Hey Guys,

Well today was amp mod day, before Fritz even arrived this morning I had 2 fellow Forum guys drop off their amps for mods. Another Champ and an Epi Valve Jnr, ah the smell of summer time mods 8)

When Fritz arrived and we got to work on his little Cub 8.





As you can see from the pics it is pretty typical Chinese assembly/parts, first time I've come across a valve amp using SMD resistors (which I'm not happy about), but it does allow them to get the whole amp onto that SMALL PCB and the contruction is fairly solid, bar the ridiculously small signal traces.

First thing to address was to see if we could lower the hum a bit. As noted the amp suffers from a couple different hums/buzzes, part of which comes from the AC heaters. This was a fairly quick fix and a turn or 2 on the internal trimpot and we found the sweetspot. The indicator lamp as I shared is not implemented that well, any change in AC voltage can mean it turns on/off... an AC lamp will be a better bet powered off the heaters and it turned itself on and off at will during our tests.

Here are some before and after clips RE the hum:

Stock Cub 8 Hum
Modded Cub 8 Hum

Following the hum mod we decided to try a couple 'quick' mods/changes.

First up I recorded a little piece of music with chords and some picking into my DAW and then used a Reamp Box to send the same signal back to the amp, it is the same performance each time, with the same mic/placement and gain settings, so any chance you hear is a sum of the mods/tweaks. Signal was via my PRS SE ONE witha single P90, DI'd into and API 312 Mic Pre into Pro Tools.

The stock amp has Ruby Tubes. Ruby source tubes from all over and rebrand them, infact Mesa use Ruby, so you know they have undergone some form of QC outside of the factories they come from.

I wasn't that surprised to notice the difference between them and the JJ's were not night and day, but rather more minute, coming in the way of being a little more defined with the JJ's, the attack was cleaner/clearer, but the stock Ruby's were not bad, WAY BETTER than the cheap no name Chinese ones in say the Fender Champion 600.

So after swapping out the tubes we decided to sub out the Super 8 Celestion speaker with a Jensen C8R, boy did THAT make a difference! The Celestion is muddy and indistinct, the Jensen is alot tighter and brighter with more note definition/clarity and that was fresh out the box, it will smooth out a bit as it is broken in.

In the end Fritz left with the amp with a bit of hum reduction, a new set of valves and speaker, and not too much money spent - not bad considering the cost of the amp to start with and a VERY different amp from stock.

I've uploaded a couple clips and you can downloaded them below, in all cases the Tone was set at 12 o'clock and the HALF gain at 5, the FULL gain at 10 on the dials.

Stock Cub 8 - Half Gain
Modded Cub 8 - Half Gain with Jensen and JJ's
Stock Cub 8 - Full Gain
Modded Cub 8 - Full Gain with Jensen and JJ's

Cheers

Matt

BTW - last link above should be
Modded Cub 8 - Full Gain with Jensen and JJ's

That makes a huge difference Matt, especially driven.

Did you by any chance try plugging it into a bigger speaker cab too?

Thanks Alan, I fixed the link!

RE the larger speaker cab, nope, didn't cross my mind at the time, even though it was sitting of my AC30 with vintage blues and RIGHT next to it my 2x12 Fender Cab with C12N's... DOH! I guess I was in the mind set of working on it as a Combo, even though it has an external 8 Ohm out socket.... Fritz, want to come back? LOL

I'm sure it will sound great, even these 'simple' mods can be done by anyone, though there is a risk of shock/electrocution with swapping the speaker and the hum mod/tweak because you need to remove the whole chassis.

I must say I'm SUPER impressed with the Jensen C8R, I bought it to use with my own Fender Champ, that I never got around to building, so we opened the box for the first time and it made such a difference, part of the 'crunch' I was missing from the stock amp showed up in the cranked amp as you shared.

Cheers

Matt

Alan Ratcliffe wrote: BTW - last link above should be
Modded Cub 8 - Full Gain with Jensen and JJ's

That makes a huge difference Matt, especially driven.

