spaners

[quote name='badboy1984' timestamp='1401965236' post='2468712'] Any reasons why you selling your CTM15? [/quote] Before I got the CTM15 I had started to tinker with and mod tube amps. I now have three home built tube amps the CTM15 , a Fender Greta, a Fender Excelsior and a BG250 2X8 plus a pair of ashdown VS cabs. I need some room lol. The Greta and the Excelsior have to go too. And mabe a couple of basses. I need to fund my next amp build, a big one this time!

I had the BH250 head and sold it, what a chump ! Went and bought a BG250 2x8 yesterday. Such a good amp and its a perfect fit on top of my 1x15 cab too. Bonus! I don't think it will be to long before its on there high end heads too. The blank pedal idea would be an awsome product, some patient that idea quick! Or a three or four pedal bank in one unit that would be cool.

If anyone is looking for a CTM15 , I have put mine up for sale (see amps for sale) also have a VS112 cab that I mite sell with it to make ap a wicked little mini rig.

That looks cool, good price too. I wounder if Ashdown could tell use two things. 1 is this the same head ? Acording to the web site this one has two preamp valves! Will the drob head cab be available seperatly for those of us who have already bought the not quite all valve CTM 15 head ? If Ashdown are intrested I have a very nice little bass amp prtotyped , simple 5751 pramp into a single 6550 power amp. Gain, single tone control, master volume and defeat able negative feed back producing abot 12 W in my prototype but I could have taken it to about 20 to 25 watts with bigger transformers.

Heres a sample [url="http://youtu.be/bkFTuMqAHPA"]http://youtu.be/bkFTuMqAHPA[/url]

Thanks 6V6, I still have a little work to do on the tone stack to make it more bass friendly

tried a few mods, mine is the v2 combo. I upgraded the powers supply smoothing caps, changed the coupling caps and cathode follower by-pass caps. added negative feedback , fitted a Hammond output transformer changed the valves a few times n settled on JJ EL-84 and GT 5751. replaced the stock speaker and added a switchable output selector switch. think that was about all. I took the Hammond OT out to use in the new amp and I'm going to put the OT from the kit back in the EVJ.

[url="https://imageshack.com/i/f6znizj"]https://imageshack.com/i/f6znizj[/url] [url="http://imageshack.com/a/img546/4641/zniz.jpg"]http://imageshack.co...6/4641/zniz.jpg[/url] [url="https://imageshack.com/i/5neengj"]https://imageshack.com/i/5neengj[/url] [url="http://imageshack.com/a/img203/9828/eeng.jpg"]http://imageshack.co...3/9828/eeng.jpg[/url] So I thought id share my latest creation with all you tube lovers out there. It is based on an Ampmker WF-55 kit with a few mods. The original kit is a 4w head based on the fender champ with a 6V6 output tube and a simple 12AX7 pre-amp I have basically changed the power amp to a 6550/KT88 powered design from the AX84 web site to give me 10 o 15 watt output. I added a simple tone control and master volume and changed the pre-amp tube to a 5751. this amp sounds fantastic (IMHO) its the first amp I have built and everything worked perfectly first time, a testament to the excellent instructions that Ampmaker provide. I have the Ashdown CTM15 and the cabs I have are the Ashdown VS112 and VS115. The wf sounds as good, if not better than the CTM15 and is just as loud. total cost of the build so far is around £200-£220 inc kit valve's and OT and took me a day to build. I'm guna call this amp the WF-65.5 as it has the 6550 power tube. Added a youtube sample here [url="http://youtu.be/bkFTuMqAHPA"]http://youtu.be/bkFTuMqAHPA[/url]

