SB3/SB2 questions

BRN · « **on:** 26 Nov 2005, 06:02 pm »

Wayne and others who have knowledge on the SB,

I have been following the continuing saga of the SB for the last few months and I 'm now thinking that it is time to move from CD to PC as a source. I have a couple of questions about your mods to the SB.

First, the fully modded SB from what I have read sounds better then a CDP and DAC combo or as good as some high priced combos. I now have a CD-Pro2M with a RAKK DAC with the passive output. I have been very happy with the sound, but I just got an Ipod and the convenience that it provides is almost priceless. I still want to get the best sound I can. Is the modded SB as good as a stand a loan?

Second do you modify the SB with the WiFi and do I lose any sound quality going WiFi?

Finally, do you do the full mods on the SB3?

Thanks,
Brad

Wayne1 · « **Reply #1 on:** 26 Nov 2005, 10:22 pm »

If you spend some time looking through this circle, you will read about more than a few folks who have sold multi thousand dollar stand alone players because they felt the modded SB2 was better than what they had.

There is no difference in the sound of the wired or wireless SB2 or 3.

I have just about nailed down the analog section mods of the SB3. The large Sonicaps will not fit inside the case. I do not like the option of mounting them on the outside. I will be using the Non-polarized blackGate caps with a Sonicap bypass. That should give very close to the sound of the Sonicap alone.

Marbles · « **Reply #2 on:** 26 Nov 2005, 11:53 pm »

What is the output voltage of the SB2/3

I have heard it's only about 1v, is that true? If so, it seems like it might not be a good fit for direct to amp systems, or even for folks with zero gain pre's if they want to play fairly loud.

Wayne1 · « **Reply #3 on:** 27 Nov 2005, 12:13 am »

It all depends on your system.

A lot of amps are spec'ed to obtain rated power with 1 volt input.

Some speakers will play very loud with very little input. Some rooms reflect more sound energy and so appear to be louder.

If you find that for "your" system, you may need more gain, a pair of transformers may be used to double to output voltage. These can be put in an outboard box or they can be installed inside your amp.

Here in Colorado, Jerry and Mike G have the exact same speakers and amps. Mike has a large reflective room, Jerry has a small, well damped room. Jerry has found that he wants more volume. Mike lent him a pair of Lundahl transformers that doubled the output voltage. He liked those but ordered a pair of more expensive Jensen transformers. I believe Mike G is installing them in Jerry's amp this weekend.

When Jerry auditioned the Lundahl transformers he said he could not tell the difference in sound. They just allowed him to reach volume levels that he couldn't before.

Using transformers would be the least harmful way to increase the gain of the system. Any preamp would change the sound quite a bit more. There are far more parts and connections that would be in the signal path with a preamp.

Marbles · « **Reply #4 on:** 27 Nov 2005, 12:17 am »

That answer confirms the output (I think) and offers a reasonably priced solution.

Thank you

Wayne1 · « **Reply #5 on:** 27 Nov 2005, 12:52 am »

Didn't mean to dodge your question, Marbles. The full rated output for the DAC chip is 3.1 volts peak to peak. That works out to 1.09 volts RMS.

Again, the volume you get out of your speakers will depend on the gain of your amplifier, how efficient your speakers are, and your room.

zybar · « **Reply #6 on:** 27 Nov 2005, 12:56 am »

Of course you can avoid the issue in its entirety by having your SB2/3 just output a digital signal.

George

mgalusha · « **Reply #7 on:** 27 Nov 2005, 04:56 pm »

One thing to keep in mind if using a transformer for additional gain is that it lowers the input impedance by the square of the winding ratio. The Lundahl's that I have and the Jensen's that I'm installing in Jerry's amps use a 1:2 ratio, for 6dB of gain. In this case it drops the Zin from 39K to about 10K (9K750).

This doesn't appear to be a problem with the SB as we noticed no loss of dynamics or bass but with an amp with a lower input impedance it might.

In Rob's case with the Kraft Mono's I don't know the Zin. If they are similar to the Stratos, which is also Symphonic Line, they are probably rated at 10K, which would be transformed into 2K5, quite low. If I get time today I'll measure the Zout of the SB. If it's under 200R, then even that wouldn't be a problem.

As Wayne mentioned, many amps will reach full power with 1V RMS on the input. The LNPA's have a gain of 26dB. The Stratos have a gain of 30dB and it's quite possible the Kraft's do as well. Given the higher gain you should be able to get plenty of volume (and power) driving the amps directly from the SB2 without using a step up transformer.

Mike

Val · « **Reply #8 on:** 28 Nov 2005, 02:36 pm »

Good tip, mgalusha. My own experience is still very limited, but the stock SB2 directly into my Stello M200 monos and ACI Sapphire XLs gave me too much output! It was a short test, and nearfield, but I couldn't go above 10 or so on the SB2 volume control. I hope the Bolder mods will allow me to use the higher end of the volume control (the losing bits thing), or I would have to use Endler passive attenuators on the Stellos.

woodsyi · « **Reply #9 on:** 28 Nov 2005, 03:00 pm »

I have been running full Bolder modified SB2 for 10 days or so to facilitate burnin and what not. I got both the analog and digital outs connected. I won't say anything yet about the sound quality between the two until they are fully broken in except the volume. Analog out is about 5 dB down compared to digital out via my DAC output (Northstar 192). They both go into a same pre and an x-over. I may try takingout the pre just to hear what my pre does in my sysem but I have too many sources to give up source switching.

