Crack Upgrade Path?

[Noskipallwd]

I installed a Goldpoint 'Mini-V' in my Crack, but only because I had it around from a project I wasn't satisfied with and tore down for parts. I don't think I would have spent the $140 just for this amp. It does sound great, much better than the Alps blue I originally installed. I don't have any experience with the PEC so I can't compare the Goldpoint with it.

Shawn P.

[TonyMc]

I installed a Alps blue velvet in mine this past weekend(along with an output cap(s) upgrade). Loving the results so far.

[levlhed]

Alps Blue Velvet is similar in price to the PEC.  I wonder who would win in a shootout?  I ordered the PEC already, just wondering if I shouldn't have waited for more info.


Can you explain the output caps upgrade you did?  What did you use?  Did it require much shoe-horning or any serious modification?

[Laudanum]

Actually, the Alps Blue velvet pots can be had for a little less than 1/2 the price of the PEC from what I have seen.   About 12 - 14 dollars at Mouser.  Twice that through audio parts suppliers.  I think they are great value for the money ... especially in terms of tracking at low volume but I think it sounds just fine.   The PEC is supposed to be a nice pot and only in the 30 dollar range so not super expensive.  I'll probably give one a try after a while just to see if I can hear a difference.  If I had to pay $25 or so for the ALPS, I probably would have spend the extra 10 bucks on the PEC.

Outputs caps fit will depend on what caps you decide on.  Something smaller, relatively speaking, like the Solen, Axon, Erse, Mundorf MKP etc.  is actually a pretty easy fit.  I went with the Mundorf MKP's.  They sound nice in Crack, I think.  I dont detect the "glare" that the Solens can sometimes impart.  It's an upgrade from the stock electrolytics that isnt difficult to detect but the stock caps dont sound bad at all.  The film caps are a bit smoother sounding and a bit more detailed and treble seems just a bit more extended as well.  I know that one Bottlehead reported a little lighter bass from whatever film cap they used (may have been solen or axon).  I havent noticed any less bass with the Mundorfs.  I think it was definitely a worthwhile upgrade, eventhough the Mundorf mkps arent considered high end or boutique caps.

[Dr. Toobz]

Just another opinion about output caps for the Crack: they do make a difference, but not as big of one as some may think. Tube rolling and the Speedball upgrade definitely changed the character of the amp; the 100uF Solens I put in there simply gave a bit of refinement. (I detect no glare in this particular application, FWIW). The stock electrolytics are surprisingly good, with solid bass and crisp (if somewhat "zingy") highs. The film caps sound smoother and less edgy in the treble, without losing detail. Bass seems to be about the same. I normally feel that output caps contribute a lot to an amp's sound, but the upgrade is surprisingly subtle in comparison to the plate loads and swapping out the 6AS7 for a 5998 (which IMO was the single biggest contributor to a change in sound quality). The only difficulty with the huge film caps is how to mount them securely. The small stock capacitors are much easier to deal with in that regard!

I also changed out the pot, and that made a small difference in clarity, in addition to better tracking/balance between channels. I used a cheapo stepped attenuator from Hong Kong, and it's holding up great so far.

[TonyMc]

The Alps seems to have perfect tracking all the way down. The stock pot didn't sound bad at all, but it didn't track as good as the Alps. With the stock pot the right side would kick in before the left. Not really a big deal as I never listen to levels that low and it didn't seem to affect the upper volume at all.
I would still like to try one of the Chinese attenuators from e-bay. I tell you though the little pins on the Alps are a PITA to see and solder.
The caps I installed are the AXON 91

[Noskipallwd]

I agree with Dr. Toobz, the speedball is by far the most effective upgrade. I settled on the 5998 as well, along with a Mullard CV4003. The 5998 provided some gain as well as giving the bass more control, less thump and more clarity. I replaced the output and the last cap in the PSU with Mundorf MKPs, as well as bypassing the other PSU caps with 2.2 uf MKPs. I think the biggest bang for the buck upgrade for me was the filter choke in the PSU, about $14 from Mouser, but it takes some creativity to fit it on the plate.

Shawn P.

[levlhed]

I already have Speedball and ran a 5998 for about a year until I hosed it on accident.  Now I run a 7236, a 'computer' version of the 5998, which sounds exactly the same if not a tiny tiny bit better. Tele smooth plate on the front end....So, upgrading the vol pot to a PEC and may as well do the caps if it's not too much trouble anyway, knowing it will only be a subtle improvement....not much else to upgrade without serious modification...I'm still trying to figure out what to do there though.

[Laudanum]

I agree 100% that Speedball provides a more signifigant change in sound than the Film output caps and also agree about the potential changes/improvement being greater with tube rolling.
I installed the film caps BEFORE I did the Speedball upgrade.  Just guessing that this could have impacted my perception of their impact, but by strict definition, I cant exactly call the change "subtle" in that I didnt have to listen intensely to recognize the change in sound.  But again, I am in total agreement that it isnt as signifigant as the other upgrades/changes mentioned.   "Smoother" is probably the best single description of the film caps affect.  As I mentioned previously, I think the stock caps sound good and in retrospect, I could happily enjoy Crack with them, and did so for a while.  But the film caps are a worthwhile addition to the upgrade path IMHO.  Just not on the top of the food chain so to speak, when prioritizing.
 

[Beefy]

Now I run a 7236, a 'computer' version of the 5998, which sounds exactly the same if not a tiny tiny bit better.

The 7236 is actually a computer rated 5998A, which is a slightly different tube to the 5998. It looks like it uses the flat plates of the 6080/6AS7 rather than the dimpled plates of the 5998, but still has the higher gain and slightly lower heater current of the 5998.

*

Back to the more recent upgrade questions, I'd put in a vote for the TKD 2CP2511 or 2508 pots. They track and sound better than an Alps, even to my tin ears. And I've personally avoided PEC pots because of numerous reports that they can be noisy and scratchy, particularly at low volumes.

[levlhed]

Thank you for the clarification on the 7236.  I highly recommend it as a cheaper alternative (though not a sexy ST shaped) to a 5998.

The TKD pot fits in there ok?

[tubeglow]

Thank you for the clarification on the 7236.  I highly recommend it as a cheaper alternative (though not a sexy ST shaped) to a 5998.

The TKD pot fits in there ok?

I used a TKD and except for having to enlarge the hole it fits fine. I can't compare it to any other potentiometer because I installed it during the original build but I can't hear any issues with it at all and it's very smooth.

[Natural Sound]

I installed a Goldpoint 'Mini-V' in my Crack, but only because I had it around from a project I wasn't satisfied with and tore down for parts. I don't think I would have spent the $140 just for this amp. It does sound great, much better than the Alps blue I originally installed. I don't have any experience with the PEC so I can't compare the Goldpoint with it.

Shawn P.

Hi Shawn,

Are you using the speedball upgrade? It doesn't look like there would be enough room between the Mini-V and the C4S board.

Tom

[levlhed]

TKD pot and Mundorf MKP's output caps installed by a tech friend of mine, I only just got the amp back at lunchtime....won't have time to listen until later tonight.

[levlhed]

Um...YES.  A definite improvement.  As other's have said, not night vs. day but noticeable.  Nicey nice.