£330 seems a lot for a 10 inch cab

Ok, correct me if I'm wrong but I am assuming that Coolwire is planning on home/recording as the sole purpose of building this amp therefore I wont involve myself in the whys and hows as far as stage rigs are concerned. suffice to say that 15w of tube power into a 1x10 bass cab will work just fine. Onto Coolewires questions. [b]Thanks for that post. Really interesting.. I've got a bunch of questions but I'll limit myself to two for the time being: 1.Don't you find the lack of a bass tone control on the Excelsior something of a problem? 2.Where did you get the replacement output transformer. I am a little concerned that the output transformer on my donor amp might be a little too small[/b] 1. I have made a few small changes to the amps tone control, these involved adding a tone control pot to replace the two position tone switch and changing the value of the high and low pass filter caps within this circuit. This was done to add a little more control rather than to change the way that the amp was voiced and to improve the quality of the components. Main reasoning behind this are that firstly I like to keep things simple and secondly that it already sounded good. why fix it if it aint broke ? 2. I got my output transformer direct from Hammond manufacturing in Baisingstoke. [url="https://www.hammfg.com/contact"]https://www.hammfg.com/contact[/url] They will sell direct to the public so just phone them. (they carry a lot of stock) Quote. [b]This is a real eye-opener for me. What surprises me is that you guys are starting with a straight-forward guitar combo. I thought the speakers would be too small and the bass would roll off far too early to be useful and the open-backed construction would cause problems. You're also foregoing more complex tone controls. I guess Big Muff tone control does at least give you some control over the bass (as I remember it the Big Muff control boosts the bass as you roll of the treble and vice versa). Perhaps I'm worrying too much.[/b] I started with the EVJ after picking it up at a boot sale for a tenner, just for something to fiddle with. The speaker in this little combo, an 8 inch, was never going to do well with bass. I fitted an old car sub I had kicking about. worked just fine and sounded good. You have to remember in days gone by all amps where basically the same so you will find early bass amps quiet often would be open backed. The reason for this is that an open back speaker cab is always louder but has less control/definition ie it adds speaker distortion (desirable for guitar/not desirable for hifi) Modern bass technique's and sounds demand a more hifi sound hence the closed back and ported cabs of the modern day and the high power output that is needed to control the speaker, that powers not just there to make it loud folks !!! something you all fail to realise. I got the excelsior after walking into a local shop and finding the shops owner playing a bass into it. We chatted for a bit about tube amps, things bass and the weather (as you do) Then after a coffee n a fag I gave the amp a go with a mustang. I just loved the way it looked and sounded, He offered me M8s rates on the amp and it was mine. This amp has a 15 inch speaker that worked well with bass and is still working well and just getting better. The only reason for modding the amp really was to satisfy my curiosity and see how much difference making the changes would make. Bear in mind that it was only ever going to be used at home. Its also worth saying that most of the mods I tried had little or no effect on the sound as far as I could tell and most were done with a view to improving power supply elements or to fit higher quality components. Again I repeat, if it aint broke why try to fix it ? Your comment about bass rolling off to quickly is where the bigger output transformer comes in. By rolling off I assume you mean drops in volume in comparison to the higher register. This is due to the small output transformers in a guitar amp where the roll off would typically be -3db @ 100hz in comparison to - 1db @ 30hz of the Transformer I have used. As I said in an earlier post I would recommend that you rebuild your amp to the original spec and try it out before you make any changes that may or may not improve the amp. That way you will have a subjective bench mark as to the effect your changes make to the sound good or bad. Make changes one at a time, that way you will know what to undo when the result is not what you expected and remember the guy that designed the amp probably knew a lot more about tube amp topology than we will ever know collectively. Therefore don't expect your mods to make it sound dramatically different. Hope you find this in some way useful

Coolwire I have had a bit of a look at the schematic in your link, to my eye this looks like quiet a basic dual purpose amp that should in principle do the job you require. as a first step I would suggest having the transformers tested. If they check out I would start by re-building the circuit on a turret board using new components as resistors and capacitors are very cheap, you should be able to find resistors of the same value. With the capacitors you may have to use close value components but I would suggest that you get the closest higher value where the same value cannot be found. I would also add a stand-by switch before the rectifier vale and probably a solid state rectifier to the heater supply to reduce hum. Update the input supply cable and fuse holder. fit a new set of input/output jack sockets and you should be good to go. If the transformers are not up to scratch then its probably not going to be cost effective though.

I have modded two guitar tube amps to use with my bass. A 5w EVJ and a 15w Fender excelsior, both combos. The EVJ is ok for quiet practice with good tone when I am away in hotels (quiet often with my job) The Excelsior is much louder and I love it for jamming with friends. In my opinion 15w is a good size for home and will get loud enough to upset the most tolerant of neighbours, it is also a very good base for modding due to the fact that the PCBs are fairly large and the tube sockets are not board mounted like most of the modern amps. The excelsior can also be picked up quiet cheaply too. The biggest difference between a bass amp and a guitar amp is the output transformer, and what you are looking for is bigger with a better low range response . I have used Hammond OTs in both of mine. I used a 1650F in the excelsior ( [url="http://www.hammondmfg.com/1608.htm"]http://www.hammondmfg.com/1608.htm[/url] )The second thing to consider is the valves you chose. Valves are graded and that grading number tells you how clean or dirty the valve is going to be (the higher the number the cleaner the sound) so you should look for matched output valves with a grading figure of 7 or higher to get max clean head room. Increasing the size of the power supply capacitors will also help as this provides a larger reserve of power for the tubes (low frequency's require more power)typical values for these would be 22uf in a guitar amp and increasing to 47uf will generally be big enough to do the job. I have also experimented with coupling capacitor values and cathode capacitor values but in my humble opinion these sort of changes don't make a great difference to the sound or volume (but it doesn't hurt to fit better quality components as you experiment) hope this is in some way helpful [size=5] Warning Valve amps should only be worked on by people with the relevant experience and understanding of the dangers involved in working with high voltage electrical components [/size] here a couple of pictures of the excelsior [url="http://imageshack.us/photo/my-images/580/q7fl.jpg/"][/url][url="http://imageshack.us/photo/my-images/69/vkrq.jpg/"][/url][url="http://imageshack.us/photo/my-images/689/pebf.jpg/"][/url][url="http://imageshack.us/photo/my-images/9/es9o.jpg/"][/url][url="http://imageshack.us/photo/my-images/818/p904.jpg/"][/url][url="http://imageshack.us/photo/my-images/405/a4jp.jpg/"][/url][url="http://imageshack.us/photo/my-images/855/6zp8.jpg/"][/url][url="http://imageshack.us/photo/my-images/35/cj33.jpg/"][/url]