Noob Stax research

[nu8reed]

Quote:

Originally Posted by ericj /img/forum/go_quote.gif The SRD-7 adapter is just that - an adapter. It contains step-up transformers and a bias voltage supply. It needs at least a few whole watts of power to go, and it's input impedance is about 8 ohms. You set the volume for the amp by turning the volume knob on whatever serves as the preamp for the power amp that drives the srd-7. That combination can be as simple or as complex as you prefer. like we say, anything from a T-Amp to a vintage integrated amp (ANYTHING that can drive speakers, really) to separate preamp and power amp.

I see, I thought the volume was controlled by the adapter. Is it possible to feed it too much power?

How do the Stax amps sound compared to the amp + adapter combo?

 

[Sherwood]

The general consensus is that the adapters give you better dynamics and more bass punch, but that the Stax amps give you better retrieval of small details.

I found my SRM-T1 amp to be slightly more refined than the SRD-6SB adapter, but not so much more that I should have bought it. If you already have a speaker amp, go for the adapter first. It's possible to feed it too much power, sure, but that's true of anything. Don't be worried about blowing it up with anything less than extremely powerful amps, though. You biamping Bel Canto Ref 1000s back there, nu8breed?

 

[ericj]

Quote:

Originally Posted by nu8reed /img/forum/go_quote.gif I see, I thought the volume was controlled by the adapter. Is it possible to feed it too much power? How do the Stax amps sound compared to the amp + adapter combo?

It's as possible to feed an SRD too much power as it is to feed a speaker too much power.

There are some who say that all the classic stax transformer boxes have better dynamics than most of the stax amps.

In a very real sense, the performance of the transformer box is dependent on the performance of the amp that drives it. If your amp doesn't sound any good with speakers, it won't sound much better through the transformer box.

In general you are likely to get better performance out of a cheap transformer box and a fair quality speaker amp than you are to get out of a low-end stax amp.

 

[kintsaki]

When I receive my sr-oo7 and srm-717 i will
conduct tests against the Trernds Audio T 1,
my AMC 85Watt tube amp, and
my DIY tube amp
with the Lynx2 in XLR mode and in RCA mode
and my Linn valhala, Ittok II, asa turntale
with the electrocompaniet moving coil cartridge
amp. Will also include the 828 sony DAP with
lossless as well as 220 kibit mp3.
The energizer will be an srd7 sb upgraded to
pro bias. If the result is good I will proceed
to build and try a high performance transformer
implementation of the srd7.

 

[krmathis]

Quote:

Originally Posted by nu8reed /img/forum/go_quote.gif I'm considering a Stax setup with the adapter. Out of curiosity, how do you set the volume for the amp?

Most of us use integrated amplifiers.
If you use a dedicated power amplifier, then you most probably want a pre-amplifier (with volume control) between the source and the amplifier.

 

[Keithpgdrb]

well, I am to be a stax owner. I should have an sr-lambda/srd-7sb setup within a couple of weeks. I've been looking into how to make these things work, and I have two questions:
1. I recall having read about "charging up" the amp/energizer? what is this all about, and how do you guys recommend me doing it when the setup arrives?
2. this is a stereo setup question. I will be running the stax through my Nakamichi receiver. I love this thing, it makes my "so so" speakers sound great. anyway. I also have a subwoofer set up. the pre-amp outputs of the stereo receiver are connected to the subs line inputs. the line outputs on the sub then return the line level signal to the power amp inputs on the receiver, which in turn power the speakers. my question is, is the bass information being covered by the sub being removed from the main speakers, or is it just added to it? I want to make sure all frequencies are reaching my headphones through the speaker outs. if the sub is replacing them, then my cans will have missing frequencies.

Am I wrong in my thought process on how subs work? I always thought they took the burden of the lower frequencies off of your speakers. but I've been wrong before.

Question 2, part B
my sub does have an off switch, if I switch it off, would the signal then be transferred unchanged? (if it was changed at all)

 

[-=Germania=-]

Change the AMP into a 2.0 channel (I.E. No Sub) and it might work just fine.

It would be helpful to know the wattage, because anything too high per channel could end very poorly as they only seem to need 10-30W/channel from what I have seen. FYI: The SRD-7/SB takes about 5 min to warm up fully which makes sense since it is a self-biasing adapter.

