Hello Everyone,
I currently have a diy OB build (cheapy Peerless 3" full ranger, 12" Peerless woofer helper, bi-amped with SS) that I enjoy very much, but want to take the full range driver to the next level.
Current situation/usage is as follows:
1) Room is a 10' x 14' upstairs loft area, vaulted ceiling (8' going to 12'), mostly open wall on the shorter walls (forcing speakers to the long wall, but this seems to work very well with OB). Love this setup as there is no head in vise listening required, and it fills the entire condo with listenable music. REW measures good to.
2) Usage is mostly 60dB@1m background music, occasionally "cranked" to 70-75dB (about 25% HT use at same base level, but of course need added headroom for HT).
3) Music of choice is mostly classical, jazz, alternative/classic rock, 80's new wave. Sources for background music are 192k internet stations (sometimes 128k, NOTHING below that), more serious listening is FLAC rips off CD and LP, HT is TrueHD/Master DTS etc.
4) I am not an "audiophile" or basshead per se, just looking for great sound, with a balance of enough resolution to make classical music shine, and 192k internet rock radio non-fatiguing.
5) Build will eventually become a full HT using same driver (i.e. center and surrounds).
My research has led me to Mark Audio produced drivers; specifically Alpair 7.3, CHR-70, CHP-70, CHBW-70, or EL70. I am worried about the Alpair 7.3's being too "true" to the source and causing fatigue on internet radio sources, and on the other something like the CHP-70 (with its high end rolloff) making good sources "dull".
I realize this in an exercise in compromise, just trying to home in on the best compromise. These new drivers will be driven by a new DIY tube build ~500USD budget, all recommendations welcomed. I am currently thinking of a Dynaco ST-35 clone build with EFB mod (Dave's Lab), seems high enough caliber for these drivers, with enough power to experiment with other speaker types in the future.
I currently have a diy OB build (cheapy Peerless 3" full ranger, 12" Peerless woofer helper, bi-amped with SS) that I enjoy very much, but want to take the full range driver to the next level.
Current situation/usage is as follows:
1) Room is a 10' x 14' upstairs loft area, vaulted ceiling (8' going to 12'), mostly open wall on the shorter walls (forcing speakers to the long wall, but this seems to work very well with OB). Love this setup as there is no head in vise listening required, and it fills the entire condo with listenable music. REW measures good to.
2) Usage is mostly 60dB@1m background music, occasionally "cranked" to 70-75dB (about 25% HT use at same base level, but of course need added headroom for HT).
3) Music of choice is mostly classical, jazz, alternative/classic rock, 80's new wave. Sources for background music are 192k internet stations (sometimes 128k, NOTHING below that), more serious listening is FLAC rips off CD and LP, HT is TrueHD/Master DTS etc.
4) I am not an "audiophile" or basshead per se, just looking for great sound, with a balance of enough resolution to make classical music shine, and 192k internet rock radio non-fatiguing.
5) Build will eventually become a full HT using same driver (i.e. center and surrounds).
My research has led me to Mark Audio produced drivers; specifically Alpair 7.3, CHR-70, CHP-70, CHBW-70, or EL70. I am worried about the Alpair 7.3's being too "true" to the source and causing fatigue on internet radio sources, and on the other something like the CHP-70 (with its high end rolloff) making good sources "dull".
I realize this in an exercise in compromise, just trying to home in on the best compromise. These new drivers will be driven by a new DIY tube build ~500USD budget, all recommendations welcomed. I am currently thinking of a Dynaco ST-35 clone build with EFB mod (Dave's Lab), seems high enough caliber for these drivers, with enough power to experiment with other speaker types in the future.
Hi Rv
Looking at your situation (well described 1 to 5), from my perspective in terms of driver design, you're likely moving into CHR-70 territory. The original design objective of the CHR was to be an all-round Full-Ranger at an affordable price. The latest Gen. 3 model retains this original concept while extending performance. Many CHR's serve duel stereo audio and HT purposes, used in paired box designs, or with woofs and subs where more low output is desired.
