sp-8 preamp ?

Why is there no bass and treble control on some preamps like the SP-8?

I've honestly been wondering this myself. I might get a sp-8 kit in the near future to go with my st-70 and it seems odd how it has no bass/treble like the old pas-2 I'm currently using.

Where the lack of tone controls fails in actual use is in playing imperfect recordings. Almost anyone can think of a recording with a shrill, rising high end that needs to be turned down. Or perhaps the deep bass rolls off and the judicious use of some bass boost would fix that, and make the recording sound better.

Your system may be ruler-flat, your speakers as close to that ideal as you can get. But the mastering engineer might not have realized that his hearing is going away. Or maybe he had a head cold that day. Or the tweeters on his monitor speakers were blown and he didn't know it (don't laugh; it HAS happened!).

Hello,I agree on the neccesity of T.C.'s,I 've always argued that the purist's arguments against them were flawed from the start.The argument that tone controls color the sound,and somehow detract from what the recording engineer was trying to accomplish at the board are ridiculous.In order for that to hold true one would have to have the same EXACT playback equipment,played in the same EXACT room with the same EXACT acoustics the engineer had when the recording was mixed.Some recordings just suck.Try listening to some early Stones records and tell me you don't need tonal adjustments!Some Tone control cuircuts do add noise,the Pas preamps tone control cuircut adds alot of noise,and I think thats why people started un hooking them,I don't think it makes them sound better soundstage wise by doing so,(I have 2,-1 Pas3x with the TC's,one Pas3 with them unhooked)Just quieter.I'd love to Have tone controls on My SP-8.I wish Roy would make a switchable Tone control cuircut that can be installed as an option on his kits,switchable,if you want it you can have it,if not a flick of a switch takes care of it.Any thoughts Roy?Or any suggestions on where a guy could find a T.C. cuircut that could be installed in the SP-8,in switchable mode?F.Y.I. I'm running Curcio upgraded Mark 3's,An SP-8 Pre,And Rebuilt/recapped Klipsch Heresys.By the way-the SP-8 Preamp does sound wonderful,crystal clear,and quiet,with a very open soundstage.it is an enormous improvement over a PAS.I highly recommend it.But I personally find not having tone controls a bit limiting.There's no way to tune your room,or your system to every recording your going to listen to other than tone controls.Any suggestion that its always the listening enviroment at fault(Room,Playback System)and not the original recording is ridiculous.I agree with GP49,tone controls are a real world neccessity.Just my 2 cents,Robert

Regarding an "add-on" tone control. I recently discovered a tone control module manufactured by S-5 Electronics (http://www.s5electronics.com/ltone.html). Since I've never done business with them, I have no recommendations, but this might be an option.

Best Regards,
Charlie

I have added tone controls to my build of the SP6/SP8 board using a passive design from http://amps.zugster.net/articles/tone-stacks using the Baxandall design.
My SP6/SP8 build is housed in a Dynaco PAT 4 chassis and the tone controls are mounted in a separate enclosure due to an issue with low level hum when the new tone control pots were inserted into the original treble and bass positions. The hum becomes a non issue when distanced from the power supply.
The tone control is inserted between the output of the SP6/SP8 board and my Dynakitparts ST70 (e/w VTA70) and is housed in a plastic enclosure and connects via RCA phono cables.
There is some insertion loss for the tone control circuit and is compensated by raising the output of my Squeezebox Duet via the controller to the SP6/SP8 preamp line stage input. I don't use the volume control on the preamp. It was setup initially and left that way. The cost of the build was approximately $20(Canadian). Time to build was a couple of hours once I had all the parts in front of me.
Performance wise, I can adjust the sound to my liking based on the source material being played and I have not experienced the negatives others have experienced in using tone controls.

It's certainly common wisdom these days that tone controls are "definitely not high fidelity."

I've heard -- I'm not arguing.

The book on good sound (that might even be the title) put out by Ultra High Fidelity magazine argues that one down side of tone controls is the added circuitry not only adds degredation to the signal, it adds frequency dependent delay in the music. Not enough that you say to yourself "hey, the cello is way behind the piccolo," but it contributes to "muddying" the sound.

Another point is that base and trebble are too crude -- you really ought to have something like a graphic equalizers many bands so it won't be like doing micro surgery with a hatchet. This, of course, comes at the cost of exacerbating the added circuitry problem. Or so goes the argument.

But at the end of the day, UHF comes to the conclusion that you really can't "correct" a bad recording with the addition of all these extra circuits.

FWIW

The common wisdom that tone controls are not High Fidelity maybe was perpetrated by people with enough money to build a room around a system.In the real world most people don't have that kind of money.Thats one of the reasons why we buy Tube preamp kits instead of $4000 C.J.'s.Also One would think that a simple Bass/treble cuircut would follow a much shorter signal path than an E.Q.,with less chance of compromising the sound,if thats the purists argument.In which case they should all be running passive preamps.I hear what you're saying about surgery with a hatchet,but most times all thats needed is a little more lowend,or a little less topend,not a whole overhaul of the sound.Tone controls that are in/out of the cuircut switchable would satisfy both needs.In the end it all comes down to personal tastes,we all have dif. hearing and tastes,(and of course budgets and homes)so for one person to design an audio component that emphasises/deemphasises certain frequencies without tone controls thinking it will fit everyones tastes as-is is fooling his/her self.Just my 2 cents.
Robert

Graphic equalizers, as usually executed with their narrow bands, introduce resonances and phase shifting which in themselves are undesirable and more damaging than those of standard broadbanded tone controls. It just can't be helped; you are introducing narrow-band nonlinearity into the system by using them, in addition to their often non-ideally executed circuitry that introduce several times more parts into the signal path than do standard tone controls. Most often they aren't necessary or even all that effective when dealing with recordings that are unbalanced in their sound. Narrow-band equalizers, particularly parametric types, can be useful in tuning out room modes; but that process is "set and forget" for most listeners who use them for that purpose.

Standard bass and treble controls are easier to use for the everyday purpose of correcting the tonal balance on recordings. What's even more appropriate to that task is a TILT control, such as was found on some British preamp/control units in the tube era. We haven't seen anything like that for many years.

The purist, "no tone control" philosophy may be acceptable to those who only listen to perfect recordings. A lot of the reviewers of multi-megabuck equipment in the audio magazines seem to always listen to the same "perfect" records all the time, while reviewing equipment. But that's an entirely different purpose for listening than what applies to most of us. They SHOULD use a fixed reference and be altering only the unit under test, without compensating by means of tone controls and such. We listen for pleasure, and if that pleasure is increased by trimming the treble or bass a bit, so be it. We don't HAVE to be like the reviewers.