Anyways Keith, you will get to hear that SAME setup (i.e. mine) this weekend. I will have it there using a Sonic Impact Gen2 AMP and using the pre-amp output of the Zhaolu (with better chips installed). Although, It will likely have a new cable put on them by the weekend (waiting for parts from a very lazy supplier who I will never do business with again for that reason) using UPOCC wire. It will give you an idea though. The SR-5 setup will be there for good measure.

STAX PEOPLE:

I would watch the Chiunify Meet this weekend!
It seems like there will be MANY of the Stax models there (namely multiple lambdas and lambda frames + more).

 

[Sherwood]

Keith,

Your sub is doing one of two things. Either it is duplicating the low frequencies and passing the whole signal straight through, or it is serving as a lowpass filter. If it's the latter, which I suspect it is, then your sub probably has a crossover knob. Everything below the crossover point is being filtered out of the signal and sent only to the sub, in that case.

This is pretty easy to test for, luckily. Set the volume (not the crossover) on your sub to zero, and listen to the headphones. Then remove the subwoofer from the circuit (i.e. place a jumper on the back of your Nakamichi that goes from the pre out to the main in) and listen to your headphones again. If you notice a change in bass information, then your sub is also a lowpass filter.

You'll need a pair of RCA splitters in that case, to send a full signal to both the sub and the main in of your Nakamichi.

Regarding wattage and chargeup time, it's not terribly complex. Your transformer itself doesn't need too much chargeup time, just enough to build up a bias voltage, which relly only needs to be a few seconds. You can test this yourself, though. Play some very soft music into it with the headphones plugged in, and hear how it gradually gets louder. You can also charge it up right away by playing some reasonably loud music into it to start. Your headphones also require a bit of a bias charge, so when you charge up the energizer have the headphones plugged in (so don't go too loud). You shouldn't really need more than a few seconds of music at a decent volume.

Regarding wattage, you're free and clear. I've run my energizer off 1 watt SET amps, and off my NAD integrated putting out about 95 watts. Both sounded great. For an acid test, I'll plug it into my 300 watt per channel monster amps tonight and give it a listen. I suspect it will work wonderfully, though I'll not have much volume knob to work with.

 

[Keithpgdrb]

Quote:

Originally Posted by Sherwood /img/forum/go_quote.gif Keith, Your sub is doing one of two things. Either it is duplicating the low frequencies and passing the whole signal straight through, or it is serving as a lowpass filter. If it's the latter, which I suspect it is, then your sub probably has a crossover knob. Everything below the crossover point is being filtered out of the signal and sent only to the sub, in that case. This is pretty easy to test for, luckily. Set the volume (not the crossover) on your sub to zero, and listen to the headphones. Then remove the subwoofer from the circuit (i.e. place a jumper on the back of your Nakamichi that goes from the pre out to the main in) and listen to your headphones again. If you notice a change in bass information, then your sub is also a lowpass filter. You'll need a pair of RCA splitters in that case, to send a full signal to both the sub and the main in of your Nakamichi. Regarding wattage and chargeup time, it's not terribly complex. Your transformer itself doesn't need too much chargeup time, just enough to build up a bias voltage, which relly only needs to be a few seconds. You can test this yourself, though. Play some very soft music into it with the headphones plugged in, and hear how it gradually gets louder. You can also charge it up right away by playing some reasonably loud music into it to start. Your headphones also require a bit of a bias charge, so when you charge up the energizer have the headphones plugged in (so don't go too loud). You shouldn't really need more than a few seconds of music at a decent volume. Regarding wattage, you're free and clear. I've run my energizer off 1 watt SET amps, and off my NAD integrated putting out about 95 watts. Both sounded great. For an acid test, I'll plug it into my 300 watt per channel monster amps tonight and give it a listen. I suspect it will work wonderfully, though I'll not have much volume knob to work with.

You Rock.

 

[Sherwood]

Quote:

Originally Posted by Keithpgdrb /img/forum/go_quote.gif You Rock.

 

[-=Germania=-]

Good info Sherwood.

I tried it with some dual mono gainclones and the volume was just too much even with it barely turned up. I think that they were 120W/channel. Sounded good once we threw a passive preamp in there, just not so much directly into the integrated amp.

 

[Sherwood]

Germania, do you know what impedance the adapter presents to the amplifier? my amp doubles up into 4 ohms and again into 2... I just want to know if I should get my papers in order before I strap that to my head.

 

[-=Germania=-]

That was into 8 ohms @ 120W/channel for the Gainclone.

I don't know what it shows up as as far as a resistive load, but I would imagine it wouldn't be too far off from that.