I'm thinking mostly from the "technical" perspective re your intended set-up. Its largely how I thought CHR's might be used in these sorts of applications. In my studio, I use Mac I-Tunes radio (ambient, jazz and classic music mainly) via an Airport feeding a vintage Sony Mofset TAF 333 EX amp to CHR's in BR boxes. This is my studio's general every-day set-up. Looking at the Dave's Lab link, a mod Dynaco ST could be a nice amp/driver combination.
Thanks
Mark.
Last edited:
Another nice contender in the same general weight class as the Dyna ST35 would be George Anderson (Tubelab) Simplepushpull. I built mine with EL84s and come recycled vintage Scott output iron. Running in pentode mode( the OPT had no UL taps) it has more than adequate power for Alpair 7s or dual EL70s per side.
My upstairs system is 2 channel music only, sourced by MBP>Airtunes>AEX toslink>Citypulse DAC>EL84P/P>dual EL70s. Occasionally I'll bypass the Airtunes and direct connect optical out from MB - big difference of course, but for non-critical listening the easy way is fine.
I also have a variant of Eli Duttman/Jim McShane "El Cheapo" - with EL84 as well - this time in triode/no feedback. It could be argued that it has an edge over the pentode amp in terms of that 3-D (pseudo) triode cream as Harvey would have described it, but with drivers like any of the Mark Audio Alpairs (or the EL70 second cousin), it's been my listening experience that the more power the better.
The downstairs system is a Denon HT receiver and 5.1 of Alpair7(.1), dual corner mounted woofers, and Alpair6M surrounds. When streaming music from Airtunes or playing the FM radio, the Alpairs are far less forgiving of the combination of source quality and the processing circuitry in the receiver. This is a less than natural system for serious music only - but of course for HT/cinema when the bulk of cerebral processing is engaged in the visual, and since much of the sound engineering is exaggerated for a larger than life perspective for which we voluntarily suspend our disbelief, the shortcomings of these particular electronics are moot.
This is one of those rigs with a not particularly intuitive control function - i.e. if there is a simple one-button bypass function, it's buried deep in the instruction manual. When I play direct from a CD player ( Jolida 603)>TubelabPP> Alpair7 Pensils, the system is transformed into something very musical.
In other words, the Alpairs have more than enough resolution to reveal the qualities of upstream components - a double edge sword, that.
My upstairs system is 2 channel music only, sourced by MBP>Airtunes>AEX toslink>Citypulse DAC>EL84P/P>dual EL70s. Occasionally I'll bypass the Airtunes and direct connect optical out from MB - big difference of course, but for non-critical listening the easy way is fine.
I also have a variant of Eli Duttman/Jim McShane "El Cheapo" - with EL84 as well - this time in triode/no feedback. It could be argued that it has an edge over the pentode amp in terms of that 3-D (pseudo) triode cream as Harvey would have described it, but with drivers like any of the Mark Audio Alpairs (or the EL70 second cousin), it's been my listening experience that the more power the better.
The downstairs system is a Denon HT receiver and 5.1 of Alpair7(.1), dual corner mounted woofers, and Alpair6M surrounds. When streaming music from Airtunes or playing the FM radio, the Alpairs are far less forgiving of the combination of source quality and the processing circuitry in the receiver. This is a less than natural system for serious music only - but of course for HT/cinema when the bulk of cerebral processing is engaged in the visual, and since much of the sound engineering is exaggerated for a larger than life perspective for which we voluntarily suspend our disbelief, the shortcomings of these particular electronics are moot.
This is one of those rigs with a not particularly intuitive control function - i.e. if there is a simple one-button bypass function, it's buried deep in the instruction manual. When I play direct from a CD player ( Jolida 603)>TubelabPP> Alpair7 Pensils, the system is transformed into something very musical.
In other words, the Alpairs have more than enough resolution to reveal the qualities of upstream components - a double edge sword, that.
Thank you Dave and Mark for your informative replies, very helpful and much information to ponder. Both of you do so much for the DIY community.
Okay need to look at the EL70 and CHR-70. How to choose between paper or metal
?
Just a more detailed check if you please, want to make sure this has a chance of working:
1) Proposed setup is bi-amped LCR speakers, EL70/CHR on top in OB (left and right driven by tubes 17W per channel, center channel 30W SS).
2) Dipole 12" woofer helpers on the bottom, crossed at ~150-200Hz driven by 100W SS per channel.
