better timing on my 300B SET

guys! pls help me decide on this 300B SET amp I'm trying out.

10watt into my Living Voice OBX-Rs using a volume pot on the amp (no pre). i love many things it does esp the transparency but feel wanting more acceleration in the music - timing, start/stop, foot tapping rhtym...call it whatever you want.

- is 10 watt to little for the OBX-Rs? typically recommended with 20watts. Room 11x13 but 10ft ceilings.
- is it just not run in - everything about 50+ hrs...and improving everyday
- is it the passive volume pot? my current valve pre adds a bit more body (rounded bass) and colours it and gives a perceived improvement but very coloured. better pre amp?
- if pre amp - TVC type? Music First, Bent? or fast/transparent e.g. modwright?
- i've tried various cables and combo got better results now but not sure if cables will do what's not there?
- tried a 4v output CDP (over my 2v CDP) - louder but not necessary 'true' timing improvement. perceived improvement yes.
- or loss cause - go P/P? mono SET out of budget and takes to much space.

 

I know the OBX-Rs are sensitive, but are they 10 watt SET sensitive? I mean, I would've thought your amp would be better matched with horns & giant tannoys.

Any way of modding the amp to push-pull config? Would probably give you the boost in power you need and save you buying PP monos.

Not too sure about how to improve leading edges & "speed" though. I can't see how a new pre-amp would solve the problem - you'd still be piping the signal through the SET which will slow it down again.

 

Which 300b amp is it??

I'm running 300b mono's with a Music First TVC pre. Upgraded from a Conrad Johnson PV-10 pre, which sounded lovely but the Music First just showed up how much vitality and bass etc was not getting through.

My DACs output is 2.9v I think and at times I think I might need a little more volume but thats a rare and minor compromise IMO.

Jeff

 

art audio

turtle - i've not bought this but trying it out. would love to buy it if only i can improve on the timing bit. lovely lovely amp. very fast, transparent with a good dash of SET qualities. Not 'classic' SETs ie. overly warm at all. they have a bigger bro with 4x300B @ 20 watts but big bucks. But the bigger bro loses out on some of the SET magic - different comprimise i guess.

Jeff - Does that mean my 2v CDP is a no no with the Music First? other than transparency - which is why people buy these TVCs...did you get better timing (not overall speed in sound, but better start/stop)?? or did you lose since it's softer and that can give a 'perceived' loss in dynamics? the inverse was true when i tried my friends 4v Gamut. Louder 'could' be perceived as more dynamic. Not true though.

 

Not necessarily, I might just like listening to my music particularly loud although TBH it's perfectly acceptable for most normal listening conditions. Important thing is to audition really. Are you near my part of London?

Don't think the MF was "softer" or anything, cos it doesn't really DO anything I dont think, more a question of hearing more of the rest of the system. The CJ imparted an archetypal tube sound, yes - softer, euphonic.

I've found a huuuuge difference in dynamics etc by changing the smaller signal tubes (5687 and 6922) in my Audions.

 

turtle - an "active" pre will add 'gain' and this gives better dynamics - don't ask me why i don't know. i just know if you use a passive pre (non-TVC type) you often get more transparency but lose on dynamics and tonal colour. But depending on your 'active' pre it could colour the sound, potentially too much - aka Jeff's CJ case. ANd I experience the same thing with my current pre.

 

From what I gather a classic drawback with resistor based passives (well certainly the dynamics, don't know if its the case with tonal colour) - and the precise supposed advantage of the TVC passive.

With passives (and I'm no expert) I'd always use the caveat - "if the rest of your system's up to it". but there are people on here with much more knowledge and experience than me.

 

Agreed. with a passive (forgetting dynamics for a sec) - you'll get that 'see thru" transparency. what sound you get will be defined by the rest of your system. Like it or hate it...

 

Difficult situation you're in here, BoyLah. In order to regain PRaT, leading edges etc., you're going to have to make sacrifices. What do you do? -

1) Sell the OBX-R's for something even more sensitive?

2) Move back to an active pre and loose the transparency/neutrality of the Music First?

3) Switch your SET's for PP's and loose some of that precious mid-range?

Personally, I'd keep the OBX-R's & MF. They have enviable reputations and are considered to be (more-or-less) the last word, in their respective fields.

IMO a good PP 300B amp should offer enough sweetness to keep you happy. The SET's are probably sacrificing too much of what you are trying to keep, in order to squeeze out that last drop of mid-range clarity. You'll have to decide wether that sacrifice is worth it.

Rgds,
DT

 

As regards passive pre's....you get what you pay for I think with these....I've had a couple here(a Creek and an Audio Synthesis)and whilst the cheap one is OK,it does flatten the sound somewhat,but it's cheap and convenient at times.

