Looking forward to your tone report. Here's what the buyer for the one I had for sale sent me a couple of days ago. "Very much in love with the 508, and much more depth , beauty and love from the Mullard you provided."
I will write up a final report when I am done. Might take a few more weeks as I have a few more parts to upgrade and they also need some burning in.
Can I ask how much burn-in time did you spend with the Mundorfs? I understand that the Jupiters are better but the cost is a deterring factor for me. I have a variety of Mundorf caps both in my integrated amp and phono pre and they were worthwhile upgrades in both applications but sounded underwhelming prior to the break-in. They are certainly better than the stock caps and IME just needed break-in time to show its qualities.
~250 hours. I hooked them up in my tube DAC as a decoupling cap and left them powered up with music running for 11 days, 24 hours a day. I knew the Jupiter is better too. The cost difference is around $100 for 4 caps. I tried to save money but I ended up now spending even more.
I see, 250 hours should be enough time, sorry it didn't work out. You could always try to sell the Mundorfs or keep it on the shelf for future projects. I sprung for them because the Mundorf SGO dropped in price, I remember 2 years ago they were selling for $80-90 per cap whereas now they go for $50.
yeah. I am pretty sure burn in isn't the issue here. Probably just not the cap for this application or no synergy with this amp. I originally followed the Humble Hifi reviews and they were the best in terms of rating/price ratio. Humble reviewed them in crossover application. Only after I ordered them then I see more DIYer who find them lacking in amp applications. I probably sell them at a loss.
Wondering if anyone has heard both the RCA 805s and the Acme 805s in this amp. A comparison would be great.
I was thinking the same. The ACME 805's seem to be the gold standard but the RCA's should be quite a bit cheaper if you can find them.
The Mullard just arrived today and it has about 1 hour on it so far. Already liking what I'm hearing versus the RCA 5691 red base that it replaced. Nice added overall weight, richness, and bass extension without any notable loss of air. The highs may be slightly more rounded although the tube is a bit more detailed.
Chinese/Russian tubes are unfortunately junk, sound-wise. Get the highest reputable NOS stuff you can afford. You'll immediately be rewarded with the best sound and reliability. It is tempting to spend on something entirely new rather than used but I've always been unsuccessful to find current production tubes that'd sound as good or better than NOS. It sucks for my wallet but my ears thank me everyday. The more a circuit is dependent tone-wise on the tubes, the more of an impact the higher quality NOS stuff will make.
You need to make one. You can find the parts on eBay, for instance. Since I don't solder, I had my tech do it but it'll likely be a piece of cake for someone like you. My tech was quite surprised to see the RCA measuring about 3x stronger than the Psvanes I had which weren't even a year old. I'm sure they'll last me quite a long time.
How important is it to have matching tubes? I see most of them for sale are singles. The tube was designed for radio transmission so they don't come in matched pairs...