Cornford Carrera - questions/issues

PCG

Hi all - I've been browsing this site for a while but this is my first post.  I'm sure I'll get some useful insight given the wealth of knowledge available.

I've had a Cornford Carrera for a number of years now but it hasn't had much use of late.  It's a 2006 model which I bought second hand, around 2011/2012.

I dug it out the other day and was reminded of a few issues which have always intrigued me slightly:

(1) As you probably know, the amp has a switchable power section, either 9 pin (EL84) or 8 pin/octal (6L6, 6V6, etc).  The specs talk about it being ca. 5w output with EL84 and ca. 8-12w output with 8 pin/octal (depending on the valve used).  I've tried a few 8 pin valves over the years (6L6, KT66, EL34, 6V6).  Despite being apparently higher wattage, each has provided noticeably less actual volume than the EL84 valve.  That's been the case since I got it and it's like that at present (EL84/EL34).  Is that normal?  I think I read somewhere in the past that it's due to the cathode bias circuit being optimised for the EL84, which effectively means that the 8 pin valves when selected run more quietly (colder?).  Is that right?

(2) More generally, the amp is (and always has been) really quiet in relative terms, on either valve setting.  I've read plenty of stuff over the years where folks have said "remember 5w valve amps cranked are still super loud" etc, and I've experienced that myself with others.  This one really isn't like that at all.  For example, a while back I owned a single EL84 Laney Lionheart L5T which was considerable louder.  I've got some other amps which, admittedly higher wattage, are also orders of magnitude louder e.g. Headstrong Lil King, Lazy J20.  Is the Carrera known for being a particularly 'quiet' amp or does mine sound iffy?  If the former, what's the technical reason for the low volume from this circuit?

(3) I've also read a reasonable amount about the Carrera being a very bassy or dull sounding amp, and seen a few vids on youtube where folks are cranking the treble (i.e. treble at 9pm, bass and mids around 3pm, etc).  Mine seems like the opposite, fairly trebly to the point where I roll that off massively in comparison to the other controls.  Again, does that sound unusual?  Could it be linked to 2 above?  I don't know if there were perhaps circuit changes at some point in the history of production (I believe they moved from being made 'in-house' to being made by an outside contractor in the years prior to Cornford effectively disappearing).

I'm just curious really.  The amp doesn't sound bad (admittedly not amazing either!) but, not having played another, I don't know whether this one actually has issues or not.  Any known issues?

The obvious thing to do is get it to a decent tech for a check, which I've been planning to do for ages, but in the meantime I thought I'd ask some questions out of general curiousity.

Thanks all!

markr76

Hi there. I have a carrera built in 2010. I'd say I find the same with all the points you mentioned. I've tried a load of different valves in the 8 pin slot. These range from 5-8 watts but all were quiet compared to the 9 pin. I liked a 5881 or kt66 the most in there. 
I found you have to be quite careful with both the mid and treble control as the treble can be quite hard/harsh sounding. I remedied this a little by changing the stock speaker to a g12m65 creamback. 
The amp is quiet compared to other 5 watters I've played but that's because it's intended as a studio and home amp really. 
The problem for home use is it sounds best when cranked. Somewhere in the last quarter of the master the amp really comes to life. But this is too loud for home use really. 
Chris from Rift checked mine over but it was all good. I got in checked as I thought it was faulty. But that's just the sound. It really needs to be cranked to sound good!
I always loved the carrera but by the time u actually got my hands on one. I think my ears/tastes have changed. That could be because I love the sound of my badcat so much. Which has a smoother top end and gain. Also masses of low end. That's what I like these days.

PCG

Thanks, that's really useful feedback. 

Sounds like mine isn't unusual, for better or worse.  Interestingly, even when fully cranked mine isn't really pushing the boundaries of "home volume".  For comparison, I rarely getting my Headstrong/Princeton much above "2" at home in normal use.

I also swapped in a Creamback speaker and noticed an improvement.

I'm interested to understand what about this particular circuit results in the apparently higher powered 8 pin valves producing less actual volume than the lower powered EL84. 

I'm also interested to understand what about the circuit results in the overall relatively low volume for a single-ended 5w-8w amp.  Is it something which is creating a form of fixed attenuation or lower than normal voltages to the valves (like some kind of fixed power scaling, I suppose)?

Any of the resident tech experts able to offer a view?  

Modulus_Amps

There is no recovery stage after the tone stack on that amp, might just be that there is not enough clean signal to drive the octals hard enough, where the EL84 is more sensitive?? Guessing... A EL34 or better yet a KT88 should crush a EL84 for volume if the amp was designed to push the power section harder than the pre-amp.

