Sherbourn PA 7-350 - Specs and AP data

[bolle]

Hello Keith,

I have 2 questions regarding the amp named above:

1. The 7-350 is said to have 29dB gain on the product page but the AP data and also tests on the web show 33dB. What is correct?

2. Some of the AP data at 4 Ohm is very bad, especially the THD vs. frequency on the last page. (http://cdn.shopify.com/s/files/1/0172/4516/t/3/assets/7-350_4_ohm.pdf?853) It is much worse than every other amp for which you published AP data. Is this measurement really true or was there a problem / failure with the measurement itself?

Thank you in advance!

Bolle / Fabian

[bolle]

Hello, any Keith out there ready to help me out?

[garbulky]

Jeez that amp is putting out 3850 kilowatts of total power all channels driven at 4 ohms. That's insane - for a thousand bucks sale price at that.

[bolle]

Aug 12, 2013 7:04:42 GMT -5 garbulky said:

Jeez that amp is putting out 3850 kilowatts of total power all channels driven at 4 ohms. That's insane - for a thousand bucks sale price at that.

And in which way does this answer my question? The sale price also has absolutely nothing to do with this. Btw. where do you get it that this THD measurement was made at full power? I don´t see this information in the document I linked to.

Really no offense meant, but please stay off if you don´t have to contribute anything regarding my questions.

Any other Emotiva amp, where those measurements were made, measures much better. So it is completely legitimate in my opinion to ask for clarification if this - perhaps - was a faulty measurement. The question regarding 29 vs. 34dB gain did also arise for a few times already on the boards. I think an official answer would be great and bring clarity.

PS: For example look at the THD over frequency measurement of the XPA-5 Gen 2 at 4 ohm (http://emotiva.com/resources/media/xpa5/xpa5_gen2_4ohm.pdf). A whole different world, so I give Emotiva the benefit of doubt, that surely something with the PA 7-350 measurement wasn´t right?

[garbulky]

Aug 12, 2013 7:47:55 GMT -5 bolle said:

Aug 12, 2013 7:04:42 GMT -5 garbulky said:

Jeez that amp is putting out 3850 kilowatts of total power all channels driven at 4 ohms. That's insane - for a thousand bucks sale price at that.

And in which way does this answer my question?

I wasn't trying to as I cannot do so.

The sale price also has absolutely nothing to do with this. Btw. where do you get it that this THD measurement was made at full power?

The THD measurement stated that it was made at rated power on page 4.

I don´t see this information in the document I linked to.

Really no offense meant, but please stay off if you don´t have to contribute anything regarding my questions.

Any other Emotiva amp, where those measurements were made, measures much better. So it is completely legitimate in my opinion to ask for clarification if this - perhaps - was a faulty measurement. The question regarding 29 vs. 34dB gain did also arise for a few times already on the boards. I think an official answer would be great and bring clarity.

PS: For example look at the THD over frequency measurement of the XPA-5 Gen 2 at 4 ohm (http://emotiva.com/resources/media/xpa5/xpa5_gen2_4ohm.pdf). A whole different world, so I give Emotiva the benefit of doubt, that surely something with the PA 7-350 measurement wasn´t right?

I think your concerns and questions are valid. I wasn't trying to invalidate your question in anyway. My comment had no hidden subtext or put down. I was just excited. Good luck with finding an answer.

[mgbpuff]

Yep, you are right - the 7-350 doesn't have THD+N numbers that the XPR (or even the XPA has). If I were you, I would not buy this POS! (I however am NOT you and I bought one) - it's my freakin HT amp, not my 2 channel/hi res/expensive speaker system. It will handle the explosive movie sounds better than anything I've ever had in my HT system! I hope to get it going today when my 1" spaced double banana jacks arrive. I'll be enjoying the realism of the invasion in Private Ryan and I will later see if my girlfriend can detect the 0.1%THD+N (horrible figure ain't it) in her chick films. Worst (best ) that could happen would be fewer chick films being watched!

[creimes]

lol exactly, worrying about specs that are produced at full power is kinda funny, personally I don't even use half the power my XPA-2 can produce so go buy a poorly made under rated amp where they give the results of THD at 1/4 of it's rated power into 1 channel....hahahahaha

To answer your question of the gain, it is indeed 29db, and man no need to be so hasty/rude to other members here, your questions are valid but no need to come down on someone when they are just sharing their joy in what an insane deal that product is/was.

peace out

[bolle]

I am not hasty or rude in my opinion, I am just precise. There are many other threads where joy about a great deal got expressed / was expressed. But this section of the board is named "Ask Keith" for a reason, and there is also a reason I asked this question here and not in the general amplifier section - because I like a thorough and valid answer.

