
Quote:
Originally Posted by gainreduction View Post
Really cool to see someone doing something new in these times of clone-the-classics.
Thanks mate! Yeah, we reckon those 'classics' were right the first time! It's about time for some new classics!
Old 29th June 2018
  #4
Gear Maniac
Hi guys,

We're happy to answer any questions about the Camden 500 feature set and the performance we've achieved. We're also happy to explain any part of the spec and why it matters. So feel to ask anything!

We know the specs can be confusing and hard to translate into things that matter - like the most important question - does the mic pre sound good? So I thought I could explain a bit more. Our specs show is that Camden 500 is perhaps THE cleanest, most transparent, most linear (both frequency and phase!), and lowest noise preamp ever designed. I'm going to use the Millennia HV-37 (not the HV-35 Millennia's 500 series version as the HV-37 performs better) for comparison- one of the cleanest/most transparent mic preamps I've ever used and a very highly regarded preamp by most- to show how good the Camden 500's noise, distortion, and linearity specs really are. I'll be taking spec information on the Millennia HV-37 from their specs:
Millennia HV-37 | Millennia Music & Media Systems

And this Sound-on-Sound article:
Millennia HV37 |


Frequency Response

We document the Camden 500's frequency response as follows:
±0.25dB, <5 Hz to >200 kHz, 35dB gain
<±1dB, <5 Hz to >200 kHz, max gain

The HV-37's is documented as follows:
< 10 Hz to > 200 kHz
typical -1.0 dB @ 10 Hz < 10 Hz to > 200 kHz
typical -1.5 dB @ 200 kHz


We spec down to 5 Hz (this ensures no subharmonic distortion) and have only ±0.25dB of deviation throughout the entire frequency range of 5Hz to 200kHz. And even at max gain, we achieve impressive linearity. Note we spec what gain value our frequency response is tested at - this is important to us as too often mic preamps have uneven response at different gain settings and often poor performance at max gain.

It's also important to understand that linearity within the audio band (20Hz - 20kHz) is important when sizing up a transparent/linear preamp, but it's also important to see what the wider bandwidth is of a preamp outside of the audio spectrum. Having a larger bandwidth provides a multitude of benefits including 1) better audio band linearity, 2) less phase shift, 3) less intermodulation distortion 4) less sub-harmonic and upper-harmonic THD. Both Millennia and us spec up to 200kHz to address the high-frequency. For low-frequencies - the HV-37 is spec'd at 10Hz and the Camden 500 at 5 Hz.


Phase Shift

We document the Camden 500's Phase Shift as follows:
<2.25°, 40dB gain, 20Hz to 20kHz
<4°, Max gain, 20Hz to 20kHz

The HV-37's is documented as follows:
< 2 degrees deviation (35 dB Gain, 50 Hz - 20 kHz bandwidth, +27 dBu Out)

Phase shift in preamps can be higher than 3600° (we were really shocked when we measured that as well!) across the frequency spectrum on entry-level mic preamps! Imagine your low end in a kick drum or bass instrument arriving almost 30ms (almost enough for you to distinguish two separate sounds), and your high-end arriving 10 wavelengths later than 1kHz with everything between on a spectrum and all the chances for phase cancellation when you start stacking in a mix... This manifests in the "smearing","muddiness", and "lack of punch" that you hear. Even high-end transformer-based preamps will have > 60° phase shift across the spectrum as transformers , by nature, introduce some phase shift (typically between 25° and 60° at 50Hz). Sometimes this causes a slight "unison" effect on transformers which can make a source sound "bigger" or "Stereolike" - which can be great! But it's an artefact nonetheless that may not be desirable.

Phase shift can be addressed by high-end transformerless designs like the HV-37 but the Camden 500 sets a new standard for phase linearity. Note that the Camden 500 is spec'd down to 20Hz whereas the HV-37 is spec'd at 50Hz. And, in our opinion, low-end phase shift is the most important to mitigate and control and gives you a tighter and punchier bottom-end. And just as with frequency response, we spec our phase shift response at Max Gain as well.