A decent tech could sort the high end out for you easily enough. Sorry don't know much about these I tried to buy one around 2006 and could not get a response from Cornford and stockist never had stock

TheBigDipper

I've got a Harlequin, not a Carrera, but I think it shares enough for this to be meaningful.

The "Master" control drives the power amp and the 'Volume' control drives the preamp. The Cornford twist is that the Volume control is a cascading preamp gain (I think that's the right word for it). My experience is there's no clean tone after you get it to 50%. It just starts to cream up and get very filthy the more you turn it without actually seeming to get too much louder. I'm sure a 'proper' clean channel on any 5W valve amp like the Laney would be louder to the ears than a Harlequin or Carrera when turned up. 

CHrisP86

I remembe my Carrera sounding louder with the EL84, but fairly quiet overall.

i would have thought the actual volume difference from 5-8w would be negligible anyway and it is possibly some other frequencies in the sound wave making the EL84 *seem* louder.

Yours does sound unusually quiet though.

I remember cranking the treble on mine, which bothered me until I realised that if the amp sounds best with the treble up high, it’s not a flaw in the amp that’s just how it is and it still sounds good.

When did you last change the valves? 

tone1

I’ve had 2 Carrera’s.  Both lacked bottom end thump as standard. My last one had been built into a handmade Teak cab which had a Tone Tubby 1x12 which was much better (I’ve still got the cab) 
For me a decent clean sound and pedals was a better way to go. Mine weren’t the loudest either 

PCG

Modulus_Amps said:

There is no recovery stage after the tone stack on that amp, might just be that there is not enough clean signal to drive the octals hard enough, where the EL84 is more sensitive?? Guessing... A EL34 or better yet a KT88 should crush a EL84 for volume if the amp was designed to push the power section harder than the pre-amp.

A decent tech could sort the high end out for you easily enough. Sorry don't know much about these I tried to buy one around 2006 and could not get a response from Cornford and stockist never had stock

Thanks - that's very nteresting.  I wonder if that could explain the low-ish volume from the single EL84 too, i.e. not enough signal to drive the octals hard enough, enough signal to drive the EL84 but still relatively low signal to begin with, hence low output volume even when amplified.  

The treble thing isn't really an issue as such, I just find it interesting that some folks have to crank the treble on theirs whilst mine definitely needs to be cut otherwise it's very harsh.  I don't think it's an issue of personal preferences, mine truly sounds terrible with the treble cranked!

TheBigDipper said:

I've got a Harlequin, not a Carrera, but I think it shares enough for this to be meaningful.

The "Master" control drives the power amp and the 'Volume' control drives the preamp. The Cornford twist is that the Volume control is a cascading preamp gain (I think that's the right word for it). My experience is there's no clean tone after you get it to 50%. It just starts to cream up and get very filthy the more you turn it without actually seeming to get too much louder. I'm sure a 'proper' clean channel on any 5W valve amp like the Laney would be louder to the ears than a Harlequin or Carrera when turned up. 

Thanks.  Good point about the volume (gain) control.  It's also a dual-gang pot on the Carrera and behaves similarly.  You're right that it could be perceived volume issues with lots of pre-amp gain vs. not much on a 'cleaner' amp.

CHrisP86 said:

I remembe my Carrera sounding louder with the EL84, but fairly quiet overall.

i would have thought the actual volume difference from 5-8w would be negligible anyway and it is possibly some other frequencies in the sound wave making the EL84 *seem* louder.

Yours does sound unusually quiet though.

I remember cranking the treble on mine, which bothered me until I realised that if the amp sounds best with the treble up high, it’s not a flaw in the amp that’s just how it is and it still sounds good.

When did you last change the valves? 

Thanks, interesting points.  You could be right in terms of the volume differences being more 'perceived' than actual.  The EL84 does seem a bit more mid-rangey, so that could explain it.  I do think there is an actual lower volume with the octal too, however.  I might do an SPL test with my phone out of interest.

Valves are all fairly new and I've swapped various ones in and out over the years with similar results.

I do wonder if there was some change in the circuit at some point in terms of treble response.  I've seen others, like you, who found it sounded best when the treble was cranked.  I've also seen a couple of clips on youtube with those settings.  Mine sounds awful like that!

tone1 said:

I’ve had 2 Carrera’s.  Both lacked bottom end thump as standard. My last one had been built into a handmade Teak cab which had a Tone Tubby 1x12 which was much better (I’ve still got the cab) 
For me a decent clean sound and pedals was a better way to go. Mine weren’t the loudest either 

Thanks for that.  It's interesting that they lack bottom end, as it's a fairly big and weighty unit for a small wattage combo.

I agree in terms of decent clean and pedals.  That's really why the Carrera's not had much use for a while, I also get more pleasing results from that.


