Ohm questions

[Sheesh]

Hello All! I'm new here and just getting into the the world of DIY audio. I apologize if my questions are simple ones, but I need some help. I did searc hand came up with nothing. I may even be in the wrong forum, let me know. Heres the background:

I recently purchased a new receiver, the Yamaha RX-V750 for my setup. It is used for about 4-5 hours per day and 40%HT/40%Music/20% PC, gaming or other media applications. This replaces an Integra DTR5.2 that I purchased used and ran for about 20 months. About four months ago, the sound quality got noticeably worse almost out of the blue. The system started to give noticeable hiss when "s" sounds were produced and the whole things just sounds generally poor. Even to the point that my old elcheapo Sony sounds better. So, I tried power conditioners and it didn't help. I had a freind of mine take a look at the reciever and test it and he said I had damaged it by running an uneven ohm load of the reciever and not providing enough ventilation. My fronts are older POlk audio monitors that he says are 6 ohm, and the rest are Polks that he says are actually 8 ohm. Does this sound plausible? It seemed to me that it would be true given that my system would sound balanced at certain volumes and the mains come blaring forward at higher volumes

Why, you may ask, did I post this in the Loudspeaker section. Its because I want to over time replace all my speaks and go to 7.1, and I enjoy DIY. Here are my questions about loudspeakers:

1. How do you figure the ohm load of a given speaker design? For example Wayne's DIII and Eros, and Joe D's Thor.
2. How much of a variance in Ohm load would a typical consumer level receiver like the RX-V750 handle? And keep it all balanced.
3. What are your suggestions for a complete 7.1 setup? given a $1000 limit for components built over the next year, and a noob who would have to follow detailed plans to build them.

Speaker designs that intrigued me seem to center around the Dayton drivers, but that is probably because there is so much info about them.

[wigginjs]

No, it doesn't sound probable that your old receiver was damaged by your front left and right speakers being 6ohm. I think you might have a general misunderstanding about how speaker impedance effects the amplifiers in your receiver though. When you're choosing speakers to connect to a particular receiver (or amp) you don't need to concern yourself with finding some sort of "balance", in fact, you have to do little more than read your receiver or amp manual. It will state in there which speaker impedances it supports for which connections (most receivers, including the RX-V750, support as low as 4 Ohm loads for the front left and right, and as low as 8 Ohm loads for the remaining speakers). As long as all of your speakers have an impedance of at LEAST the values shown in the manual, you will be fine. The problem is that lower speaker impedances require the amplifier to output more current and the power supply of the amplifier has to be able to provide it. Most receivers (all?) have weak power supplies compared to stand alone amplifiers. I don't know of a receiver that supports as low as 4 Ohm loads for all speakers. The bit about ventilation is possible, but it would have to be really horrible ventilation. In regards to a DIY speaker suggestion for 7 speakers all for less than $1000 in parts, I think that a pair of Eros speakers for the front and the other 5 being the ones from the "Dayton Home Theater" would work well and fit into that budget. I wouldn't, however, consider the Eros a beginner project.

[Nappylady]

S sound problems and worse quality in general?

The first thing I would check would be sample-rate converters--if your resampling is anything less than spectacular, your SSSSS sounds are going to sound like SHHHHHH(it).

The worst kind is when Windows Media Player (or some other idiotic piece of software) resamples 48khz material to 44.1khz; it often uses very poor resampling algorithms, and the quality is as if it were 11khz material.

One question: Is the problem noticeable at very low volume levels, or does it suddenly appear at a certain SPL? If this is the case, it's probably the tweeters running out of excursion, or their poor little voice coils rubbing against something.

Good luck, and let us know how it all turns out...

[Sheesh]

Thanks for the replies!

mOtion- Thanks for the info, you're right I know nothing about the affect of ohm load on a recievers amplifier. I will check the Integra's manual when I get home tonight to see what Ohm loads it supports. I guess I will find out more when my Yam comes in next week and compare. T

Thanks for the input on the speaker choice. How important is it to match drivers throughout a HT setup? If I am not mistaken the Dayton Home Theater and the Eros have different drivers. Most of my freinds argue about wether it is better to have the tweeters be "timbre matched" or that the mid/woofers be matched throughout. I am to get some other opioions before I move ahead.

nappylady- I completely understand about certain software affecting sound quality. I didn't have an understanding of why, but I have heard it first hand. Even the sound card makes a huge difference, even if they are supposed to be SDIF "passthroughs". The only thing is that the horrible "s" sounds happens regardless of volume or source. It still occurs from a DVD/CD(optical), cable(coaxial), the PC(optical via coxial to optical converter), or analog VCR and Xbox.

