I built amp back in June. Basically all new system I had polk audio rti a3 with polk powered sub and an emo preamp i thought it sounded ok but wanted to get full sized speakers. I gave a3s to my son and bought on sale monitor60 series ii . still sounded ok but these speakers were lacking (just the weak link in the system. I sprung for a set of polk rti a9s. I know not true high end but i'd say near high end and what should 've been good enough for what i was doing. Anyway these shouldn't have needed sub woofer and without it i foundi had poor lows. I tried speakers with mac receiver i had and sure enough speakers sounded fine,so i figured amp or preamp. i came by cheapy pre(which didn't sound all that hot but it did have mids and lows. so i blamed it on emo pre which as it turned out probably wasn't my problem., Which brought me to at least now as far as know the only sp-13 Roy has made. Anyway i bought on ebay (planning to build a kit). Ok so, system now loud clear still not right. I contact Bob (in fact i had been in contact with bob through most of the problems and can't say enough about his patience and support. Ok , so i'm a little frustrated, so reading reviews i came upon reality that EH new issue 12BH7 i had in driver positions were severly lacking (being a nube in tube audio i didn't realize the world of tube rolling and characteristics of different brand and different issue tubes) Although now that i've spent i don't know how many hours reading, searching, shopping and listening, i know ,let's say more than i used to. While i know my sonic quest isn't quite over i've learned a good deal about how certain tubes change sound in my application. I understand everybody elses systems are different and also their ears. I do hope this might help at least some of you out there.
side l center side r result
amperex 7316 jan6189w A 4/87 amperex 7316 not bad a little bassy lacking some highs
12au7 philips
amperex 7316 long blackplate rca amperex 7316 hummed probably bad tube
12bh7
amperex 7316 short blackplate rca amperex 7316 too bassy highs fragile weak unnatural
12bh7
amperex 7316 long blackplate rca amperex 7316 too bassy highs fragile weak unnatural
12bh7
amperex 7316 EH 12bh7 amperex 7316 maybe not quite so bassy highs sound almost like echo on them no true body
hum gone
amperex 7316 Jan-89 ge amperex 7316 bass more nuetral highs a little screetchy 9maybe most nuetral so far
12au7
amperex 7316 rca black plate amperex 7316 too bassy weak mids weak highs
12au7
amperex 7316 amperex 7316 amperex 7316 too bassy
amperex 7316 telefunken amperex 7316 all highs there bass more nuetral
12au7
amperex 7316 cifte 12au7 amperex 7316 best so far best mids best highs bass not overpowering
amperex 7316 Mullard cv4003 amperex 7316 Sound overall good Bass overpowers mids and highs
Telefunken 12au7 Mullard cv4003 Cifte12au7 I tried to tame bass with brighter outside tubes It was better with amperex still too
bassy mids and highs not as balanced (I don't think its good practice to mix outside tubes
left position mid position right position
amperex 7316 cifte 12au7 amperex 7316 baseline start best of mid position tests
ge jan 6189w 8/85 cifte 12au7 ge jan 6189w 8/85 makes bass boomier takes out transparency in mids and highs
philips jan 6189w 11/87 cifte 12au7 philips jan 6189w 11/87 nicer than ges muddled mids
eh 12bh7 cifte 12au7 eh 12bh7 bass too boomy highs too screechy mids muddy
RCA long black plate 12bh7 cifte 12au7 RCA long black plate 12bh7 bass still too strong but better not as boomy mids and highs pretty good (really all in all not bad)
slight static (very low) by speakers only with ear right by speaker
telefunken 12au7 cifte 12au7 rca 6189 12au7 pretty pleasant still a little too much bass
mullard 12au7 cv4003 cifte 12au7 brimar12au7 a little too bassy a little flat in the middle (probably not as bad as it sounds it was ok) not as good as some others
I don't know why copying excel file skews in this format . i apologize for that. Bob seems to feel i need a brighter tube in the middle to compensate for softness in the highs in my speakers. I'm not sure i agree. Maybe its combo of synergy between speakers and amp. I'm probably going to be dumping tubes at end of experiment, if your interested please ask. hope this helped or entertained.
side l center side r result
amperex 7316 jan6189w A 4/87 amperex 7316 not bad a little bassy lacking some highs
12au7 philips
amperex 7316 long blackplate rca amperex 7316 hummed probably bad tube
12bh7
amperex 7316 short blackplate rca amperex 7316 too bassy highs fragile weak unnatural
12bh7
amperex 7316 long blackplate rca amperex 7316 too bassy highs fragile weak unnatural
12bh7
amperex 7316 EH 12bh7 amperex 7316 maybe not quite so bassy highs sound almost like echo on them no true body
hum gone
amperex 7316 Jan-89 ge amperex 7316 bass more nuetral highs a little screetchy 9maybe most nuetral so far
12au7
amperex 7316 rca black plate amperex 7316 too bassy weak mids weak highs
12au7
amperex 7316 amperex 7316 amperex 7316 too bassy
amperex 7316 telefunken amperex 7316 all highs there bass more nuetral
12au7
amperex 7316 cifte 12au7 amperex 7316 best so far best mids best highs bass not overpowering
amperex 7316 Mullard cv4003 amperex 7316 Sound overall good Bass overpowers mids and highs
Telefunken 12au7 Mullard cv4003 Cifte12au7 I tried to tame bass with brighter outside tubes It was better with amperex still too
bassy mids and highs not as balanced (I don't think its good practice to mix outside tubes
left position mid position right position
amperex 7316 cifte 12au7 amperex 7316 baseline start best of mid position tests
ge jan 6189w 8/85 cifte 12au7 ge jan 6189w 8/85 makes bass boomier takes out transparency in mids and highs
philips jan 6189w 11/87 cifte 12au7 philips jan 6189w 11/87 nicer than ges muddled mids
eh 12bh7 cifte 12au7 eh 12bh7 bass too boomy highs too screechy mids muddy
RCA long black plate 12bh7 cifte 12au7 RCA long black plate 12bh7 bass still too strong but better not as boomy mids and highs pretty good (really all in all not bad)
slight static (very low) by speakers only with ear right by speaker
telefunken 12au7 cifte 12au7 rca 6189 12au7 pretty pleasant still a little too much bass
mullard 12au7 cv4003 cifte 12au7 brimar12au7 a little too bassy a little flat in the middle (probably not as bad as it sounds it was ok) not as good as some others
I don't know why copying excel file skews in this format . i apologize for that. Bob seems to feel i need a brighter tube in the middle to compensate for softness in the highs in my speakers. I'm not sure i agree. Maybe its combo of synergy between speakers and amp. I'm probably going to be dumping tubes at end of experiment, if your interested please ask. hope this helped or entertained.