dhodo
Well-Known Member
Adjustable temp controlled is so worth it.
Edit: Also, a decent sized screwdriver tip for the big lugs and a small one for PCB stuff. Not sure if the Reduction has PCBs.
Totally Tubular: The Tube Thread
- Thread starter displayname
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Edit: Also, a decent sized screwdriver tip for the big lugs and a small one for PCB stuff. Not sure if the Reduction has PCBs.
I am not a pro. I have put together some crossovers for two sets of DIY speakers, but that's about it. I'm currently doing research on the iron but I will defiantly go with the adjustable one. I have two setups, so I'm hoping to do the reduction first, add the upgrade if it works, then get the Eros. Frankly, I'd also like to do some of the other kits down the road as well. I went with the reduction because of the sale and I wouldn't be out as much money if I turn out to be hopeless.
Thanks, will do on both recommendations.
Splunders
Well-Known Member
Is THD (total harmonic distortion) an indicator of an amp's tubeyness? Does a lower number mean less "tubey" and more "accurate"? Are measurements even a reasonable way to get a ballpark idea where on the "tubey" spectrum a particular amp might fall? Are there characteristics of a tube amp, beyond midrange lushness, that are hallmarks of a tube amp? I'm really drawn to the idea of them, but haven't really heard one. I would love to hear what it is you hear from your amps that you hadn't gotten from solid state.
displayname
Well-Known Member
I believe THD is mostly a mark of how low the noise floor is. I don't know of any specs that would indicate "tubey". It's already a subjective term. Listening really is the best bet.
Splunders
Well-Known Member
I believe SNR (Signal to Noise ratio) is the noise floor measurement. I've read how THD, particularly 2nd order harmonics within THD, and which is technically distortion, is what provides the lush body attributed to tubes. I'm know listening is best, but that's not always possible, so I'm trying to see if any measurements can help me infer the sound if at all possible.
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displayname
Well-Known Member
Ah, you're right. Thank you for that correction!
I would say tube type and the power supplies are likely one of the better indicators. But I've heard pure tube amps that sound fairly analytical, and solid state that has a lush and holographic sound normal attributed to tubes.
But I'm also not a specs chaser at all, so someone who is normally checking all those details might have better insight.
Splunders
Well-Known Member
I think that's the crux of my question - how do you know when it's a more analytical tube amp? I have a solid state amp that has a relatively high THD of 0.7% (vs .01% for example) that I think sounds sweet, and I assume tube like. I'm all for auditioning the gear, but if I could narrow the field somehow, to a flavor I'd like, that'd be ideal.
displayname
Well-Known Member
Yeah, I get that. I’m not the right person to answer your question on specs though. I check a few key points for compatibility, and then focus on reviews from people I’m familiar with and listening whenever possible. And after a certain price point, I really just hold off on purchasing unless I get a killer deal that I know I can break even on.
I tried to get into specs previously to help determine a sound, and so many things ended up different than I expected. So I don’t lean on specs for that because I simply don’t believe specs are a good indication of sound.
Splunders
Well-Known Member
And that very well may be the answer I'm looking for.
THD stands for Total Harmonic Distortion.
Let's imagine an amplifier is reproducing a 100 Hz bass tone. The amplifier will also produce harmonics of that tone at much lower levels. How high in amplitude these harmonincs are and what type of harmonics will make a difference on how the amplifier sounds.
A solid state amp will produce harmonics from that 100 Hz tone, so 300 Hz, 500 Hz etc. These are called odd order harmonics. A tube amp will produce even order harmonics- 200 Hz, 400 Hz etc. Why this happens, I don't know. Many (including me) find even other harmonics less offensive (or even pleasing) compared to odd order.
The lower the amounts of the harmonics are compared to the desired frequency, the lower the THD.
But lower THD doesn't necessarily mean better sound. Crank up negative feedback in a circuit and THD drops. My experience tells me most amplifiers with low or even no negative feedback sound better.
I'm not surprised that your amp with higher THD sounds good. It's a Pass design and has very low or no negative feedback.
How quiet an amp is is measured in signal to noise ratio. The SNR of vinyl is around 70 dB, a CD is >90 dB. Any quality amp should be around 85 dB and higher. Usually this is where tubes fall short- it's easier to make a quiet solid state amp. In any event, the amp will be quieter than the vinyl itself. Don't get too hung up on this. Sutherland for example does not publish this spec, but anyone who's heard one knows they are quiet as church mice.