Noise

We document the Camden 500's Equivalent Input Noise (EIN) as follows:
<-129.5dBu, 150 ohm source, unweighted
<-131dBu, 150 ohm source, A-weighted
<-135.5dBu, Inputs common, unweighted

The HV-37's is documented as follows:
-130 dB EIN, 60 dB Gain, 10 Hz - 30 kHz, Inputs common

Equivalent Input Noise (EIN) measures the noise floor of a circuit. In terms of how this affects audio - the lower the noise floor, the "cleaner" your recording is and the more dynamics you have (quiet parts are actually quiet!). It's especially helpful as with a lower noise floor you have more dynamic range for compression and similar effects. But the confusing thing with EIN is how it's measured - A-weighting, inputs common/shorted, unweighted with a load (50-150 ohm), and others. The way it's measured is hugely important in understanding it's performance and which preamp actually is the quietest...

We spec our EIN performance the 3 different ways we most commonly see it. if we compare apples to apples with the HV-37, we see the Camden 500 is 5.5dB quieter at the common spec - inputs common. But an amazing sign of the Camden 500's low-noise performance is the 150 ohm unweighted number - the number which best illustrates the noise performance you can achieve with a microphone attached - which is an unbelievably low -129.5dBu.



THD (Distortion)

We document the Camden 500's THD+N as follows:
<0.0004%, 1kHz test tone, 10 Hz - 20 kHz bandwidth, 35dB gain, 24dBu out

The HV-37's is documented as follows:
< .003%, Typical < .001%, 35 dB Gain, 10 Hz - 20 kHz bandwidth, +24 dBu Out

THD (Total Harmonic Distortion) is a measurement which shows how much distortion is being added to the signal. The lower the number, the less distortion. The tricky thing is THD can sound "good"! Most transformer-based designs have very high THD numbers. But this distortion sounds good - it's an iron-core of the transformer "saturating" and introducing low-end and high-end harmonics in nice places. But THD can often sound bad as well - as with entry-level mic preamps when the front-end transistor is "saturating" due to hard, nasty clipping, or with A/D converters when digital artefacts are the distortion. So all we can really objectively say is - the LOWER the THD ratio the more transparent the preamp is.

It is said that THD is inaudible at between 0.1% and 0.05%, but THD rises in the low-end and high-end of the frequency spectrum and becomes harder to achieve at high gains. So a preamp that is 0.05% THD at 1kHz might be as high as 0.5% THD at 50Hz and a transformer-design might be as much as 5-10% THD at 50Hz! But most brands only post the THD ratio at 1kHz because it's the smallest number... We achieve <0.0004 THD at 1kHz, whilst we achieve <0.0008 from 20kHz-20kHz from min gain to 40dB of gain. And <0.01 from 20Hz-20kHz at max gain (68dB of Gain)... So THD is still inaudible even with 68dB of gain!

Both us and Millennia spec THD+N, which is actually the distortion plus noise ratio together - a more challenging number to hit! So if we're talking THD only, the Camden 500 will be <0.0001% THD.


Intermodulation Distortion

We document the Camden 500's Intermodulation Distortion as follows:
<0.0006%, 50Hz and 7kHz, 35dB gain, +15dBu out
<0.0008%, 50Hz and 7kHz, 35dB gain, +20dBu out

The HV-37's is documented as follows:
< .0006% +12 dBu Out, 50 Hz & 7 kHz, 35 dB Gain
< .001% +20 dBu Out, 50 Hz & 7 kHz, 35 dB Gain

This is the industry's crude way of showing that THD is low across the entire frequency band (beyond the audio band). If you have bad distortion artefacts high in the audio band or above, it can then intermodulate with other distortion products in the low frequencies and appear in the audio spectrum... And the worst part about Intermodulation Distortion is it's completely harmonically unrelated - it sounds harsh and nasty, unlike "pleasant-sounding" THD from transformers and valves, and will only produce "bad-sounding" distortion.

Hope this is a semi-decent explanation of some of the more confusing and important specs in preamps. If anyone wants to know any more or has any other questions, we'd be happy to explain more!
Old 29th June 2018
  #5
Gear Guru
 
Brent Hahn's Avatar
Quote:
Originally Posted by Ells View Post
We’ve truly designed a preamp that will stand shoulder-to-shoulder with those great preamps whilst costing less than half the price. We haven’t cut corners…
Looks very interesting.