Did you by any chance try plugging it into a bigger speaker cab too?

Now if you could just get hold of a Cub 10 ?

I notice a lot of the boxiness of the amp is also gone with the Jensen fitted and the amp sounds a bit louder (if your settings were the same). The speaker is definitely the weak link (unsurprisingly), but it's nice to know that a cheapish speaker (about R450-R500 by my reckoning) can take it from being a cool little amp to a pretty good sounding one.

Unfortunately those SMD resistors are a bit of a dealbreaker for me.

Hey Alan,

Yeah man, really sadden by the SMD resistors

My suggestion to Fritz was to not even bother having me mod the existing circuit beyond what I did to with the hum/valves/speaker as he would be over capitalizing the amp. If he is keen to do something I'd rather just build a point to point 5F2 in there, on turret/tag board, we can use the existing transformers, the replacement speakers and valves... it would prob take me as long, if not longer to hack away at the PCB than to just start a fresh with better quality components, handbuilt and easier to repair in the field.

But yes, the speaker mod alone is worth the expense, my feeling is the same would be said of the Cub 10, the magnet on the stock Celestion is a joke, I should have taken a pick of them side by side in retrospect, the Jensen is a MUCH better speaker, but also twice the price, but as you said, for R450 it ain't bad at all!

RE settings, yip all the same, I wrote them all down, measured out the distance and placed tape on the grill to position the speaker exactly where it should be, hence why I also wanted to use the same performance so any changes were purely from the mods.

Cheers

Matt

Alan Ratcliffe wrote: I notice a lot of the boxiness of the amp is also gone with the Jensen fitted and the amp sounds a bit louder (if your settings were the same). The speaker is definitely the weak link (unsurprisingly), but it's nice to know that a cheapish speaker (about R450-R500 by my reckoning) can take it from being a cool little amp to a pretty good sounding one.

Unfortunately those SMD resistors are a bit of a dealbreaker for me.

Wow ... what a difference the mods have made.
Hello ... I'm interested !!
?

Well, I'm pretty interested in changing the speaker. On the Laney site it says that the Cub 8 has a Celestion Super 8 and the Cub 10 a Celestion Tubes 10 driver. What Jensen would be the right one for the 10? Also the tubes, looks like the 10 just has twice what the 8 has. But I get the impression that the suggestion is that changing the tubes is not really something to do as a matter of urgency? Where would I get hold of the speaker and tubes? Tell yo waht makes me tense is this talk of electrocution. Dunno if I'm up for that right now.

Well for a similar tone/sound you would just go for the larger 10" speaker in the same range, the C10R instead of the C8R. I'd def. recommend the speaker mod over the tube mod if budget is a concern, though doing both is not a bad idea. The Cub 10 uses a pair of 6V6's and 2 x 12AX7's, so double the tube compliment of the Cub 8. There a couple places to get valve from though the Jensen's are not as easy to get a hold of and I import them on a case by case basis.

I feel that anyone with a bit of know how could do the swap, but if safety is a concern I would get a tech to do it for you, it shouldn't take more than 20-30 mins to do.

Cheers

Matt

Ray wrote: Well, I'm pretty interested in changing the speaker. On the Laney site it says that the Cub 8 has a Celestion Super 8 and the Cub 10 a Celestion Tubes 10 driver. What Jensen would be the right one for the 10? Also the tubes, looks like the 10 just has twice what the 8 has. But I get the impression that the suggestion is that changing the tubes is not really something to do as a matter of urgency? Where would I get hold of the speaker and tubes? Tell yo waht makes me tense is this talk of electrocution. Dunno if I'm up for that right now.

Hell yea! I really dig the new sound. To be honest my untrained ear couldn't hear the difference after just the tube change, but the speaker definitely made a big improvement!

The highs are much more defined and the amp sounds a lot less muddy and boxy, not that I thought that it did initially, but after hearing it with the new speaker its hard to think how I liked it with the old one hehehe.

