funkydoug

Well it has passed the female vocal test with flying colours. Played Sade, Stevie Nicks, London Grammar and Bjork. All sounds brilliant and far better than my Sony hifi Also pinned the issue down to preamp distortion. Turning the Lpad right down is one way to dirt-proof the box, another is to use the onboard preamp as it was intended ('grind', not wild distortion) and leave any real dirt to pedals with tone dials / cab sims which seems to be a pretty standard approach. I am amazed this doesn't happen more often though, especially on cabs with tweeters crossed over at 3.5khz and lower ... or do all dirt pedals really roll off the highs sufficiently to prevent this? Curious because as we know, Barefaced cabs crossover low, as do Bill's, and both are well regarded and road tested by countless players. Anyway, this is now just a matter of curiosity. The combo works very well for my intended use. It has lovely low end, crisp top end and as a small amp it is very satisfying. The modelling suggests that there are no problems in terms of driver excursion or port chuffing up to 100w which is as much power as it will see with the 16ohm driver and play testing supports that, at least to my ears. It will marry up with an 8ohm cab (2x10) without asking too much of the onboard driver and port, and the tweeter can be turned up in that situation to balance the 3x10s rather than 1x10. And it looks smart! Very happy. Thanks for all your input guys.

Thanks Stevie, those 2 possibilities are what I also arrived at. I've got this right, feeding it a clean but hot and very bass heavy sound will test whether the problem is too much bass for the crossover (in which case the problem will reappear) or an unfiltered distortion (in which case it will not reappear). I'd hope that it is scenario 1 (of stevies 2) because 3.5khz 2nd order crossover is what eminence recommend for the APT80. In the event that I need more HF protection it isn't game over, I'll just need to go back to the drawing board for HF protection.

Thanks @Chienmortbb Any excuse to play a bit of Sade and Dire straits is a good plan Will report back. Hopefully the ABM eq will help with handling peaks and troughs.

Thanks Bill. In that case I'm especially glad I added the Lpad, and that in all real world situations my dirt pedals all have some kind of LPF / cab sim. I have to say I'm surprised at how bad it the dirt sounds up in the tweeter territory. I'd read alot about distortion sounding nasty with a tweeter without LPF but this was far worse than I expected. Im happy to report that in all but those extreme tests the combo is now doing great.

Another update on this project, and another question. I added an APT80 to it which was a drop-in replacement for the cheap piezo that Ashdown had used. I also used a custom 2nd order crossover (thanks to Blue Aran's great email support) which crosses over at 3.5khz but was built for my 16ohm woofer and the APT80 at 8ohms. Controlling the level on the tweeter was important as it's both very sensitive and is an 8ohm unit. My aim was to be able to run the tweeter 'loud' in the event that this combo sits on top of a tweeterless cab but dial it down in normal use. I used an eminence LPad to do it. Seems to work very well. I had to remove the wadding I'd added to do all that, but will re-do it once I'm sure Im happy. The question is about using distortion with a tweeter. It all sounds good at any realistic setting but if I fully max what is a very mild dirt dial on the ABM, max the bass and max the preamp gain even at very low volume (like bedroom volume) I get a horrible, unmusical distortion sound from the tweeter that is in the 'malfunction' ballpark - not musical in anyway. It did this with the piezo and with the new tweeter. Is it just that running that much bass overpowers the HF protection offered by the crossover?? Or maybe it is the sound of the input stage or valve being overpowered? Anything to worry about?? I wouldn't run it like that in any real situation - only did it as part of testing everything - but I am slightly concerned it is a warning sign that something isn't right.

It appears that someone is selling a combo that you might say is a light weight reincarnation of those trace 715s in the marketplace. Pm me if you need further signposting

Could be good news if G4M start making decent amps using the Eden brand. Hope so.

Surely this deserves a prize! Almost too BC to be true. Asking myself some serious questions now 🤦‍♂️

Thanks Bill. With that combination of 2nd and 4th order, do I need to reverse the polarity of the woofer to avoid phase problems?

Yep I will do. It currently has a simple 1st order filter on the tweeter, with nothing on the woofer side. Will start to look at filters and crossovers now, starting by revisiting the BC cab threads. Suggestions from you learned lot will be much appreciated.

Quite a bit more bottom end in a pleasing way. Happy with the result. WinISD suggests that is tuned to about 57 hz with the current port length but is very close to Agedhorse and Stevie's suggested dimensions. If they'd be happy then I'm happy:) Probably going to swap the cheap tweeter for an APT80 or a BGH25-8 and will no doubt spend the next month agonising over that 🤦‍♂️

Thanks to all who have given their advice on this. I added to 100mm port today. Also lined it and changed the speaker for a very good 16ohm SICA that I picked up on ebay for £40. It is ideal. The idea is to run this as a 16ohm small combo that I can hook up to an 8ohm 210 with two of the same drivers and with the same tuning. Very happy with the result. Next job is to upgrade the tweeter. It is certainly a fun project

In the effects loop, which I'm pretty sure is after the front panel stuff. I've asked about whether there is a HPF built into ABMs a few times and have read directly contradictory replies from different people at Ashdown. As a result , if I need an HPF on an ABM I take matters into my own hands.

Bill is if course right here but players have used octavers for decades so don't let this very sensible advice stop you making music! Good good bass cabs are pretty robust in reality. If in doubt a good HPF will help, even with an octaver / sub.

Looks like the perfect size, and a quick Google suggests it's great value too. Thanks, you might have just sold me on a TTPB4

That looks brilliant, bet it sounds even better. Is the board a PT classic Jr?

very cool indeed. I love the actual board itself (wooden case with lifty-up bit) and noticed another post in this thread looks as if it uses a similar one. Would you mind sharing what it is?? I'm sure it is explained somewhere but I have managed to miss it. Thanks

Thanks Stevie. I'm tempted to ask why it is so component specific, but I guess it's because of how all the different properties of a cab design interact in reality 'on the bench' rather than in the software? The tailoring analogy is great. It is of course possible to buy a perfectly decent suit off the peg from M&S (dare I say Asda or is that a 'bodge' too far!?). I guess the difference is that making it bespoke means it is a perfect fit rather than 'good enough'. Cheers, I'm learning loads from this ... mainly about how much there is to learn

Is this a 2nd order LPF and 3rd order HPF design? Testing myself here... In case you haven't seen it, blue aran has a crossover configuration thing on their website. It is interesting and maybe even useful in this case.

Sorry to hear you are struggling @KbD. For what it is worth, I think a big part of the reason many of play is about identity. Do you think of yourself as a bass player? Or would you like to? Everything that comes with it - the sense of having an identity, membership of some kind of group (whether thats a band or a internet forum!) etc is important to lots of us. If you have that, or want it, keep playing. The good thing is that it is a very easy club to join and no one can kick you out. I spend more time reading about bloody speaker excursion than playing bass at the moment, but I still think of myself as a bass player and it is actually part of how I see myself. I have pretty crappy technique and a very bad ear but it doesn't mean I should quit. If you're not bothered about that - or just don't get what I mean - then maybe let your gut be your guide my friend. That said, I do believe there is something inherently beneficial about playing music os I'd say stick with it unless it is making you miserable. Learn a new line, or a new scale and you will soon get a little hit of dopamine Wishing you well, Doug