I regard it as rather rude to hijack my thread and turn it into something which it wasn´t intended to be from the start. It´s ok to be joyful and to share that - but do it where it is appropriate. I am also glad that I got lucky and such a great deal on a great product - but that´s not what this thread is about. In fact this is about a product, which I think being pictured worse than it really is in one measurement.

garbulky: Thank you for your kind answer, I think you understand what I meant. I didn´t connect the data on page 4 with the measurement on the last page, because Emotiva gives different data for the different measurements in their AP diagrams. So in my opinion you can´t be sure how the data on the last page was measured.

mgbpuff: You obviously didn´t read my posts and also even didn´t look into the AP data I linked to. Otherwise you wouldn´t talk about 0,1% THD - it is in fact up to 5% THD in the measurement I linked to. As a retired electrical engineer you find 5% THD acceptable? This is what I meant as "a whole different world". I also don´t get it why people like you can´t live with another person to have another opinion. Of course you don´t have to agree with the way I interprete the data, but you also don´t have to make sarcastic / ironic comments or to make fun of me.

Btw. sorry but I don´t have the money for different systems for movies and SQ / music - so in my case both systems are identical. Yes I bought a 7-350 and I am sure I will enjoy it, but that measurement caught my attention and looks fishy to me. This wouldn´t be the first faulty measurement, there where more in the past which Emotiva corrected. Also the 7-350 is based in large parts on the XPR-5 - so if there is a large delta between their perfomances, I am interested why.

creimes: It is you who is being rude. I am laughing at nobody, I am not making fun of anyone - I just have a valid question, even give Emotiva the benefit of doubt regarding the one measurement mentioned. All you are doing is giving me ironic advice and telling me that in your opinion my question is nonsense - why? I didn´t insult you - I just have a different opinion and don´t get it why you have a problem with this.

Btw. perhaps some of my perceived rudeness stems from me being not a native english speakers - so again sorry if I appear rude. I just try to be precise and logical - and get an answer from Keith (just repeating if perhaps someone forgot this one the way ).

[creimes]

creimes: It is you who is being rude. I am laughing at nobody, I am not making fun of anyone - I just have a valid question, even give Emotiva the benefit of doubt regarding the one measurement mentioned. All you are doing is giving me ironic advice and telling me that in your opinion my question is nonsense - why? I didn´t insult you - I just have a different opinion and don´t get it why you have a problem with this.

Not laughing at you or anyone else for that matter, I am laughing at the poorly rated specs that some companies advertise their products at and like I said your questions are valid and that is why I answered your gain question and your English is very good. I for one wouldn't worry too much about the specs, they can be wrong and I find too many worry about little details insted of just listening and enjoying the music/movies.

Take Care,
Chad

[bolle]

Hey Chad,

thanks for your answer - now I get what you meant. I agree, the 7-350 will probably sound great - that measurement just got my attention and I am a curious guy.

I agree with you, there are a lot of "blenders" on the market.

Thanks for the 29dB answer!

Take care 2,

Fabian

[deltadube]

we better call in the FBI this thread has been hijacked across international lines..

hey if your worried about thd get and xpr 5 and xpr 2 ..

cheers

[bolle]

Hi,

no I am not really worried - the one (and really only this one) measurement I am talking about is just so very different / worse than any other measurements of this and other Emotiva amps, that it caught my attention.

Hi-five... ehm ...-jack

Fabian

[mgbpuff]

Aug 12, 2013 9:23:33 GMT -5 bolle said:

I am not hasty or rude in my opinion, I am just precise. There are many other threads where joy about a great deal got expressed / was expressed. But this section of the board is named "Ask Keith" for a reason, and there is also a reason I asked this question here and not in the general amplifier section - because I like a thorough and valid answer.

I regard it as rather rude to hijack my thread and turn it into something which it wasn´t intended to be from the start. It´s ok to be joyful and to share that - but do it where it is appropriate. I am also glad that I got lucky and such a great deal on a great product - but that´s not what this thread is about. In fact this is about a product, which I think being pictured worse than it really is in one measurement.

garbulky: Thank you for your kind answer, I think you understand what I meant. I didn´t connect the data on page 4 with the measurement on the last page, because Emotiva gives different data for the different measurements in their AP diagrams. So in my opinion you can´t be sure how the data on the last page was measured.

mgbpuff: You obviously didn´t read my posts and also even didn´t look into the AP data I linked to. Otherwise you wouldn´t talk about 0,1% THD - it is in fact up to 5% THD in the measurement I linked to. As a retired electrical engineer you find 5% THD acceptable? This is what I meant as "a whole different world". I also don´t get it why people like you can´t live with another person to have another opinion. Of course you don´t have to agree with the way I interprete the data, but you also don´t have to make sarcastic / ironic comments or to make fun of me.