I imagine a good deal of the cost-savings lies in the elimination of transformers. I'm not sure I buy your rationale behind why I don't want transformers, but the proof is in the listening, I guess.

And would it be reasonable to assume that another reason those great preamps cost more than yours is because it costs them more to market them?

And a late add on a whole 'other subject: A Cat5 cable has (4) twisted pairs but no ground wire(s). When you repurpose it to carry analog audio, isn't it stretching the definition a bit to call that "balanced?"

Last edited by Brent Hahn; 29th June 2018 at 04:07 PM..
Old 29th June 2018 | Show parent
  #6
Gear Maniac
Cheers Brent! Good questions/observations!

Quote:
Originally Posted by Brent Hahn View Post
I imagine a good deal of the cost-savings lies in the elimination of transformers.
Yes absolutely. Transformers are quite expensive, whereas we are using discrete analogue components to get the RF rejection, common-mode rejection, etc that transformers provide - which carries significant cost savings if done well.

Quote:
Originally Posted by Brent Hahn View Post
I'm not sure I buy your rationale behind why I don't want transformers, but the proof is in the listening, I guess.
Oh no not at all! Transformer-based preamps are great when you want to get that flavour and thickening. And different brands' transformer-based designs will have signature flavours and sounds... "Neve' vs. "API" vs "Trident"... And
transformers are a huge part of this. And in terms of RF rejection, transformers are a great solution. So we definitely think transformer-based preamps are wicked and there's tons out there to choose from and lots of them are great - we have many of them! But the "cleanest" and most linear preamps by the numbers are transformerless mic preamps.

The reason we decided to make Camden transformerless is that we couldn't accomplish what we wanted to with Camden if we used transformers. We wanted something that could be absolutely perfectly clean - which is what you would want for lots of sources - but then add a variable (and bypassable) control to tune the amount of "saturation" you can add to signal to give it "vibe" and - what we ultimately decided to call it - Mojo.

Transformers are usually used in audio kit to impart character - as in add THD, have non-linear frequency response, and introduce phase shift. Since we wanted to minimise these non-linearities when its in the "clean" mode - "vibey" transformers wouldn't work. But there are transformers that can be very linear -but not as linear as we were able to achieve using a transformerless discrete design. And if you make a transformer that's very "neutral" - well isn't that kind of not the point? When we think of "transformers" we think big, thick tone... or at least I do!

But you are 100% right... your ears will decide whether "Mojo" is up to the task of adding that transformer-style saturation that we all love. I know it's compressed streamed audio, but if you want to check out our Soundcloud page, we have examples of the "Mojo" on various sources:
MOJO Audio Examples by Cranborne Audio | Free Listening on SoundCloud


Quote:
Originally Posted by Brent Hahn View Post
And would it be reasonable to assume that another reason those great preamps cost more than yours is because it costs them more to market them?
Yes spamming Gearslutz rather than paying money for advertising helps

But yes, lots of reasons why we are able to charge less - certainly our smaller size (only 5 of us... and 3 are engineers!) helps. But most of the cost savings comes from designing the Camden really carefully and validating good low-cost components. We are pretty ruthless with cost - but never at the expense of performance... usually at the expense of our Engineers' time crawling through data sheets to find good components that aren't outrageously expensive!

Cheers for the questions!
Old 29th June 2018 | Show parent
  #7
Gear Guru
 
Brent Hahn's Avatar
Quote:
Originally Posted by Karpmentalise View Post
Cheers for the questions!
You skipped one. :-)
Old 29th June 2018 | Show parent
  #8
Gear Maniac
Sorry Brent - just saw this edit from your comment.

Quote:
Originally Posted by Brent Hahn View Post
And a late add on a whole 'other subject: A Cat5 cable has (4) twisted pairs but no ground wire(s)
Camden 500 doesn't have CAST, but the 500R8 and 500ADAT do. CAST must be used with a shielded Cat5 cable as it is 4 twisted pairs plus the shield.