Its a mystery to me. Do you think I made a step down in quality of components? Most people I talked to think so. In a head to head comparison on some def tech speakers I actually preferred the sound of the Yam to the new INtegra 5.4. Also, the yam has a lot more of that I was looking for in terms of features, which are important to me. The YPAO is a audio noobs dream.

[wigginjs]

I find it to be marginally important to have the front 3 speakers timbre matched. This does not, however, REQUIRE that you have the same tweeters in all of the front 3 speakers. Your new yamaha reciever has a graphics equalizer for the center speaker that you can adjust until the sound closely matches your other two front speakers. As for the tweeters of the surround speakers it would be nice is they were all the same, but they don't really have to match the front. IMHO it isn't very important because if the (unlikely) event that sound does transition from the front speakers to the back speakers you probably won't notice the (slight) difference in the tonality of the highs. It isn't worth spending a bunch of money on.

I very much like Yamaha's receiver line. I just bought an RX-V650 myself and with the 192khz 24bit DACs on all 7 channels, adjustable subwoofer crossover, center channel graphic equalizer, etc. I don't know that you could ask for a more feature filled receiver at that price range. I've yet to use YPAO, but I've got a feeling that you can still do a better job with test tones and an SPL meter, it's certainly better than nothing though.

[Sheesh]

Thanks mOtion-

Is that RX-V650 in the theater in your signature? I doubt it but....I looked at the RX-V650 and it seemed like the best value I found, but the Component video up-conversion was worth the $75 for my FAF (fiancee approval factor). Having to hit more than one button to switch from cable to a DVD was just a little too much for her to take. I count myself lucky tho, I could really pout almost any speaker in here and as long as they weren't bare MDF, sound decent, and she can run everything from the basic buttons on the remote she is cool with it.

BTW- I agree with you about the timbre matching, but I have very little experience with it. This INtegra has very little adjustments for anything, so the differences in my speakers are very noticeable. Even more so than the timbre is the relative "volume" of the individual speakers at different volumes on the receiver. The center comes through at lower volumes, there are even in the middle settings (where I calibrated it at) and the mains overpower everything at higher volumes. I figured it had something to do with the relative efficencies of the speakers being so different. So, I am going to try to match my new speakers as best I can. We spend a lot of time in front of it at varying volumes, so I think this is a priority to me. In fact I am sitting in front of the system listening to Mark Knopfler while I type this from my sofa. Sounds pretty OK right now for MP3's.

Anyways thanks for your input!

[wigginjs]

Yes, I just set it up last night in the theater shown on my webpage, I'm extremely pleased with all the setup options they give and also the overall sound quality. I'm using the pre-outs for the front left and right channels and running those through my newly completed Leach Amp. Sounds really wonderful. BTW, if you're ripping these CDs yourself I highly recommend using FLAC instead of MP3, it's lossless. You can use it in conjunction with EAC.

[Sheesh]

Nice! Its good to hear another positive review of the receiver. I can't wait to pick it up.

DIY Amps?? I'm kinda jealous. As you can my electrical background is somewhat limited. Maybe a couple years down the road when I get a bigger, better room for a dedicated home theater.

How do you like the Dayton HT speakers you use as surrounds? How did you choose the Dayton HT design vs Dayton budget 2-waydesign? I have not heard either, but from the reviews I feel like the silk tweeter would be more to my liking. Is the titanium dome slightly bright?

I probably should switch to FLAC. I personally haven't ripped anything in several months. I'm kinda stuck with most of my 9000 mp3's, most of which I would not take the time to rerip(or I no longer own them). Also, the mp3's are a lot easier to share with all my iPod toting friends. I didn't see an iPod plugin or anything on the FLAC homepage. Besides when I really want to listen to music I usually put in actual CD's in the old five disc changer. I really like shuffling thru 5 discs at a time, about a perfect variety for me. Anything I truly "like" I buy the CD anyways, packaging and all. The mp3's are set to shuffle for background noise. Also, the mp3's help me remember what I actually do and don't like. Contrary to music industry belief I have bought many full CD's from a mp3 given to me or downloaded. I hate the current state of the music industry.

Thanks again mOtion!

[Hybrid fourdoor]

I think are you referring to like during speech, the S's get distorted sounding?? I have the same problem on some cable channels...like TLC. I think its the level is too high and the signal clips a little. I don't know, might want to see if maybe your front level has been adjusted or something by accident. My H/K Sig 2.0 has a levels adjustement for each input...and if you go too high, it will clip.

[wigginjs]

As I'm sure you can tell the Dayton Home Theater speakers and the Dayton Budget are pretty similar. I chose the Home Theater design because it used a sealed enclosure and that made for a more simple construction, but the Budget ones seem like a good design as well. The titanium domes are a bit bright, you can pick it up pretty easily doing tests, but it's not noticable in my system because they are used as surround speakers.