Btw. sorry but I don´t have the money for different systems for movies and SQ / music - so in my case both systems are identical. Yes I bought a 7-350 and I am sure I will enjoy it, but that measurement caught my attention and looks fishy to me. This wouldn´t be the first faulty measurement, there where more in the past which Emotiva corrected. Also the 7-350 is based in large parts on the XPR-5 - so if there is a large delta between their perfomances, I am interested why.

creimes: It is you who is being rude. I am laughing at nobody, I am not making fun of anyone - I just have a valid question, even give Emotiva the benefit of doubt regarding the one measurement mentioned. All you are doing is giving me ironic advice and telling me that in your opinion my question is nonsense - why? I didn´t insult you - I just have a different opinion and don´t get it why you have a problem with this.

Btw. perhaps some of my perceived rudeness stems from me being not a native english speakers - so again sorry if I appear rude. I just try to be precise and logical - and get an answer from Keith (just repeating if perhaps someone forgot this one the way ).

1) You should have sent a private message to Keith, then, because I do not see a single thread under 'Ask Keith' where the dialog is strictly between just Keith and the OP.

2)The 1khz THD+N for both amplifiers is very similar between 1 watt and rated watts with the XPR being only slightly better.

3) The curve that shows THD+N vs frequency is unique for the 7-350 in that it shows THD+N as a function of frequency all the way down to 20HZ. True, the THD+N at 20hz is aout 3.5%. But nowhere does the XPR have data on THD+N at that low a frequency - it is only given at 1khz. THE FREAKIN NUMBERS ARE NOT COMPARABLE.

4) Please do not try to debase my engineering credentials - that is offensive and not something you are in a position to make judgement.

[bolle]

I didn´t (mean to) debase your engineering credentials. Sorry if it felt that way - I simply meant that especially regarding your background, I wonder that you find the figures I linked to acceptable. I don´t know you and your work so of course saying anything (good or bad) about your skills would be, well, just stupid.

To 3) - I know that you can´t compare different measurements. I got a basic degree in electrical engineering myself btw. If you look at the AP data of the XPA-5 Gen 2 or the XPA-3 there is also a function of THD / frequency. Of course those are different amps, but the difference is so great, that it looks fishy to me. Of course there was a difference to be expected - but of this magnitude? Don´t you agree with me that this looks more like a faulty measurement than the real data of the amp? Why should the 7-350 be the only amp so far out of line? Of course it is also a whole lot more difficult to measure such a powerhouse like the 7-350 (getting a stable power supply e.g.)...

Best regards

Fabian

PS: Nice systems in your sig (links)!

[KeithL]

Hi, guys,

Sorry to not be around.... I see nobody can live without me

The published AP reports were done on a late prototype - and the gain on them is wrong.
I am told that the gain on production PA 7-350's is indeed 29 dB (although I fail to see why it matters especially).

The THD+N vs Frequency graph is at full power, and is indeed correct.
And, yes, at low frequencies - and at 4 ohms - where the current drain is worst - it is higher than most of our other amps.

As has been mentioned, however, we ARE talking about almost 4 KW here, which is NOT something you will likely ever use in real life.
In fact, with real music, the most you will ever be using ON AVERAGE is about 10% of maximum peak power - which is way lower.
(And maximum peak power on the 7-350 into 4 ohms is about 6 KW at a guess - but don't quote me on that - so we're talking about 600 watts or so average....)

[mgbpuff]

O.K. I was looking at the specs for the XPR-5 which does not have a THD+N vs freq plot. The XPA-5 gen 2, as you say does have this plot, and yes you are correct that it is quite a bit better. Having said that, most manufactures only list THD+N at 1khz and usually with only one channel driven. Emotiva/Sherbourn give much more data than that, but perhaps they should standardize their data offerings so equipment can be compared. I'm not concerned about the difference, because there is not enough published information about THD+N across the frequency spectrum for me to know if this is unusual or not.

I am sure Keith will comment when he sees this and has the time.

Peace!

Ok I see Keith commented as I was typing!

[bolle]

Thanks both of you!

Keith, do I understand you correct, that the THD this high should only occur when all channels are stressed? So in stereo use even when stressing 2 channels with a 4 ohm load each, THD shouldn´t get so high?

Thanks again and yes - peace!

[creimes]

One thing nice about Emotiva's test results is they are at full power and like Keith has said, nobody will ever be driving the amp that hard and if they are they must be running it on an outdoor concert or have no speakers/eardrums left lol.

Chad