The AS is a completely different thing,and has no real effects other than to act as an attenuator,but it is several times more expensive,and as with all passives,you can have problems with running long interconnects,and also with source impedance.

The problems with your 300B....as with badchamp,I found that changing the input and driver tubes on mine can make an enormous difference,and whilst expensive in the short term,using good NOS tubes is a very worthwhile investment,in terms of speed and clarity.
There are a lot of quite poor 5687s on the market currently,and I've certainly had a few duffers off eBay...my current ones are Raytheons.

The other route to improve a stock 300B amp is upgrading the coupling caps internally,but not an option for the faint hearted.....mine have had this done.

 

DT, nicce one, great summary.

Mind you i'd have thought that the OBX-R at 94db are fairly sensitive.

FWIW when I auditioned amps I wasn't knocked out by an Art Audio (forget which model), it sounded quote err..cool, the Audions - to me, were far sweeter. In fact head and shoulders above most others although I did hear a pair of Trilogy monos which were pretty good. (Not 300b's though)

 

Thanks

There are more sensitive speakers around, but that would be missing the point - they are sublime transducers.

Changing them for something else, purely because of their senstivity, is like dumping a stunning girlfriend because her tits aren't big enough!

DT

 

Once again...nicely put!....and I would have thought at that sensitivity,they should go quite well,as my 25W PP 300b's can manage a pair of Quad ESLs quite easily.

As to bigger tits.....I'd have to consider that one verrrry carefully!

 

I've been quite lucky with my NOS (both from Audiogon and Ebay), all mine have been OK. I've got Amperex 6922 and Tung Sol for the 5687

Hmm....I've thought about this too. The amps are probably about 7 years old. Must confess though I don't how long caps last or even how you tell if they need replacing

 

ummm....i think my girlfriend (opps...wife) would concur with your small tits perspective! 8 )

no...the OBX-R2s stay. Just got them for god sake! The amp is on trial and if they don't work...they go back. Don't have a MF.

As for 300B push pull, someone else suggested that. Also I'm considering the Tom Evans Linear A - hybrid SS w/ EL34s...

The Art Audio is neutral sounding yes - but with right speaker and cables...it's magical. you can really tell the difference between different CD's, different halls, different musicians. But, the rest of your gear has to be up to it. My friend's Gamut CD player was more hifi and didn't work at all.

 

LV's claimed 94db is "optimistic". Even Kevin Scott recommends 20watts plus. Think more 90db?

 

My Tung-Sols were from eBay....nothing wrong with them in terms of measured values(both fine on my AVO MkIII tester),but awful sound....harsh and clipped easily,but the replacement Raytheons have been superb from the start.

Replacing coupling caps....I dont think you'd notice any slow deterioration,but you may find a dramatic improvement in simply upgrading if the originals are cheapish polyesters or similar...I changed from the stock Philips "orange drop" types to Jensen PIOs,and the gains are very obvious.

 

Maybe I ought to give some Raytheons a bash (but I wouldn't necessarily describe my Tung Sols as harsh)

Alex, could you expand a bit on the nature of the gains from the Jensens? Mind you I've no idea what type of caps Audion use and I'm a bit too faint hearted to open the things up

 

I think it was just the ones I had the misfortune to buy,as others have sworn by Tung-Sols....these measured fine,but sounded awful,to the point I was thinking I'd soldered something incorrectly in both amps.

Ok...I dont know what caps Audion use,but I would expect something reasonable,and many use things like Wima caps as their standard parts.

The Jensen(and also the almost identical Audionotes) are much more expensive(to give a comparison,the polyester caps I described cost about 10-20p depending on brand,and the PIOs start at about £10,and go up from there)...the sound is however much smoother,detailed and open,and in my opinion well worth the cost.

Black Gates can be very useful in PSU settings,but do have a very long burn-in time,and need to remain charged for best results.

If you did decide to look inside....remember all the usual precautions but also that valve amps although having small sized PSU caps,will retain a high voltage for some hours potentially,and the voltages even on a 300B are lethal.....gloves and a multimeter please!

 

Hi,

I am almost exactly in the same situation as you. Using OBX-R2s with 300B push-pull. Room size: 16x12 feet. Ceiling 10 feet high.

1. Leave your LV's to burn in for at least 200 hours. For me there definitely was a subtle but definite improvement. Better yet at 400 hours.

2. Check your speaker positioning. Before this I was living in a flat with 7 feet high ceilings. Having just moved to London with taller ceilings, the speakers have lost abit of their immediacy but have gained soundstaging. I am having to listen at higher volumes as well. That said, I am using 22W push pulls. I also had to move my speakers away from the back wall by about 120 cm after the move.

3. Agree with most of the pre-amp and NOS tube suggestions. But obviously option 1 and 2 are free and will keep you busy for a while.

JJ