Thanks again all for the thoughts.  This was a bit of an exercise in satisfying curiosity rather than fixing a specific problem, and I feel reasonably satisfied...!  I'll probably put it back into retirement for a while again...

bodhi

I also have a Carrera (built in 2010, I believe), which I only ever use at very low volume.

The way I use mine, there's a noticeable volume difference between the 8-pin and 9-pin settings, with the former being quieter.

To my ears, mine sounds best with Bass and Middle somewhere between 9 and 12 o'clock, and Treble at around 3 o'clock.

Question for those who have changed speakers:  Is it true that the speaker is glued in, and quite difficult to remove?  I think I read/heard that somewhere.

Modulus_Amps

PCG said:

The treble thing isn't really an issue as such, I just find it interesting that some folks have to crank the treble on theirs whilst mine definitely needs to be cut otherwise it's very harsh.  I don't think it's an issue of personal preferences, mine truly sounds terrible with the treble cranked!

either everyones ears are shot, your amp has been modded with a bright cap or two or there is something wrong with the amp/speaker

PCG

bodhi said:

I also have a Carrera (built in 2010, I believe), which I only ever use at very low volume.

The way I use mine, there's a noticeable volume difference between the 8-pin and 9-pin settings, with the former being quieter.

To my ears, mine sounds best with Bass and Middle somewhere between 9 and 12 o'clock, and Treble at around 3 o'clock.

Question for those who have changed speakers:  Is it true that the speaker is glued in, and quite difficult to remove?  I think I read/heard that somewhere.

I’ve seen a few clips on YouTube where folks have similar settings (treble at 9pm).  Interesting - mine is really thin and harsh like that but the clips on YouTube (and yours, I’m sure) are not at all.

On the speaker, mine was glued in - a bit of a pain to remove but not too bad. Used a blade and some careful leveraging.  If I recall correctly, there was a ring of high density foam stuff between speaker and baffle which didn’t survive well.  Most remained on the speaker but some on the baffle. It was worth it in my case, I do prefer the creamback to the v30.

Modulus_Amps said:

PCG said:

The treble thing isn't really an issue as such, I just find it interesting that some folks have to crank the treble on theirs whilst mine definitely needs to be cut otherwise it's very harsh.  I don't think it's an issue of personal preferences, mine truly sounds terrible with the treble cranked!

either everyones ears are shot, your amp has been modded with a bright cap or two or there is something wrong with the amp/speaker

I can’t see any sign of mods to the circuit.  I still wonder if there might have been tweaks to the circuit in later years of production. Perhaps a bright cap in earlier versions (like mine) which was removed from later versions?

Don’t think ears are the issue but could be I suppose! Definitely not the speaker as roughly the same results before/after being swapped and via exerenal cab.

I should just get it checked by a tech to be sure, perhaps.

Collings

I had a Victory Baron amp which was Martin Kidd,s update on the Carrera. It sounded ok but like the Carrera was very quiet even for a 8w amp. Again I found the EL84 valve louder than whatever other valve was fitted with the same volume settings on the controls.

dallcorp

I still love my Carrera......and I also normally have the Treble somewhere in the top 20% of it's adjustment range to get a sound I Iike......have you tried plugging straight into the Return jack of the effects loop? I believe this will possibly bypass the preamp tone stack and help troubleshoot whether that's your issue?

RiftAmps

Based on the OP measurements I did on @markr76 ‘s amp, the stated wattage for both valve types are optimistic and were probably fudged to fit a marketing strategy and/or consumer expectations.

Of course, OP and perceived volume may not be intrinsically linked, see Vox AC30.

PCG

Collings said:

I had a Victory Baron amp which was Martin Kidd,s update on the Carrera. It sounded ok but like the Carrera was very quiet even for a 8w amp. Again I found the EL84 valve louder than whatever other valve was fitted with the same volume settings on the controls.

Thanks - sounds like the circuits are fairly similar. dallcorp said:

I still love my Carrera......and I also normally have the Treble somewhere in the top 20% of it's adjustment range to get a sound I Iike......have you tried plugging straight into the Return jack of the effects loop? I believe this will possibly bypass the preamp tone stack and help troubleshoot whether that's your issue?

Thanks - I’ll give that a try. RiftAmps said:

Based on the OP measurements I did on @markr76 ‘s amp, the stated wattage for both valve types are optimistic and were probably fudged to fit a marketing strategy and/or consumer expectations.

Of course, OP and perceived volume may not be intrinsically linked, see Vox AC30.

Thanks, that’s very interesting.  If you can recall, what is it about the circuit that would result in the low OP measurements, e.g. low plate voltage, lack of recovery stage as noted by @Modulus_Amps above?