3) Sealed rear EL70/CHR single driver surrounds.
I hope this will get me close to a budget friendly setup, that is good for stereo music firstly, some HT secondly. No subwoofers due to cool (and quiet!) neighbors in the condo next door. Want to stick to bipole/dipole mains for the same reason (current OB's are placed perpendicular to neighboring wall, and measured levels are down 5-6dB by the time they reach there). Gotta' love North American paper mache housing 🙄.
Okay need to look at the EL70 and CHR-70. How to choose between paper or metal
?Just a more detailed check if you please, want to make sure this has a chance of working:
1) Proposed setup is bi-amped LCR speakers, EL70/CHR on top in OB (left and right driven by tubes 17W per channel, center channel 30W SS).
2) Dipole 12" woofer helpers on the bottom, crossed at ~150-200Hz driven by 100W SS per channel.
3) Sealed rear EL70/CHR single driver surrounds.
I hope this will get me close to a budget friendly setup, that is good for stereo music firstly, some HT secondly. No subwoofers due to cool (and quiet!) neighbors in the condo next door. Want to stick to bipole/dipole mains for the same reason (current OB's are placed perpendicular to neighboring wall, and measured levels are down 5-6dB by the time they reach there). Gotta' love North American paper mache housing 🙄.
Thanks chrisb also, I got your post after my last response. I will take a look at the tubelab and el cheapo as well!
hmm, metal vs paper? between the two named ( CHR / EL) , I'd take the paper.
Keep in mind that in properly processed cinema mode, the center is predominant channel of the front row, and I'm not so sure that you wouldn't hear some differences in between the tube and SS amps.
As my own system is one of the 7.1 receivers with 5 channel amps and pre-outs for LFE and either front height or rear-surrounds, but not for the "main 5", I've not had opportunity to test the thesis, but suspect that the surrounds / height effect channels would be less critical of matching amps.
That all said, it sounds like you've got an interesting rig planned
Keep in mind that in properly processed cinema mode, the center is predominant channel of the front row, and I'm not so sure that you wouldn't hear some differences in between the tube and SS amps.
As my own system is one of the 7.1 receivers with 5 channel amps and pre-outs for LFE and either front height or rear-surrounds, but not for the "main 5", I've not had opportunity to test the thesis, but suspect that the surrounds / height effect channels would be less critical of matching amps.
That all said, it sounds like you've got an interesting rig planned
Hi,
I have a pair of CHP-70, for my ears they are superb I think these are going to be my favorite full ranges. The mid band is to die for, percussion instruments sound so real i'm well made up with them just what i'm looking for not heard anyother MA drivers so just my pennies worth.
Ta
I have a pair of CHP-70, for my ears they are superb I think these are going to be my favorite full ranges. The mid band is to die for, percussion instruments sound so real i'm well made up with them just what i'm looking for not heard anyother MA drivers so just my pennies worth.
Ta
My set up is similar to yours (Radio Shack 5 1/4" Foster OEM with Goldwood 10" helper). My plan for amplification is SE UL 6LU8 (Kegger's "$250 amp" configuration) for the FR With the same tubes PP for the woofers using tube preamp with custom crossover.
The little 4" MA drivers should do nicely I think for the FR part and probably be much less shouty than my rat shacks. I would think that 200Hz or so would be the right crossover especially if using those smaller drivers. You could go lower with larger FRs but with OB I think it makes more sense to cross higher and let the helpers do the heavy lifting.
The little 4" MA drivers should do nicely I think for the FR part and probably be much less shouty than my rat shacks. I would think that 200Hz or so would be the right crossover especially if using those smaller drivers. You could go lower with larger FRs but with OB I think it makes more sense to cross higher and let the helpers do the heavy lifting.
Last edited:
Good info, keep it coming.
chrisb: The Simple PP looks like a great solution for me, I am pursuing it further. Regarding the center amp, it will be interesting to see if I can notice differences or not. I am hoping that by using an identical driver and speaker config they will be minimized. If not, well another amp build is warranted 😀.
chrisb: The Simple PP looks like a great solution for me, I am pursuing it further. Regarding the center amp, it will be interesting to see if I can notice differences or not. I am hoping that by using an identical driver and speaker config they will be minimized. If not, well another amp build is warranted 😀.