Your best test instruments are on the sides of your head. Trust them over a spec sheet.
Splunders
Well-Known Member
As always great info @HiFi Guy ! I'll keep an eye on the negative feedback aspect, which I wasn't aware of. I agree hearing is the only way, and that specs can be misleading. I think I'll have to find companies with lenient return policies to find exactly what I like. Not for some time though, however I do really enjoy the research
A few things I look for:
As you said, lenient return policy.
When researching a piece of equipment, I look for the bad comments, if you can find them. They tend to be a bit more honest. There are a few pieces/brands that that have no bad comments that I can find- Sutherland phono stages are a good example.
Look at the context too. Someone who bought a Grado cartridge did complains that it hums? That's not a cartridge fault. That's someone that doesn't understand why this can happen or what turntables will be incompatible. Twenty years ago, this was excusable. Not now. The info is out there and easily located.
In some instances, you may find better value with brands that sell factory direct. Zu, Audio by Van Alstine (AVA) and Decware come immediately to mind.
Splunders
Well-Known Member
Good point on the negative reviews, especially if there's a recurring theme of shoddy build quality or product failure. The factory direct companies tend to have a lenient return policy as well.
wmeugene
Well-Known Member
Replaced the tube as instructed, was pretty easy. Have 1 hour in, will check back after another 100 or so!
I don't know how many here use 6922's in their gear. If you do these are an absolute steal for the price. I bought 4 to try in my Audio Research preamp. I must say for the money they are quite good. I think they are as good as the Seimens 7308's that was using in it. If you use 6922's these are worth trying.
Brand New, MINT NOS 1971 Original Tesla PCC88 7DJ8 Yellow Print tubes with Gray Risers and 32 Factory Code for Tesla Ronov n.p. Závod Vrchlabí from Czechoslovakia (now Czech Republic).
Brand New, MINT NOS 1971 Original Tesla PCC88 7DJ8 Yellow Print tubes with Gray Risers and 32 Factory Code for Tesla Ronov n.p. Závod Vrchlabí from Czechoslovakia (now Czech Republic).
www.tubemonger.com
dhodo
Well-Known Member
What's the difference between 7DJ8 and 6DJ8, I thought 6DJ8 was the same as 6922.I don't know how many here use 6922's in their gear. If you do these are an absolute steal for the price. I bought 4 to try in my Audio Research preamp. I must say for the money they are quite good. I think they are as good as the Seimens 7308's that was using in it. If you use 6922's these are worth trying.
Brand New, MINT NOS 1971 Original Tesla PCC88 7DJ8 Yellow Print tubes with Gray Risers and 32 Factory Code for Tesla Ronov n.p. Závod Vrchlabí from Czechoslovakia (now Czech Republic).
Brand New, MINT NOS 1971 Original Tesla PCC88 7DJ8 Yellow Print tubes with Gray Risers and 32 Factory Code for Tesla Ronov n.p. Závod Vrchlabí from Czechoslovakia (now Czech Republic).www.tubemonger.com
The 7DJ8 is basically the same as the 6 but use 7 volts. The 6922 is very close also as is the 7308. They are all interchangeable. The 6922 is the premium version of the 6dj8. The 7308 is the premium version of the 6922. You can also add the 6h23 in the mix.
Did I mention I bought 4 more of the 7dj8 Tesla's just to have on hand.
Did I mention I bought 4 more of the 7dj8 Tesla's just to have on hand.
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kvetcha
Well-Known Member
The difference in imaging between the Jolida’s stock Tung-Sol 12ax7 and the Genelex Gold Lion is night and day. The center image, somewhat nebulous with the Tung-Sol, has snapped completely into focus and is just floating in space between the speakers. Haven’t had time to make any tonal comparisons, but just by virtue of the soundstage it’s the Gold Lions by a mile.
I'm glad you like the JoLida. It's a really good sounding amplifier. I ran the next model down for a couple of years.
kvetcha
Well-Known Member
I discovered the variable output runs at too low of a signal level for my SVS to pick up, so I wired the Jolida through the high level speaker inputs instead and spent a little while getting the crossover and gain sorted. I have bass again!