Quote:
Originally Posted by Brent Hahn View Post
When you repurpose it to carry analog audio, isn't it stretching the definition a bit to call that "balanced?"
Nope - both lines per Cat5 channel have the same ground referenced impedance. And full balanced-impedance noise cancellation is carried out on every pair.
Old 29th June 2018 | Show parent
  #9
Gear Guru
 
Brent Hahn's Avatar
Quote:
Originally Posted by Karpmentalise View Post
... full balanced-impedance noise cancellation is carried out on every pair.
Okay -- if it works, it works.
Old 29th June 2018 | Show parent
  #10
Gear Guru
 
Brent Hahn's Avatar
Quote:
Originally Posted by Karpmentalise View Post
Transformers are usually used in audio kit to impart character - as in add THD, have non-linear frequency response, and introduce phase shift. <> And if you make a transformer that's very "neutral" - well isn't that kind of not the point?
That's why I like them. But the folks at, oh, Jensen, might say something like "no, transformers are for isolation. And the best ones are the ones you can't hear."

If you guys can do isolation that well or better for cheaper, you're onto something.
Old 29th June 2018
  #11
Gear Head
 

Hi Brent, I'm Ed, Cranborne's engineering director. I was just mucking about with my audio analyzer when I spotted your post.

I thought "how does the RF rejection compare to a transformer?" was a good question (and I was curious) and I'd do the best comparison I can with the bits I have on hand.

Shoved in the only transformer coupled preamp I have on hand (between 700 and 900 odd quid unit value wise. Won't say the brand as I'm not here to start a fight. Never known it to show any RFI though.) Max gain.

Measured CMRR at 50hz as 88dB, 1kHz = 88dB, 20kHz= 53dB, 100kHz=23dB, 200kHz=12dB.

OK neat, we have a baseline. Time for the Camden, same settings:
50hz = 85dB, 1kHz = 85dB, 20kHz= 83dB, 100kHz=79dB, 200kHz=77dB.

Well now, that's interesting! See the thing about transformers is that unless it's a very expensive unit with an electrostatic shield to minimise capacitance between primary and secondary windings, CMRR falls off rapidly with increasing frequency. As everything in analog audio, it's the implementation not the ingredients that matters. Is the Camden RF rejection better than a world class preamp that has excellent CMRR on it's own right AND a high quality Jensen? Doubt it. Is it very very good and better than a hell of a lot of transformer inputs? Yup.


Also, as I'm mucking around and finally coaxed the sub 5Hz measurements out of my AP... You guy's like bass extension and nice tight linear low ends right? here's a picture that tells a thousand words:
Attached Thumbnails
Cleanest 500 series preamp on the market? - Welcome to Camden 500-camden-low-end.jpg  
Old 10th July 2018
  #12
Old 11th July 2018
  #13
Lives for gear
 
the fxs's Avatar
 

@ Mod s:

could you please merge both threads?
Old 3rd November 2018
  #14
Gear Maniac
Hi All,

Our n00bery has resulted in two separate threads with different answers and explanationa across both threads. Sorry about that! This thread is more current and active at the moment:

Cranborne Audio releases the cleanest, most transparent preamp on the market
📝 Reply

Similar Threads

Thread / Thread Starter Replies / Views Last Post
replies: 5 views: 5655
Avatar for BeHappy
BeHappy 30th March 2015
replies: 14 views: 1281
Avatar for Ben Dial
Ben Dial 21st July 2016
replies: 185 views: 21878
Avatar for monkeyxx
monkeyxx 15th October 2020
Topic:
Post Reply

Welcome to the Gearslutz Pro Audio Community!

Registration benefits include:
  • The ability to reply to and create new discussions
  • Access to members-only giveaways & competitions
  • Interact with VIP industry experts in our guest Q&As
  • Access to members-only sub forum discussions
  • Access to members-only Chat Room
  • Get INSTANT ACCESS to the world's best private pro audio Classifieds for only USD $20/year
  • Promote your eBay auctions and Reverb.com listings for free
  • Remove this message!
You need an account to post a reply. Create a username and password below and an account will be created and your post entered.


 
 
Slide to join now Processing…
🖨️ Show Printable Version
✉️ Email this Page
🔍 Search thread
🎙️ View mentioned gear
Forum Jump
Forum Jump