johnsonad
New member
Last week we demo'd a First Watt M2 in the system that unfortunately didn't make the cut. It did though shake up the system some and the end result is fantastic. Change can be a good thing and my system needed it.
The BeePre hadn't been updated since we switched from the 19's to the Altec 755A's with Rythmik subs. These little drivers are like microscopes back into your system and until last night, we didn't feel like they were right. First, attached are a couple of photos of the Dynamat Extreme applied to the base and the bottom of the chassis plate. It makes a difference but takes a lot of work to get it on there.
A wondering trip to get to the end.... Tubes.... We had been using the EML solid plates. If you have read through this thread, it took a bit of work to get them to work right but they have a special sound to them. For fun, we took the EML mesh plates and plugged them in and they sounded better, more correct. We were both impressed but they will not work in the BeePre and they felt distant, like listening through something. One last attempt at tubes ended up with the Russian 6C4C's back in and they sounded nice and as I've said before, are the least microphonic of any tube I've tested. Not perfect but better than the EML's. To fill the void of the M2, I dug out the old rebuilt Quad 303 so I could revisit the Paramount-ish amps. The Quad bested the M2 (and my Paramount-ish amps) in every way and really took control of the speakers with a beautiful sound. I guess having been designed to drive 57's, it can drive and damp about anything, including the 755A's in WE boxes.
The EML's draw more current than the original WE tube and I had to mod the BeePre to accommodate them. For the life of me I couldn't find the 8 Ohm resistors and in the spirit of trying something new, I ordered some Caddock thick film resistors (4 Ohms) to fill the void of the paralleled 8 Ohm resistors. Attached is a bad photo of their installation which went well. The Caddocks are 30 watt rated but need a heat sink. I drilled a couple of holes in the plate and super glued them in. They put off some heat but I can still hold my fingers at the top of the heat sink for 2 seconds. I need to borrow my buddies heat gun again to get some real numbers off of the fins, but they are well within the temp specs and the chassis plate is much, much cooler now. I didn't hear an immediate difference in sound and didn't expect to. This was more to see if it would work.
Now updated, the system was sounding better but still a little off and painful for long sessions. Last night I pulled a Grainger and starting testing output caps on test leads. I had been using KBG 10uF's and first up tried the Rike Audio PIO's. This actually wasn't an improvement but did change the sound. Next up, a pair of Panasonic 10uF that had been in a different build. They sounded better than the Rike's but nothing to write home about. Last up was a pair of Auricap 5uF's. These sounded great! A remarkable improvement over all of the others tested. I got my wife to actually sit down and listen to them and even she agreed it was better but to me they still were not quite there. So again following Grainger's lead, I bypassed them with a pair of V-Cap Teflons 0.047uF that were sitting around and that really took it to the next level. That little bypass cap added considerable depth and clarity to the sound. We listened for a couple of hours after that and this is the best those little 755's have sounded to date!
Change is good and it's nice to have a stash of random caps to try. I can only imagine what's it like for guys and gals who can't make mods to their own gear.....
The BeePre hadn't been updated since we switched from the 19's to the Altec 755A's with Rythmik subs. These little drivers are like microscopes back into your system and until last night, we didn't feel like they were right. First, attached are a couple of photos of the Dynamat Extreme applied to the base and the bottom of the chassis plate. It makes a difference but takes a lot of work to get it on there.
A wondering trip to get to the end.... Tubes.... We had been using the EML solid plates. If you have read through this thread, it took a bit of work to get them to work right but they have a special sound to them. For fun, we took the EML mesh plates and plugged them in and they sounded better, more correct. We were both impressed but they will not work in the BeePre and they felt distant, like listening through something. One last attempt at tubes ended up with the Russian 6C4C's back in and they sounded nice and as I've said before, are the least microphonic of any tube I've tested. Not perfect but better than the EML's. To fill the void of the M2, I dug out the old rebuilt Quad 303 so I could revisit the Paramount-ish amps. The Quad bested the M2 (and my Paramount-ish amps) in every way and really took control of the speakers with a beautiful sound. I guess having been designed to drive 57's, it can drive and damp about anything, including the 755A's in WE boxes.
The EML's draw more current than the original WE tube and I had to mod the BeePre to accommodate them. For the life of me I couldn't find the 8 Ohm resistors and in the spirit of trying something new, I ordered some Caddock thick film resistors (4 Ohms) to fill the void of the paralleled 8 Ohm resistors. Attached is a bad photo of their installation which went well. The Caddocks are 30 watt rated but need a heat sink. I drilled a couple of holes in the plate and super glued them in. They put off some heat but I can still hold my fingers at the top of the heat sink for 2 seconds. I need to borrow my buddies heat gun again to get some real numbers off of the fins, but they are well within the temp specs and the chassis plate is much, much cooler now. I didn't hear an immediate difference in sound and didn't expect to. This was more to see if it would work.
Now updated, the system was sounding better but still a little off and painful for long sessions. Last night I pulled a Grainger and starting testing output caps on test leads. I had been using KBG 10uF's and first up tried the Rike Audio PIO's. This actually wasn't an improvement but did change the sound. Next up, a pair of Panasonic 10uF that had been in a different build. They sounded better than the Rike's but nothing to write home about. Last up was a pair of Auricap 5uF's. These sounded great! A remarkable improvement over all of the others tested. I got my wife to actually sit down and listen to them and even she agreed it was better but to me they still were not quite there. So again following Grainger's lead, I bypassed them with a pair of V-Cap Teflons 0.047uF that were sitting around and that really took it to the next level. That little bypass cap added considerable depth and clarity to the sound. We listened for a couple of hours after that and this is the best those little 755's have sounded to date!
Change is good and it's nice to have a stash of random caps to try. I can only imagine what's it like for guys and gals who can't make mods to their own gear.....
I just ordered some 50mil Butyl sound damping sheets for my BeePre base I'm assembling now.