I liked the improvement while listening to Matt's guitar track, but since I plugged me slide machine into the modded amp, I LOVE it. I had an issue on my slide guitar with hearing the notes on the high e string clearly, no more problem there, it all sounds clearer and smoother. AWESOME!

I would really recommend all Cub 8 owners to get the Jensen C8R fitted, I don't think the valves are really worth it, rather wait until the stock ones go bad and then replace with better ones. That said, its not all that expensive so if you got the bucks why not? I am keeping the stock valves as spares.

Thanks Matt, awesome job, decent price, and lekke guy to hang out with.

+1000

I will post some clips at a later stage, need some time to get to know me new baby hehe.

Nah dude, u'd be hard pressed to out geek me!

BTW both of the loudspeakers used in the Cub amps are bottom range Celestions (to keep the amps within a price rnage) so any loudspeaker change IMO will probably be an improvement in tone.

I agree with Matta that the loudspeaker change on it's own probably is the best bang for buck upgrade for the amps. Not that I'm against Celestion....I'm getting a Blue next month, but bottom of the range is bottom of the range......just my 2c worth....

Pity the Jensens are not easy to come by.

I have no problem with the speaker, but everywhere I roam on guitar forums on the interweb, I see the same. The first thing that anyone reccomends for entry to mid-range amps is a speaker upgrade. Usually Celestion Blue is reccomended, but there are others from Eminence and Jensen that get mentioned. I might try the Jensen in mine next year, just to see what difference it makes.

I think they're pretty easy to get. Matta can get from Mojotone, right? Also, Take2 can get them for you - maybe at a higher price, but it is pretty easy

http://more.take2.co.za/usa?sup=usa&deptname=MusicalInstruments&node=11973171&subsearch=jensen&order=

Hey Tom,

The problem is the market in SA for speakers is so small and they are so expensive!

I wish I could keep a decent range, but firstly you not only have brands, but sizes and then type. Some will want Ceramic (more cost effective) others will want Alnico (most expensive) and then size, some want an 8" others 10", 12" and maybe even a 15". On the 'higher end' each of these speakers RETAILS stateside for up to and over $300+, though average is between $80-$150, that is still alot of money for any small one man shop to outlay esp. if you need to keep a wide range esp. with such a slow turnover.

It is in part why I started the Mojo Orders. I'm hoping to hand these savings BACK to you guys, if we aim to do these group buy orders every 3-4 months everyone wins. We can start to extend it to companies like Tubes & More who are the US dealers for Jensen and offer a line that compliments what Mojo offers.

As shared I've since learned that the real savings only kick in when shipments are 50Kg's plus, but that is not a hard thing to achieve, a Alnico Blue weighs in @ 4.2Kgs, and a 12" Ceramic Jensen like the C12N is 3.2Kgs, so even just ordering 10+ speakers covers the weight, if someone orders say a Fender Deluxe Amp Kit it weighs in at over 22Kg's.

So as you can see it isn't implausible to be able to do this, I'm just asking the USA street price, the price you see is the price you pay on these orders outside of taxes, VAT & shipping.

A quick check on 'Tubes & More' shows an Alnico Blue can be landed for around R3,000+, that is FULL landed price INC VAT and duties, ex postage if outside of CPT worked out on today's exchange rate. And by the way that is UK MADE Blue not the Chinese ones VOX are using.

I'm doing this as a loss leader, it helps you guys, it helps me in saving a bit on shipping and hopefully builds up some goodwill amongst this great community.

As a community we have alot of power over how we shape the goods that are available locally and the costs.

Cheers

Matt

TomCat wrote: BTW both of the loudspeakers used in the Cub amps are bottom range Celestions (to keep the amps within a price rnage) so any loudspeaker change IMO will probably be an improvement in tone.

I agree with Matta that the loudspeaker change on it's own probably is the best bang for buck upgrade for the amps. Not that I'm against Celestion....I'm getting a Blue next month, but bottom of the range is bottom of the range......just my 2c worth....

