New Phono wanna-be - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 3 Old 05-24-2019, 06:05 AM - Thread Starter
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New Phono wanna-be

Hey all, new to 2 channel, so please bear with me. Most of my experience is in the Dedicated HT stuff, so wrapping my brain around "More power isn't necessarily better" is hard for me.

I've been getting back into collecting vinyl, and have done a bunch of research into putting together a nice turntable system, but I'm stuck on the amp decision.

I'm looking to start what I'd call "midrange", around $1500-$2000, and want to hit double duty as "sounds great" and "awesome looking setup" in my office. I'm a huge fan of DIY, so I'm also using this as an excuse to build some more DIYSG speakers, and hopefully a tube amp (or two). In order to keep the system streamlined, I'm looking at a phono w/integrated pre-amp (Pro-ject Debut Recordmaster is in the lead). I've mostly decided on DIYSG Apollo-7s for bookshelves, and I'm trying to do the math for what I'd need out of an amp.

The room itself isn't large (12 x 16), so the max listening distance would be about 4-5 meters. The bookshelves are 85db sensitivity @ 1m, and I'd probably listen around 70db. By my math (and the handy Crown Audio calculator) I'm seeing that I'd only need 5w out of an amp. From my guitar experience, I feel like tube watts are warmer and louder than digital, so I'm sure anything in the 5-8w range is plenty. I'm also considering building a matching pair and running them each mono, further reducing the power needs of each channel.

Ok, so to the Questions:
- Anyone have any suggestions for DIY tube audio kits that would meet my needs? I'm seeing a few but would appreciate directions to trusted vendors.
- The Apollos are rated 10-120w, will I have a problem powering them with a 5-8w amp?
- Surely I'm not the first to try this? I searched but couldn't find any prior build threads?
- What else am I not thinking about?

Last edited by DougUSMC; 05-24-2019 at 06:16 AM.
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post #2 of 3 Old 05-24-2019, 10:40 AM
 
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Quote:
Originally Posted by DougUSMC View Post
I've been getting back into collecting vinyl
I'm curious:

A. why did you leave?
B. what change of events has made you decide to return?

"The room itself isn't large (12 x 16), so the max listening distance would be about 4-5 meters. The bookshelves are 85db sensitivity @ 1m, and I'd probably listen around 70db. By my math (and the handy Crown Audio calculator) I'm seeing that I'd only need 5w out of an amp"

5 watts would not be enough for me and I would not describe my needs as "loud". YMMV. Calculators don't really work because some music has dynamic peaks 15-20 dB above the average level whereas other forms of music are heavily compressed and never fall outside of a narrow 3-6dB range of level change. If you use a calculator based on a compressed song you will end up clipping your peaks when you one day select a song with a greater dynamic range.

Another reason is because it is nearly impossible to describe a song as playing at a specific dB level in a room based on speaker distance, speaker efficiency, and amp power despite people often doing so. The level bounces around by ten's of dBs from start to end; it is not fixed nor is it easy to give it an "average" level. Compare the beginning of this song, which starts 17 seconds into the video, to its end, as an example:

This record unusually plays from the center outward so as to place the most important content where the record surface has the least distortion.

Last edited by m. zillch; 05-24-2019 at 11:37 AM.
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post #3 of 3 Old 05-24-2019, 11:47 AM - Thread Starter
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Quote:
Originally Posted by m. zillch View Post
I'm curious:

A. why did you leave?
B. what change of events has made you decide to return?
a) The 90s hit, and everything I wanted to listen to went to CD
b) I was visiting my brother the other day, and was digging on his listening room and vinyl collection. Eventually I found one and said "Hey, that's mine!". His (completely fair) response was "No, it WAS yours, but you gave me all your records".

After having to agree that I had, I decided that I wanted to try to try my hand at collecting again.

Quote:
Originally Posted by m. zillch View Post
Calculators don't really work because some music has dynamic peaks 15-20 dB above the average level whereas other forms of music are heavily compressed and never fall outside of a narrow 3-6dB range of level change. If you use a calculator based on a compressed song you will end up clipping your peaks when you one day select a song with a greater dynamic range.

Another reason is because it is nearly impossible to describe a song as playing at a specific dB level in a room based on speaker distance, speaker efficiency, and amp power despite people often doing so. The level bounces around by ten's of dBs from start to end; it is not fixed nor is it easy to give it an "average" level. Compare the beginning of this song, which starts 17 seconds into the video, to its end, as an example:
https://www.youtube.com/watch?v=TKZ73wtBzcY

This record unusually plays from the center outward so as to place the most important content where the record surface has the least distortion.
Ok, I understand all of that. It's not much difference than what I do in my home theater calibrations. As a matter of fact, "only" having two channels makes it easier than the 13 I have in the HT. The only reason I quoted the calculators was to try something different than "Must have 300 wpc", which is the case downstairs. I'd really like to build a DIY tube amp, but was confused by most of the kits being in the 8-16w range. I used the calculator to determine what I'd really "need", and found the results interesting.
I guess what I'm really saying is "Thanks for the explanation, but I don't know that it gets me any closer to determining which amps I need??"
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