Has anyone calculated or actually measured the lower end of comfort zone for the smaller MA drivers when used in such an OB configuration? I'd imagine it would simplify things if they could safely reach down into the 100-120 range that is in the default range of XO points of most current HT receivers.
My system was set up by allocating all speakers as small, which enabled option to selection of independent XO for each channel, which is then followed by rotating a test tone and measuring with included mic. This sure makes life simple- the whole procedure takes less than 10 minutes, and even flags when any of the speakers are out of phase. The XO frequencies ranged in 10s from 80 to 120 - I settled on a combination of 100/110/120. Higher for the center as it's a much smaller enclosure than the Pensils, and the surrounds are pretty teeny sealed boxes.
mashaffer: I googled Kegger $250 amp and found the thread over at audiokarma (all 65 pages!!!). Haven't been able to dig the final schematic/specs out of there yet, how many watts is it? Do you have info on the PP version you plan to use (I assume it will be ~double watts of the SE version)?
General question to all: How many watts do you think these 4" drivers will need, supporting only ~150Hz on up, in my application (see first post)? I keep thinking I will need 15+ watts/ch given the ~85dB sensitivity, but could be way off base. If an 8W SET will do it I would certainly go that way instead!
Sorry for the noob questions, this is my first foray into DIY tubes. I am used to having overkill SS watts on hand, and have to gain a new mindset
.
General question to all: How many watts do you think these 4" drivers will need, supporting only ~150Hz on up, in my application (see first post)? I keep thinking I will need 15+ watts/ch given the ~85dB sensitivity, but could be way off base. If an 8W SET will do it I would certainly go that way instead!
Sorry for the noob questions, this is my first foray into DIY tubes. I am used to having overkill SS watts on hand, and have to gain a new mindset
.I can't speak to the 4" drivers being discussed here, but my 3" FR low end response is as follows:
1) Roll off at ~100Hz (factory spec, I assume on infinite baffle)
2) Roll off at ~2kHz (in room open air, measured)
3) Roll of at ~500Hz (in room on 15" wide baffle, measured)
I expect the 4" drivers would behave similarly, as OB low end response seems predominantly controlled by baffle width (i.e. cancellation frequency). My current 12" Peerless woofer has flat response out to 1kHz, and is bi-amp crossed to the 3" at ~200Hz. I suspect the reason I have a flat response between the two drivers is my helper woofer has extended high end response, and I am using a shallow crossover (12dB/oct).
To sum up, I would guess if you crossed any lower than 200Hz (especially with low end drivers that can't make it up to 500+Hz), combined with higher order HT crossover slopes, would leave a big hole in response if used OB.
mashaffer: I googled Kegger $250 amp and found the thread over at audiokarma (all 65 pages!!!). Haven't been able to dig the final schematic/specs out of there yet, how many watts is it? Do you have info on the PP version you plan to use (I assume it will be ~double watts of the SE version)?
General question to all: How many watts do you think these 4" drivers will need, supporting only ~150Hz on up, in my application (see first post)? I keep thinking I will need 15+ watts/ch given the ~85dB sensitivity, but could be way off base. If an 8W SET will do it I would certainly go that way instead!
Sorry for the noob questions, this is my first foray into DIY tubes. I am used to having overkill SS watts on hand, and have to gain a new mindset
similar line of discussion here:
http://www.diyaudio.com/forums/full-range/197001-tube-t.html
A short answer to part of that might be - as Mark himself might attest - not all 8w SET/P are created equal. It's very easy to get quite spendy not only the valves themselves, but also on output iron and power supply components.
Without muddying the waters with the "tube watts are bigger / better / because" nonsense, during the past 12 yrs or so of my 45+ yr career in this hobby, I've enjoyed systems with mostly "full-range" drivers on power from 1.5W EL84SET to 75W surround receiver (I'm assuming some type of digital, but frankly don't care) .
