![]() ![]() Well, I triple checked my work versus the diagram. So maybe that's why I didn't like the sound? It should be close enough not to matter though, IMO.Īlso, I know someone might be thinking "he didn't wire it up correctly". Like I said though, I used a 390pf cap instead of the 500pf cap that the Harvard mod calls for. Other than that, some fresh tubes is all it needs unless your stock speaker is shot. I'm prepared to live with the amp as-is, it's not perfect but the tone makes up for it. Also, while the mod was in place, the tone knob was honestly not that much more usable. When I reversed the mod, the sparkle was back and it sounded great. The amp lost a bit of sparkle, and I couldn't get it back no matter where I set the tone knob. The Harvard mod was definitely NOT for me. I wiped down the tolex with Armor-All wipes and this great little amp is good to go! It's even more dynamic and touch-sensitive (and I didn't think that was possible, it sounded so good already). I kind of want the sound of the old/stock CTS speaker back, but with slightly more balls so I can hit it with fuzz and not worry about shredding it to bits.Īfter I played it for awhile with the Greenback installed, I let it cool down and replaced the original 6AQ5A's with the NOS Svetlana matched pair - WOW that added a significant amount of sparkle/life to the amp. I was thinking a 1230-55 with pre-rola treatment would be great in this amp, but I'm also thinking something like a 12F125 or 12F150. I'm a big Ted Weber guy - have been for years (RIP Ted). I'm leaving the Greenback in there for now but I'll probably try to find something better eventually. The Greenback added some low-end so that's a big plus. The downside is that the Greenback is new and tight, so it did sorta lose a little of that vintage sound, but only slightly. On one hand, I like the lo-fi vintage ratty sound from the CTS, but the Greenback adds more complexity/dimension/detail. I hit it with some compressed air to dust it off, then put it in a box and installed the Greenback reissue. It looks pretty good, no real issues there except for a small ding/dent near the outside edge of the cone, but it isn't ripped through so I think it's fine. Next I removed the ceramic CTS 12" speaker so I could get a look at the cone. BINGO, got that sparkly lively punchy sound back. 0047 uf cap, and then I didn't have a 500 pf so I used a 390 pf mica cap (+/- 5%) so maybe that was the problem? The amp lost a significant amount of sparkle, and even though the tone knob became slightly more useful, I could not get the amp to sound as good as it did before the mod, so I switched it back. Well, first I tried the popular "Harvard tone stack mod" and I gotta say - I didn't like it. I also bought a used Celestion Greenback off Craigslist (8 ohm, 25 watt, reissue) for $65. ![]() I ordered a matched pair of NOS Svetlana 6AQ5A's from a local source (lips are sealed, sorry, but PM me if you're in Chicago and want to know a great source for NOS tubes). The tone knob is a little weird/useless and seems to be mostly just a bass freq rolloff knob? But I really like the sound of this amp. ![]() The only mods that were done - all the electrolytic capacitors have been replaced and C1 was removed and jumpered. The 6AQ5A's are RCA (faint logo still there) but I can't tell what brand the 12AX7 is, although it says USA on it. '72 Musicmaster with original ceramic CTS 12" speaker and original tubes. The amp was shipped to me in Chicago from Colorado and was well packed and arrived without issue. Nothing real ground-breaking but here goes. ![]() I just wanted to share some info and give back to this fine community. I recently bought a 1972 Musicmaster Bass Amp from a gentleman that frequents these forums (pchilson I think his user name is). ![]()
0 Comments
Leave a Reply. |