Pity the Jensens are not easy to come by.

matta wrote: ...if we aim to do these group buy orders every 3-4 months everyone wins.......A quick check on 'Tubes & More' shows an Alnico Blue can be landed for around R3,000+, that is FULL landed price INC VAT and duties, ex postage if outside of CPT worked out on today's exchange rate

Hmmm, this is not good...I'm beginning to get an idea that's going to land me in trouble...

Hia folks,

Well I guess I can now comment a little on the Cub 10 for those interested. Got mine for a xmas present from myself to me.

I reckon for the price I paid it's worth every cent. So far the amp's been really good to me and my Line 6 Spider III is gathering dust a little unfortunately. The tone is much better than I prepared myself for, the amp really brings my Strat and Telly to life. I really love the little things which is probably mostly attributed to it being a valve amp, the little noises and sounds which accompany the strings..awesome.

I mostly use it clean at the moment working on my lessons and strat just has so much more character now I find myself sometimes just plucking away randomly taking in the beautifull noise. ? I have bumped the gain and overdriven I must say the valve amps really kick the solid state stuff's behinds all over the house. There's just no comparison. Hard to describe but it's just 10 times more fun.

So far no real issues to report but a few. My pilot light is working so far..haha. The amp's finish is in my books really good, it's far from a sore spot in the living room's decor. No distinctive muddy sound on the 10 in my books either, I do quite like the sound coming from it. One of the issues I had was the grill on the back get a little resonant rattle at high volumes if you play specifically an A5 or strummed the A on low 6 really hard, the guys in the shop assured me it's not really a strange phenomenon. This one was an easy fix though, just needed a little gasket (Which started as a piece of folded paper hehe).

My next small issue is with my Line6 floorpod (pedal). The problem is definitely attributed to the pedal and most probably fixable by tweaking the settings which it has ALOT of, I just haven't fiddled enough probably. I can't get a good sound playing through the pedal though, plugging straight into the amp gives me most joy at the moment. I'll work on this one though but through the pedal the sound is muffled and not nearly as sparkly. Kinda like it just loses character.

Last problem is not really a problem either. The amp is loud..very very loud. Definitely do not recommend it for anyone in a flat or townhouses with common walls, the neighbours will not appreciate your new toy. I'm working hard on getting used to using the amp at low volumes where it really doesn't shine as much, because I'm in the process of buying a townhouse which will most probably have noise issues.

My valve amp experience is obviously not the stuff of legends so it's hard for me to rate the amp. But I will say this however, if it got stolen (knock on wood), I would replace it first thing and I'll do same again and go for the Cub10. I've only played a bit on a Fender Twin Reverb and some giant cabs in my lifetime, considering the price of these I have to give it a 9/10.

Groetnis,
Rudolf

I took some pics of the Cub 10 while I had it open for the speaker upgrade:





And I think this is the trimpot that Matta referred to - the one to fiddle to reduce hum.
But ... it's labelled "bias adj" rather than "hum removal" ?
And ... I don't know what I'm doing
And ... every 2nd post on this forum says that if you play with open valve amps you die.
So ... I'll leave it alone.

You can fiddle with the bias as long as you think of it like a truss rod - do not make more than a tiny change at a time and evaluate the results before taking any further steps. Hot bias will make your amp sound alive and raunchy but too much and it will fry tubes. Cool bias will give you cleaner tone but might lead to sterile sound.
Bias adjust has got F''ol to do with hum. If there is not another trim pot and there is hum then someone should put in one.

You're not going to get fried if you keep two things in mind:
1. amp switched off AND power lead disconnected does NOT mean that there is no high voltage remaining - discharge the power supply caps BEFORE doing anything else. Just hold a 5W 1K resistor (or similar) by the body and push one lead on the ground and one on the B+ and hold it for a while
2. once discharged, work on the amp, check your own work twice and close it before switching back on.

Looks like there are some nice cap upgrades possible on that Cub ?

Gearhead wrote: Looks like there are some nice cap upgrades possible on that Cub ?

And what effect do cap upgrades have?
And what is the nature of the upgrade?