I've owned systems in the past with speakers of much lower sensitivity ( Dahlquist DQ10, Spica SC50i, little KEF something or other) or complexity of loads ( Quad ESL57, Acoustat 1) than any of the MA drivers, and power as high as 100W SS (certainly not overkill but as much as could afford/justify at the time) . Even my first tube amp was a nominal 50W (Jolida 302 EL34 P/P UL), but every time I downsized the power levels and complexity of audio circuitry, there seemed to be an inverse appreciation to the music - what's that called... "less is more"? If it's placebo or self-hypnosis, or whatever, it worked for me.
As it happens the current 2 systems I use daily are Mark Audio drivers, and I find them both to come into their own with a tube amp of approx 12-15W - in this case Tubelab SimplePP EL84 pentode, but any reasonable candidate would suffice.
First off, appreciate everything in your post. And with the above quote, you are really hitting an itch that's been nagging at me for sometime.
When I got back into audio a couple of years back, out came the old Paradigm monitors hooked up to SS. On a whim I tried some Hawthorne OB's, and really liked something about the OB part. Tried boxed speakers again, which led me back to my current DIY OB's. Just really like something about OB what can I say. Anyways the current OB's bring complexity. Bi-amp means crossovers and lots of amps. OB bass (on narrow baffles anyways) needs EQ. More junk in the chain as you alluded to.
Part of me says just get a couple of Mark's drivers, put them in one of the many nice boxed designs available, on a nice small tube amp....and go from there. I can always use the drivers and go on with my OB venture if I don't care for it. Hmmmm need to think on this....thanks for some much needed eye opening
.Chris;
I haven't calculated anything but I have experimented with CHR-70 in sealed and ported using a KT-88 SE amplifier (about 8-10WPC) I found that in order to be safe a crossover of 100Hz was necessary if high level drums etc. were to be reproduced. Otherwise I felt that the excursion that I was getting was excessive for long term reliability unless the user was very careful.
On OB you won't have the protective cushion of air so I would recommend going to one of the larger Alpairs if you want to cross in the 100-120Hz range. Also unless your baffles are quite large you will probably get quite a bit of roll off below 200Hz anyway. The high Q woofer of course covers this for you as it has the cone area and displacement needed to overcome the baffle roll off.
You could post to Mark's forum here and get recommendations straight from him if you like. He is very helpful to us DIY'ers.
RVsixer;
This is the latest schematic I have.
As I recall the power output is in the 5 to 7 watt range. The KT-88 that I am using for the other project has somewhat higher maximum output but the preamp I used in testing would not drive it to full output. I figure that I was probably getting output in about the range the the 6LU8 should give and it was quite loud. If you end up crossing at 200 I am pretty sure that anything in the 5-10W range should give you plenty of umph for a normal sized room. Much beyond that would require either very expensive or push-pull.
One thing to keep in mind is that the general rules of thumb for power requirements are usually stated for full frequency reproduction. The vast majority of the power is in the bass. When you filter out most of the bass your power requirements drop substantially. If you put 7 watts of 1K sine wave into a CHR-70 I think you would risk inducing hemorrhage. 😀
As to the PP design for the helper, I haven't designed it yet but my plan is to use some cinemag input transformers that I have as input and phase splitter and then use the small signal triode section to drive the power pentode in either pentode or UL mode class AB. First inclination is UL with cathode bias as it is simpler and should have good overdrive characteristics. If I really need more power I might consider fixed bias pentode mode but I doubt that it will be necessary. In my case there will also be a sub-woofer so the helper really only has to handle 50Hz to 200Hz.
Given the conservative ratings on these tubes (they were used as sweep tubes so audio use is much less stressful on them) I suspect that 20 to 30WPC should be doable. Right now my helpers are being driven by a 35WPC sand amp and that is plenty so I think we will have enough output.
I haven't calculated anything but I have experimented with CHR-70 in sealed and ported using a KT-88 SE amplifier (about 8-10WPC) I found that in order to be safe a crossover of 100Hz was necessary if high level drums etc. were to be reproduced. Otherwise I felt that the excursion that I was getting was excessive for long term reliability unless the user was very careful.
On OB you won't have the protective cushion of air so I would recommend going to one of the larger Alpairs if you want to cross in the 100-120Hz range. Also unless your baffles are quite large you will probably get quite a bit of roll off below 200Hz anyway. The high Q woofer of course covers this for you as it has the cone area and displacement needed to overcome the baffle roll off.
