Which power amp for bass?

[Sickneedhelp]

.....As an amp designer, what is a better way to go from say a 2tk source to an amp for such a test?

I have always assumed that a channel strip with EQ off was about as transparent a piece of gear that one would find in a studio.
Ironicaly, I have found that the Sony consoles from that era were much less colored than the Neve console that I spent years using and have not spent enough time on some of the new SSL or Neve desks to be able to accurately form an opinion of new vs. old (other than quieter and MUCH better automation).

Also of interest is how projects get mastered.
I've done a few records with Jack Skinner over at Sterling Sound 25 years ago. Back in the day his mastering room was loaded with many different speakers and amps. Always told him that he knew his room better than I and I was there because I liked the way his records sounded.
He preferred Canton home stereo speakers (as opposed to some high end B&W's, JBL's, Tanoy's, etc) and some old tube amp (instead of Bryston, Revox, Crest, etc) as he liked the sound better and trusted that rig for consistent mastering as he was so used to it.

Maybe not transparent but his mastering was solid; go figure.

Hi Jim

I've found simply getting rid of as much circuitry as possible in the signal path is the key. In the early music store demo days, I generally used a Harry James direct disk playing through a strain gauge cartridge with a flat response, line level output. The signal then went through a single selected LM318 (very high speed IC for the day) that was over-voltaged & cooking at +/- 25 volts. This single IC out went directly to the amp inputs. The amount of undertones of the trumpets would tell you instantly what the basic amp topology was. All the topologies had their characteristics. Post CD years, I'd spiff up the player's headphone amp and go directly to the amplifiers under test. That evolved to CD player digital out directly into the digital in of a Sony Elite 1000 preamp. That gave me gain and parametric EQ in the digital domain. Burr Brown supplied the AD conversion patched directly to a modified headphone output.

Speaker switching was done through 70 amp automotive relays that were frequently changed. I was not unusual to discover we were listening to relay contact distortion instead of amp distortion.

Jack Skinner's comment that he "trusted that rig" is important. It's obviously good to know what is speaker and what is amp related. When possible, I'd also use speakers I knew and trusted. If the amplifiers under test were close to the same, the test could easily take an hour or two. When I finally settled in on one switch position and focused on the music, I had my conclusions.

One could make the point that if a test took that long, there wasn't enough difference in the amplifiers to matter. I don't agree. I've always been big on listener fatigue. It doesn't matter if it's a restaurant or a dance club. If the sound system doesn't annoy me, or if I like the system, I stay longer and spend more $$. There are various degrees of being annoyed and liking. Accordingly there are various degrees of spending $$ in the venue. As a former Austin bar fly, I know from lots of observation, I'm not alone.

You also said about Jack, "Maybe not transparent but his mastering was solid; go figure". Great respect goes to those with track records.

Sorry for the excessive use of words.

 

[Jim C]

Wow, you guys really did go to a lot of trouble to kep as close to a straight wire as possible between source material and amp

Regarding testing that the average guy could do at home:
Do you think that going straight from a consumer CD player, headphone out, to power amp in, is a good test format?

Have been furstrated with just using a bass guitar to evaluate amps even if I was only using them for MI use.

 

[Sickneedhelp]

Wow, you guys really did go to a lot of trouble to kep as close to a straight wire as possible between source material and amp

Regarding testing that the average guy could do at home:
Do you think that going straight from a consumer CD player, headphone out, to power amp in, is a good test format?

Have been furstrated with just using a bass guitar to evaluate amps even if I was only using them for MI use.

Jim, it really depends on the CD player. Since they are such a commodity item now, it's doubtful there is much effort put into the analog signal chain. Worse yet, it's darn near impossible now to modify & improve the head phone amp. Regardless, it's probably still better than going through a small mixer or something that has several stages. Consider that each time you add a stage of something in the signal chain, one source of imperfection is added to the overall total. One amp and one additional imperfection is easier to sort out than one amp competing with five or ten additional imperfections. We are talking about subtitilies, but don't underestimate the ability of your brain to process them in some fashion eventually. You have the advantage of being a musician. You have already trained yourself to listen. That gives you a huge advantage. Now you just need to figure out what to focus on. Try it again and let us know the results. Be wary of the switch box. If it has compromised contacts, they could dominate. Details matter.

 

[BassmanPaul]

you obviously have no idea about how any amplifier works, (class d or otherwise). if you did, you would understand why your claim of 3000 continuous watts RMS at 7 amps is impossible. and BTW, yes, i do own a few class amps, but there is no sense in educating you of that if you are unwilling to learn.

This is possible but only with a supply in the 450V range. John is perfectly right in his statement.

Paul

 

[higgi]

Great amp sickneedhelp! Nice clean power at ~7lbs. Looks sharp, I like the blue LEDS.

 

[Jim C]

Jim, it really depends on the CD player. Since they are such a commodity item now, it's doubtful there is much effort put into the analog signal chain. Worse yet, it's darn near impossible now to modify & improve the head phone amp. Regardless, it's probably still better than going through a small mixer or something that has several stages. Consider that each time you add a stage of something in the signal chain, one source of imperfection is added to the overall total. One amp and one additional imperfection is easier to sort out than one amp competing with five or ten additional imperfections. We are talking about subtitilies, but don't underestimate the ability of your brain to process them in some fashion eventually. You have the advantage of being a musician. You have already trained yourself to listen. That gives you a huge advantage. Now you just need to figure out what to focus on. Try it again and let us know the results. Be wary of the switch box. If it has compromised contacts, they could dominate. Details matter.

Thank you; I appreciate the advice
Hadn't considered the brain's ability to process multiple subtleties, and the compounding of these imperfections

 

[Sickneedhelp]

Great amp sickneedhelp! Nice clean power at ~7lbs. Looks sharp, I like the blue LEDS.

Thank you Higgi!