Nick B · « **Reply #10 on:** 15 Dec 2005, 09:44 pm »

Wayne I've decided to go the Squeezebox route. I'll likely use the internal DAC rather than buy a separate DAC. I prefer the SB3 over the SB2 due to looks and the internal antenna. However, I'm concerned about the lack of room inside the new chassis. Is there any feedback yet on how your
modded SB3 sounds? I would like to place an order before Christmas and save $50 (assuming there is another A/C member whose ready to order).

DSK · « **Reply #11 on:** 15 Dec 2005, 10:08 pm »

Quote from: mgalusha

One thing to keep in mind if using a transformer for additional gain is that it lowers the input impedance by the square of the winding ratio. The Lundahl's that I have and the Jensen's that I'm installing in Jerry's amps use a 1:2 ratio, for 6dB of gain. In this case it drops the Zin from 39K to about 10K (9K750).

This doesn't appear to be a problem with the SB as we noticed no loss of dynamics or bass but with an amp with a lower input impedance it might.

In Rob's case with the Kraft Mono's I don't ...

Great information Mike.

If I were to place Y-connectors on the RCA analog outputs of an SB2 with full Bolder mods, do you believe it would be happy driving the following combination without bass/dynamics issues etc?
Amp: AKSA 100N+ (Zin 47k, 32db gain, approx 0.8v for full output - IIRC)
Sub: Zin approx 30k (not sure of other data)

If not, would the transformers you mentioned resolve the issue, or would there still be side effects? I guess the transformers could be placed in a separate enclosure with 1 input pair and 2 output pairs of RCA's, though the additional RCA's may cause minor degredation.

Thanks for the info!

Val · « **Reply #12 on:** 15 Dec 2005, 10:27 pm »

Quote from: DSK

If I were to place Y-connectors on the RCA analog outputs of an SB2 with full Bolder mods, do you believe it would be happy driving the following combination without bass/dynamics issues etc? ...

Y-connectors would double the SB2 output impedance to 440 Ohms, which is low for a preamp and would still drive the 47kOhms and 30kOhms with no problems, IMHO.

Giving a bit more thought to this, the stock SB2's output impedance is 220 Ohms; I don't know if the Bolder mods change this value or not, so take my opinion with a handful of salt.

mgalusha · « **Reply #13 on:** 15 Dec 2005, 10:36 pm »

Quote from: DSK

If I were to place Y-connectors on the RCA analog outputs of an SB2 with full Bolder mods, do you believe it would be happy driving the following combination without bass/dynamics issues etc?
Amp: AKSA 100N+ (Zin 47k, 32db gain, approx 0.8v for full output - IIRC)
Sub: Zin approx 30k (not sure of other data)

The SB would see a Zin of about 18K, and given the gain of the AKSA it should work quite nicely without a step up transformer. A modded SB will put out about 1.03V at full volume which should be more than enough to drive the 100N+ to full power.

Mike

Wayne1 · « **Reply #14 on:** 15 Dec 2005, 11:26 pm »

I have received no feedback about the sound of the analog only mods for the SB3. Given that I used BlackGates and Sonicaps for coupling, I do not expect the final sound to settle down for about a month.

There have been more than a few "problems" with the SB3. It seems to be somwhat picky about what routers it will work with. Some folks have had problems with the Silver cladding coming off. I am sure these will all be worked out in time.

If it was me, I would go with the SB2. I do have a couple of them already

CornellAlum · « **Reply #15 on:** 15 Dec 2005, 11:32 pm »

If anyone has problems they need help with re: the sb3, I am your man

Mine is working wonderfully, and I don't have to get off my ass and put down my beer to switch tunes either!

Review of mods forthcoming.

D~

Nick B · « **Reply #16 on:** 15 Dec 2005, 11:40 pm »

To me, that SB2 is kind of an ugly beast and has the antenna. One reason I wanted the SB3 is because of the apparent much larger font size. That's good for my aging eyes. Pls advise about visibility when you get a chance. Do you use the same caps that Vinnie uses for the SB2? Also, is your fee for the mods the same for both units? I'm only interested in wireless. Thanks

Wayne1 · « **Reply #17 on:** 15 Dec 2005, 11:59 pm »

The display is the same in both of the units. You can vary the size of the font with either the SB2 or 3.

No, I do not use any of the same caps as Vinnie. He uses a couple of small BlackGates for the power going into the DAC chip.

I did not want any holes in the back of the SB3 so I used non- polarized Black Gate caps with Sonicap bypasses for the audio output coupling cap. A completely different application.

The mods are the same either wired or wireless. It doesn't make a difference. The SB3 analog mods won't be put on the website until after the first of the year. I am currently backed up about 5-7 weeks with my present workload. Right now, I am not looking to add to it.

CornellAlum · « **Reply #18 on:** 16 Dec 2005, 12:02 am »

Wayne, did you happen to see the mod posted over on the slimdevices forum where the gentleman hacked the board in half

What did you think if so?

D~

Nick B · « **Reply #19 on:** 16 Dec 2005, 12:14 am »

FYI regarding alleged SB3 cosmetic problems. I called SlimServer and they advised there were 2 issues: 1) There is a clear plastic protectant that needs to be removed. Some were mistaking that for bubbling of the silver surface. 2) Due to manufacturing error, there were scratches on some units. That has been resolved.