You could post to Mark's forum here and get recommendations straight from him if you like. He is very helpful to us DIY'ers.
RVsixer;
This is the latest schematic I have.
As I recall the power output is in the 5 to 7 watt range. The KT-88 that I am using for the other project has somewhat higher maximum output but the preamp I used in testing would not drive it to full output. I figure that I was probably getting output in about the range the the 6LU8 should give and it was quite loud. If you end up crossing at 200 I am pretty sure that anything in the 5-10W range should give you plenty of umph for a normal sized room. Much beyond that would require either very expensive or push-pull.
One thing to keep in mind is that the general rules of thumb for power requirements are usually stated for full frequency reproduction. The vast majority of the power is in the bass. When you filter out most of the bass your power requirements drop substantially. If you put 7 watts of 1K sine wave into a CHR-70 I think you would risk inducing hemorrhage. 😀
As to the PP design for the helper, I haven't designed it yet but my plan is to use some cinemag input transformers that I have as input and phase splitter and then use the small signal triode section to drive the power pentode in either pentode or UL mode class AB. First inclination is UL with cathode bias as it is simpler and should have good overdrive characteristics. If I really need more power I might consider fixed bias pentode mode but I doubt that it will be necessary. In my case there will also be a sub-woofer so the helper really only has to handle 50Hz to 200Hz.
Given the conservative ratings on these tubes (they were used as sweep tubes so audio use is much less stressful on them) I suspect that 20 to 30WPC should be doable. Right now my helpers are being driven by a 35WPC sand amp and that is plenty so I think we will have enough output.
Attachments
I decided about 3 years ago that I would only build amps and preamps with DHTs - to me they were sufficiently better than indirectly heated tubes (and especially pentodes with feedback) not to bother with anything else. I went through experiments with 300b and 2a3 outputs driven by tubes like 26, 01A, 71A, 10Y and such. After long experiments finally settled on 26 preamp into 46 driver, all transformer coupled. Still deliberating between 300b SET and 2a3PP outputs.
Right now I have Alpair 10s which booted out Jordan JX92s. But I have four CHP-70 on the way to build a MicroTower. So very much work in progress. For the Alpair 10s looks like you need at least 8 watts in a smallish room. Will report on any developments.
I've been through stacked Quads, Apogees, big Vitavox horns and all kinds of things. In the end I got fed up with speakers that were so big you couldn't see out the French windows so I downsized. Contrary to most, I think the amplification has a huge effect, not just the speakers. At least it does with DHTs. As it stands you have to build all-DHT systems yourself - nothing commercial.
Andy
Right now I have Alpair 10s which booted out Jordan JX92s. But I have four CHP-70 on the way to build a MicroTower. So very much work in progress. For the Alpair 10s looks like you need at least 8 watts in a smallish room. Will report on any developments.
I've been through stacked Quads, Apogees, big Vitavox horns and all kinds of things. In the end I got fed up with speakers that were so big you couldn't see out the French windows so I downsized. Contrary to most, I think the amplification has a huge effect, not just the speakers. At least it does with DHTs. As it stands you have to build all-DHT systems yourself - nothing commercial.
Andy
The amp has been decided, I will be having a Simple PP as soon as George at Tubelab can kit some up.
Is there any danger in running either the CHR-70 or EL70 full range open baffle (any excursion issues, etc)? This would allow ditching the crossover, and just dialing in the woofer helper to match, in an effort to eliminate whatever possible in the audio reproduction chain.
Is there any danger in running either the CHR-70 or EL70 full range open baffle (any excursion issues, etc)? This would allow ditching the crossover, and just dialing in the woofer helper to match, in an effort to eliminate whatever possible in the audio reproduction chain.
Yes, there is danger of over excursion (see alpairs are not woofers thread in MA forum). I would at least put a series cap inline with the FR to provide some protection.
nice amp - as the OPT (vintage Scott LK48/222) in my own lack UL taps, I find the EL70s like the pentode mode with stock feedback value.
yes - as per Mike's reply below. there is another trick you can use when building a kit tube amp - install multiple line inputs and put a HP filter on one to eliminate the need for passive component at speaker output.
- Status
- Not open for further replies.