aircoutix

20 years of getting basses (more than 180) and strings, removing them almost new (especially with flats) when not pleasant on a new bass. I do not play professionally, just for the pleasure. I spend less on bass stuff than some friends on Hi-Fi devices. Finally came back to the Dunlop flats. A bit less pleasant to play with (metal feel vs nylon) but a bit less meow, which seems normal since flatwounds vs tapewounds (nylon coated roundwounds).

Just resurrecting this thread again, as I got my Ibanez UB804 yesyerday. It is used but like new, strung with D'addario flats. Nice instrument. Never played something else than fretless basses up to now. Was willing to try for my last jazz-soul group. The sound was anyway closer to a big fretless than to a double bass. Tried to rise the action to get a more double bass sound. It worked but was then very difficult to play. Tried several strings. Tried the Roto nylon first which were the lower sustain ones on the several fretless bass on which I tried them. Surprisingly not on this UB804: fretless sound with those strings. Moreover the strings were very high at nut (also with the D'addario, had to dig the nut a bit). Tried the Galli nylon, the La Bella Deep Talking, the Dogal flat and the Galli flat (steel). Did not try the GHS flat nor the Ernie Ball cobalt flat nor the TI nor the La Bella White Nylon (steel) which favored the meow on my fretless basses. Tried several foams. It worked but was losing too much of something (presence maybe or hgh). Did not try the D'addario nylon that I like much since I was not willing to remove a set from my Fender fretless or my Carvin Bunny Brunel 5 (now with frets). Did not try the Fender nylon since I don't have a set. But I am going to order one since I got the best close to DB result with those on an Epiphone Zenith fretless that I do not have any more. Finally the best for my taste are the La Bella Copper White Nylon. Second the Galli flats. Third the D'addario flats (originally strung on this bass). I now have to dig the nut once again (already did it with the D'addario) since these Copper White nylon (as well as the Roto nylon and the Galli nylon) are larger (e.g. 115 for the E). Some fretless meow still remains (certainly due to the rosewood fretboard instead of the ebony which reduces the medium frequency band level, thus also the meow). This is part of the instrument signature. Hope this helps.

Maybe you shoud not cure your GAS, GrammeFriday. This amp is awesome. I certainly got one of a faulty sample, very likely one of the first manufacturing series. The problem may have been corrected now. The "rather recent" use by industry of lead-free soldering raised new problems, to be discovered once equipments are getting old. This is a common situation applying to any new design. Additional efforts and associated delays before manufacturing launches are made only for equipments involved in safety of life systems, which is not the case with guitar amps. I re-soldered the joints (my apologies for my English language which is not my mother tongue) of the input part of the preamp replacing the lead-free by traditional lead-including soldering, which solved the hiss problem. I should do the same for the remaining part of the preamp but removing lead-free soldering on all soldering joints is such a pain. And noise/hiss problems are much more sensitive on the input stages. The dead resistor on the third tube stage is a second topic. It looks like being the only mistake on this preamp. This should not prevent you to keep in mind all the awesome rest of this amp design.

If you have the opportunity, try to insert a Demeter VTDB-201S preamp in the effect loop of the DB-751 and mix the dry signal (from the DB-751 preamp) with the wet signal coming from the Demeter (but first passing in the DB-751 preamp). This keeps the meat of the DB-751 while adding the clarity of the Demeter. This head which is tremendous becomes even more.

I searched for a very long time before determining the cause of this hiss (with crackles from time to time). I had to draw the schematics in order to be in a position to follow the signal all along the circuit, Aguilar boss refusing to provide me with the schematics even only the preamp part (I had determiend that the problem was located in the preamp part). It took me hours. Since I got no help from Aguilar, I have no reason to keep for Aguilar only what I discovered. The first thing that I discovered was a dead resistor as R449. My conclusion is that it died because it is simply under-dimensionned in power (having to support 0,8 watts while looking like a resistor dimensionned for 0,5 watts). I thus guess that I am not the only one with this problem. It is not easy to be sure that a head has this problem without opening it since the preamp works rather well with a dead R449 resistor. But the third tube simply does not work properly and this surely degrades the sound. I replaced this resistor by a simply more powerful one (1 watt). But the hiss was not coming from this problem since still being there. I determined the several circuit output stages and, using an oscilloscope, located the output with the biggest problem occurence. I then tried to temporarily amplify or surppress it with the help of a cold spray. But the problem was moving from a stage to another one from time to time. I finally determined that the weldings of the preamp components were involved, despite looking nice. I made back the weldings of one third/one half (left part) of the preamp and it came back to life without hiss. Making back this weldings requires to remove the existing welding and it is a pain since being tin-free. I hope this will help some of you.

Hi Snorkie635 (MTD 635 player?), I recently got a used DB-751 and it has the same problem (+ the fan noise problem). I guess that it is not a major problem. I replaced the tubes and the AOPs without any effect. I asked Aguilar, mentionning that I was in a position to perform the correction by myself, and would prefer avoiding sending the complete 20 Kgs head for the replacement of a simple less than 1 g resistor. But they only answered that I had to contact my local seller. Living in Europe, I know that asking my local seller would require several months for a repair (friends currently experience several months for an acquisition) and much cost since it is not under warranty anymore. Probably for a stupid less than 1€ component replacement. Can you let me know how you solved yours?